Extracellular polymeric substances (EPSs) play an essential role in the performance of biological wastewater treatment. It is necessary to understand the correlation between EPSs and the carbon sources and sludge-retention time (SRT) of the activated-sludge process to gain efficient operational strategies.

Polysaccharides (PSs) and proteins (PNs) were the main constituents in EPSs. The percentage of PSs and PNs in the loosely bound (LB-) EPSs and tightly bound (TB-) EPSs were 18%-90% and 18%-85%, respectively. The PS / PN ratios in the LB-EPS and TB-EPS were in the range of 0.38-2.50 and 0.30-2.34, respectively. The contents of LB-EPSs and TB-EPSs were both slightly higher in the sludge samples cultivated by starch than by glucose. Compared to the sludge samples grown in glucose, the content of PSs of the LB-EPS was higher than in other samples, whereas the content of PNs was lower in the LB-EPS from sludge flocs grown in starch than in glucose. PSs yield of TB-EPSs was almost equal in the two carbon sources, whereas PNs yield was slightly higher in TB-EPSs from samples cultured with glucose than with starch.

Laboratory studies were performed to evaluate the effect of carbon sources on EPSs production. The total contents of LB-EPSs and TB-EPSs were affected by the kinds of carbon sources. PS and PN in LB-EPSs and TB-EPSs were both dependent on carbon sources. In addition, cofocal laser scanning microscopy (CLSM) observations indicated microbial cells were cross-linked by EPS, forming a polymeric network with pores and channels.

The disposal of sewage sludge becomes an issue of particular concern due to its continuous increase quantity. In this study, sewage sludge derived carbon (SC) was employed as the support of iron oxide containing catalyst (FeSC). The catalysts were characterized in terms of inorganic elemental composition, XRD, SEM and TGA-FTIR. The catalytic activity of the catalyst was evaluated from the discoloration and mineralization of acid orange II (AOII) in the presence of H₂O₂ and visible light.

The FeSC catalyst that pyrolyzed at 800 °C for 2 h displayed the highest catalytic activity. Almost complete discoloration and 67 % mineralization of 100 mg/L AOII were achieved after 30 min adsorption and 60 min oxidation under visible light irradiation, by using 1.5 g/L catalyst, 15.0 mM H₂O₂ and initial pH 4.0. The prepared FeSC also exhibited very limited iron leaching (0.56 mg/L after 90 min reaction) and a high stability since the activity kept constant upon ten consecutive runs.

This study demonstrated the high activity and stability of the sewage sludge-derived carbon supported iron oxide catalyst in photo-Fenton-like reaction.

Ammonia (NH₃) was converted to dinitrogen gas (N₂) in cooperation between ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) with low amounts of nitrous oxide (N₂O) as the side-product in the completely autotrophic nitrogen removal over nitrite (CANON) process. Contributions of anaerobic ammonia oxidation (anammox) by AnAOB and nitrifer denitrification by AOB for nitrogen (N) removal and the characteristics of N₂O production were investigated comprehensively in this study.

AnAOB was the dominant contributor to autotrophic nitrogen removal, and the contributions from nitrifier denitrification were less than 13.55% of the N removal. Nitrite (NO₂^-) addition increased the N removal rate of CANON process under oxygen-limiting conditions; N₂O primarily produced from nitrifier denitrification by AOB was 0.41%-7.25% of the N removal, and there was a positive correlation between NO₂^- concentration and N₂O production. Under anaerobic conditions, 10mM methanol did not completely inhibit the activity of AnAOB, and N₂O production rate was significantly decreased with addition of methanol.

The contribution from nitrifier denitrification by AOB was less than 13.55% of the N removal, and AnAOB played an impotent role in N₂O production by providing hydroxylamine as an electron donor for AOB to reduce NO₂^- in CANON process.

This work analyzes the synthesis of H₂O₂ from dilute NaOH solutions under 0.1 MPa O₂ using a batch reactor with a three-dimensional rotating cylinder electrode. The centrifugal force produces a radial co-current flow of the gas and liquid phases. Thus, good mass transfer conditions are achieved and the O₂ reduced to H₂O₂ is easily replenished in the liquid phase.

Experiments with a glassy carbon rotating disc electrode identified 0.5 mol L^-1 NaOH at 30°C as suitable operating conditions. Galvanostatic experiments with three-dimensional rotating electrodes concluded that the best performance was obtained for a reticulated vitreous carbon structure of 100 ppi, at 40 mA cm^-2 of macrokinetic current density and 1000 rpm rotation speed. Long term experiments showed 79% current efficiency and 8.2 kWh kg^-1 specific energy consumption until 6 h of electrolysis, with 8.4 g L^-1 H₂O₂ concentration. However, the current efficiency decreases at higher electrolysis times and consequently the specific energy consumption is increased. Thus after 10 h electrolysis the concentrations were H₂O₂ 10.4 g L^-1 and NaOH 1.41 mol L^-1.

A three-dimensional rotating cylinder electrode with co-current oxygen and liquid flows inside the structure showed promising performance for H₂O₂ production.

Enantiopure epoxides and diols have attracted much attention as the important building blocks for the production of flavorings, agrochemicals and pharmaceutical products. Enantioselective hydrolysis reaction of rac-epoxide in a biphasic system using whole cell catalysts is one of the promising methods to obtain enantiopure compounds.

We carried out the kinetic resolution of racemic 1,2-epoxyhexane using whole cell biocatalyst in a hydrophobic solvent/buffer biphasic system and examined the effect of organic solvents and ionic liquids on the initial reaction rate of (R)-enantiomer, r_R0 and enantiomeric ratio, E. In the case of using hydrophobic hydrocarbons, r_R0 increased with the hydrophobicity of hydrocarbon (log P_O/W), and a linear correlation was observed between r_R0 and log P_O/W. On the other hand, there were no correlations between r_R0 and log P_O/W of ionic liquids. Moreover, effects on E were small in both solvents. However, the addition of 1-heptanol on dodecane was very effective at increasing E value. The kinetic data correlated well with the reaction kinetic model, considering the distribution between two liquid phases and competitive product inhibition.

The high enantiomeric ratio of (R)-diol (E>100) without significant decrease in the reactivity was accomplished by adding 1- heptanol in minute amounts to dodecane.

The limited output power is a great challenge for the practical application of sediment microbial fuel cell (SMFC). One of the effective strategies to obstacle this problem is to develop better-performed cathodes.

Polyaniline (PANI)-graphene nanosheets (GNS) modified cathode was fabricated and applied as the cathode of SMFC to improve its electricity generation capacity. PANI-GNS cathodes were fabricated through situ-polymerization of aniline in the solution containing homogeneously dispersed GNS. The mass ratio between aniline and GNS in the polymerized solution was the key factor for the property of the modified cathode and the optimal ratio value was 9:1. Because of the outstanding electrical conductivity of GNS, PANI-GNS cathode outperforms the blank and PANI cathodes. Furthermore, the PANI-GNS_0.1-SMFC exhibited the highest output voltage of 640 mV, increased by 5 times compared with that of the blank SMFC; whilst, the maximum power density was impressively improved from 0.85 mW/m² of blank-SMFC to 99 mW/m² of the optimal PANI-GNS_0.1-SMFC.

This study provides a simple electrode modifying method and the as-synthesized PANI-GNS cathode can dramatically promote the performance of SMFC.

This study explored the feasibility of a waste to resource strategy by using incineration ash of sewage/waste-water treatment sludge as part of raw materials for ceramic processing. Reactions between metal oxides (CuO, ZnO), common metal containing form in incineration ash, and kaolinite based ceramic raw materials (kaolinite, mullite) were observed. The metal incorporation behavior was determined using quantitative X-ray diffraction analysis.

The optimal sintering temperature for copper incorporation was 1000 °C, with CuAl₂O₄ phase dominating the system. For zinc incorporation, ZnAl₂O₄ and Zn₂SiO₄ formed in competition, with ZnAl₂O₄ found to predominate at temperatures higher than 1150 °C. To determine the preferred phases for long term metal stability, a prolonged toxicity characteristic leaching procedure was carried out to quantify metal leaching performance and explore the leaching behavior. Metal leaching following incorporation in spinel leachates was significantly lower than those in oxide and silicate leachates, and the surface leaching behavior was also analyzed for the consideration of long-term metal stability.

The overall results indicate that spinel formation is a preferred metal stabilization mechanism when incorporating sludge incineration ash into ceramic products and is also a key control step to safely implement this waste to resource strategy for a more sustainable engineering solution.

Membrane separation technologies seem to be the one of the best available techniques in order to fractionate protein hydrolysates containing bioactive peptides and obtain peptide fractions with increased functionality. The influence of the molecular weight cut-off (MWCO) of the membrane and its hydrophilic/hydrophobic characteristics on the fractionation of a β-lactoglobulin tryptic hydrolysate were studied in this research work in order to obtain more purified peptidic fractions.

The molecular weight of the solutes, their charge and, ultimately, their hydrophobicity influenced peptide transmission. As regards the composition of the active layer of the membrane, high permeate flux values were maintained throughout the pH working range (from pH 4.0 to pH 10.0) when an extremely hydrophilic membrane was employed, even in the presence of peptide aggregates at acidic pH values. In addition, the decrease in the MWCO of the membrane (from 5 kDa to 1 kDa) did not improve the selectivity of the fractionation process but, however, it supposed a significant decrease of the permeate flux through the membrane.

The low efficiency of the process in terms of peptide recovery and the poor separation observed between bioactive and non-bioactive peptides work against the use of extremely hydrophilic membranes in order to fractionate peptide hydrolysates.

Accidents at nuclear fuel cycle plants may lead to contamination of areas of land and water. Cheap and available sorbents including natural aluminosilicates can be used for rehabilitation and decontamination of large volumes of radioactively contaminated water, including drinking water, prevention of migration of radionuclides into ground and surface waters through the soil and returning contaminated soil to farming.

A comparative study of sorption properties of various natural and surface-modified aluminosilicates with respect to caesium is made. It is shown, that sorption features of surface-modified aluminosilicates for Cs were improved by 100–1000 times compared to respective natural aluminosilicates. It is shown, that surface modification of glauconite by a mixed nickel-potassium ferrocyanide phase allows it to considerably increase its specificity (cesium distribution coefficients (2.9 ± 0.8)·10³ mL g^-1 for natural and (4.5 ± 0.5)·10⁵ mL g^-1 for modified glauconite) as well as making it selective to caesium in the presence of other alkaline ions and also provides irreversible caesium sorption.

Due to improved features, modified aluminosilicates can be more successful than natural ones, used for rehabilitation of radioactive contaminated territories (including agriculture) and water areas, as well as for decontamination of liquid radioactive wastes and for creation of geochemical barriers in solid radioactive waste storage.

Expanded vermiculite is widely used in many fields, especially as ameliorant in agricultural field. Although it is known as cation-exchanger, in a search for a new cesium adsorbent for environmental conservation, the ion-exchange behaviour of cesium on vermiculite in various grain sizes was investigated. The adsorption of cesium from artificial seawater was also investigated.

The effect of the vermiculite grain size was clearly identified. Preferable gain size for general use was found to be 500 µm. The amount of adsorption was low in these artificial seawater samples, however, almost similar ion-exchange behaviour was observed in both of the pure water and artificial seawater samples.

Adjustment of grain size according to the end use makes unlimited availability for the application as an adsorbent of cesium. The results showed that vermiculite is a promising material for the recovery of cesium from contaminated seawater.

Several pretreatment methods at lab-scale have been developed to inactivate methane-producing and hydrogen-consuming microorganisms. The need to obtain a hydrogen-producing inoculum by a more practical method is still necessary. The objective of this study was to evaluate the adaptation of anaerobic granules to suppress the methanogenic activity for hydrogen production.

Preliminary tests in discontinuous operation indicated that methanogenic bacteria were hardly suppressed. The continuous adaptation of the granules, at pH of 4.5 and HRT of 5.5 h, produced hydrogen and successfully suppressed the methanogenic activity. It was observed an even distribution of β-polysaccharides and cells when the adapted granules were stained with fluorescent molecular tags. The reactor productivity was 71 ± 6 mL-H₂ L_reactor^-1 h^-1 with a yield of 2.6 ± 0.2 mol H₂/mol glucose.

Hydrogen was produced from methanogenic granules. The continuous strategy successfully suppressed the methanogenic activity of the seeded granules and the hydrogen production was stable. The high yield and even distribution of cells suggests that the continuous adaptation generated a more active biomass due to an improved mass transfer present in the process.

A wet scrubbing process with in-situ electro-generation of ferrate(VI) has been developed for removing odour from foul gas in wastewater treatment plants. In this process, methyl mercaptan (CH₃SH) in synthetic gas is removed through absorption and oxidation by contacting the gaseous stream with aqueous NaOH electrolyte that offers in-situ generation of ferrate(VI).

The process parameters including electrolyte concentration, applied current density, initial CH₃SH concentration, gas flow rate and gaseous CH₃SH compositions were investigated to conclude on the best operating conditions and design parameters for a scale-up design. Under all the experimental conditions, gaseous CH₃SH was completely removed by the wet scrubbing process at room temperature and atmospheric pressure. The process proved to be quite effective for dissolved CH₃S^- degradation under the optimum experimental condition at the NaOH concentration of 6 M, current density of 2.22 mA cm^-2 and CH₃SH loading below 30 g m^-3 h^-1. A very short contact time of 0.06 s between the gas and the liquid phases was achieved in this in-situ ferrate(VI) generation reactor.

This process is effective for CH₃SH control, and holds great promise for industrial applications due to its high efficiency, simplicity and stability.

The large Itaya zeolite deposit in Yonezawa, Japan produces good quality, natural zeolite. Its properties as an adsorbent and a functional carrier were assessed and the ion exchange characteristics examined. Natural zeolite has a useful high cation exchange capacity, but has a disadvantage in scattering of the powder. In this study a non-woven fabric containing zeolite was tested for the removal of cesium.

The XRD peak pattern confirmed that Itaya zeolite is mainly clinoptilolite and contains some mordenite. Ion exchange selectivity of the natural zeolite was Ag⁺ > Pb²⁺ > Cu²⁺ > Zn²⁺ > Cd²⁺ > Cr³⁺ > Ni²⁺ with almost 100% removal of Ag⁺ and Pb²⁺ ions.

The cation exchange capacity (CEC) of Itaya zeolite was 131 cmol kg^-1. Low concentrations of Cs⁺ were removed effectively from the solution with natural zeolite. Cesium ions were removed by ion exchange with potassium and sodium. Cs⁺ was desorbed from the zeolite with ammonium salt solutions. Elution of Cs⁺ was influenced by coordination ability of counter anions.

The satisfactory results were obtained by using zeolite-containing nonwoven fabric for the removal of cesium ions.

Developing the economical biological nitrogen and phosphorus removal technology with high efficiency has become the research emphasis in current sewage treatment area. In order to solve the problems within the anaerobic-anoxic-oxic (A²/O) process including the substrates competition and high energy consumption, microbial fuel cell (MFC) was embedded in the A²/O process to enhance the removal efficiencies of nitrogen and phosphorus, along with electricity production.

Three A²/O reactors, one of which was embedded with MFC, were set up, nitrogen and phosphorus removal efficiencies and the electricity generation were investigated. At the stage of stable operation, the chemical oxygen demand, total nitrogen and total phosphorus removal efficiencies of the MFC-A²/O reactor, compared with blank control, were increased by 15.9%, 9.3% and 1.4% on average, respectively. The average output power density of MFC was 14.3 ± 1.4 mW m^-3 and the internal resistance was 6000 Ω. Grey relational analysis was applied to study the most significant operational parameter of A²/O process affecting the electricity production of MFC.

This research proved that nitrogen and phosphorus removal efficiency could be obviously improved by embedding MFC in the A²/O process. And the MFC-A²/O reactor can generate electricity continuously.

With the rapid growth of the semiconductor and thin film transistor liquid crystal display manufacturing industries, large quantities of the potent greenhouse gas nitrogen trifluoride (NF₃) is in demand. But perfluorocarbons are very stable compounds because of their molecular structures. Therefore, in atmosphere, NF₃ is difficult to be oxidized by O₃, NO, NO₂, and OH radicals, except by excited oxygen atoms O(¹D) that can react with it to form NF₂ or other products. In this study the possible degradation process of NF₃ in the “controlled release of radicals” reactor is discussed.

Under the conditions of 5 mmHg partial pressure of NF₃ and 600 mmHg total pressure with the buffer gas of argon, NF₃ was photodegraded in an in situ reactor with a “controlled release of radicals” system. The results indicated that reductive double bonds and allyl radicals, slowly released from polyisoprene irradiated by a UV lamp emitting 185 and 253.7 nm of light, could contribute to the NF₃ degradation in the CRR system. The NF₃ degradation efficiency, significantly affected by O₂ and almost independent of N₂, reached 96% with a kinetic rate constant k ≈ 1.77 × 10^-4 s^-1 after 300 min of ultraviolet irradiation.

According to the experimental results, we found a potential way of continuous photoreduction of NF_3, since excited double bonds and allyl radicals are consequently released by irradiating the surface of the polymer matrix. The considerable degradation reaction constant of NF₃ and no fluoride byproducts in gas make it possible for industry application.

The effectiveness of xylanases on lignin removal from pulps differs widely depending on the enzyme family, the type of pulp and the bleaching sequence among other factors. Xylanases can also reduce the presence of undesirable hexenuronic acids in the papermaking fibers. We have evaluated the performance of non-commercial xylanases belonging to families GH10, GH30, GH30-CBM35 and GH11, and of the multicomponent xylanase from Paenibacillus barcinonensis on lignin and hexenuronic acids removal from sisal (Agave sisalana).

Sisal pulps were bleached by an XP sequence, where X denotes the enzyme treatment and P a hydrogen peroxide extraction stage. Kappa number, brightness, viscosity and hexenuronic acid content of samples were determined. Sugars released from sisal pulps, other non-wood fibres and also eucalyptus fibres, by the treatment with xylanases were also analysed. The best results were obtained with the GH10 xylanase and with crude supernatants of P. barcinonensis, which produced a lignin removal of 23% and a reduction of 25% in the hexenuronic acid content of sisal pulps without a significant loss of viscosity.

The release of sugars in the effluents from the X stage applied to sisal correlated with the effectiveness of the xylanases tested. The xylan content of wood and non-wood fibres, the type of xylan and its accessibility also presented an influence on the xylanase activity on pulps.

Amino acids are valuable intermediates in the biobased economy for the production of chemicals. Electro-membrane processes combined with enzymatic modification have been investigated as an alternative technology for the fractionation of a mixture of amino acids with almost identical charge behavior. Up to now, the modification and subsequent separation were performed in two separate reactors. An interesting approach is the integration of both unit operations into one single device using mixed matrix membranes (MMMs) as platform for enzymatic conversion.

MMMs containing the enzyme glutamic acid decarboxylase (GAD, EC 4.1.1.15) Relizyme EP403/S as carrier were prepared showing satisfactory mechanical stability and enzymatic activity for L-glutamic acid conversion into γ-aminobutyric acid (GABA). ED with integrated MMM for simultaneous enzymatic decarboxylation of L-glutamic acid to GABA (33% conversion) and further separation of L-aspartic acid and unconverted L-glutamic acid from GABA was successful leading to current efficiency of 40% and low energy consumption of 3 kWh kg^-1.

Together with the high mechanical stability obtained for the MMMs, this opens the route towards process intensification, combining enzymatic conversion and separation with electrodialysis in one integrated process for the successful isolation of amino acids for biorefinery applications.

The incorporation of 4HB units into P(3HB) improves the material application potentials as the copolymer show a wide range of physical properties ranging from crystalline plastic to elastic rubber depending on the copolymer composition. Thus, the prospects of synthesizing P(3HB-co-4HB) copolymer with various compositions of 4HB would increase its effectiveness as biomaterial.

The residual cell dry weight (RCDW) and PHA concentration obtained under optimized conditions viz. C/N ratio, 30, K₂HPO₄, 6.1 g/L, incubation period, 66 hours, temperature, 32 °C and volume-to-flask ratio, 47/250 ml increased from 2.9 g/L to 4.9 g/L and 4.2 g/L to 7.6 g/L, respectively. P(3HB-co-4HB) with varied M_n between 26 kDa and 270 kDa were successfully synthesized using combinations of oleic acid, 1,6-hexanediol and/or 1,4-butanediol. The tensile strength and Young's modulus of the copolymers varied between 2 MPa to 24 MPa and 13 MPa to 192 MPa, respectively. T_m and T_g decreased with increasing 4HB molar fractions from 170°C to 68°C and 2.5°C to −31°C, respectively.

Oleic acid and (NH₄)₂SO₄ was the best carbon and nitrogen source for PHA biosynthesis. P(3HB-co-4HB) copolymer with targeted 4HB molar fractions ranged from 0–65 mol% were synthesized using combinations of two or more carbon substrates by Cupriavidus sp. USMAA2-4 (DSM 19379) using mixture design.Cupriavidus sp.; P(3HB-co-4HB); Mixture design; copolymer; One-stage fermentation

Zeolite omega is used as a catalyst in various fields. Expensive tetramethylammonium cations are the conventional structure-directing agents for the synthesis of zeolite omega. In this work, glycerol was used as both solvent and structure-directing agent instead of expensive quaternary ammonium compounds. Zeolite omega has been obtained through conversion of magadiite in this glycerol-water system. The effects of various parameters such as reaction time, temperature, alkalinity and glycerol content were discussed.

Pure zeolite omega could be obtained at 120 °C for 10 d with the reactants molar composition of 14 SiO₂: Al₂O₃: 10 Na₂O: 169 H₂O: 200 glycerol. Water content plays an important role in the solvothermal conversion of magadiite to zeolite omega.

The zeolite omega obtained from this system is a rather pure phase free from impurities. A preferential location of the Al atoms in the six-membered rings of the gmelinites in zeolite omega was observed. A method including extraction and calcination was introduced to remove organic species by which highly ordered pore structure of zeolite was well retained. The present work develops a novel synthesis method for zeolite omega.

Biosynthesis of silver nanoparticles (AgNPs) is considered as a green method. Sunlight could induce the synthesis of AgNPs with bacteria and plant biomass, while animal and fungus biomass have not been investigated for synthesis of AgNPs under sunlight radiation.

Under the 80000 lx of sunlight intensity and 4 mg/mL of tryptone solution, the maximum AgNPs yield was obtained at 60 min, and the Ag⁺ (1 mM) conversion rate reached 98±2%. Transmission electron microscopy revealed that T-Ag (tryptone-mediated) were circular and oval, with an average diameter of 11.63±4.17 nm, and Y-Ag (yeast extract-mediated) displayed similar shape and size with T-Ag. X-ray diffraction confirmed that T-Ag and Y-Ag were in the form of nanocrystals. As-prepared AgNPs showed obvious antimicrobial activity against B. subtilis and E. coli. Capping with peptides helped to maintain colloidal stability of AgNPs. Without sunlight, AgNPs showed high stability at pH 7–11 due to high ζ-potential values, while the stability was destroyed at pH 4. Further exposure to sunlight for 48 h also resulted in sedimentation of AgNPs.

Sunlight could induce tryptone and yeast extract to synthesize AgNPs, and the AgNPs stability could be regulated by capping peptides, pH, and sunlight exposure.

Electricity production in single-anode/cathode MFCs fed with simulated synthesis gas (syngas) as the sole electron donor has been recently demonstrated. This study evaluated the ability of a multi-anode/cathode MFC fed with syngas to achieve improved volumetric efficiency at several operating temperatures and electrode arrangements.

A maximum power density of 33 m (normalized to the anodic compartment volume) and a Coulombic Efficiency (CE) of 43 % was achieved at an operating temperature of 37 °C. The MFC operation at 50 °C resulted in a much lower power density of 10 m and a CE of 15 %. The MFC power density was greatly impacted by the electrode arrangement and the highest power density was achieved in a three anode-two cathode (3A-2C) arrangement.

The multi-electrode design enhanced the performance of a syngas-fed MFC, which could have major economic and operational implications for designing large scale syngas-fed MFCs. The MFC performance at elevated temperatures was restricted by low microbial activity, implying that a thermophilic rather than a mesophilic inoculum might be required for successful operation under thermophilic conditions.

A large quantity of heavy metal contaminated wastewater sludge is produced during the treatment of the printed circuit board (PCB) manufacturing wastewater. The PCB wastewater sludge containing high concentrations of heavy metals, such as Cu and Zn, increases the potential for metal recycling. Although the bioleaching is indicated as a promising technology to remove metals from electronic scraps and waste PCBs, its application for metal recovery from PCB wastewater sludge is still very limited. The purpose of this study was to develop a thermophilic bioleaching process operated in a sequencing batch reactor (SBR) for recovering heavy metals from the PCB wastewater sludge.

The results show that an increase of sludge solid content from 0.5 to 5% (w/v) decreased the rate of pH reduction during the bioleaching process. It was also found that the efficiency and rate of metal solubilization decreased with increasing sludge solid content. At sludge solid content of 0.5% (w/v), after four repeated feed/decant cycles with 10 day per cycle (40 days) of the SBR operation, the maximum efficiencies of metal solubilization in the treated sludge were 65% and 100% for Cu and Zn, respectively.

The solubilization efficiency of heavy metals was lower in the SBR operation with a longer 20-day cycle time. Therefore, a shorter 10-day cycle time of SBR operation is preferable to the thermophilic bioleaching process of PCB wastewater sludge. In the treated sludge, the potential mobility and environmental risks of heavy metals were decreased significantly after the thermophilic bioleaching process.

Bisphenol A (BPA) and 4-n-nonylphenol (4-n-NP) present significant research interests due to their extensive use and toxicological properties. Batch experiments were conducted to investigate the sorption and degradation behavior of BPA and 4-n-NP using acclimated activated sludge either under anoxic condition in the presence of nitrate or under anaerobic condition in the absence of nitrate.

Sorption of BPA and 4-n-NP on sludge was a spontaneous physical and exothermic process; partitioning played a dominant role. The values of partitioning coefficients of BPA and 4-n-NP under different redox conditions follow the order of anaerobic > anoxic > aerobic. While BPA was degraded under both anaerobic and anoxic conditions, 4-n-NP was only degraded under anoxic condition. The degradation rate of BPA under anoxic condition is much greater than that under anaerobic condition, and they are much greater than the degradation rate of 4-n-NP under anoxic condition. Mixed liquor suspended solid and temperature influenced their sorption and degradation. The suitable COD/NO₃^--N ratio was 15 for both BPA or 4-n-NP elimination, and nitrate reduction.

Effective degradation of BPA and 4-n-NP under nitrate reducing condition provides an alternative removal method for refractory endocrine disrupting compounds in wastewater treatment plants.

Among LaAl_xNi_1-xO₃ series, the LaAl_0.2Ni_0.8O₃ had the highest catalytic activity, but suffered a slow deactivation with time-on-stream (TOS). It is observed that all samples presented similar activity at low reaction temperatures (500–600 °C), while at higher temperatures (600–850 °C) the prepared solid was more active and perovskite phase was transformed into Ni⁰ or La₂O₂CO₃. It is found that among the noble metal samples, La_0.4Rh_0.6Al_0.2Ni_0.8O₃ showed significant performance possessed the high surface area and surface oxygen concentration and the best low-temperature reducibility. For the Rh catalyst the CH₄ and CO₂ conversions were 89.1, 86.2%, which were the most resistant against coke deposition and showed very high stability without decrease in reforming and remained constant during the 3000 min TOS. The following order of activity was observed: La_0.4Rh_0.6Al_0.2Ni_0.8O₃ > La_0.4Ru_0.6Al_0.2Ni_0.8O₃ > LaAl_0.2Ni_0.8O₃> La_0.4Ir_0.6Al_0.2Ni_0.8O₃ ≥La_0.4Pt_0.6Al_0.2Ni_0.8O₃ > La_0.4Pd_0.6Al_0.2Ni_0.8O₃.

We believe that the high surface area, surface oxygen concentration and good low-temperature reducibility were responsible for the good catalytic performance of the La_0.4Rh_0.6Al_0.2Ni_0.8O₃ sample.

Whereas multi-species biofilm reactors are commonly used for the treatment of liquid and solid wastes, new strategies are progressively arising for the development of single species biofilm for the production of high-value metabolites. Technically, this new concept relies on the design of bioreactors able to promote biofilm formation and on the identification of the key physico-chemical parameters involved in biofilm formation.

An experimental setting comprising a liquid continuously recirculated on a metal structured packing has been used in order to promote Bacillus subtilis GA1 biofilm formation. The colonization of the packing has been visualized non-invasively by X-ray tomography. This analysis pointed out an uneven, conical, distribution of the biofilm inside the packing. Compared with a submerged culture carried out in a stirred tank reactor, significant modification of the lipopeptide profile has been observed in the biofilm reactor with a disappearance of fengycin and iturin fractions and an increase of the surfactin fraction. In addition, considering the biofilm reactor design, no foam formation has been observed during the culture.

The configuration of our biofilm reactor set-up allows for a higher surfactin production by comparison with a submerged culture while avoiding foam formation. Additionally, scale-up could be easily performed by increasing the number of packing elements.

In this study, membrane absorption and vacuum membrane distillation were integrated to effectively recover ammonia and water respectively from saline ammonia-containing wastewater discharged by metallurgical plants.

Ammonia was removed by membrane absorption with parallel hollow fiber membrane(HFM) module to decrease the ammonia content to below 5 mg L^-1. Then the wastewater was concentrated by vacuum membrane distillation with cross-flow HFM module to maximize fresh water recovery, while maintaining higher permeate flux levels. The Taguchi method was used for experiment designs and contributions of operating parameters were determined over the specified parameter ranges through variance analysis. Recovery of ammonia and fresh water reached 99.8% and 80% within 250 min and 160 min, respectively. Membrane fouling in membrane distillation process could be mitigated at lower concentrate rate in semi-batch running mode, while permeate flux was maintained at high levels for a longer time duration. Permeate flux could be greatly restored through the cleaning technique consisting of alkaline cleaning, acid picking, EDTA washing and drying. Permeate flux loss due to the irreversible membrane fouling was 0.7%.

The experimental results demonstrate the potential for resource utilization of saline ammonia-containing wastewater by combining membrane absorption and vacuum membrane distillation.

A major hurdle with algal biodiesel production has been the energy required to dry algal biomass prior to lipid extraction and/or conversion. Water interferes with the extraction and/or conversion of algal lipids to biodiesel. The focus of this study was to evaluate the efficiency of the in situ transesterification method for biodiesel recovery when processing algal biomass with varying amounts of moisture and to evaluate changes in efficiency as in situ transesterification reaction parameters were varied.

Results indicate moisture content affected biodiesel recovery. Specifically, algal biomass moisture contents above 20% by mass led to statistically significant reductions in biodiesel recovery. However, increasing the amount of catalyst and/or methanol in the reaction resulted in higher recoveries when using algal biomass containing 84% moisture. Using 10% (v/v) sulfuric acid in methanol with a wet biomass to solution ratio of 25 mg (dry mass equivalent)/mL resulted in the recovery of approximately 81% of the maximum biodiesel yield.

This study showed that the presence of moisture at greater than 20% by mass in algal biomass significantly decreased biodiesel recovery when using in situ transesterification. Increasing the amount of methanol and/or catalyst in the reaction improved biodiesel recovery from wet algal biomass.

In order to replace petrochemicals by bio-based lignin products in a lot of high value-added applications, a formic/acetic acid treatment was adapted to beech wood (Fagus sylvatica L.) for lignin extraction.

Beech wood particles were delignified at atmospheric pressure by a formic acid/acetic acid/water mixture. Cooking time and temperature were optimized for delignification, pulp yield and 2-furfural concentration. Response surface design analysis revealed that delignification yield increased with cooking time and temperature.

The multi-criteria optimization of delignification was used to find the ideal cooking conditions (5 h07 min, 104.2 °C) which could be satisfactory for the maximization of delignification (70.5%) and pulp yield (58.7%) and, to a lesser extent, for the minimization of 2-furfural production. Treatment conditions were found to influence the chemical structure of extracted lignins. Cooking time and temperature influenced inversely lignin molecular weights.

Complex polysaccharides are important in the pharmaceutical industry, yet, due to their large molecular weight and reduced charges, their purification is a highly demanding process that requires binding matrices with unique properties. In this work, we demonstrate for the first time that complex polysaccharides biosynthesized by microalga Porphyridium purpureum can be adsorbed onto Q fibrous anion exchangers.

When the polysaccharides were characterized, the extent of sulfation was higher in native polysaccharides than in ethanol- or alkali-extracts. The zeta potentials increased with pH rise and the highest charge was observed at pH 8 while the Z-average diameters of the polysaccharide at pH 6 were highest for alkali-extracts. Instead of pellicular resins, Q fibrous adsorbents were used to determine Langmuir thermodynamic properties and dynamic binding capacities. The parameters included static binding capacity and dissociation constant of 13.47 ± 1.02 mg g^-1 and 0.141 ± 0.027 mg ml^-1, and 10 and 50% breakthrough capacities of 4.46 ± 0.22 and 5.51 ± 0.28 mg g^-1, respectively. The antiviral activity of the polysaccharides was demonstrated by minimizing bacteriophage lysis of Streptococcus thermophilus.

This work demonstrates that polysaccharide extraction can be optimized and the adsorption and desorption of a complex polysaccharide onto Q fibrous matrix is feasible. These parameters could be exploited for up-scaling of polysaccharides for nutraceutical and pharmaceutical applications.

Catalytic transformation of bio-oil into higher olefins can provide valuable bio-fuels and chemicals used in the manufacture of high-octane gasoline, detergents, plasticizers and other petrochemicals. This work is to explore production of higher olefins from bio-oil through catalytic cracking of bio-oil along with light olefins oligomerization.

For the bio-oil catalytic cracking, the olefins yield reached 43.8 C-mol% with a nearly complete bio-oil conversion. The oxygenated organic compounds in bio-oil go through deoxygenation, cracking and hydrogen transfer reactions and form light olefins over the zeolite acid sites. For the oligomerization of light olefins, the highest selectivity and yield of C₅⁺ olefins over the LTGO catalyst reached 85.4 C-mol% and 326.7 g/(kg_cata·h), respectively. Main products below 300 °C were C₆⁼ - C₁₂⁼ olefins, originating from light olefin oligomerization. The influences of the reaction conditions were investigated in detail, and the reaction mechanism was addressed.

The bio-oil can be catalytically converted to C₂⁼-C₄⁼ light olefins over HZSM-5, and further selectively transformed to C₅⁺ high olefins via the oligomerization of light olefins over LTGO. The transformation of bio-oil to higher olefins may be useful for the production of bio-fuels and high value chemicals using renewable biomass.

The effects of current distribution and cell hydrodynamics on the performance of an electrocoagulation (EC) reactor were studied. This analysis only considered the distributions of primary potential and current density. The hydrodynamic behavior was analyzed by means of computational fluid dynamics (CFD) using a turbulent model (k-ɛ). For this study, only the fluid movement between electrodes was taken into account.

The analysis of current distribution showed the effects of cell geometry and electrode configuration on both the potential and current distributions on the anodes. Insulators placed at the edges of the electrodes produced border effects on the potential values that favored a secondary reaction and diminished the formation of aluminum clots. The CFD analysis indicated that the cell geometry arrangement generates low velocity profiles between the electrodes. From the experimental evaluation, it was observed that EC performance was improved when uniform potential and current densities were achieved with low flow velocity profiles.

The analysis of the hydrodynamic behavior showed the impact of different hydrodynamic phenomena on both the formation of clots and the removal of the sludge formed. Likewise, it was confirmed that in optimizing energy consumption, an analysis of current distribution is a very useful tool for evaluating the arrangement of electrodes and the cell geometry.

An unstructured model for batch culture production of L-asparaginase by Bacillus aryabhattai ITBHU02, by means of the Luedeking–Piret incorporated logistic equation, was developed explaining the correlation between growth dynamics and enzyme production kinetics with respect to glucose depletion at different levels. The main goal was to build up a means for process optimization, design, control and analysis of L-asparaginase production. Various thermodynamic parameters were estimated to comprehend enzyme stability and affiliated industrial applicability.

Specific growth rate maxima were increased with increasing initial glucose concentration, whereas the specific productivity was best supported at a glucose concentration 5.0 g L^-1. The fermentative production of L-asparaginase was greatly influenced by oxygen supply, reaching a maximum level at an aeration rate of 0.6 vvm. The activation energies for growth and death rate were 33.8±6.0 and 99.8±9.0 kJ mol^-1, respectively, with activation enthalpy values of enzyme formation and thermal deactivation 70.2±9.0 and 46.1±11.0 kJ mol^-1, respectively.

The economic production of L-asparaginase by B. aryabhattai was achieved efficiently at low glucose concentration and mild aeration. Endogenous metabolism of the strain for L-asparaginase synthesis was thermostable up to 40°C, which makes the strain commercially important as it can be utilized for cost-effective L-asparaginase production within countries such as India, where 35–40°C temperatures are quite common. © 2013 Society of Chemical Industry

The models presented for bed optimum fluidization velocity (u_opt), which was worthwhile for treatment efficiency and operation stability of anaerobic fluidized-bed bioreactors (AFB), were developed for AFB, and the anaerobic granular sludge diameter (d_p) and shape were analyzed by a dynamic image analyzer.

The results showed that the granular size from 0.05 to 0.30 cm sludge dominated the total biomass (accounted for 92.34%) in an expanded granular sludge bed reactor, the mean sphericity 0.835 and mean granular diameter 0.1606 cm were achieved. The u_opt range was 0.000949–0.2851 cm s^-1 when d_p was 0.05–0.30 cm, and the fluidization number was 8.43–38.77. The maximum value of 0.2851 cm s^-1 was the basic parameter for pump power matching. From parametric sensitivity analyses, u_opt was significantly influenced by liquid holdup, granular diameter, granular density and liquid viscosity.

According to the models of u_opt, a better operating scheme for AFB can be provided; from parametric sensitivity analysis, further optimizing designs of such bioreactors can be achieved. © 2013 Society of Chemical Industry

Since extrusion has many desirable characteristics such as high shear, rapid mixing, short residence time, controllable barrel temperature, and adaptability to process modification, the technology has been applied as a viable continuous pretreatment method for empty fruit bunches (EFB).

Optimized conditions for a continuous twin-screw-driven reactor (CTSR) were determined to be 170°C barrel temperature, 1.6% (w/v) sodium hydroxide, 1:8 solid to liquid ratio, and 5 rpm screw rotational speed. Under these operating conditions, 56.55% of lignin and 39.18% of hemicellulose fractions were solubilized from raw EFB, which increases the glucan content in pretreated EFB from 39.25% to 53.60%. After subsequent 48-h enzymatic hydrolysis of pretreated EFB, the highest digestibility of 92.4% was achieved with an enzyme loading of 30 FPU g⁻¹-glucan for cellulase and 70 pNPG g⁻¹-glucan for β-glucosidase.

CTSR processing has great potential for increasing the efficiency of EFB pretreatment compared with batch pretreatments. © 2013 Society of Chemical Industry

It is necessary to find an effective method for the removal of dyes and heavy metals from aqueous solutions. In this work, the effects of carboxymethyl-β-cyclodextrin (CMCD) on the photocatalytic degradation of Acid Red R (ARR) and photocatalytic reduction of Pb²⁺ were investigated in TiO₂ suspensions, and the synergistic effects on the simultaneous conversion of ARR and Pb²⁺ in the presence of CMCD were also evaluated.

The results showed that CMCD can enhance the photocatalytic degradation of ARR and photocatalytic reduction of Pb²⁺ in a single system with ARR or Pb²⁺, respectively. When CMCD was added to the mixed reaction system of ARR and Pb²⁺, the synergistic effects on the simultaneous conversion of ARR and Pb²⁺ in aqueous solutions were further enhanced. The photocatalytic removal rates of ARR and Pb²⁺ in the mixed system were markedly enhanced compared with those in the single systems, and the reaction rate constants of ARR and Pb²⁺ in the presence of CMCD were higher than those in the absence of CMCD.

CMCD can simultaneously enhance the photocatalytic removal of ARR and Pb²⁺ in mixed systems. CMCD-enhanced photocatalytic technology may be a good alternative for the treatment of wastewaters containing dyes and heavy metal ions. © 2013 Society of Chemical Industry

Heterogeneous hydrogenation catalysts for fine chemical synthesis are a convenient alternative to homogeneous catalysts because of the ease of separation and reuse. In order to be good catalysts they must have high activity and selectivity and good mechanical properties. Appropriate kinetic models should also be available for reactor design.

Novel composite supported Pd catalysts were synthesized and tested in the liquid-phase selective hydrogenation of 2,3-butanedione to 3-hydroxy-2-butanone (acetoin). The composite support comprised a mixture of an organic polymer and γ-Al₂O₃. The support and the Pd catalyst were further characterized by XRD, SEM, EMPA and XPS spectroscopy. Catalytic tests at various conditions were performed in order to elucidate the kinetics of the system.

The composite had better mechanical properties (resistance to radial and axial compression) in comparison with other commercial supports. Good activity and high selectivity to acetoin, a product of partial hydrogenation, were obtained at different reaction conditions. A Langmuir–Hinshelwood chemical rate expression useful for reactor design was regressed from the kinetic data.

The experimental results could be explained by a Horiuti–Polanyi mechanism in which the addition of an H atom to the carbonyl group in the adsorbed state is the rate limiting step. © 2013 Society of Chemical Industry

Solid–liquid two-phase partitioning bioreactors (TPPBs) use polymers as the sequestering phase to reduce the concentration of substrates to sub-inhibitory levels and enhance biodegradation performance. Polymer selection for TPPBs is challenging due to the almost infinite variety of target substrates to be degraded, and the variability and complexity of polymer composition and structure.

Three different polymer selection criteria, based on either solubility parameters or activity coefficients, were assessed via experimental partitioning coefficients (PCs) for phenol and butyl acetate, two substantially different target contaminant molecules, and the relative ability of the three methods to predict effective polymers was assessed. The best method was also applied to predict which waste polymers would be effective for sequestering these molecules, and TPPB degradation tests were conducted to confirm the effectiveness of a single identified polymer and selected waste polymers.

An effective polymer selection criterion was identified and the identified polymer showed a high capacity to absorb both phenol and butyl acetate. Both substrates were successfully degraded in solid–liquid TPPBs using the selected polymer and using mixtures of waste polymers. © 2013 Society of Chemical Industry

Alkylguanidinium and alkylamidinium hydroxides have been developed as new basic ionic liquids for the first time from cyclic guanidine (TBD) and amidines (DBN, DBU). The method of preparation of [bmim]OH decribed in the literature was adopted for the synthesis of new ionic liquids. Synthesis was carried out using cyclohexane as the solvent for the synthesis of alkylguanidine and alkylamidine bromides. Anion metathesis was carried out over anionic resins in water as solvent. The structures of the new ionic liquids were confirmed by spectral analysis. The catalytic activity of the new ionic liquids was tested in transesterification of fatty acid methyl esters with trimethylolpropane, neopentyl glycol and 2-ethylhexyl alcohol.

The new ionic liquids have good thermal stability and can be applied for transesterification processes. The highest conversion of FAME (83%) was obtained for TMP ester of oleic acid and ionic liquid [TBD-Bu]OH.

Among the ionic liquids derived from cyclic guanidine and amidine only ionic liquids obtained from TBD are good catalysts for transesterification of FAME and polyols. In comparision with [bmim]OH, catalytic activity of TBD ionic liquids was comparable in the synthesis of TMP ester but better in the synthesis of 2EH esters. © 2013 Society of Chemical Industry

In this work, the electrolysis of dimethyl phthalate (DMP, a widely-use plasticizer) with conductive-diamond anodes is studied.

Results show that this technology is capable of depleting this pollutant in a wide range of initial concentrations. Although mass transfer limits the kinetics of the process, there is a significant contribution of mediated oxidation and the rate of the processes improve with increasing current density, while the efficiency decreases. A first stage in the oxidation of DMP consists of the attack on the methyl ester groups, and monomethyl phthalate and phthalate are the main aromatic intermediates. Further oxidation of these species results in the formation of maleic and oxalic acid, which behave as intermediates and are completely mineralized during the electrolysis. The presence of chloride in water leads to the formation of many more aromatic chlorinated intermediates from the action of hypochlorite on aromatics intermediates. Intermediates found and oxidation mechanisms proposed are consistent with those reported in the literature for other advanced oxidation processes.

DMP, TOC (total organic carbon) and COD (chemical oxygen demand) can be successfully removed using electrolysis with conductive-diamond anodes. DMP removal is faster than that of COD and TOC indicating the formation of reaction intermediates. © 2013 Society of Chemical Industry

CuS nanocrystals with excellent properties are widely applied as semiconductor materials, but little work has been done on their application to electrochemical analysis. This paper reports on a very straightforward method to synthesize pure hexagonal phase CuS nanocrystals with an average diameter of 20 nm by a solvothermal method. A glassy carbon electrode was modified by drop casting the suspension of CuS nanocrystals and chitosan onto its surface. The new electrochemical sensor was developed for the determination of hydroquinone.

The crystallization, morphology and composition of as-prepared CuS nanocrystals were characterized by XRD, SEM, Raman and EDS, respectively. The electrochemical oxidation behavior of hydroquinone at a CuS nanocrystals/chitosan/glassy carbon electrode was investigated by cyclic voltammetry. The electrode exhibited a wide linear dynamic range between 4.5 µmol L⁻¹ and 4.5 mmol L⁻¹ hydroquinone, and a detection limit of 1.5 µmol L⁻¹.

The electrode was successfully applied to the determination of hydroquinone in real water samples with satisfactory accuracy and precision. © 2013 Society of Chemical Industry

This paper presents the study of the sorption performance of a novel poly[N-(4-vinylbenzyl)-iminodiacetic acid)-montmorillonite nano-composite. The composite was obtained through in situ polymerization of the previously synthesized monomer N-(4-vinylbenzyl)-iminodiacetic acid in the presence of organic-modified montmorillonite and N,N-methylene-bis-acrylamide.

The water uptake of the nanocomposites increased with increasing montmorillonite content. Metal ion retention studies as a function of montmorillonite content showed an unexpected trend in which the adsorption capacities decreased as the montmorillonite content increased. Selectivity experiments reveals that composites present a certain selectivity towards Cu²⁺ and that montmorillonite content does not provide selectivity to the composite. Kinetic experiments were conducted using a Cu²⁺ aqueous solution at pH 5.0 and it was observed that after 60 min contact the maximum retention is reached. Kinetics and diffusion models reveal that the metal ion retention occurs mainly at the surface of resin particles, suggesting a film diffusion process.

The nano-composite showed the ability to remove metal ions. The process can be described by a Langmuir isotherm, whereas kinetic studies indicated that the pseudo-second-order model could describe the sorption process. The intra-particle diffusion model suggests that sorption mechanism is film diffusion. © 2013 Society of Chemical Industry

TiO₂-based heterogeneous photocatalysis is an effective way to degrade harmful refractory organic compounds. However, the rate of photocatalytic reaction is significantly decreased by film diffusion resistance and several other factors. To overcome this problem, TiO₂ immobilized on a stainless steel screen is hydrophobically treated using a (γ-aminopropyl) triethoxysilane–toluene solution and the performance of the silanized TiO₂ for the photocatalytic decomposition of 2,4-dinitrophenol (2,4-DNP) is investigated.

The reactant 2,4-DNP is slowly decomposed when its aqueous solution is treated using an unsilanized TiO₂ screen without mixing the solution, whereas the rate of decomposition is certainly increased by use of a silanized TiO₂ screen, and further increased by mixing the solution. The use of sunlight as a UV light source provides a higher rate of decomposition than does the use of an artificial UV lamp. The rate of decomposition in a well-mixed solution is less affected up to 1.5 cm in solution depth.

The use of the TiO₂ screen silanized with a 2% silane–toluene solution under liquid mixing decreases film diffusion resistance and facilitates rapid decomposition of 2,4-DNP. The simultaneous use of sunlight as a UV light source and a wind-powered propeller for liquid mixing is effective. © 2013 Society of Chemical Industry

Commercial filter media are commonly regular in shape and the flow patterns can be predicted with simple tools. Using lava stones as filter media, this study analyzes the influence of particle size and aeration on the hydraulic behaviour of a submerged filter prior to biofilm colonization.

The filter was packed, separately, with two different sizes of lava stones (4.7 and 9.5 mm) and operated under different hydraulic retention times to establish the causes of deviations from ideal models. Tracer curves were analyzed using two mathematical models (Axial Dispersion and Wolf and Resnick models). The curves show that the tracer appeared in the effluent in a shorter time than expected indicating an effective volume reduction. It was estimated that the dead volume of the filter with aeration was 83% and 22% for the filter without aeration.

The dead volume is caused, in the case of the filter with aeration, by the combination of two phenomena: the liquid volume displaced by the air bubbles and the turbulence caused by aeration generating preferential channelling along the filter media and creating large zones of stagnant liquid. In the case of the filter without aeration the volume reduction is caused by channels developed by the media irregular shape. © 2013 Society of Chemical Industry

Crude glycerol (CG), the major by-product of the biodiesel production process, could be used for biohydrogen production. However, fermentative hydrogen production is limited by the cost of buffer and additional nutrients required for the process. Thus, the purpose of the present study was to determine maximum H₂ production potential of CG in the absence of any additional expensive supplement. Another objective was sustainable utilization of the waste from the H₂ production process.

A maximum production of 2022.5 mL H₂ L⁻¹ media was achieved by CG bioconversion (without any additional nutrient) and 10 g L⁻¹ CG was found to be optimum. Further, the addition of spent biomass (50 mg L⁻¹) from the process into a subsequent process was found to improve production by 32.5% with a maximum rate of 1040 mL L⁻¹ day⁻¹. Similarly, nearly 75% of total H₂ was produced at a pH as low as 3.8, indicating high acid tolerance of the strain (Enterobacter aerogenes NRRL B407) used.

Meat processing and restaurant waste based CG has been characterized and evaluated for maximum H₂ production potential. Utilization of spent biomass from the CG bioconversion process (as supplement) was found to improve process performance. © 2013 Society of Chemical Industry

The integrated approach of using metal chelate (e.g. Fe(II)EDTA) absorption combined with microbial reduction for nitric oxide (NO) removal has been a frequent topic of much recent study. The present study was undertaken to evaluate simultaneous Fe(II)EDTA-NO and Fe(III)EDTA with Paracoccus denitrificans as a model microorganism.

The experimental results suggested that Fe(III)EDTA reduction was severely inhibited by Fe(II)EDTA-NO while the addition of Fe(III)EDTA could have a positive effect on the reduction of Fe(II)EDTA-NO. Riboflavin, AQDS and vitamin B12 at 0.1 mmol L⁻¹ did not have significant effects on simultaneous reduction of Fe(II)EDTA-NO and Fe(III)EDTA. Addition of sulfide not only could directly react with Fe(II)EDTA-NO and Fe(III)EDTA but also might play multiple roles in biological Fe(II)EDTA-NO reduction and Fe(III)EDTA reduction. The respiratory inhibitor CuCl₂ inhibited Fe(II)EDTA-NO reduction as well as Fe(III)EDTA reduction while NaN₃ and rotenone showed no measurable effects.

The present study showed that Fe(II)EDTA-NO reduction and Fe(III)EDTA reduction reacted upon each other. The roles of sulfide were divided in terms of biological and chemical interactions during the simultaneous reduction. CuCl₂ could inhibit the simultaneous reduction rates. © 2013 Society of Chemical Industry

Rapeseed straw is an agricultural residue increasingly produced in recent years due to a growing interest in biodiesel production. In the present study, rapeseed straw pretreated by liquid hot water was tested as a substrate to optimize ethanol production by simultaneous saccharification and fermentation (SSF). Temperature, time, substrate loading and cellulase charge were selected as operation variables and modified according to a three-level four-variable experimental design. Ethanol concentration, ethanol yield and volumetric productivity were monitored and adjusted to a quadratic model using response surface methodology.

Optimal SSF conditions, based on the mathematical model in terms of ethanol yield and concentration, were found to be 40°C, 71 h, 10% substrate loading, and 40 FPU g⁻¹ substrate. The resulting ethanol concentration was 23 g L⁻¹, which corresponds to 69% ethanol yield.

Liquid hot water is an effective pretreatment that increased the cellulose concentration of rapeseed straw, making it a good substrate for SSF, with a maximum yield of 0.12 g ethanol g^–1 dry straw. The novel combination of hydrothermal pretreatment and SSF configuration results in yields comparable yields with those previously reported, and has additional advantages, e.g. no chemicals use and high solid concentration operation. © 2013 Society of Chemical Industry

Dyeing industry effluent is one of the most problematic waste waters needing to be treated. New adsorption materials, supported ionic liquids (SILs), have been successfully applied for dyes separation.

In this study, five SILs including two novel SILs were prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis, thermogravimetric analysis (TG-DTA) and nitrogen adsorption–desorption isotherms. The new benzothiazolium hexafluorophosphate-supported silica (SiO₂·Bth⁺·PF₆⁻) was screened out as the most effective adsorbent for adsorption of bromophenol blue (BPB), and had excellent adsorption and desorption capacity in dynamic adsorption and desorption experiments. It could be reused easily after elution with 0.01 mol L^-1 NaOH. Studies showed that the kinetic data were well described by the pseudo-second-order kinetic model. Moreover, the isotherm experiments revealed that the Langmuir model yielded better fitting than the Freundlich model for BPB adsorption. The calculated thermodynamic parameters indicated that the adsorption of BPB was spontaneous and endothermic.

Five SILs including two novel SILs were prepared and characterized, and their application in the adsorption of BPB was investigated in detail. Among them, SiO₂·Bth⁺·PF₆⁻ was found to be the best. This study is expected to be helpful in expanding the type of SILs and their application in the treatment of dyes pollution.© 2013 Society of Chemical Industry

Long pipeline transportation of wastewater usually generates high concentration of sulfide; however, information on nitrification inhibition by sulfide in the anaerobic–anoxic–aerobic (AAO) process is still scarce. This study focused on how sulfide could inhibit nitrification activity in the AAO process, and the inhibitory effect of initial sulfide concentration and anaerobic exposure time on the behavior of nitrifying biomass.

The net maximum specific growth rate (μ_AUT-b_AUT) was, respectively, 0.06 ± 0.01 and 0.31 ± 0.03 d⁻¹ at 15 and 20°C in a full-scale AAO wastewater treatment plant for long-pipeline transported wastewater. The μ_AUT-b_AUT was not affected by 6.2 mg L⁻¹ sulfide under aerated condition, but reduced by 75.9% after unaerated exposure for 0.5 h. The first-order kinetic constant of sulfide inhibition under anaerobic conditions was 0.658 h⁻¹, and half maximal inhibition concentration of sulfide on nitrification was 36.0 and 10.0 mg L⁻¹ after 1.0 h and 1.5 h anaerobic exposure, respectively.

Nitrifying biomass was sensitive to the presence of sulfide under anaerobic conditions. The inhibitory reaction of sulfide on nitrifying biomass under anaerobic conditions conformed to the first-order kinetic reaction, while the effect of initial sulfide concentration on nitrification inhibition matched the modified Monod model. © 2013 Society of Chemical Industry

Most experts acknowledge that low aqueous solubility results in low mass recovery rates using pump-and-treat (P&T), making such systems ineffective for coal tar (a multi-component NAPL) recovery. It is proposed to increase the apparent aqueous solubility of coal tar by orders of magnitude as an enhancement to conventional P&T schemes (or ‘P&T–E’), increasing coal tar recovery rates, reducing the pore volumes and time required for complete recovery, thus translating into cost savings.

Batch test results of aqueous solutions containing anionic surfactant, co-solvent, and electrolyte are presented that were studied for both compatibility with a field-obtained coal tar and effectiveness at solubilizing the coal tar above its aqueous solubility. Seven surfactants were tested at room temperature (23C) in aqueous solutions containing the surfactant with co-solvents and electrolytes. The most promising surfactant solution solubilized upwards of 40 000 mg L⁻¹ coal tar. A 1–D column test resulted in 97% recovery using the promising surfactant.

P&T–E could significantly increase coal tar solubility without causing the formation of a rate-limiting, solid-like film and offers a promising approach for the remediation of coal tar from the subsurface. © 2013 Society of Chemical Industry

There is a need to examine the impact of anaerobic reactor type and wastewater strength on anaerobic–aerobic two-stage biological systems for temperate wastewater treatment An expanded granular sludge blanket reactor and an anaerobic membrane bioreactor for crude wastewater treatment with downstream aerobic biological treatment were studied together with increasing the organic concentration by fortifying the crude wastewater with primary sludge.

A chemical oxygen demand and ammonia compliant effluent was produced from the anaerobic–aerobic two-stage process. Due to the enhanced organics removal achieved by the membrane, a lower denitrification rate, k_d, was recorded for the anaerobic membrane bioreactor effluent treatment. However, the residual organic carbon in the anaerobic effluents from both the expanded granular sludge blanket reactor and the anaerobic membrane bioreactor treating crude wastewater was not of sufficient quality to support denitrification. Complete nitrification was achieved during downstream treatment of the fortified effluent. In addition, fortification increased k_d to values analogous to exogenous carbon substrates.

It is postulated that fortification currently presents the most sustainable strategy for anaerobic–aerobic two-stage biological systems due to a combination of enhanced methane production and denitrification. © 2013 Society of Chemical Industry

Glycolysis has been the subject of increased interest as a valuable feedstock recycling for poly(ethylene terephthalate) (PET). However, there are no reports in the technical literature that deal with the design and optimization of the global process.

Conversion into bis(2-hydroxyethyl) terephthalate (BHET) of the non-glycolyzed solid was feasible, carried out in the presence or absence of fresh PET. The yield varied between 63 and 80%. The monomer was recovered by extraction with hot water followed by crystallization at 4 °C. The optimized H₂O:BHET ratio was 6.7 mL g^-1. The EG(ethylene glycol)/H₂O mixture was effectively separated by vacuum distillation and EG of 99.6% purity was recovered, which could be used again. Finally, the highly active catalytic role of sodium carbonate salt for glycolysis was evident not only for transparent PET wastes but also for complex wastes.

The recirculation of the solid residue from extraction, the separation of EG/H₂O mixture from crystallization and the subsequent refeeding of the organic reactant into the reactor, the minimization of the amount of water to efficiently recover the monomer and the suitability of the chemical recycling of complex PET wastes are operational aspects that significantly increased the global efficiency. © 2013 Society of Chemical Industry

Biodiesel is a clean-burning, renewable and biodegradable diesel fuel substitute derived from animal fats and plant oils, which may play an important role in replacing diminishing fossil fuel reserves and combating climate change. Conventional biodiesel production uses soluble base catalysts, such as Na or K alkoxides, to convert oils into fuel, and as a result requires energy intensive aqueous quench cycles to isolate the biodiesel product.

Cs-doping nanoparticulate MgO, prepared via a novel, supercritical sol–gel method, yields a solid base catalyst with improved activity for the transesterification of pure triacylglycerides (TAGs) and olive oil.

Here, X-ray absorption spectroscopy (XAS) is used to probe the local chemical environment of Cs atoms in order to identify the nature of the catalytically active species as Cs₂Mg(CO₃)₂(H₂O)₄. © 2013 Society of Chemical Industry

Aluminum (III) hydroxy-gels find important applications in areas such as paint pigments, pharmaceuticals and water treatment or toxic metal sequestration. Since the method of preparation may affect their properties and performance, in this work we prepare aluminum hydroxy-gels from either chloride or sulphate salts and subject them to comparative characterization.

Aluminum (III) hydroxy-gels were produced by partial quick neutralization of 2 mol L⁻¹ AlCl₃ or Al(SO₄)_1.5 salt solutions with 5 N NaOH at room temperature. The gels were found, following ageing and water washing, to consist of 60–70 wt% Al(OH)₃, 5–18 wt% Cl or SO₄ and ∼20 wt% water. Both gel materials upon drying were seen to be highly porous formed from aggregates of very fine particles nucleated during the fast neutralization process. The Al(SO₄)_1.5-derived gel was found to differ significantly from the AlCl₃-derived gel both in terms of surface area (38 m² g⁻¹ vs. 18 m² g⁻¹) and chemical features. The aluminum chloride gel material is probably composed of chains of aluminum octahedra (Al_n(OH)_2.5Cl_0.5n(H₂O)_3n) while the aluminum sulphate gel of SO₄-stabilized Keggin Al₁₃ structure: AlO₄Al₁₂(OH)₂₄(SO₄)_3.5(H₂O)₁₂.

The distinct molecular structure of the aluminum sulphate-derived gel may provide an effective matrix for hazardous metal containment. © 2013 Society of Chemical Industry

5-hydroxymethylfurfural (HMF) has attracted increasing attention so that an efficient process for HMF production from high-sugar solution is needed for the successful commercialization of this versatile intermediate in the production of high value chemicals.

Two simple operations, mechanical stirring control and high-fructose solution addition, were applied to the water/butanol system for enhancing fructose-to-HMF reaction using HCl as catalyst. The optimization of stirring speed led to a high HMF yield of 81.7% with 92.0% fructose conversion (0.3 moL L⁻¹ HCl, 1000 rpm). Moreover, a reasonable mechanism describing the effect of stirring speed on HMF yield was proposed. During the process of high-fructose solution (54.6 wt%) addition, the yields of HMF after four additions in every experiment all exceeded 55%, and a HMF yield of 83.3% was achieved after three additions at 1000 rpm.

The optimization of mechanical stirring in aqueous/butanol media led to a high HMF yield. By studying the kinetics of the fructose-to-HMF reaction, it was demonstrated that a low value of reaction rate constant is of benefit to obtain high HMF yield for this biphasic system. The simple addition process greatly reduced the side-reaction and made the operation more continuous and stable, and thus provided a practical and effective method of HMF preparation in high-fructose solution. © 2013 Society of Chemical Industry

Continuous ethanol fermentation productivity strongly depends on yeast concentration. Therefore apparatuses, which can handle high cell concentrations, separation and recycling of adapted yeasts are of high interest.

In our work, an enhanced sedimentation rate (ESR) settler for a Blenke cascade system, avoiding large electrical power consumption, was designed. To improve the sedimentation rate, the ESR settler was connected in series with a small conventional gravitational settler. Yeast recycling was executed in two modes, direct and activation modes. Yeast cell samples taken from both cascade and settler were counted and tested for cell viability using methylene blue staining technique and a haemocytometer. The samples were cultured on agar plate with yeast extract peptone dextrose broth and analyzed by HPLC to determine ethanol, residual sugars content and by-products (of yeast and bacterial origin).

The results showed that, using ESR settler in series with a small conventional gravitational settler, more than 85% of the yeast cells were sedimented and were recycled by the direct or activation mode. The ethanol productivities were Q_p = 19.45 ± 0.13 and Q_p = 20.31 ± 0.11 g L⁻¹ h⁻¹ for direct and activation recycle mode, respectively. Continuous fermentation, yeast recycling and sedimentation were contamination-free processes.

With an ESR settler, more adapted yeast can be recycled into the continuous process. High ethanol productivity can be achieved by an activation recycling mode. © 2013 Society of Chemical Industry

The effect of the combination of acetic acid, furfural and 5-hydroxymethylfurfural on 2, 3-butanediol fermentation of Klebsiella oxytoca was studied by statistical analysis. The compounds were selected taking into account their concentration in the hydrolysate from the acid pretreatment of biomass and their toxicity. A central composite design was used to investigate the influences of these compounds on 2, 3-butanediol yield and biomass formation.

Two models were developed to describe the effect of the combination of acetic acid, furfural and 5-hydroxymethylfurfural on biomass and product yield in 2, 3-butanediol fermentation. The proposed model is suited to fit experimental data and to simulate cell growth and 2, 3-butanediol yield, which was confirmed by 2, 3-butanediol production using real hydrolysate as substrate.

Biomass yield was affected mainly by the ‘main effects’ of the tested compounds and no interaction relationship among acetic acid, furfural and HMF was found. 2, 3-butanediol yield was more sensitive to acetic acid concentration. Selective removal of furfural in hydrolysate would contribute to the simultaneous improvement of 2, 3-butanediol yield and cell growth. © 2013 Society of Chemical Industry

Steam explosion is widely used on a variety of plant biomass for the hydrolysis of hemicellulose. However, hydrolysis by steam explosion suffers from low xylose yield, long hydrolysis time and high energy consumption, which impede the xylitol fermentation step. This study used a dilute sulfuric acid pre-impregnation prior to the steam explosion to prepare corncob hemicellulose hydrolysate which offers high xylose yield for xylitol fermentation by Candida tropicalis.

After pre-impregnation with 0.3% (wt) dilute sulfuric acid at a liquid to corncob ratio of 3 for 6 h, corncobs were steamed at 200 °C for 5 min to obtain a maximum xylose yield of 23.5% in the hydrolysate. The hydrolysate was detoxified by concentrating with vacuum evaporation followed by adsorption using activated carbon. The detoxified hydrolysate was then used for xylitol fermentation. Maximum xylitol yield of 75.1%, volumetric productivity of 2.01 g L^-1 h and biomass of 20.9 g L^-1 were obtained from the detoxified hydrolysate.

Findings suggested that this acid pre-impregnated steam explosion strategy provides a highly effective way to prepare hemicellulose hydrolysate with high xylose yield, and could be potentially applied to industrial xylitol fermentation. © 2013 Society of Chemical Industry

N₂O is a powerful greenhouse gas emitted in nitric acid plants, and emission control technologies are required.

A 0.25%Rh/50%Ce_0.9Pr_0.1O₂/γ-Al₂O₃ catalyst has been prepared and tested for N₂O decomposition in a real nitric acid plant gas stream. The catalyst is active enough to achieve 100% N₂O removal, maintaining a constant catalytic activity after 40 h operation without deactivating. Characterization of the fresh and used catalyst, using different techniques, revealed no changes during the N₂O decomposition experiments: (i) XRD and Raman spectroscopy show the fluorite structure of the Ce–Pr mixed oxide before and after the catalytic tests, (ii) the crystal size of the Ce–Pr mixed oxide particles and the BET surface area of the catalyst is maintained, evidencing no sintering of ceria particles, (iii) H₂-TPR indicates that the reducibility of the catalyst is similar before and after the catalytic tests, revealing chemical stability, and (iv) TEM and XPS analysis indicated the high stability of the rhodium particle size and oxidation state.

An active and stable catalyst with formulation 0.25%Rh/50%Ce_0.9Pr_0.1O₂/γ-Al₂O₃ has been prepared and successfully tested for N₂O decomposition in a real nitric acid plant gas stream. © 2013 Society of Chemical Industry

The electrochemical treatment of brackish and seawaters with boron doped diamond anodes (BDD) can be particularly suitable for the removal of microorganisms, microalgae and pollutants: the high conductivity of these waters and the high content of chloride ions can be exploited in disinfection/oxidation processes mediated by active chlorine. A correct choice of operating conditions can limit the formation of such undesired by-products as bromate and chlorate ions.

Galvanostatic electrolyses of synthetic waters containing chloride and/or bromide ions using BDD anode were carried out both in batch and continuous mode in an undivided cell. Bromide ions were oxidized to form bromate ions with high conversion rate, while chlorate ions were found as by-products of the oxidation of chloride ions together with active chlorine. When solutions containing Br⁻ and Cl⁻ were treated, the increase in the concentration of chloride up to that of seawater (20 g dm⁻³), hinders the formation of BrO₃⁻ and ClO₃⁻.

The electrochemical process with BDD anode could be applicable to the disinfection of high salinity waters: in synthetic solution simulating the composition of seawaters, high amounts of active chlorine are formed and the occurrence of bromates and chlorates is highly limited. © 2013 Society of Chemical Industry

The high in vivo corrosion rate of magnesium alloy vascular stents is a primary problem. Smooth TiO₂ film has excellent antithrombotic properties and could improve the corrosion resistance of magnesium alloy stents. Research into special nanostructured TiO₂ film, which may provide improved biocompatibility and act as a drug carrier, has seldom been reported in vascular stent applications.

Flower-like nanostructured TiO₂ film was prepared on Mg-Zn-Y-Nd alloy substrate by an improved solvothermal method. Aqueous NH₄F solution and hydrofluoric acid were added to ethanol solvent to adjust the hydrolysis rate of titanium butoxide, and thus the TiO₂ nanostructure size. This reaction system was suitable for magnesium alloy due to its non-corrosive characteristic. Under properly chosen hydrolysis conditions, compact TiO₂ film consisting of continuous flower-like nanostructures was obtained on substrate, with single sheet thickness of 50–100 nm. The charge transfer resistance of Mg-Zn-Y-Nd alloy in simulated body fluids was increased about 40 times by the nanostructured TiO₂ film.

Through a solvothermal synthesis process, nanostructured TiO₂ film can be prepared on the surface of Mg-Zn-Y-Nd alloy. Corrosion resistance of Mg-Zn-Y-Nd alloy in simulated body fluids can be improved by protection with the TiO₂ film. © 2013 Society of Chemical Industry

The immobilization of biomacromolecules on carbon nanotubes has attracted considerable attention. Based on the specific affinity between concanavalin A (Con A) and glycosyl, and the ability of alkyl polyglucoside to disperse single-walled carbon nanotubes (SWNTs), a new self-assembly immobilization strategy is developed.

Using laccase (Lac) and horseradish peroxidase (HRP) as models, it is demonstrated that this new self-assembly immobilization strategy has obvious advantages over the direct adsorption immobilization strategy in enzyme loadings ( 1.34-fold (Lac) and 1.46-fold (HRP) higher) and in the specific activity ( 5.06-fold (Lac) and 4.77-fold (HRP) higher). Circular dichroism (CD) spectra and fluorescence spectra also indicate that the present new indirect immobilization strategy has less impact on the enzyme conformation compared with the direct adsorption strategy. For the catalytic oxidation of dibenzothiophene (DBT), the immobilized HRP prepared using the present self-assembly strategy was more effective than that using the direct adsorption strategy.

Based on these findings, it is concluded that the present self-assembly strategy can greatly improve the enzymatic properties of the immobilized enzymes. © 2013 Society of Chemical Industry

Enzymatic hydrolysis of cellulose in lignocellulosic materials suffers from slow reaction rates due to limited access to enzyme adsorption sites and to the high crystallinity of the cellulose. In this study, an attempt was made to facilitate enzymatic hydrolysis by pretreatment of cellulosic materials using the ionic liquid (IL) 1-allyl-3-methylimidazolium formate ([Amim][HCO2]) under mild reaction conditions. The effect of the IL was compared with that of thermochemical pretreatment under acidic conditions.

The lignocellulosic substrates investigated were native and thermochemically pretreated Norway spruce and sugarcane bagasse. Microcrystalline cellulose (Avicel) was included for comparison. The IL treatments were performed in the temperature range 45–120 °C and, after regeneration and washing of the cellulosic substrates, enzymatic saccharification was carried out at 45 °C for 72 h. After 12 h of hydrolysis, the glucose yields from regenerated native spruce and sugarcane bagasse were up to nine times higher than for the corresponding untreated substrates. The results also show positive effects of pretreatment using [Amim][HCO2] on the hydrolysis of xylan and mannan.

The present work demonstrates that both native wood and agricultural residues are readily soluble in [Amim][HCO2] under gentle conditions, and that pretreatment with ionic liquids such as [Amim][HCO2] warrants further attention as a potential alternative to conventional pretreatment techniques. © 2013 Society of Chemical Industry

An 8-hydroxyquinoline (HQ)-type composite chelating material with high performance was designed and prepared. Monomer hydroxyethyl methacrylate (HEMA) was first grafted onto silica gel particles via surface-initiated graft-polymerization, forming grafted particles PHEMA/SiO₂ with a high grafting degree. Subsequently, through the substitution reaction between 5-chloromethyl-8-hydroxyquinoline (CHQ) and the grafted macromolecules PHEMA, HQ groups were bonded onto the grafted particles, obtaining the composite chelating material HQ-PHEMA/SiO₂. The chelating adsorption performance and mechanism of HQ-PHEMA/SiO₂ towards Cu²⁺ and Ni²⁺ ions was studied, and the adsorption thermodynamics was investigated.

The experimental results show that HQ-PHEMA/SiO₂ possesses a strong adsorption affinity for heavy metal ions owing to the high density of the HQ group, and for Cu²⁺ and Ni²⁺ ions, the adsorption capacities were up to 63.4 mg g⁻¹ and 51.1 mg g⁻¹, respectively. The adsorption behavior fits the Langmuir model, and the adsorption enthalpy change ΔH is positive, indicating endothermic chemisorption. The value of the entropy change ΔS is also positive, and the higher value of |TΔS| suggests that the adsorption process is entropically driven.

HQ-PHEMA/SiO₂ is a promising material for the effective removal of heavy metal ions from water. © 2013 Society of Chemical Industry

Aconitic acid (propene-1, 2, 3- tricarboxylic acid) is the most prevalent organic acid found in sugar cane. It is used in the food processing industry as an acidulant and can be used in the synthesis of plasticizers. It can also be used to synthesize biodegradable polyesters for tissue engineering applications. In this study, aconitic acid was isolated from sugarcane molasses via liquid–liquid extraction with ethyl acetate. Six combinations of time and temperature (1–6 h at either 30 or 40°C) were tested. In order to conserve solvent, ethyl acetate was recovered and reused for subsequent extractions. The recovery of aconitic acid from vinasse was also evaluated.

Under the most efficient set of conditions, 69% of the aconitic acid was recovered as free acid. The purity (HPLC) of the extracted acid was found to be 99.9%. Ethanol was an additional stream that was generated by fermentation of molasses and yields of 12.4% (g per 100 g of molasses) were obtained.

The yield of aconitic acid from molasses varied from 34–69%, depending on the extraction conditions, with purity of the extracted acid being 99.9%. The aconitic acid is of a quality sufficient to synthesize polymers that could realize high-value in biomedical applications. © 2013 Society of Chemical Industry

During recent years several computer-based operator training simulators (OTS) have been developed that are suitable for the virtual training of operators and other professionals. In the field of bioprocess engineering OTS are rarely used. Furthermore, the effects of using training simulators in bioprocess applications have not been evaluated.

The OTS BioProcessTrainer was applied to bioreactor operations for two biological processes, Saccharomyces cerevisiae, for ethanol production, and recombinant Escherichia coli, for production of green fluorescence protein (GFP). The simulator used a multi-shell model platform that described the biological and physical conditions of the bioreactor for the two bioprocess systems. The simulator enabled the user to plan, operate and control the processes in real or accelerated time. The training resulted in improved ability to manage the whole bioreactor procedure for the two processes.

The study showed that the simulator can be an efficient tool for training of operation, optimization and control of bioprocesses. The mathematical model framework of the simulator can be adapted to a variety of industrial bioprocesses. Thus, it appears likely that this type of OTS may serve as a useful resource in industry for training and continuing education of plant operators and engineers. © 2013 Society of Chemical Industry

Hybrid materials are being developed with improved separation properties as pervaporation (PV) membranes. Mixed matrix membranes (MMMs) containing surface-functionalized fumed silica (SiO₂) nanoparticles in polydimethylsiloxane (PDMS) were investigated for PV recovery of 1-butanol. The MMMs were characterized through water contact angle, pure 1-butanol sorption, degree of swelling and 1-butanol partition coefficients.

Most MMMs outperformed pure PDMS for the PV of 1.5% (w/v) 1-butanol at ≤40°C. Functionalized SiO₂ fillers enhanced the affinity of 1-butanol to the MMMs (K_BuOH^G) which consequently improved 1-butanol permeability more than that of water. Thus the MMMs exhibited better separation efficiencies, but those with octyl-functionalized (Si-DMOS) and phenyl-functionalized SiO₂ (Si-DMPS) exhibited the best PV performance. Filler loading of 10 wt% Si-DMOS and Si-DMPS were found optimal for the PV performance of both MMMs. With temperature, component fluxes of both MMMs increased whereas permeability decreased. Based on PV separation index, both MMMs performed better than PDMS at ≤60°C, Si-DMPS/PDMS MMM outperformed PDMS even at 70 °C.

Improved performance of PV membranes was achieved when nonporous functionalized SiO₂ nanoparticles, especially when Si-DMPS is used as the filler. The MMMs developed may also be useful for organic compounds recovery from dilute aqueous solutions. © 2013 Society of Chemical Industry

The objective of this study was to evaluate the chemical extraction efficiency of five metals (Cu, Ni, Zn, total Cr, and Fe) from galvanic sludge using molasses hydrolysate produced from molasses, a by-product of the sugar industry. The study was also aimed to compare the extraction efficiency of the molasses hydrolysate with those of nitric acid and EDTA.

The experimental results showed that the metal removal (%) increased with extracting solution concentration, but decreased with increasing solid:liquid (S:L) ratio. The highest removal efficiencies using molasses hydrolysate were: Cu 90%; Ni 100%; Zn 90%; total Cr 100%, and Fe 81% at 10 min extracting time and S:L = 1:10 g mL⁻¹.

Molasses hydrolysate was found to be more effective than nitric acid and EDTA in the extraction of metals from the sludge. It was concluded that although using HNO₃ was more economical than Na₂EDTA and molasses hydrolysate, using molasses hydrolysate which is a novel, environmentally friendly, biodegradable extracting agent would be appropriate to prevent secondary pollution. © 2013 Society of Chemical Industry

In Part1 of this work, a process integrating vapor stripping, vapor compression, and a vapor permeation membrane separation step, ‘membrane assisted vapor stripping’ (MAVS), was predicted to produce energy savings compared with traditional distillation systems for separating 1-butanol/water and acetone-butanol-ethanol/water (ABE/water) mixtures. Here, the separation performance and energy usage of a MAVS pilot system with such mixtures and an ABE fermentation broth were assessed.

The simple stripping process required 10.4 MJ-fuel kg^–1-butanol to achieve 85% butanol recovery from a 1.3 wt% solution. Addition of the vapor compressor and membrane unit and return of the membrane permeate to the column raised 1-butanol content from 25 wt% in the stripping vapor to 95 wt% while cutting energy usage by 25%. Recovery of secondary fermentation products from the ABE broth were based on their relative vapor–liquid partitioning. All volatilized organic compounds were concentrated to roughly the same degree in the membrane step. Membrane permeance, selectivity, and overall MAVS energy usage were the same with the broth as with the ABE/water solution.

Energy usage of the MAVS experimental unit corroborated process simulation predictions. Simulations of more advanced MAVS designs predict 74% energy savings compared with a distillation–decanter system. © 2013 Society of Chemical Industry

Fermentative production of butanol is limited to low concentrations, typically less than 2 wt% solvent, due to product inhibition. The result is high separation energy demand by conventional distillation approaches, despite favorable vapor–liquid equilibrium and partial miscibility with water. In previous work, a process integrating steam stripping, vapor compression, and vapor permeation separation was proposed for separating ethanol from water. Such a membrane assisted vapor stripping (MAVS) process is considered in this work for 1-butanol/water and acetone/butanol/ethanol/water (ABE/water) separation.

Using process simulations, the earlier MAVS design was estimated to require 6.2 MJ-fuel kg⁻¹-butanol to produce 99.5 wt% 1-butanol from a 1 wt% 1-butanol feed, representing an energy savings of 63% relative to a benchmark distillation/decanter system. Adding a fractional condensation step to the original MAVS design is predicted to reduce energy demand to only 4.8 MJ-fuel kg⁻¹-butanol and reduce membrane area by 65%.

In the hybrid distillation/membrane MAVS systems, the stripping column provides high butanol recovery and low effluent concentration while the vapor compression and membrane steps enable the efficient recovery of latent and sensible heat from both the retentate and permeate streams from the membrane system. Addition of the dephlegmator condenser reduces both compressor size and membrane area. Published 2013. This article is a U.S. Government work and is in the public domain in the USA

Chemical plants, oil refineries and petrochemical plants discharge wastewaters polluted with phenolic and nitrogen compounds. Denitrification is an economical and feasible process, however, metabolic and kinetic information is required in order to know and to control the limitations involved when nitrite is present or accumulated. The goal of this study was to study the kinetic behavior of a denitrifying sludge and to reduce nitrite at several p-cresol-C (p-Cr) concentrations.

Over the 10 to 45 mg p-Cr L⁻¹ concentration range tested, nitrite reduction was linked to p-Cr oxidation and the specific rate increased to 7.02 mg NO₂⁻-N g⁻¹ VSS h, with CO₂ and N₂ the products. At higher initial p-Cr concentrations, inhibition was observed, diminishing the specific rate to 1.60 mg NO₂⁻-N g⁻¹ VSS h. Electron balance showed that p-Cr consumption was carried out by two biological processes; denitrification and fermentation. The kinetic profile followed the Haldane model, with inhibition constant (K_i) of 35.75 mg p-Cr L⁻¹, affinity constant (Ks) of 20.32 mg p-Cr L⁻¹ and maximum specific nitrite reduction (q_max) of 9.48 mg NO₂⁻-N g⁻¹ VSS h.

The results suggest that p-cresol can be removed by denitrification and fermentation. Kinetic information should be considered for designing and operating denitrifying reactors to treat industrial wastewaters containing phenolic compounds and nitrite. © 2013 Society of Chemical Industry

To investigate the effects of post-translational modifications in different recombinant expression systems on the catalytic properties of recombinant β-glucuronidase. The β-glucuronidase (GUS) gene from Penicillium purpurogenum Li-3 was cloned and successfully expressed in Escherichia coli BL21 and Pichia pastoris G115.

The recombinant E. coli produced a 15-fold increased level of β-glucuronidase while the recombinant P. pastoris strain produced a 6.9-fold increased level of β-glucuronidase compared with their parent strains. The β-glucuronidases from recombinant E. coli (PGUS-E) and P. pastors (PGUS-P) were purified to 35.9- and 47.4-fold, respectively, through affinity, ion exchange and gel filtration chromatography. PGUS-E from E. coli was a non-glycosylated protein with an apparent molecular mass of 72.43 kDa, while PGUS-P from P. pastors was appropriately glycosylated with a molecular mass of 78.83 kDa measured by MALDI/TOF-MS. Although both recombinant β-glucuronidases exhibited similar pH optima, the glycosylated PGUS-P showed a significantly higher thermal stability and less sensitivity to metal ions compared with the non-glycosylated PGUS-E. The glycosylated PGUS-P also displayed lower K_m values, and higher k_cat/K_m ratios than the non-glycosylated enzyme towards glycyrrhizin.

These results revealed the key role of post-translational modifications in the P. pastors expression system on the catalytic properties of β-glucuronidase and its potential stability over the prokaryotic expression system which could be applied as an important tool for the functional enhancement of industrial enzymes. © 2013 Society of Chemical Industry

Acetone and tetrahydrofuran are commonly used as solvents in the chemical industry. The separation of acetone–tetrahydrofuran mixtures is often faced in the pharmaceutical and special chemical industries. As acetone and tetrahydrofuran can form a minimum azeotrope, they cannot be separated by conventional distillation. But acetone and tetrahydrofuran are important organic raw materials and solvents, so the mixture should be separated for reuse.

The process of continuous extractive distillation was used to separate the mixture of acetone (62% mass fraction) and tetrahydrofuran (38% mass fraction) using butyl ether as solvent. The characteristics of the continuous extractive distillation were simulated via ASPEN and experiments also showed the feasibility of separating the acetone–tetrahydrofuran mixture. Effects of the reflux mass ratio (R), mixture feed stage (FS), the solvent feed stage (SFS) on the extractive distillation column and the volume ratio of solvent to mixture (S/F) on the distillate mass fraction of acetone and bottom product mass fraction of acetone were investigated. The results of the extractive distillation simulation were verified by experiment data. With the following operation conditions for the extractive distillation column: number of theoretical plates 53; mixture feed at 24th plate; solvent feed at 7th plate, solvent to mixture ratio 3 and reflux mass ratio 3, the mass fraction of acetone in the distillate can reach 99%.

The process of continuous extractive distillation using butyl ether as solvent can separate the acetone–tetrahydrofuran mixture. The solvent to mixture ratio and reflux mass ratio are important factors that affect the mass fraction of the product. © 2013 Society of Chemical Industry

Studies with peroxidase (EC 1.11.1.7) have demonstrated that phenolic precipitate adsorbs free enzyme, inactivating it. The end-product inactivation model has been proposed to explain the effect. Additives, such as polyethylene glycol and Triton X-100, were reported to effectively extend enzyme lifetime by preventing the adsorption.

It was found that soybean peroxidase (SBP, EC 1.11.1.7) trapped in precipitate during phenol polymerization retains activity. Contrary to the end-product inactivation model, recycling precipitate effectively utilized the active SBP. The minimum SBP concentration required for the subsequent batch reaction removal of 1 mmol L^-1 phenol from aqueous solution was reduced from 1.2 to 0.5 U mL^-1. SBP adsorption on the precipitate was proven to be reversible by the addition of Triton X-100. Thus, a new explanation of SBP fate during the reaction is suggested: SBP is immobilized in situ in an active form with reduction of specific activity rather than inactivation. The adsorption is characterized by a Langmuir isotherm.

The phenolic precipitate immobilizes SBP in an active form, consistent with the Langmuir isotherm model. Recycling the precipitate improves the enzyme economy in phenol removal. © 2013 Society of Chemical Industry

Although the oxidative removal of organic compounds by the Al/O₂/acid system has been previously studied, the in situ generation of reactive oxygen species (ROS) and its influencing factors are not well understood. 2,4-dichlorophenol (2,4-DCP) is one of the priority control pollutants and widely present in the environment. In this study, the oxidative removal of 2,4-DCP by the Al/O₂/acid system was investigated, especially the in situ generation of ROS and influencing factors.

More than 90% of 2,4-DCP was removed within 10 h in pH 2.5 solutions initially containing 10 g L⁻¹ Al and 8.25 mg L⁻¹ dissolved oxygen. The removal of 2,4-DCP was acid and oxygen driven and was accompanied by the release of chloride ions. While the reduction of oxygen to H₂O₂ by Al was obtained only under conditions of pH < 4.0, the subsequent Al-mediated transformation of H₂O₂ to •OH was achieved under pH < 5.0 conditions. Furthermore, five primary intermediates were identified and oxidation pathways of 2,4-DCP by the Al/O₂/acid system were proposed.

This work describes a potential method for the removal of 2,4-DCP in aqueous environments. Oxygen levels and solution pH played important roles in the removal of 2,4-DCP by Al/O₂/acid system. © 2013 Society of Chemical Industry

In the present study, an electrochemical technique was used to remove nickel from aqueous solutions on a laboratory scale using a self-made Plexiglas cell. Electrodes comprising a stainless steel net coated with single-walled carbon nanotubes (SWCNTs@SSN) were used as both the anode and the cathode. The effects of various parameters on the percentage of nickel removed were investigated, including the solution pH, applied voltage, electrolyte concentration, and the amount of SWCNTs coated on the electrodes.

The optimal parameters were found to be pH 10.0, applied voltage 2.5 V, and electrolyte concentration 10 g dm^-3. Under optimal conditions, 95.1% of the nickel present in nickel-contaminated factory wastewater was removed. The mechanism of nickel removal was also investigated. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analyses showed that the nickel ions were being removed in the form of Ni(OH)₂, which was deposited on the cathode. The SWCNTs@SSN electrodes were regenerated easily.

The results of the study proved that the method is a potential technique for the treatment of industrial wastewater containing heavy-metal ions. © 2013 Society of Chemical Industry

The removal of tributyltin (TBT) from shipyard process wastewater using fly ash, activated carbon and fly ash/activated carbon composite was investigated.

Adsorption experiments performed on TBT-contaminated artificial process wastewater revealed that the adsorption capacity of TBT increases with increase in the adsorbent amount, contact time, pH, stirring speed and initial TBT concentration. The adsorption isotherms and the kinetic data were well described by the Freundlich and pseudo-second-order kinetic model, respectively. The negative values of the Gibbs energy change (ΔG^o) indicated the spontaneous nature of the adsorption and the positive values of the enthalpy change (ΔH^o) showed that the adsorption process is endothermic. Optimal conditions for the adsorption of TBT from contaminated artificial process wastewater were applied to TBT removal from natural shipyard process wastewater and the results showed that 94.2%, 99.2% and 99.8% TBT were removed by the fly ash, activated carbon and fly ash/activated carbon composite, respectively.

This study showed that the precursors as well as the composite could be employed as efficient adsorbents for the removal of TBT from contaminated shipyard process wastewater with the composite material exhibiting the highest adsorption efficiency. © 2013 Society of Chemical Industry

In nuclear medicine, the discharge of the radionuclides waste into the environment can cause serious environmental problems. It is preferable to remove these radionuclides from aqueous waste before discharging. Biosorption as an alternative has been becoming more important. The aim of the present work is to remove radioactive Tl-201 by biosorption from the aqueous media using the solid waste of an oleum rosea processing plant as a biosorbent.

Radioactive Tl-201 was removed from aqueous solution by biosorption in a stirred batch process with experimental parameters pH, temperature, adsorbent dose, nominal adsorbent size, and stirring speed. The effectiveness of the parameters in decreasing order was found to be initial pH, particle size and adsorbent dose. The biosorption yield is slightly reduced with increasing temperature, and no considerable effect of stirring speed was observed. The process is multi-layered on the heterogeneous surface and has a physical character. Negative ΔG showed that the process is spontaneous, and negative ΔH indicates that the process has exothermic character.

The process has serious potential because of its fast biosorption rate with an equilibrium period of about 10 min and high biosorption yields up to 93%. © 2013 Society of Chemical Industry

A tumor-targeted and pH-responsive drug release system based on poly(ethylene glycol) (PEG) and dodecylamine (DDA)-modified poly itaconic acid (PIA) with doxorubicin (DOX) and quantum dots (QDs) (PIA-PEG-DDA-DOX@QDs) has been constructed successfully. These nanocomposites with outstanding capabilities were further designed to target liver cancer cells with vascular endothelial growth factor receptor (VEGFR) overexpressed.

The nanoparticles constructed were spherical and monodispersed with very small diameter. The cumulative release rates of DOX conjugates were studied at pH 5.5 and pH 7.4, and the release behavior at pH 5.5 fit the first-order kinetics model, Q=46.5991 –45.2394e^-0.24355t for PIA-PEG-DDA-DOX and Q=46.7094–38.5588e^-0.20123t for PIA-PEG-DDA-DOX@QDs. The nanoparticles show low cytotoxicity at pH 7.4 and high cytotoxicity at pH 5.5 in cell viability studies. In the intracellular localization observation, the targeting molecule anti-VEGF conjugated NPs exhibited efficient receptor-mediated endocytosis in anti-VEGF receptor-overexpressing cancer cells, compared with nontargeted nanoparticles.

The targeting imaging and pH-responsive drug release system could target the tumor cells and fluoresce quantum dots sensitively due to the conjugation of VEGF, and enabled pH-controlled-activation of the DOX. The water soluble conjugates have the potential of becoming a promising diagnostic tool in clinical application for cancer detection and treatment. © 2013 Society of Chemical Industry

Biodiesel production is not economically competitive with petroleum diesel particularly when using virgin and refined vegetable oils. Rich-in-oil miscella obtained from the extraction of soybean oil with ethanol may be a promising feedstock for taking off the refining process, simultaneously introducing an environmental friendly step by replacing hexane by ethanol as a renewable solvent in the oil extraction process. The aim of this study was to investigate the production of biodiesel from the oil–ethanol miscella by direct transesterification using Novozym®435 as catalyst and ethanol as acyl acceptor; simultaneously optimizing the process by response surface methodology and enzyme reuse.

The best experimental conditions indicated by the empirical model were temperature 40 °C, oil:ethanol molar ratio 1:4.5 and catalyst concentration 9.5% for 24 h, reaching 85.4% fatty acid ethylic esters (FAEE) yield. Tert-butanol used as co-solvent increased the ethyl esters yield from 18%, keeping a high FAEE yield (over 70%) for more than 3 cycles of enzyme reuse.

Rich miscella has great potential as a low cost feedstock for biodiesel production when Novozym®435 is used as catalyst, simultaneously introducing an environmentally friendly step by using the renewable solvent ethanol in the extraction and transesterification. © 2013 Society of Chemical Industry

The efficiencies of removal of Cu²⁺, Cd²⁺, Ni²⁺, Pb²⁺, Fe²⁺, and Zn²⁺ from aqueous solution with olive stone activated carbon (OSAC) were investigated in this work. A central composite design (CCD) method was used to optimize the preparation of OSAC using microwave assisted potassium hydroxide.

The optimum conditions obtained were 565 W radiation power, 7 min radiation time, and 1.87 impregnation ratio. This resulted in 98.55% removal of Cu²⁺, 95.32% of Cd²⁺, 98.19% of Ni²⁺ 98.83% of Pb²⁺, 99.32% of Fe²⁺, 98.36% of Zn²⁺, and 85.15% of OSAC yield. The surface characteristics of the AC prepared under optimized conditions were examined by pore structure analysis, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The BET surface area, total pore volume and average pore diameter of the prepared AC were 1280.71 m² g⁻¹, 0.604 cm³ g⁻¹ and 4.63 nm, respectively. The equilibrium data of the adsorption was well fitted to the Langmuir equation and the highest value of adsorption capacity (Q) on the OSAC was found for Fe²⁺ (62.50 mg g⁻¹), followed by Pb²⁺ (23.47 mg g⁻¹), Cu²⁺ (22.73 mg g⁻¹), Zn²⁺ (15.08 mg g⁻¹), Ni²⁺ (12.00 mg g⁻¹), and Zn²⁺ (11.72 mg g⁻¹).

OSAC prepared by microwaves can be used for the removal of metals from contaminated wastewater. © 2013 Society of Chemical Industry

Bioreactors are widely used in the chemical, food and medical industries. However, enzyme immobilization in the bioreactor often results in the loss of activity and stability to varying degrees. To resolve the problem, a new functional conducting polymer monomer, 2,5-di(2-thienyl)-1H-pyrrole-1-(p-phenylacetic acid) (DPP), was designed, synthesized and electrodeposited on copper net to form ultrathin poly(DPP) film containing free carbonyl groups. Then, pseudomonas cepacia lipase was covalently coated on the film with 1-ethyl-3-(3-dimethyl-aminopropyl)-carbodiimide /N-hydroxy-succinimide as activator, and 1,3-di(isobutyl)-imidazolium hexafluorophosphate ionic liquid was finally coated on the surface of the film. In this study, an as-prepared bioreactor was employed for the resolution of (R,S)-1-phenylethanol to investigate catalytic characterization of the enzyme immoblized on the bioreactor.

The enzyme immobilized on the bioreactor offers high activity, reactivity and stability. Under optimal conditions, initial reaction rate, the conversion of (R,S)-1-phenylethanol and enantiomeric excess of (R)-1-phenylethyl acetate was 1.76 U mg^-1, 47.4% and 99%, respectively. Also, the stability of the lipase immobilized on the bioreactor was 5.1-fold that of the native lipase in hexane. The lipase immobilized on the bioreactor was recycled 10 times without substantial diminution in activity.

The functional conducting polymer combined with the ionic liquid for the enzyme immoblization provided good enzyme activity and stability. It is also promising for both the construction of bioreactors and industrialized continuous production. © 2013 Society of Chemical Industry

The main problem encountered during processing of cereals in distilleries, in particular by pressureless methods, is the relatively high viscosity of mashes that in turn retards their fermentation. It is caused by the extraction (along with starch) of pentosans, ß-glucans, cellulose and hemicelluloses from cereal grains.

Experiments carried out within this work centered on the determination of the effect of treatment of corn mashes with xylanase, pullulanase, cellulase enzyme complex and cellobiase on chemical composition, viscosity of these mashes and yield of fermentation. The treatment with xylanase caused the greatest decrease in viscosity of the corn mash, by c. 41% in relation to the reference mash (9.08 ± 0.45 mPa s). In the mash digested with pullulanase the ethanol yield was increased from 70.85 ± 0.71% (reference mash) to 76.09 ± 0.76% of theoretical. The most beneficial impact on the synthesis of ethanol was afforded by the treatment of mashes with cellulase enzyme complex preparation. The yield of ethanol reached 79.59 ± 0.8% of theoretical productivity and the intake of sugars was 92.85 ± 0.93%.

Under the optimal conditions found in these experiments, i.e. in corn mash supported with cellulase enzyme complex (CeluStar XL preparation) 61.69 ± 0.62 L of absolute ethanol could be obtained from 100 kg of starch. © 2013 Society of Chemical Industry

The anode material is considered a key factor influencing the energy conversion in microbial fuel cells (MFCs) because it links microbiology and electrochemistry. To further improve power generation, carbon mesh anodes modified by hydrazine hydrate chemical reduction were applied in air-cathode MFCs.

The power densities of MFCs using hydrazine-treated anodes were all higher than the untreated control, among which a 30% hydrazine hydrate-modified anode (CM-30%) showed the best performance. The maximum power density reached 865 mW m⁻², which was 31% higher than the unmodified control (CM-0%, 662 mW m⁻²). The Coulombic efficiency (CE) increased from 10.7% to 13.3% (improved by 24.3%). Furthermore, the acclimation time was reduced from 142 h to 95 h, shortened by 32% compared with the control. Such improvement in MFCs performance was correlated with the increased surface area revealed by scanning electron microscope (SEM) and the change of surface functional groups revealed by X-ray photoelectron spectroscopy (XPS) analysis. This enhancement in MFCs performance was also proved feasible when using real swine wastewater as substrate.

The results indicated that hydrazine hydrate chemical reduction was an effective method for anode modification to improve the performance of MFCs. © 2013 Society of Chemical Industry

Produced water (PW) is the most important wastewater of the oil industry and if disposed of without adequate treatment can cause serious environmental pollution. Biological treatment is one option explored in recent years for treatment of PW but traditional biological processes potentially fail when the salinity level of the PW is high. In the present study, a halophilic bacterial consortium was employed for treatment of high salinity synthetic PW in a membrane bioreactor (MBR).

During the 112 days operation of the MBR at hydraulic retention time (HRT) and sludge retention time (SRT) of 48 h and 80 days respectively, there was a consistently low turbidity in the MBR effluent. Oil and grease (O&G) content of the effluent was also consistently below international limits for discharge to the sea or re-injection to oil wells. With increase in organic loading rate from 0.3 to 0.9 kg COD m⁻³ d⁻¹, O&G removal efficiency increased from 89.2% to 95.5% whereas chemical oxygen demand (COD) removal efficiency (c. 83%) did not change. Also, the transmembrane pressure during operation of the MBR remained in the range 1–2 kPa.

The results of the present study indicate the very good potential of the MBR, both in terms of removal performance and membrane fouling, for treatment of high salinity PW. © 2013 Society of Chemical Industry

Polyhydroxybutyrate (PHB), an important member of the family of polyhydroxyalkanoates (PHAs), is a biodegradable thermoplastic synthesized by numerous microorganisms under different cultivation conditions.

A simple dynamic model for producing PHB in a fed-batch reactor is presented. The kinetic model accuracy is quantified by the specific error measures. The dynamic manipulation scheme with prescribed stepwise changes is used to improve PHB productivity. A multi-objective optimization algorithm is used to determine the optimal feeding strategy.

Reduced kinetic models in a mixed culture cultivation process for PHB production are successfully verified. An optimization-based feeding strategy with stepwise changes has been derived and successfully validated. © 2013 Society of Chemical Industry

It is vitally important to understand the effect of sub-/super-critical CO₂ pretreatment on enzyme conformation and its activity, which should improve the understanding of enzymatic biotransformation applications in nonaqueous media. This study evaluated the effect of sub-/super-critical CO₂ treatment, including pressure (6 and 10 MPa), exposure time (20, 30 and 150 min) and temperature (35 and 40 °C), on the conformation (e.g. 1D, 2D and 3D structures) and catalytic properties (e.g. residual activity, kinetics constants (K_m and V_max), activation energies (E_α), thermo-stability and organic solvent tolerance) of two commercial enzymes, CALB and lipase PS in their solution forms.

Compared with the blank control, the 1D structure of both treated lipases was unchanged, whereas their 2D and 3D structures were altered to some extent. The highest relative activities were 105% and 116% for CALB and lipase PS, respectively. For CALB, V_max/K_m value significantly increased, while for lipase PS, V_max/K_m value was almost constant. Both treated enzymes showed high thermo-stability with recovery of enzyme activity up to 76% and 80%, respectively. Also, both treated enzymes presented high organic solvent tolerance.

It was speculated that 2D, 3D structure alterations were probably responsible for the satisfactory catalytic properties of enzymes treated with sub-/super-critical CO₂. © 2013 Society of Chemical Industry

A surface thermodynamics approach can be utilized to understand protein interaction during adsorption chromatography. Ceramic hydroxyapatite has been widely used in the purification of biomolecules during downstream bio-processing. Protein interaction with this adsorbent is a complicated process.

In this work, interaction between model proteins and an adsorbent (ceramic hydroxyapatite Type I) was studied via extended DLVO (Derjaguin, Landau, Verwey and Overbeek) theory. The surface energy parameters of proteins and adsorbent were determined from experimental contact angle and zeta potential values. In ceramic hydroxyapatite chromatography, protein adsorption takes place under mixed mode conditions i.e. cationic exchange and calcium chelation. The sample is loaded in low salt and eluted at increasing phosphate gradient. The XDLVO approach calculated the free energy of interaction as a function of distance, between the interacting surfaces under de-binding conditions. The calculated interaction energy of the model proteins with CHT were correlated with the actual elution behavior. This revealed that all the proteins show minimum binding energies, i.e. |0.005| ± 0.002 kT under the observed conditions. These energy values are considered to be a cutoff between retaining and non-retaining conditions. Higher energy values will explain binding and lower energies will explain elution (binding > |0.005| kT > elution).

Knowledge generated from these studies will assist understanding of adsorption of proteins to the process supports which could facilitate better bioprocess design and optimization. © 2013 Society of Chemical Industry

Because of its rough surface and the hydrophobic property of porous activated carbon (AC) particles, it is more difficult to grow a zeolite layer on an AC surface than on metal oxides. The aim of the present study is the in situ hydrothermal synthesis of continuous ZSM-5 zeolite layer encapsulated porous AC particles (AC@ZSM-5) through an alumina intermediate layer strategy. To evaluate the effects of the zeolite layer on its catalytic application, active species (Co and Zr) were introduced into the AC and used for Fischer–Tropsch synthesis.

A continuous zeolite layer cannot be formed on the surface of the irregular AC particles, even when pretreated by air oxidation or concentrated nitric acid, but can be synthesized using the alumina intermediate layer method. A catalytic test of CoZr/AC@ZSM-5 indicates that the zeolite layer shell has a marked effect on product distributions.

Aided by the alumina intermediate layer, zeolite crystals nucleate at the support/solution interface rather than in solution. For Fischer–Tropsch synthesis over CoZr/AC@ZSM-5, the product distributions are shifted to methane and light hydrocarbon compared with that of CoZr/AC. © 2013 Society of Chemical Industry

Polymalic acid (PMA) is a water-soluble polyester with many attractive properties for biomedical application. Its monomer L-malic acid is widely used in the food industry and is also a potential C4 platform chemical. Hydrolysate of raw sweet potato as a low-cost renewable feedstock was applied for the production of PMA by immobilized Aureobasidium pullulans cells in an aerobic fibrous bed bioreactor system (AFBB).

Under the initial hydrolysate sugar concentration 120 g L^-1, yeast extract 5 g L^-1, and citrate 7.5 g L^-1, PMA production in a shake flask was improved. Comparison of the kinetics of fed-batch immobilized-cell fermentation using the AFBB with those of batch or fed-batch free-cell fermentation in a 5 L fermentor showed that immobilized-cell fermentation gave much higher PMA production and productivity. The maximum PMA production and productivity in AFBB were 57.5 g L^-1 and 0.34 g L^-1 h, which was 30.6% and 21.4% higher than that in free-cell mode.

Raw sweet potato is an efficient renewable feedstock for PMA fermentation. This present work demonstrated the great potential of AFBB and renewable feedstocks for the economical production of PMA and malic acid at industrial scale. © 2013 Society of Chemical Industry

Two pilot scale horizontal subsurface flow constructed wetlands (HSFCWs), with a planted area of 15 m² each, were constructed in Puglia, Italy, and planted with hydrophytes (Phragmites australis and Typha latifolia), while a similar field of equal size was used as a control. The primary aim of the present work was to assess the removal of three heavy metals from waste water, in relation to the evapotranspiration, using HSFCWs.

Residence time distributions in both planted HSFCWs indicated that the Typha field had porosity of 0.16 and exhibited more ideal plug flow behavior (Pe = 29.7), compared with the Phragmites field (Pe = 26.7), which had similar porosity. The measured hydraulic residence times in the planted fields were 35.8 and 36.7 h, for Typha and Phragmites, respectively, at waste water flow rates of 1 m³ d⁻¹ (corresponding to hydraulic loading rate of 66.7 mm d⁻¹). Heavy metals concentrations at the inlet were 2 mg/L, for each heavy metal, while at the outlet of the fields were Cr = 0.23 mg L⁻¹, Pb = 0.21 mg L⁻¹ and Fe = 0.18 mg L⁻¹ in the Phragmites field, and the removal rates were 87, 88 and 92% of Cr, Pb and Fe, respectively. The Typha field showed a similar behavior with concentrations equal to Cr = 0.19 mg L⁻¹, Pb = 0.23 mg L⁻¹ and Fe = 0.16 mg L⁻¹ and removal percentages of 90, 87, and 95% of Cr, Pb and Fe, respectively. The control field showed metal removals slightly lower (86, 78 and 88% for Cr, Pb and Fe, respectively).

HSFCWs are appropriate for removing heavy metals from waste water. Evapotranspiration may significantly reduce the amount of discharged flow and may influence the removal rate of heavy metals. © 2013 Society of Chemical Industry

This study compared the physical-chemical characteristics and the nutrient potential of brewery wastewater (BWW) and apple juice industry sludge referred to as pomace (POM). The use of these wastes as alternative nutrients by replacing the standard components (soya flour, wheat germ and yeast extract) allowed production of a balanced diet for rearing codling moth (CM) larvae.

The hydrolysis pretreatment (100 °C/30 min) contributed to enhancing the nutritive potential (almost 600%) and improved the viscosity (decreased from 770.5 to 435 mPa s for BWW and from 460 to 383 mPa s for POM) of the waste. The BWWH+SF diet supplied higher assimilated nutrients (2.071 mg proteins, 2.274 mg carbohydrates and 0.974 mg lipids) showing higher breeding efficiency (93% hatching, 85% larvae, 76% cocoon and 70% adults). Furthermore, the results of the larvae breeding on BWWH+SF diet was the best which for the enzymatic activity (59.7 UI mL^-1 protease, 2.9 mg L⁻¹ amylase and 1.93 U mg⁻¹ lipase), consumption rates of proteins (451.79 mg kg⁻¹), carbohydrates (396.43 mg kg⁻¹) and lipids (91.07 mg kg⁻¹) consumed on these diets.

BWWH+SF was the best diet with respect to enzymatic activity, consumption of nutrients and larval breeding efficiency compared with POMH+SF and the standard diet. © 2013 Society of Chemical Industry

A study of the effect of different ion exchange resins, Amberlyst 15, Amberlite 200 and Amberlite IRC-50, on glycerol etherification with tert-butyl alcohol was performed. The best catalyst was selected based on the activity and selectivity values. The capability of reusing this catalyst after different pre-treatments was analysed. A kinetic model was developed including the effect of catalyst concentration and temperature.

Amberlyst 15 led to the highest glycerol conversion, the highest product yield, and it could be reused following proper pre-treatment with methanol. The effect of catalyst concentration was evaluated and included in a previous kinetic model. Simulated results were found to be suitably fitted to the experimental ones.

The high activity value of Amberlyst 15 is related to its high acidity and better textural properties. Reuse of this catalyst was possible with an appropriate previous treatment. A kinetic model was validated including the effect of catalyst concentration and temperature on reactants conversion and products distribution. © 2013 Society of Chemical Industry

Bio-recovery of metals from dilute industrial waste using bacteria is a promising alternative to primary raw material resources. Therefore, the search for and identification of palladium resistant bacteria with the ability to remove that metal from solutions is very important. The main goal of this study was to find a palladium(II) resistant bacterial community able to bio-recover this metal from solution.

A palladium(II) resistant bacterial community able to precipitate that metal from the growth medium was obtained from a sludge sample from a municipal waste water treatment plant. This community was able to remove 60% of palladium(II) from an aqueous solution containing 18 mg L^-1 of Pd(II) and 43% in the presence of 26 mg L^-1 Pd(II) plus sulphate. TEM-EDS analysis showed the presence of nanosized palladium deposits in the surface of cells. Phylogenetic analysis of the 16S rRNA gene showed that this community was mainly composed of bacteria closely related to several Clostridium species. However, bacteria affiliated to genera Bacteroides and Citrobacter were also present in the community.

The current study for the first time reports the bio-recovery of Pd(II) as nanoparticles by a bacterial consortium, and is a relevant demonstration of the biotechnological potentialities of this community. © 2013 Society of Chemical Industry

Biological methods for metal nanoparticle synthesis using plant extracts have been suggested as possible ecofriendly alternatives to chemical and physical methods. In the present study, copper nanoparticles were biologically synthesized using Magnolia kobus leaf extract as reducing agent and their antibacterial activity was evaluated against Escherichia coli.

On treatment of aqueous solution of CuSO₄·5H₂O with Magnolia kobus leaf extract, stable copper nanoparticles were formed. UV–vis spectroscopy was used to monitor the quantitative formation of copper nanoparticles. The synthesized nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HR-TEM). Electron microscopy analysis of copper nanoparticles indicated that they ranged in average size from 37 to 110 nm. Antibacterial tests were carried out by counting viable E. coli cells after 24 h growth in shake flasks containing latex foams coated with copper nanoparticles. As a result, foams coated with biologically synthesized copper nanoparticles showed higher antibacterial activity compared with foams untreated and foams treated with chemically synthesized copper nanoparticles using sodium borohydride and Tween 20. The antibacterial activities were inversely proportional to the average nanoparticle sizes.

The present results show that stable copper nanoparticles can be ecofriendly synthesized using Magnolia kobus leaf extract, offering an inexpensive alternative to antibacterial silver nanoparticles. © 2013 Society of Chemical Industry

A validated model describing the nitritation-anammox process in a granular sequencing batch reactor (SBR) system is an important tool for: (a) design of future experiments; and (b) prediction of process performance during optimization, while applying process control, or during system scale-up.

A model was calibrated using a step-wise procedure customized for the specific needs of the system. The important steps in the procedure were initialization, steady-state and dynamic calibration, and validation. A fast and effective initialization approach was developed to approximate pseudo steady-state in the biofilm system. For oxygen mass transfer coefficient (k_La) estimation, long-term data, removal efficiencies, and the stoichiometry of the reactions were used. For the dynamic calibration a pragmatic model fitting approach was used – in this case an iterative Monte Carlo based screening of the parameter space – to find the best fit of the model to dynamic data. Finally, the calibrated model was validated with an independent data set.

The calibration procedure presented is the first customized procedure for this type of system and is expected to contribute to achieving a fast and effective model calibration, an important enabling tool for various biochemical engineering design, control and operation problems. © 2013 Society of Chemical Industry

Biodiesel is an alternative to fossil fuels and can be used directly in internal combustion engines when mixed with diesel. The economic feasibility of biodiesel production necessitates the valorisation of glycerol, which is produced in large quantities (equal to 10% of the biodiesel produced). Anaerobic digestion is applicable to a variety of organic residues yielding biogas rich in methane. In order to estimate the net potential of glycerol to yield methane, pure glycerol was selected to avoid any effect from the impurities in crude glycerol.

The anaerobic digestion of pure glycerol was studied in two types of bioreactors: a continuous stirred tank reactor (CSTR) and a baffled reactor (periodic anaerobic baffled reactor, PABR). Both reactors were operated in mesophilic conditions (35 °C) at various organic loading rates. The maximum glycerol loading achieved in a CSTR was 0.25 g COD L^–1 d^–1, yielding 0.074 ± 0.009 L CH₄ L^–1 d^–1. On the other hand, PABR allowed glycerol degradation at a loading of 3 g COD L^–1 d^–1 yielding 0.993 ± 0.102 L CH₄ L^–1 d^–1.

PABR was proved to be more efficient since it was subjected to a 10-fold higher organic loading rate than CSTR. Moreover, its performance was much higher in terms of COD removal and methane productivity. © 2013 Society of Chemical Industry

Oligoamides containing intramolecular hydrogen bonds have proved to be excellent extractants for metal cations, but their polymeric counterparts have never been used. Thorium separation from rare earth elements has long been a research subject due to its importance in nuclear energy and metallurgy. In this work a novel polyaramide has been synthesized and investigated for solvent extraction and separation of thorium and rare earths.

The synthesized polymer 1 [(C₃₂H₄₆N₂O₆)_n], shows a high extractability of 89.4% towards Th(IV) compared with only 36–48% for rare earths. The optimized pH value for extraction of Th(IV) was 3.97. At C₁/C_M = 2.0, the extraction for Th(IV) reached 95.1%. When adding NaNO₃, the separation of Th(IV) from La(III) is more efficient than that from Eu(III) or Yb(III), especially at higher NaNO₃ concentration. Th(IV) can be thoroughly stripped from organic phase at 1.50 mol L^-1 HNO₃ concentration.

Direct condensation of aromatic diamine and diacid led to a novel polyaramide with introverted chelating groups. Selective extraction of Th(IV) with respect to rare earths was observed and the extraction was an endothermic process. The salting-out agent and C₁/C_M ratio can affect the separation efficiency. Thus, the polymer 1 may be a potential candidate for separating thorium and rare earths under specified conditions. © 2013 Society of Chemical Industry

In order to conserve resources without affecting the environment, an energy efficient leaching process has been studied to recover platinum group metals (PGMs) from spent automotive catalyst using electro-generated chlorine as a strong oxidant in a separate reactor.

The different process parameters studied showed an increase in the dissolution of PGMs (Pt, Pd, Rh) with HCl concentration, current density, time, and temperature but not pulp density. Leaching efficiencies of 71% Pt, 68% Pd and 60% Rh were obtained under the optimized conditions of 6.0 mol L⁻¹ HCl, 714 A m⁻² current density, 363 K, 20 g L⁻¹ pulp density, 700 rpm agitation speed. The PGMs dissolution kinetics followed ash diffusion control with activation energies for Pt, Pd and Rh of 29.6, 26.4, 20.6 in kJ mol⁻¹, respectively over the temperature range 298–363 K. The leaching studies carried out after treatment with 20% formic acid at room temperature showed a remarkable increase in dissolution efficiencies to 97% Pt, 94% Pd and 90% Rh.

A process for the leaching of PGMs using electro-generated chlorine showed almost total dissolution of PGMs in hydrochloric acid solution after pretreatment of the spent automotive catalyst with formic acid. The proposed leaching system is eco-friendly and has high leaching ability for PGMs from spent materials. © 2013 Society of Chemical Industry

This paper reports an extractant screening study for the recovery of putrescine (butylene-1,4-diamine, BDA) and cadaverine (pentylene-1,5-diamine, PDA) from aqueous solutions (e.g. fermentation broths) by liquid–liquid extraction. Several extractants were studied, including 4-nonylphenol, 3,4-bis((2-ethylhexyl)oxy)phenol, di-2-ethylhexyl phosphoric acid (D2EHPA), Versatic acid 1019, di-nonyl-naphthalene-sulfonic acid (DNNSA), and 4-octylbenzaldehyde. 1-Octanol, 2-octyl-1-dodecanol and heptane were used as diluents, and temperatures of 25 °C and 65 °C.

The most promising solvent is 4-nonylphenol, hardly leaching into the aqueous raffinate (19 ppm), and showing BDA distribution coefficients very strongly dependent on the extractant concentration, ranging from very low distribution ( D ∼ 1 at <20 wt% 4-nonylphenol in 1-octanol at 25 °C) to high distribution (D > 100) for pure 4-nonylphenol at 25 °C. The strong dependency of the distribution on extract phase composition was applied to efficiently back-extract up to 90% BDA in a single step. To achieve this, the pure 4-nonylphenol used in extraction was diluted to a 20 wt% dilution in 1-octanol. The use of 4-nonylphenol as extractant was also examined for PDA, and higher distributions were observed than for BDA, which can be attributed to the longer hydrocarbon chain of PDA.

Recovery of diamines from aqueous medium can be accomplished in an effective way using 4-nonylphenol as extractant. These results may be used to develop a bio-based butylene-1,4-diamine production route. © 2013 Society of Chemical Industry

Enantioselective liquid–liquid extraction is a very attractive technology for the production of enantiomerically pure compounds. The objective of this research is to investigate enantioselective liquid–liquid extraction of valine (Val) enantiomers with metal–BINAP complexes as enantioselective extractants.

Results show that BINAP complex with copper(I) as central ion allows the separation of Val enantiomers with the highest operational selectivity. Efficiency of the extraction depends, often strongly, on a number of process variables, including types of organic solvents, pH of the aqueous phase, concentration of host and substrate, and temperature. Extraction performance of the system can be accurately predicted by the model. By modeling and experiment, an optimal extraction condition was obtained at a pH of 8 and the host concentration of 2.0 × 10^-3 mol L^-1 with the highest enantioselective (α) of 3.65 and performance factor (pf) of 0.086.

The presented data indicate that Val enantiomers can be efficiently separated by enantioselective liquid–liquid extraction. The model provides a powerful tool for calculating distribution ratio, enantioselectivity, enantiomeric excess and performance factor. It can be used for optimization of the reactive extraction systems. This paper can provide some valuable fundamental data for the production of enantiomerically pure amino acid enantiomers. © 2013 Society of Chemical Industry

Exopolysaccharides (EPS) from mushrooms have many health properties such as anti-tumor effect and immunoenhancing activity. Light-emitting diodes (LEDs) with various light wavelengths (red, yellow, green, blue and white) were applied to study the effects on mycelial growth and EPS production of Pleurotus eryngii.

In solid-state culture, red and yellow light showed stimulatory effects on P. eryngii hyphal growth. In submerged culture, darkness was the best condition for biomass production. The highest EPS production was obtained when using blue light, where the EPS production and specific EPS production rates were 455 mg L^-1 and 79.8 mg g^-1 dry-cell-weight day^-1, respectively.

The results indicate that a decreasing biomass and an increasing EPS yield in P. eryngii culture were obtained with decreased light wavelength. © 2013 Society of Chemical Industry

Glycerin is produced as an 11% by-product in biodiesel manufacturing. Impurities are concentrated in the glycerin phase. High-vacuum distillation of glycerin is an energy-intensive process. A new low-cost purification strategy for glycerin is needed. This paper reports the refining of the glycerin phase obtained from palm-oil biodiesel synthesis by ion-exchange with cationic resins. In the literature and to the best of the authors' knowledge, the use of a real glycerin phase from biodiesel has not been reported. The ion-exchange equilibrium was determined in a batch process, while variables for the industrial scaling-up were studied in continuous operation.

The sodium content obtained with low amounts of resin is lower than that obtained with mineral-acid refining. Almost complete sodium removal could be achieved in continuous operation. Langmuir and Freundlich models give a good fit to the equilibrium data. Amberlyst was the best resin. Breakthrough capacity was 96% of static exchange capacity. 95% of the static ion exchange was recovered by washing with water-soap.

A 96.6% purification level of glycerol was obtained with the resin Amberlyst 15, using a methanol content of 60%, liquid phase flow of 0.8 mL min⁻¹ and 0.3 g resin g⁻¹ glycerin phase; dynamic exchange capacity was 96% of the static exchange capacity. Exchange capacity is almost completely regenerated by washing with water-soap. © 2013 Society of Chemical Industry

The post-denitritation sequencing batch reactor (SBR) is widely-used and can achieve high levels of nitrogen removal. In this study the effect of influent COD/TN (total nitrogen) ratio (i.e. C/N ratio) on nitrogen removal performance was investigated.

The experimental results showed that polyhydroxybutyrate (PHB) was the internal carbon source for denitritation, so PHB degradation rate following first-order kinetics was the rate-limiting step both for simultaneous nitritation–denitritation (SND) in the substrate famine period of the oxic stage and endogenous denitritation in the anoxic stage. Higher influent C/N ratio resulted in more PHB fractions in microorganisms, which facilitated a higher efficiency of SND and a faster endogenous denitritation rate (DNR). Consequently, mean TN removal ratio in oxic stage dropped from 32.81% to 8.61%, and average endogenous DNR in the anoxic stage fell from 1.50 to 0.27 mgN h^-1 gVSS^-1, when influent C/N ratio changed from 6.82 to 1.89. Furthermore, PHB fraction in the biomass did not drop drastically when influent C/N ratio dropped for a short-term period, which facilitated better resistance to shock loads.

High influent C/N ration benefits nitrogen removal in this process, and an influent C/N ratio of 4.00 was suitable for advanced nitrogen removal. © 2013 Society of Chemical Industry

A passive planar micromixer with dislocation sub-channels, based on the principle of planar asymmetric split and recombination, has been proposed for its effective mixing. Both numerical simulations and experiments were used to design and investigate the effect of parameters and flowing feature on mixing with Reynolds numbers ranging from 1 to 100. The mixing index, which is used as the measurement criteria, is dependent upon Reynolds number and geometrical parameters.

Through the results of numerical and experimental simulation, it is evident that the arrangement of dislocation sub-channel structure will result in better fluid mixing owing to the combination of the unbalanced inertial collisions, the multidirectional vortices and the collision-induced flow in mixing cavities between every two-looped structure. The effect of transverse Dean Vortices in the vertical plane and expansion vortices in the horizontal plane is beneficial for the increased interfacial area between two species and promoting mixing. The increased width ratio, w₃/w₄, provided by the dislocation structures, results in better mixing performance, but also causes a higher pressure drop. Experimental results allow better validation of the mixing efficiency of this micromixer.

The best mixing performance was achieved with width ratio of the dislocation sub-channels at w₃/w₄ = 1.0 and Reynolds numbers less than 80. To consider the mixing effect and the packaging requirements of the experiment, the mixing index of the micromixer with a dislocation sub-channel can reach 86%. © 2013 Society of Chemical Industry

The present study reports the functionalization of multiwalled carbon nanotubes (MWCNTs) with vinyl groups through nitric acid oxidation along with reaction with allylamine. MWCNTs based imprinted polymer (MWCNT-MIP) were synthesized by means of methacrylic acid (MAA) as the monomer, trimethylol propane trimethacrylate (TRIM) as the cross linker, α, αʹ-azobisisobutyronitrile (AIBN) as the initiator and chlorpyrifos (CPF), an organophosphate pesticide molecule as the template.

The prepared material was characterized by means of FTIR, XRD and SEM analysis. The competence of MWCNT-MIP to adsorb CPF from aqueous solutions was calculated. The maximum adsorption was found to be at pH 7.0 and adsorption capability attained saturation in 3 h. The kinetic information was found to follow pseudo-second-order model, indicating chemisorption. The strong conformity of equilibrium data with the Langmuir isotherm model confirms the monolayer coverage of CPF on the MWCNT-MIP surface. The maximum adsorption ability based on the Langmuir isotherm model was found to be 38.14 mg g⁻¹ at 30°C. The spent adsorbent was successfully regenerated by means of 0.1 mol L⁻¹ CH₃COOH.

Analysis revealed that MWCNT-MIP could be a useful substance for the removal of CPF from aqueous solutions. © 2013 Society of Chemical Industry

To operate the fermentation process effectively and efficiently, the kinetic modeling of cell growth and ethanol fermentation is necessary to predict the results of industrial fermentations under the optimized conditions.

A kinetic study was conducted for glucose utilization for growth of the yeast strain Kluyveromyces sp. IIPE453 and ethanol formation. Effect of temperature, pH and initial glucose concentration on cell growth and ethanol formation was studied. The data obtained experimentally were validated with existing kinetic models for product and/or substrate inhibition.

Of all the models, the Aiba model for substrate inhibition was found to be the best fit to the experimental data for the growth of Kluyveromyces sp. IIPE453, and the Luong model for product inhibition was found to be the best fit for ethanol formation using Kluyveromyces sp. IIPE453. © 2013 Society of Chemical Industry

In this study, the efficiency of Guar gum as a biopolymer has been compared with two other widely used inorganic coagulants, ferric chloride (FeCl₃) and aluminum chloride (AlCl₃), for the treatment of effluent collected from the rubber-washing tanks of a rubber concentrate factory. Settling velocity distribution curves were plotted to demonstrate the flocculating effect of FeCl₃, AlCl₃ and Guar gum. FeCl₃ and AlCl₃ displayed better turbidity removal than Guar gum at all settling velocities.

FeCl₃, AlCl₃ and Guar gum removed 92.8%, 88.2% and 88.1% turbidity, respectively, of raw wastewater at a settling velocity of 0.1 cm min⁻¹, respectively. Scanning electron microscopic (SEM) study conducted on the flocs revealed that Guar gum and FeCl₃produced strong intercoiled honeycomb patterned floc structure capable of entrapping suspended particulate matter. Statistical experimental design Response Surface Methodology (RSM) was used to design all experiments, where the type and dosage of flocculant, pH and mixing speed were taken as control factors and, an optimum operational setting was proposed.

Due to biodegradability issues, the use of Guar gum as a flocculating agent for wastewater treatment in industry is highly recommended. © 2013 Society of Chemical Industry

Water pollution is a serious problem for the entire world. Photocatalysis is an accepted way to decontaminate water. As the key factor influencing photocatalysis, an environmentally friendly photocatalyst should possess good visible-light-response. Additionally, an efficient catalyst should have good separation of e^-/h⁺ pairs. On account of the special f electron orbital structure, the ions of rare earths exhibit the ability to accelerate the abruption of photogenerated e^-/h⁺ pairs. In this work, visible-light-driven α-Bi₂O₃ enhanced using Pr³⁺ doping was prepared by hydrothermal synthesis.

The as-prepared catalysts calcined at 500 °C exhibited only the characteristic peaks of Bi₂O₃ and presented irregular plate-like structures. The separation efficiency for electron–hole was enhanced when α-Bi₂O₃ was doped with Pr. The photocatalytic activities, which were evaluated by degradation of Rhodamine B (RhB) and 2,4-dichlorophenol (2,4-DCP) under visible light irradiation, was enhanced significantly by doping Pr into α-Bi₂O₃.

Doping α-Bi₂O₃ with Pr significantly enhanced the photocatalytic activity. The optimum percentage of doped pr was 3.0 mol %. ·OH radicals were the dominant photooxidant. This study demonstrates an efficient pathway to improve the photocatalytic performance of α-Bi₂O₃. © 2013 Society of Chemical Industry

Production of lysophosphatidylcholine (LPC) via enzyme-catalysed hydrolysis was studied. Three enzymes were employed to conduct the reactions at different temperatures. The starting material, phosphatidylcholine (PC), was dispersed in water (system A) and in ethanol (system B) to define the reaction mixture to carry out the trials.

It was found that the media employed and the type of biocatalyst (free or immobilized), clearly determine the kinetics of the reactions. PC was well dissolved in ethanol but an opaque emulsion was obtained when it was dissolved in water. Immobilized PLA₁ and Novozym 435 were able to convert PC into LPC in ethanol, with yields of 50% and 58.51%, respectively, after 48 h at 50 °C. The highest degree of hydrolysis (70%) was reached with Lipase PS after 48 h at 60 °C in water.

Both reaction media enabled fairly good yields but water was better. The present work proposes a simple reaction scheme compared with other reports in the literature where different substrates, additives and polar solvents have been employed. LPC has interesting properties as a bioemulsifier, which led us to develop new methods for its production. © 2013 Society of Chemical Industry

Pretreatment methods used to break down lignocellulose structure lead to the generation of compounds that inhibit ethanol fermentation. Hence, removal of these compounds is essential for improved fermentability. The surfactant-based cloud point extraction (CPE) aqueous two phase system is a new method having the potential for separation and recovery of inhibitors. The present work examines the potential of surfactants-based CPE systems as a detoxification method.

Surfactants L62D and L62LF achieved more than 90% removal of phenolic compounds and less than 20% removal of acetic acid and HMF from a model system when the surfactant concentration was 1% and 5%. With untreated simulated hydrolysate containing inhibitors the fermentation was inhibited completely. Detoxification of the same hydrolysate with L62D (1% and 5%) and L62LF (1% and 5%) showed complete fermentation with high ethanol productivity (0.61 g L^-1 h^-1). Similarly, the detoxified corn stover hydrolysate showed delayed fermentation. The productivity increased by 30% after detoxification with 1% of the two surfactants and by 100% with 5% of the surfactants (L62D and L62LF).

The new surfactant-based detoxification method significantly improved the fermentability of simulated hydrolysate and corn stover hydrolysate. © 2013 Society of Chemical Industry

The press juices resulting from a compacting operation on fish by-products were subjected to a depuration treatment in order to reduce the high COD (120 g O₂ L^–1). The process included an initial de-particulation step by means of two metallic filter cartridges of 465 µm and 250 µm, followed by concentration with a 200 nm ultrafiltration ceramic membrane. The polishing efficiency of each unit was assessed in terms of COD and protein removal.

Dead-end metallic filtration of the press waters reduced their suspended matter content by 28%, but achieved only 5.6% decrease in chemical oxygen demand (COD), which suggested further processing by membrane ultrafiltration. The de-particulated stream was then subjected to ultrafiltration for 8 h in batch concentration mode, attaining a COD reduction of 87%. The observed flux of permeate was successfully fitted to a cake-forming model adapted to cross-flow filtration. The permeability of the fouled membrane was completely restored (99.87%) by a cleaning treatment comprising an alkali step with NaOH and a final disinfection with NaOCl.

The treatment proposed has proved to be a feasible technology, able to render a final permeate with reduced organic load. © 2013 Society of Chemical Industry

Thorium is a natural radioactive element which is often associated in different minerals with rare earth elements (REs). In order to satisfy application for nuclear fuel, thorium should be separated from REs and other elements. Calixarene derivatives have been proved to be excellent extractants towards thorium and REs. In this study, a p-phosphorylated calixarene derivative was applied for extraction and separation of thorium and REs.

p-phosphorylated calix[4]arene, 5,11,17,23-tetra(diethoxyphosphoryl)- 25,26,27,28-tetrapropyloxy-calix[4]arene (L), exhibits good selectivity towards thorium which is extracted into the organic phase as Th(NO₃)₄·3 L. The thermodynamic functions, ΔH, ΔG, and ΔS have been calculated as 5.55 kJ mol⁻¹, −57.28 kJ mol⁻¹ and 210.84 J mol⁻¹ K⁻¹, respectively. The salting-out agents (NaNO₃ and KNO₃) can weaken the separation of Th and Yb but barely affects the separation of Th and La or Gd.

The extraction of thorium with the calixarene derivative occurs with a neutral extraction mechanism and the extraction reaction of thorium is an endothermic process. This ligand exhibits high extraction ability towards thorium over a wide range of acidity while the extraction of REs changes more with the solution acidity. Added salts can affect the separation of thorium and REs. This ligand may be used to separate thorium from REs under appropriate conditions. © 2013 Society of Chemical Industry

Large improvements in productivity are required to make massive scale biodiesel production from microalgae an economic reality. Although the maximum neutral lipid content of microalgae has received much attention as a target for optimization, there are other factors that are equally important. These are (1) the rates of accumulation of both biomass and lipids and (2) the maximum densities of algal cells that can be sustained in continuous cultivation. The combined effect of these factors for lipid production has not been thoroughly examined in Dunaliella species. Hence this study examines the rates of growth and lipid accumulation in Dunaliella salina using Fourier transform infrared spectroscopy (FTIR) under several combinations of temperatures and cell densities.

The FTIR signal at 2926 cm⁻¹ (rather than 1740 cm⁻¹) is better for measuring lipids and the PCA of the full spectrum showed a clear separation between the nitrogen replete and nitrogen depleted cells. As expected, cells subjected to nitrogen starvation (N-depleted) showed very little growth compared to the N-replete cells. N-depleted cells achieved a final lipid content that was 78% more than the N-replete samples at 26 °C, while the differential for 16 °C was 28%. However, the slower growth rates caused by the stress of nitrogen starvation meant that the total lipid production over the starvation period was lower for many samples. Indeed, the only stress condition that gave significantly higher total lipid production was the highest cell density studied at 26 °C.

For optimization of lipid productivity for biodiesel, the trade-off between lipid content, growth rate and cell density needs to be considered. © 2013 Society of Chemical Industry

This study introduces a method for simultaneous removal of 2-mercaptobenzoxazole (2MBO) and 2-mercaptobenzothiazole (2MBT) from water samples. The method uses a cartridge loaded with copper oxide nanoparticles as an efficient adsorbent to separate these hazardous mercaptans from aqueous solutions in a flow process.

The effects of some important parameters such as amounts of adsorbent, pH, buffer type and its volume, electrolyte concentration, contact time, flow rate, tolerable volume of solution, reusability of cartridges and interfering ions on removal efficiency were studied. Data on adsorption were analyzed using linear and non-linear forms of first- and second-order kinetic equations and also Langmuir and Freundlich isotherm models and results showed that maximum adsorption amounts of 90.9 mg g⁻¹ and 158.7 mg g⁻¹, were obtained for 2MBO and 2MBT, respectively.

The proposed removal method is independent of pH level of the sample solution and is effective over a wide range of pH values. Using a copper oxide nanoparticle loaded cartridge (CONLC) has the advantage that there is no need to collect nanoparticles after the removal process and that CONLC can be reused for further removal processes (at least three times). This method was successfully applied to remove 2MBT (≥95% removal) from the cooling water of a 3000 MW power plant. © 2013 Society of Chemical Industry

Improvement of the mammalian cell culture process is based on the implementation of culture strategies with higher productivities, such as fed-batch or perfusion processes. The efficient development of these culture strategies depends strongly on the availability of suitable monitoring tools to determine the activity of cell culture and adjust nutrient feeding correspondingly.

In this study oxygen uptake rate (OUR), cell density and glucose concentration on-line monitoring systems are applied to control fed-batch processes. Different combinations of these monitoring systems were used to determine cell growth and metabolic activity of cell culture in order to adjust substrate feeding in a balanced manner. Application of these monitoring tools in fed-batch processes allowed extension of the exponential growth of hybridoma cells up to 2–3-fold and increased antibody productivity from 84 to 168% with respect to conventional batch culture.

The three control strategies tested have been successful in providing improvement of the fed-batch culture of the hybridoma cell line used. Among the different alternatives studied, the use of OUR on-line monitoring to simultaneously determine cell growth and metabolic activity appears to be the best method to adjust substrate feeding owing to its simplicity and robustness. © 2012 Society of Chemical Industry

Effects of co-substrate sorbitol different feeding strategies on recombinant human growth hormone (rhGH) production by Pichia pastoris hGH-Mut⁺ were investigated by eight designed experiments grouped as: (i) fed-batch methanol feeding without the co-substrate; (ii) fed-batch methanol feeding with pulse sorbitol feeding; (iii) fed-batch methanol feeding together with fed-batch sorbitol feeding at t = 0–15 h, followed by fed-batch methanol feeding; and (iv) fed-batch methanol and sorbitol feeding at t = 0–30 h, followed with fed-batch methanol feeding.

The highest rhGH and cell concentrations were achieved, respectively, as 0.64 g L⁻¹ and 105 g L⁻¹ at t = 42 h of induction phase, with the strategy where methanol was fed to the system at a pre-determined feeding rate of μ_M0=0.03 h⁻¹, and sorbitol concentration was kept at 50 g L⁻¹ at t = 0–15 h of the rhGH production phase where the specific growth rate on sorbitol was μ_S0=0.025 h⁻¹. The overall cell and product yield on total substrate were found as 0.26 g g⁻¹ and 2.26 mg g⁻¹, respectively.

This work demonstrates that co-carbon source, sorbitol, feeding strategy is as important as methanol feeding strategy in recombinant protein production by Mut⁺ strains of P. pastoris. © 2013 Society of Chemical Industry

The coenzyme NAD⁺ (nicotinamide adenine dinucleotide) is commonly used in biocatalytic oxidations catalysed by the enzyme alcohol dehydrogenase (ADH). As the price of the coenzyme NAD⁺ is extremely high, it is essential to regenerate the reduced form of the coenzyme back into the oxidized form. In this work the regeneration of the coenzyme NAD⁺ was carried out in a microreactor by reversible oxidation of ethanol to acetaldehyde with the ADH enzyme.

A 100% conversion of NADH was achieved for a residence time of just τ = 0.8 s when the concentration of acetaldehyde was in excess (c_i,NADH = 5.5 mmol dm^-3, c_{i,acetaldehyde} = 44 mmol dm^-3, γ_i,ADH = 0.2 g dm^-3, 75 mmol dm^-3 glycine-pyrophosphate buffer pH = 9; T = 25°C). A 2D mathematical model for the description and prediction of microreactor performance was developed. Model simulations were validated using data from independent experiments.

The high conversions that were obtained for short residence times mean that the microreactors can be considered as good and efficient methods for coenzyme regeneration. © 2013 Society of Chemical Industry

Fermentation of the industrial vitamin B₁₂ by Pseudomonas denitrificans usually utilizes sucrose or maltose as the sole carbon source, which results in increased medium costs. In order to decrease the fermentation cost, it is crucial and essential to employ a low-cost and convenient raw material as an alternative medium substrate for industrial vitamin B₁₂ production.

The results obtained in chemically defined medium showed that glutamate and sucrose were favorable for cell growth and vitamin B₁₂ biosynthesis of P. denitrificans. Due to containing a mass of ingredients such as sucrose, glutamate and betaine, beet molasses was consequently chosen as the main medium substrate for industrial P. denitrificans fermentation in a 120 000 L fermenter. Vitamin B₁₂ production reached 181.75 mg L^–1.

Beet molasses is a by-product of the sugar industry and is thus very inexpensive, and it was proved that beet molasses was an efficient and economical medium substrate for industiral vitamin B₁₂ fermentation by P. denitrificans. © 2013 Society of Chemical Industry

N-doped TiO₂ can narrow the TiO₂ forbidden band and thereby increase its catalytic activity under visible light. In this work, three methods (the sol–gel method (SG), the tetrabutyl titanate hydrolysis precipitation method TN', and the H₂O₂-modified method (TNH)) were used to prepare N-doped TiO2 photocatalysts. The Reactive Red-Violet dye (KN-R) was used as the target pollutant. The catalytic activities of the photocatalysts prepared via the three methods were compared and studied.

The structures and optoelectronic properties of these catalysts were characterized by various means. The results demonstrated that the N-doped TiO₂ catalyst synthesized using the TNH method exhibited the most efficient catalytic activity under visible light and produced a degradation rate of 90% for the Reactive Red-Violet dye. The N-doped TiO₂ prepared using the SG method exhibited the lowest catalytic activity under both UV and visible light. The kinetics of photocatalysis degradation for KN-R by N-doped TiO₂ prepared by TNH method was studied and found to be zero order due to the good adsorption effect between KN-R and TiO₂.

The N-doped TiO2 prepared by TNH method showed good photocatalytic activity in the case of degrading dye under both UV and visible light. © 2013 Society of Chemical Industry

Groundwater quality is threatened by nitrate accumulation in several regions around the world. Nitrate must be removed from contaminated groundwater to use it as drinking water. Microbial fuel cells (MFCs) can be used for autotrophic denitrification. Thus, the use of MFCs is a potential alternative to using traditional methods for treating nitrate-polluted groundwater.

The objective of this study was to evaluate the potential of MFC technology to treat nitrate-polluted groundwater (28.32 ± 6.15 mgN-NO₃⁻ L⁻¹). The bioanode was fed with an acetate solution that permitted electron and proton flux to the biocathode. Initially, nitrite was observed in the effluent. After 97 days of operation, the denitrifying-MFC reduced the nitrate and nitrite concentrations in the effluent (12.14 ± 3.59 mgN-NO₃⁻ L⁻¹ and 0.14 ± 0.13 mgN-NO₂⁻ L⁻¹).Thus, this method improved water quality to meet World Health Organisation standards. However, nitrous oxide emissions were deduced from the electron balance, cathode coulumbic efficiency and Tafel plots. Bioelectrochemical evolution of the biocathode was related to the denitrification nature (sequential reaction steps from NO₃⁻ to N₂, through NO₂⁻ and N₂O as stable intermediates) and was supported by the Tafel plots.

The bioremediation of nitrate-polluted groundwater with a MFC biocathode is feasible. © 2012 Society of Chemical Industry

Produced water is generated in huge volumes from oil and gas production facilities. Different alternatives including physical, chemical, and biological methods can be applied for the treatment of produced waters. In this study, different pre-treatment alternatives used before a final nanofiltration and reverse osmosis membrane system were evaluated. A membrane bioreactor and pressurized microfiltration and ultrafiltration systems were used in the pre-treatment stage.

According to the results, the highest flux was obtained by the combination of ultrafiltration/microfiltration and nanofiltration; whereas, the maximum removal efficiencies for conductivity and chemical oxygen demand were obtained by the combination of membrane bioreactor and reverse osmosis systems.

The results of this study show that the emphasis should be placed on applying the right combination of membrane treatment processes instead of focusing only on pre- or final treatment units. © 2012 Society of Chemical Industry

Proper treatment technologies are required to address the environmental issues associated with increasing volumes of slurries. Ammonia stripping reduces the nitrogen content of the slurries and allows for its recovery in a valuable form. Herein the influence of pig slurry characteristics on ammonia stripping efficiency and the quality of the recovered ammonia solution were assessed.

Substrates characterized by low organic matter content, below 10 g COD L^-1, resulted in ammonia stripping efficiencies greater than 80%. Changing slurry pH to 9.5 significantly improved the process, even though high COD contents kept the efficiencies below 70%. Ammonium sulfate solutions could be concentrated up to nitrogen contents greater than 40 g N L^-1, while maintaining low organic contamination. Introducing a basic trap (pH > 12) before the acid one, allowed for the retention of more than 60% of the stripped organics with less than 3% of the stripped ammonia.

Ammonia stripping coupled with absorption proved to be a suitable technical solution for the recovery and valorization of the nitrogen contained in pig slurries. Clear enhancements in process efficiency were observed in the case of slurries with low organic matter content. The introduction of a basic trap, together with a slight increase in the operational pH level, further increased organics abatement. © 2012 Society of Chemical Industry

Chitosan flake is a bio-adsorbent that has been studied for adsorption of lead. However, its adsorption capacity for lead was low. To enhance its adsorption capacity, chitosan flakes were modified with citric acid by crosslinking with glutaraldehyde to supplement the functional groups with high affinity for Pb(II) ions.

Modified chitosan flakes with citric were prepared with maximum capacity for Pb(II) of 101.7 mg g⁻¹ at 303 K, pH 5, and 300 min contact time. The experimental data were used to fit kinetic and isotherm models. The results show that the adsorption of Pb(II) on modified chitosan flake followed a pseudo-second-order model, and the rate of adsorption was controlled by the mass transport mechanism and intraparticle diffusion. In an equilibrium study, it was found that the Langmuir and Freundlich isotherm models were appropriate to describe the adsorption process, indicating a chemisorption process of Pb(II) on the modified chitosan flake. The negative value of the free energy (ΔG) and the positive values of the enthalpy (ΔH) and entropy (ΔS) indicated an endothermic and spontaneous adsorption process of lead (II) on citric acid grafted chitosan flakes (C-Gch).

Chitosan flake modified with citric acid by crosslinking with glutaraldehyde remarkably enhanced the adsorption capacity for Pb(II) ions. This material could be used as an effective adsorbent for the removal of Pb(II) from wastewater and contaminated water sources. © 2012 Society of Chemical Industry

In this work, photochemical treatment (UV/H₂O₂) of a municipal secondary effluent was studied to assess its suitability for preparing water for reuse. Ten water reuse criteria obtained from the legislation of eight countries were used as indicators of water quality. Effluents from the municipal wastewater treatment plant (WWTP) of Gavà-Viladecans (Barcelona, Spain) were subjected to UV/H₂O₂ treatment with low H₂O₂ concentration ([H₂O₂]_o = 5 mg L⁻¹ and UV fluence = 8.04 mW cm⁻²) and the most common water reuse parameters, such as disinfection indicators, turbidity, total suspended solids and microcontaminant removal (atrazine), were monitored.

Treatment inactivated 100% of the disinfection indicators after 5 min. Afterwards, three levels of treatment corresponding to different reuse applications were defined according to the legislation used. In addition, according to the LuminoTox® bioassay, oxidative treatment of the secondary effluent favoured the formation of less toxic intermediates. Finally, a study was performed to determine the costs of each reuse condition.

Findings suggest that UV/H₂O₂ is a suitable method to obtain water of sufficient quality for further reuse. © 2012 Society of Chemical Industry

A novel hybrid material, chitosan-modified zeolite (Ch-Z), was synthesized for defluoridation. The structure was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA).

The maximum defluoridation capacity onto Ch-Z was 4.16 mg g⁻¹ from an initial fluoride concentration of 40 mg L^-1, which was almost three times higher than that of unmodified zeolite. The adsorption kinetics of fluoride onto Ch-Z and zeolite followed pseudo-second-order and intra-particle diffusion models, respectively. Based on a nonlinear method, the adsorption of fluoride onto Ch-Z fitted the Freundlich and Redlich–Peterson isotherm models well. Various physicochemical parameters affecting the adsorption of fluoride onto Ch-Z were investigated. It was observed that the maximum uptake of fluoride occurred in a pH range 4.5–5.5.

Although among various ions the presence of high concentration carbonate ions in aqueous solution had the greatest adverse impact on the adsorption of fluoride, Ch-Z can be successfully used for treatment of real water samples. © 2012 Society of Chemical Industry

Sulfate-reducing fluidized bed reactors represent an alternative for the treatment of wastewaters that contain dissolved metals. However, the low acetate consumption achieved through sulfate reduction affects the organic matter removal efficiency. The aim of this present work was to develop a sulfidogenic biofilm able to consume acetate via sulfate reduction within a short start-up period (21 days). Three experiments were conducted in a down-flow fluidized bed reactor with different acetate/lactate proportions in the feed (50/50, 80/20 and 90/10). Reduction of the influent pH from 6.0 to 4.0 was also studied at the higher acetate content.

Organic matter oxidation efficiency was similar in the three experiments (∼67%), nonetheless the sulfate reduction rate was higher in the experiments with 80 and 90% acetate in the feed (744 and 730 mg L⁻¹ d⁻¹). Acetate oxidation via sulfate reduction was highest (39% of inlet) at the ratio 90/10, at which the biofilm specific sulfate reducing activity with acetate was 4.3 times higher than that developed at 50/50. Influent pH reduction to 4.0 was not detrimental to acetate consumption via sulfate reduction, which was 56%. Analysis of the biofilm through DGGE found a similar community in the three experiments and the presence of acetotrophic microorganisms affiliated to Desulfobacca acetoxidans.

Limiting the substrate (lactate) was an appropriate strategy to enrich acetate-consuming sulfate reducers and improve the low acetate removal efficiency that sulfate-reducing reactors face. © 2012 Society of Chemical Industry

Low yields of oil, hazardous organic solvents or demanding supercritical conditions hinder energy utilization of Jatropha Curcas L.

A new complex procedure for processing the oilseeds is presented. The method consists of deshelling, grinding, shockwave pretreatment, enzymatic hydrolysis, oil expelling, anaerobic fermentation and charcoal production. No additional energy, hazardous solvents or expensive catalysts are needed.

The biotechnological impact of the processes involved was screened at different levels. Mass balances with kinetic data are plotted in detail, allowing further process modeling and technology design as well as determining the optimal operation parameters for further financial judgments. © 2013 Society of Chemical Industry

To achieve the goals of economically feasible auto-catalyzed organosolv pretreatments in bioethanol production, chemical conversion of the isolated lignin is needed. However, the structures and properties of lignin molecules produced after pretreatment have not been thoroughly investigated before its effective utilization.

The study focused on the auto-catalyzed ethanol–water pretreatment of southwest birch, with the aim to clarify the structural transformations of birch lignin after pretreatment. Chemical structural elucidation of the isolated lignins was performed using multiple NMR methodologies (³¹P-, ¹³C- and 2D-HSQC NMR techniques). Results showed that the amount of β-O-4 linkages decreased in the order of AEOL (auto-catalyzed ethanol organosolv lignin) < EHL_P (enzymatic hydrolysis lignin, pretreated) < EHL_U (unpretreated). The homolytic cleavage of β-O-4 linkages resulted in an increase of free phenolic hydroxyl groups and carboxylic acids in AEOL and EHL_P compared with that of EHL_U. In addition, α-ethoxylation was the only modification in the auto-catalyzed ethanol organosolv pretreatment (AEOP). Moreover, the thermal stability of the lignin samples is related to its inherent and condensed structures.

These findings would facilitate the further utilization of lignin as starting material for developing value-added products in chemical and catalytic process. © 2013 Society of Chemical Industry

Solvent extraction using organic extractants is an important technology for purifying wet process phosphoric acid. The purification of the wet process phosphoric acid by liquid–liquid extraction using solvent mixtures of N-octanol and tributylphosphate has been investigated.

The purification process comprised extraction, scrubbing and stripping operations. The extraction conditions, i.e. shaking time, temperature, composition of solvent mixtures and P₂O₅ concentration for purification of the wet process phosphoric acid were studied. The phase diagram of the pseudo-ternary system H₃PO₄-H₂O-solvent mixtures at 313.15 K was determined. The McCabe–Thiele diagram showed that three counter-current stages achieved about 91 wt% P₂O₅ extraction at 313.15 K. Scrubbing and stripping operations using pure phosphoric acid with 10 wt% P₂O₅ and doubly distilled water, respectively, were studied.

The phosphoric acid finally produced was found to be high grade which met the special requirements of the user. Optimization of the extraction conditions and system was capable of providing academic and technical foundations to realize industrial production. © 2012 Society of Chemical Industry

This work presents a novel approach for the recovery and purification of superoxide dismutase (SOD; EC 1.15.1.1) produced in the yeast Kluyveromyces marxianus var. bulgaricus (NBIMCC 1984). Electroextraction was evaluated as an alternative to bead milling for SOD release. Seven anion exchange resins were studied in order to optimize SOD purification using ion exchange chromatography.

Electroextraction produced an enzyme solution with a specific activity 13 times higher than with mechanical extraction, demonstrating the potential of this novel technique for the selective liberation of SOD. Regarding the anion exchange resins that were studied, Amberlite™ IRA-96 and Q Sepharose™ XL were chosen as the best options for purifying SOD using chromatography in negative adsorption mode. The process developed, involving electroextraction, enzyme concentration and negative anion exchange chromatography, rendered a highly active and pure SOD preparation (specific activity: 2056 U mg⁻¹ and 66-fold purification) with an overall recovery yield of 84%.

The results presented herein demonstrate the potential of the process developed for the recovery and purification of SOD from the yeast Kluyveromyces marxianus var. bulgaricus (NBIMCC 1984). The preparation obtained could be used in the food industry as an antioxidant agent. © 2013 Society of Chemical Industry

Microcystin-LR (MC-LR) is very stable under natural sunlight and resistant to high temperatures and UV radiation. Conventional treatment techniques are found to be inefficient in removing these toxins from potable water systems. Advanced oxidation technologies (AOTs) are considered a promising technique for the destruction of microcystins. Among the various AOTs, electrochemical oxidation (EO) has been proved to be very successful in degrading the organic pollutants. The purpose of this study was therefore, to determine the feasibility of MC-LR removal and its mechanism by EO. The effect of operational parameters on the degradation efficiency of MC-LR has been studied.

The degradation of MC-LR followed a pseudo-first-order kinetic with a rate constant (k₁) of 0.017 min⁻¹. Current density and electrolytes can affect the degradation rate; the pH of the different anionic solutions had a negligible effect on the degradation of MC-LR. The destruction of the key functional groups of MC-LR effectively inhibits its toxicity, which is confirmed by toxicity tests.

The results demonstrated the feasibility of electrochemical oxidation on boron-doped electrode for the removal of MC-LR from the aquatic environment. © 2012 Society of Chemical Industry

Microbial fuel cells (MFCs) are potentially advantageous as an energy-efficient approach to wastewater treatment; however, the quality of the MFC effluent has not been well addressed. In this study, a membrane bioelectrochemical reactor (MBER) was developed through integrating hollow-fiber ultrafiltration membranes into a tubular MFC to improve the effluent quality.

This MBER was operated with an acetate solution or domestic wastewater (primary effluent) for more than 200 days. The MBER removed 43–58% of total chemical oxygen demand (COD) from the acetate solution and achieved 30–36% coulombic efficiency. When treating the wastewater, the MBER was able to maintain almost 90% COD removal and an effluent turbidity <1 NTU. A strategy of periodic backwash and membrane relaxation led to a slow increase in the transmembrane pressure (TMP) from zero to 15 kPa in more than 40 days at hydraulic retention time (HRT) 36 h. However, both lower HRTs and high organic loading rates rapidly increased the transmembrane pressure.

A proof of concept of an MBER was presented and shown to be effective in contaminant removal. Preliminary energy analysis suggests that the MBER could theoretically produce sufficient energy from the acetate solution to support the pumping system. These results demonstrate the feasibility of the MBER concept and the challenges for further development of the MBER system. © 2013 Society of Chemical Industry

Anaerobic fermentation slurry (AFS) is a type of high-pollution load wastewater that can cause water eutrophication and algal blooms. The current study focused on the response of microalgae nutrient removal efficiency to various light-emitting diode light wavelengths and intensities.

The microalgae Chlorella vulgaris was able to remove nutrients from AFS effectively. Furthermore, only moderate light intensities (800, 1300, 1800, and 2300 µmol m⁻² s⁻¹) were required to culture C. vulgaris and induce nutrient removal. Exposure to higher light intensities produced greater dry weight (DW) biomass and achieved higher nutrient removal efficiencies. The order of light wavelengths based on the DW biomass yield of C. vulgaris was red > white > yellow > blue. The order of light wavelengths, according to the nutrient removal efficiencies reached by C. vulgaris, was red > white > yellow > blue. Red light was also the light wavelength with the best economic efficiency for nutrient removal.

In this study, red light was used as the optimum light wavelength. Furthermore, the optimum light intensity range was from 1300 to 1800 µmol m⁻² s⁻¹ when both nutrient removal and economic efficiencies were considered.Moreover, the optimum treatment time was determined to be 120 h. © 2012 Society of Chemical Industry

Packed bed biofilm reactors (PBBR) are gaining interest for the bioremediation of wastewater contaminated with heavy metals. The study of both hydrodynamics and microbial growth kinetics are equally important for assessment of the overall bioremediation efficiency of a PBBR.

Hydrodynamics of a Bacillus cereus (JUBT1) based biofilm reactor of diameter 45 mm and length 460 mm undergoing removal of Hg²⁺ ions up to a conversion efficiency of 90% have been determined using both actual and Ca-alginate based artificial biofilms. The Peclet numbers obtained using biotic and abiotic biofilms have been determined to be 9.74 and 8.8, respectively. The micrographs of the biofilm with the variation of aging period suggest its stability up to 150 days of operation. A mathematical model has been developed and validated incorporating both the dispersion parameter and microbial growth kinetics.

This work demonstrates that in order to carry out hydrodynamic studies of a PBBR, the use of abiotic films rather than biotic films is much more beneficial and time efficient as it does not require strict biochemical precautions. Moreover, using lower inlet concentrations of Hg²⁺ ions, the exit conversion of the PBBR is found to be maximum.

Electrochemical oxidation has attracted wide attention in wastewater treatment because of its strong oxidation performance and ease of control. This work investigated the feasibility of electrochemical treatment using a Ti/RuO₂–IrO₂ anode as an advanced treatment of coking wastewater. The influential operating factors including current density (9.6–108.2 mA cm⁻²) and electrode gap (0.5–2.5 cm) were evaluated.

The current density and electrodes gap had significant effects on COD and NH₄⁺-N removal and the energy consumption. The degradation of COD and NH₄⁺-N followed pseudo-first-order kinetics. In most experiments, high levels of NH₄⁺-N removal (NH₄⁺-N removal ratio > 95%) was achieved along with moderate mineralization (COD removal ratio: 60–80%). COD (178.0–285.0 mg L^-1) and NH₄⁺-N (55.0–76.0 mg L^-1) were degraded by 62% and 96%, respectively, at the optimum conditions (electrode gap: 0.5 cm, current density: 15.6 mA cm⁻²) after 60 min treatment. Under this optimal condition, the corresponding energy consumption was 8.60 kWh m^-3 for effluent meeting the discharge standards. Furthermore, gas chromatography–mass spectrometry (GC-MS) analysis indicated that this technique could be employed to eliminate bio-refractory and toxic compounds such as phenanthrene, indole, quinoline and pyrimidine in coking wastewater.

Ti/RuO₂–IrO₂ anode systems were confirmed to be effective in advanced treatment of biologically pretreated coking wastewater.© 2013 Society of Chemical Industry

This paper reports a bioinspired emulsion polymerization approach through biosurfactants (rhamnolipid and surfactin) templating for synthesizing highly monodisperse, spherical polymer bionanocomposites consisting of polystyrene (PS) (core)/biosurfactants (shell) (50–190 nm) and their feasibility as a biocompatible and biodegradable drug delivery vehicle.

Conversion profile, particle size dependence on biosurfactant concentration and structural characterizations of resulting polymers from bioinspired emulsion polymerization were similar to conventional emulsion polymerization. In vitro biodegradation studies revealed >2.5-fold increase in bacterial growth (Pseudomonas aeruginosa MTCC 7926) and gravimetric weight loss (10% w/w) in biosurfactants templated PS, compared with the conventional route. Soil burial biodegradation tests supported these findings. In vitro and in vivo biocompatibility studies showed unchanged cell viability of adult rat (Rattus norvegicus) hepatocytes for polystyrenes synthesized using biosurfactants, while conventional PS beads proved to be cytotoxic in a dose-dependent manner. Reactive oxygen species (ROS)-induced oxidative stress, increased lipid peroxidation, alterations in GSH detoxification and histopathology corroborated these results. Release of bovine serum albumin (BSA) from BSA loaded polystyrene/biosurfactant bionanocomposites were 2.5–5-fold higher in physiological buffer (pH 7.4) than in acidic buffer (pH 1.2).

Taken together, polystyrene/biosurfactant bionanocomposites could serve as a biocompatible and biodegradable colon or intestine-specific drug delivery vehicle. © 2012 Society of Chemical Industry

As an important extraction technique, aqueous two-phase extraction is especially applicable to bioseparation. This work has focused on using a novel kind of aqueous two-phase system (ATPS), for the enantioseparation of tryptophan.

Only limited kinds of salts could form effective phases with ethanol. The salting-out abilities of various salts and the final characteristics of ATPS were investigated. The results show that increase in the amount of phase-forming components and decrease in pH from 6 to 2.5 are both beneficial for the enantioseparation of tryptophan; enantioselective extraction and partitioning behavior are mainly dependent on the pH of solution, the type of chiral extractant and its concentration. Furthermore, salt, ethanol and temperature also have some effects on the enantioseparation. Finally, the most reasonable extraction mechanism of the tryptophan enantiomers was suggested.

The novel ATPS composed of ethanol/ammonium sulfate proposed in this studyhas good ability for the extraction of tryptophan enantiomers.© 2013 Society of Chemical Industry

In some disease therapy, it is necessary to release multiple drugs continuously and orderly. This paper describes a technique for preparing a microparticle that can load two kinds of substances and release them at two different rates.

A core–shell structural microparticle was designed using liposome as core and hyaluronan/poly(N-isopropylacrylamide) (HA/PNIPAM) gel as shell. The core liposome keeps its vesicle structure after undergoing the whole crosslinking process. The microparticles are injectable at room temperature and become sticky when heated. The fluorescent loaded in the shell released 80% in 1 h, while that in the core kept releasing for 35 h.

The stability and function of liposomes are improved after being coated with a gel shell. Two kinds of fluorophores were successfully loaded into microparticles and released at two different rates. The main factors controlling the tracer diffusion are the microparticle properties, e.g. crosslink density and shell thickness. These microparticles can be used as injectable or implantable drug carriers by minimally invasive techniques. © 2012 Society of Chemical Industry

Aluminosilicate catalysts have the potential to promote the formation of oxygenated derivatives from carbohydrates in a hydrothermolysis reaction. Levulinic acid (LA) can be obtained from glucose, sucrose and starch hydrothermolysis reactions, and is a very versatile building block for diverse organic synthetic compounds. In this work, the catalytic performance of Ni- or Ru-doped aluminum-loaded SBA-15 (Al-SBA-15) was compared with ZSM-5 catalyst in order to achieve high LA selectivity.

All catalytic hydrothermolysis reactions tested gave remarkably higher LA selectivity than non-catalytic reactions for every carbohydrate substrate used. The acid contents and porous properties are important keys to control yield and selectivity of LA. The highest selectivity of LA (44%) was attained from glucose hydrothermolysis at 200 °C (for 1 h) using a 15 wt% loading of the 20 wt% Ru-doped ZSM-5 catalyst.

Moderately raising Ru in ZSM-5 and Al-SBA-15 catalysts increased the levels of LA. The MFI structure of ZSM-5 is suitable for hydrothermolysis of glucose monosaccharide, while the hexagonal mesoporous structure of Al-SBA-15 is preferred for starch polysaccharide hydrothermolysis at the optimum condition.© 2012 Society of Chemical Industry

Effluents discharged from tannery industry contain significant amount of chromium and synthetic dyes. Both chromium and dyes can be transformed individually into less toxic forms, but very little is known about their simultaneous treatment. The present study was aimed at isolating bacteria capable of removing toxic hexavalent chromium (CrVI) and reactive black-5 azo dye simultaneously in liquid mineral salt medium (MSM).

About 150 bacterial isolates were collected from tannery wastewater and sludge through enrichment of the MSM with CrVI (2 mg L⁻¹) and reactive black-5 dye (100 mg L⁻¹) under static (batch) condition. Bacterial strains KI (Pseudomonas putida ) and SL14 (Serratia proteamaculans) were able to reduce simultaneously 93% CrVI and 100% color of reactive black-5 azo dye in 24 h at pH 7.2 and 35 °C in a batch culture. Individually, 100% reduction of CrVI and reactive black-5 dye was achieved in 12 h by strain KI and SL14.

These bacterial strains are one of the most efficient bacteria capable of reducing toxic CrVI and synthetic reactive dye simultaneously and could be used for developing bioreactors to treat tannery effluent prior to its discharge into the environment. © 2012 Society of Chemical Industry

Arabitol has many potential industrial applications and it can be produced by fermentation from glycerol, a major byproduct of biodiesel industry. This work aims at developing a new process for collecting and purifying arabitol from the broth of osmophilic Debaryomyces hansenii containing arabitol, unconsumed glycerol, and other minor impurities. RESULTS: The process developed and optimized in this study had the following steps: first, the broth supernatant was treated with 8 g L⁻¹ activated carbon at 30°C and pH 6 for removal of colored organics and some impurities. Then glycerol was selectively removed by acetone extraction at 30°C. The acetone amount was optimized according to the measured solubility data of simulative glycerol-xylitol-acetone systems and real fermentation broth. The glycerol-removed remainder was next extracted for arabitol with butanol (90% of supernatant volume) at 90 °C. White arabitol crystals were collected from the cooled butanol extract. The overall recovery and purity of arabitol crystals were 66% and 95%, respectively.

Successful arabitol purification was achieved with an optimized process. Fundamental phase equilibrium data of glycerol-xylitol-acetone systems were obtained. The process developed would prove valuable for arabitol production and potentially for separation of other polyols. © 2012 Society of Chemical Industry

In this study, highly ordered titanium dioxide (TiO₂) nanotube arrays with tunable inner-diameter and morphology were synthesized by an anodizing method from titanium (Ti) foil by optimizing different preparation parameters, and acyclovir was degraded to test the photoelectrocatalytic activity of prepared nanotubes in a thin layer reactor.

The results indicated that anodization time, the concentrations of NH₄F and HAc had significant effect on the surface morphology and inner-diameter of TiO₂ nanotubes. Various morphologies including honeycomb films and nanotube arrays were obtained under given conditions. Photoelectrocatalysis showed higher degradation efficiency than that of photocatalysis or electrolysis due to TiO₂ nanotubes regular nanotubular effectively reducing the recombination of photo-generated electron–hole pairs. The photoelectrochemical responses and degradation efficiencies of acyclovir were well related to the TiO₂ crystallinity and morphology of TiO₂ nanotube photoanodes. Regular nanotube array photoanodes displayed better crystallinity, higher photoelectrochemical response and higher photoelectrocatalytic activity than those of nanopore photoanodes. The best TiO₂ nanotube photoanode was prepared at 30 V for 24 h in the ethylene glycol solution containing 0.20 mol L⁻¹ NH₄F and 0.50 mol L⁻¹ HAc.

TiO₂ nanotube photoelectrocatalysis technology is an effective way to decontaminate organic contaminants in water. © 2012 Society of Chemical Industry

Military areas such as firing ranges have serious contamination problems due to both heavy metals and nitroaromatic compounds (NACs). The feasibility of modified Fenton reactions for remediation of NACs is studied by investigating the fate of lead (Pb) and copper (Cu) during the modified Fenton reactions and its effect on the degradation of 2,4-dinitrotoluene (2,4-DNT) in soils at various hydrogen peroxide (H₂O₂) concentrations.

During the reactions, the Pb fate was not affected at ≤0.2 mol L⁻¹ H₂O₂, but final aqueous phase Pb was higher in the samples than in the controls at >0.2 mol L⁻¹ H₂O₂. These changes in the Pb fate resulted in interference with 2,4-DNT degradation at ≥0.2 mol L⁻¹ H₂O₂. Similarly, aqueous phase Cu was higher in samples with >0.2 mol L⁻¹ H₂O₂ than in the controls; however, unlike Pb, these changes did not have adverse effects on 2,4-DNT degradation.

The different effects of heavy metals such as Pb and Cu on 2,4-DNT degradation in soils during modified Fenton reactions need to be understood to optimize 2,4-DNT degradation performance. The results help to advance the Fenton reaction applications for the remediation of soils contaminated with Pb or Cu and 2,4-DNT mixtures.

Ion-exchange has been a powerful tool for metal recovery. Germanium has been recovered using the commercially available N-methylglucamine resin. To treat waste-water from solar panel displays a method to separate selectively germanium from silicate ion was required. A novel recovery of germanium is proposed in which germanium is complexed with catechol in solution and the complex solution flowed through a membrane or bead-packed bed.

By changing pH, germanium was complexed with catechol, 3-methylcatechol and 4-nitrocatechol in solution and the solution was adsorbed on the membrane in a batch mode, demonstrating that catechol exhibited a high adsorption performance in neutral pH. In a continuous system, the membrane achieved faster adsorption of the germanium complex than a bead-packed bed.

The high-speed recovery of germanium was due to the transport to the vicinity of quaternary amino group in the membrane via convection. A germanium solution containing silicate ions was passed through the membrane system, resulting in highly selective recovery of germanium ion. © 2012 Society of Chemical Industry

There is growing interest in employing sludge-based carbons (SC) from waste treatment as adsorbents. However, the application of SC is limited by its poor porosity caused by large amounts of minerals blocking the pores. It is thus, highly desirable to develop a post-washing process to remove the minerals in SC.

In this paper, SC was washed with deionized water (DW), hydrochloric acid (HCl), citric acid (CA) and a mixed solution of hydrochloric acid and citric acid (HCl-CA), respectively. Results showed that HCl-CA washing had the highest demineralization efficiency (63%), so that HCl-CA washed SC had the lowest ash content (32%) and largest total pore volume (0.455 m³ g^-1), and presented the highest adsorption capacities of 319 mg g^-1 for acid orange II (AOII) and 250 mg g^-1 for methylene blue (MB).

HCl-CA washing has the highest demineralization efficiency. The high efficiency is attributed to the synergetic effects of both protonation and chelation. Demineralization has a strong influence on the development of pore structures, which further influences adsorption capacity. © 2012 Society of Chemical Industry

Bio-based thermoplastic composites with high-performance and low cost have attracted much interest due to their sustainability and their potential applications. The reinforcement of poly(butylene succinate) (PBS) with recycled carbon fiber (RCF) not only gives this biodegradable material excellent physical properties to compete with conventional composites, but also provides a new route to the use of RCF with well controlled cost.

Bio-based PBS/RCF composites were prepared by simple melt extrusion through a twin-screw extruder. The evaluation of mechanical properties confirms a significant enhancement effect of RCF on PBS as a result of surface treatment of RCF with silane coupling agent. Morphological study indicates a homogeneous dispersion of RCF in the matrix due to the good interfacial interaction between fibers and PBS. The investigation of crystallinity verifies that RCF plays the role of nucleation agent in the crystallization process of PBS matrix and remarkably accelerates its crystallization rate.

The incorporation of RCF is advantageous for the enhancement of mechanical properties, heat resistance, and processability of PBS-based materials. PBS/RCF composites can be used to many fields as a low-cost biodegradable material having high performance. © 2012 Society of Chemical Industry.

Depletion of primary resources, stringent environmental regulations, and the requirement for energy efficient and eco-friendly processes have created research interest in recovering Pt from secondary resources using electro-generated chlorine in HCl solution.

Platinum dissolution rate was found to increase by a factor of 2.5 by increasing the HCl concentration from 3.0 to 5.0 mol L^-1 at 70°C, while maintaining total chloride ions at 5.0 mol L^-1 with NaCl. Increasing the aqueous chlorine concentration made no improvement to the dissolution rate. A theoretical calculation of distribution for chlorine species showed a predominance of Cl₃⁻ ions in comparison with Cl₂(aq) upon increasing the acid concentration to above 5.0 mol L^-1; raising temperature also increased the dissolution rate. The activation energies of Pt dissolution in the 5.0 mol L^-1 HCl solution were 82.3 and 83.5 kJ mol^-1 at 5.0 and 15 mmol L^-1 aqueous chlorine concentration, respectively.

Eco-friendly electro-generated chlorine leaching was applied for the dissolution of Pt in hydrochloric acid solutions. Increasing HCl concentration and solution temperature effectively enhanced Pt dissolution during leaching. A quantitative investigation of Pt dissolution rate verified the chemical reaction control of Pt dissolution rather than mass transfer.

Ionic liquids are regarded as future effective absorbents of CO₂, however high viscosity of this medium limits its use in industry. To resolve the problem a mixture of alkanolamine, ionic liquids and water was proposed as a CO₂ absorbent and the influence of solution composition on the volume of CO₂ absorbed was determined.

In most binary mixtures of ionic liquids and water tasted the presence of water does not affect the overall capacity of absorption mixture except for the 1-butyl-3-methylimidazolium acetate where each mol of water added to the mixture reduces the volume of CO₂ that could be absorbed by more than one mole. The capture of CO₂ using three-component systems of water/ionic liquid/monoethanolamine (MEA) was systematically investigated with two selected ionic liquids: 1-butyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium octylsulfate. It was shown that the volume of CO₂ absorbed is linearly dependent on the mass fraction of components for 1-ethyl-3-methylimidazolium octylsulfate over the entire experimental domain whereas in 1-butyl-3-methylimidazolium acetate the interaction between ionic liquid and water substantially decreases the volume of CO₂ absorbed.

The best results for CO₂ absorption were obtained using the three component system 1-butyl-3-methylimidazolium acetate/monoethanolamine/water. Optimization of the composition of an IL-MEA-water mixture allows tuning of the properties of the medium. The CO₂ absorption capacity of the mixture is mainly a function of MEA concentration and, to a lesser degree, of the concentration of IL possessing chemisorption abilities. The presence of water decreases the viscosity of the mixture and therefore facilitates the application of IL-based media in industrial applications. © 2012 Society of Chemical Industry

A lab-scale anaerobic-anoxic/nitrification (A₂N) two-sludge sequencing batch reactor (SBR) system was operated to assess the relationship among intracellular polymer conversions, bacterial population dynamics and nutrient removal performance in response to the varying influent COD/N/P.

Complete nutrient removal was achieved in the A₂N-SBR in Run 3 where the COD/P and COD/N were 20.6 and 6.9, respectively. This coincides well with the highest P release/HAc uptake ratio occurring in Run 3, confirming high abundance of denitrifying phosphorus accumulating organisms (DPAOs) in the biomass. Under the stress of N or P limitation, more poly-β-hydroxyalkanoates (PHA) was synthesized, with the increasing proportion of poly-hydroxyvalerate (PHV) in PHA. The population biodiversity decreased with increasing carbon loading when P loads were maintained at constant levels, and recovered to the initial level after P loading decreased.

Increasing COD/P promoted anaerobically synthesized PHA amount and favored P removal. Also, PHB seems to be the crucial internal carbon source relating to P release and uptake, whereas high nitrogen and P removal efficiencies always relate to a high proportion of PHV in PHA. Increasing carbon loading led to a decreased biodiversity of the community structure but favored higher PAO enrichments, if only P loading is not limited.© 2012 Society of Chemical Industry

Enhancing the efficiency of process development is a key issue for the production of recombinant therapeutic protein. To maximize both cell mass and productivity with limited time and effort, an improved top-down approach was adopted in the development and optimization of fed-batch culture.

Two-round optimization was carried out to refine the nutrients following an investigation into the effect of complete feeding medium. After the first round of optimization, cell growth was improved with the integral of viable cell concentration increased by 32.2%. After the second round of optimization, cell productivity was improved with the specific antibody production rate increased 1.5-fold, and cell longevity was also prolonged using improved feeding strategy. In the optimized fed-batch culture in a 2 L bioreactor, the maximum cell concentration was increased by 68% and final antibody titer was increased 3.9-fold compared with the fed-batch culture with simple feeding medium.

The improved top-down approach helps to reveal the interaction of different nutrients and their important roles in the improvement of cell proliferation and production. Thus, the common defects of a top-down approach can be avoided. This approach is practicable and satisfactory for efficient development of a high-yielding process. © 2013 Society of Chemical Industry

In new biorefineries the use of new green solvents is essential in order to minimize the employment of volatile organic solvents.Lignin is the most abundant residue in paper industries, however, it is necessary to purify it in order to obtain revalorized products.

In this study, soda and organosolv lignins obtained from apple tree prunings (Malus domestica) were purified using [Bmim][MeSO₄], and the lignin extracted from raw material was tested comparing different conditions. [Bmim][MeSO₄], EtmimAc(1-Ethyl-3-methylimidazolium acetate) and BmimCl, were the ionic liquids chosen for the experimentation. The lignins obtained were characterized by FTIR, TGA, RMN and HPLC, in order to determinate the influence of the different treatments on their structures. Lignin of 91.2% purity was obtained directly from raw material using ionic liquids, whereas organosolv lignin purity ranges from 85.7% to 90.9%, and soda lignin from 12.9% to 89.6% after treatment with [Bmim][MeSO₄].

Results showed that the use of [Bmim][MeSO₄] is the best option to purify and extract lignin from raw material. In addition, microwave radiation enhanced the energy consumption of the process.© 2012 Society of Chemical Industry

Selective catalytic reduction (SCR) of NO with NH₃ has been proved to reduce nitric oxides in exhaust flue gas from coal-fired power plants. The commercial V₂O₅ -WO₃ (MoO₃)/TiO₂ catalyst has the disadvantages of high reaction temperature (573–673 K), high conversion of SO₂ to SO₃ and toxicity of vanadium pent-oxide to the environment and human health. Therefore, it is of some urgency to develop SCR catalyst, which works effectively in medium and low temperature ranges. In this study, a series of cerium–iron mixed oxide catalyst were prepared through a co-precipitation method and showed strong low-temperature SCR activity.

The SCR activity over iron oxide was improved significantly by adding a small amount of cerium, especially the low-temperature activity. Cerium sharply increased the BET surface area and the pore volume of iron oxide, and also enhanced its oxidation activity of NO to NO₂. The NO_x conversion was improved when partial NO₂ was introduced into the flue gas. Iron oxide in catalyst was amorphous phase after adding a small amount of cerium.

The SCR activity over iron oxide was improved by substituting partial Fe with Ce, and the optimized conditions for SCR with iron–cerium mixed oxide catalyst were validated in this study.© 2012 Society of Chemical Industry

The bioconversion of lignocellulosic biomass to second generation ethanol has the potential to replace some fossil fuels. Sugarcane bagasse (SB) is a readily available feedstock for ethanol production. The aim of this work was to study the enzymatic saccharification of consecutively acid–alkali pretreated SB using different commercial enzyme preparations.

Under the most favourable enzymatic hydrolysis conditions, a maximum sugar recovery of 0.89 g of reducing sugars g^-1 acid–alkali pretreated SB was obtained. Scanning electron microscopy (SEM) revealed the structural disruption in the SB morphology after acid–alkali pretreatment followed by enzymatic hydrolysis.

These results improve research strategies and show the susceptibility of SB under different enzymatic actions. This is thought to be the first report on utilization of cellulase AF28918 for SB saccharification into fermentable sugars.

Short chain chlorinated paraffins SCCPs are priority hazardous substances classified by the European Water Framework Directive and have been detected in sewage sludge of wastewater treatment plants worldwide. However, studies on the biodegradation of SCCPs presented in sewage sludge are very scarce.

In this study, a bacterial strain that can utilize SCCPs as a sole source of carbon and energy was isolated from soil. This strain was identified as Pseudomonas sp. N35. The efficacy of SCCP degradation by strain N35 was tested in pure culture and sewage sludge microcosms containing 66.1 mg kg^–1 SCCPs. The results showed that 57.5% of chloride was released into the medium as chloride ions in pure culture within 20 days. Mesophilic temperature and near-neutral pH were most favorable for SCCP degradation. The addition of low concentrations of glucose, Tween-80 and acetone (20 mg L^–1) enhanced SCCP degradation. Bioaugmentation resulted in 73.4% removal of SCCPs in the sludge microcosm after 30 days of treatment.

Bioaugmentation with specific strains may be of great significance in bioremediation of SCCP-containing sewage sludge.© 2012 Society of Chemical Industry

Fortification utilizes pre-hydrolysed sludge to increase organic sewage strength for support of anaerobic development. Significantly, enhancing organic strength also permits organic loading rate to be de-coupled from hydraulic retention time, enabling greater contact times for temperate, municipal wastewater. This study therefore describes the application of fortification to facilitate anaerobic treatment of crude wastewater in temperate climates.

Fortification with primary sludge significantly increased methane (CH₄) from 0.021 m³CH₄ m^-3 for crude wastewater to 0.095 m³CH₄ m^-3. This increased yield demonstrates that fortification enables methane yields equivalent to conventional full-flow anaerobic treatment through only partial treatment of wastewater (up to 50%) which lowers both capital and operational costs. Total chemical oxygen demand (COD) and soluble COD removals of 89% and 5 % were recorded following fortified crude wastewater treatment, permitting a similar effluent COD profile to treated crude wastewater. Pre-hydrolysis of the fortified wastewater maximized methane production to 0.156 m³CH₄ m^-3. Furthermore, a similar yield was reported for wastewater fortified with pre-hydrolysed waste activated sludge, providing new opportunities for on-site treatment with concomitant benefits in sludge reduction and enhanced energy production. Solids breakthrough occurred with pre-hydrolysed fortification and reduced effluent quality; it is postulated that optimizing pre-treatment and upflow velocity will improve effluent quality to that attained with standard fortification. However, fortification also reduced losses of dissolved methane in the effluent stream.

With a reduction in aeration requirements and potential savings in primary treatment and sludge treatment, fortification represents a major advance upon current practice. © 2012 Society of Chemical Industry

A mathematical modeling approach was used to obtain a simulation model to predict the performance of an industrial rotating disc contactor (RDC) in the extraction of lubricating base oils by furfural. The field data of a lube-oil producing plant was used to validate the model. This model can be used for the parametric study of the RDC column and to investigate the effect of operational data such as solvent and feed temperatures, solvent to feed ratio, and agitation rate on the yield of extraction and on the energy saving value of the extraction.

The mathematical modeling of RDC shows good agreement with the plant data with an accuracy of 95% and the model was used to investigate the effect of adding a co-solvent.

Results show that by using furfural with added 2,2,4 trimethylpentane it is possible to perform the extraction process at a lower process temperature, 363.15 K, compared with 393.15 K using furfural as solvent, and also at a lower 1.3 solvent/feed ratio, compared with 1.5 when furfural alone was used for as the solvent. This process modification leads to saving of 38% of the consumed energy per cubic meter of product in the extraction process.© 2012 Society of Chemical Industry

The aim of this study was to investigate biopolymers and extracellular enzymes in whole activated sludge flocs originating from a full-scale wastewater treatment plant, by means of confocal laser scanning microscopy (CLSM) techniques. Both sectioned and whole activated sludge floc samples have been stained using specific fluorochromes and immunostains in order to visualize the structural and functional characteristics of these bioaggregates. Samples were stained for visualization of lipids, sugars, total cells, esterase enzyme producing bacteria, and for β-glycosidase (EC3.2.1.21), alkaline phosphatase (EC3.1.3.1) and trypsin (EC3.4.21.4) enzymes. Simultaneous staining schemes were applied and immunostaining specificity tests were performed.

By the CLSM imaging and the 3-D reconstruction of the stained flocs the distributions of the targeted floc components were successfully assessed. The immunostain specificity controls gave satisfactory results in each case. The reflected total cells-to-enzymes ratio was repeatedly higher for the sectioned samples.

The CLSM imaging of whole sludge flocs delivers valuable information on the spatial distribution of the floc build-up materials, with a satisfactory visualization accuracy of the individual components. The images of whole and sectioned samples showed similar distributions of the floc components, but the consistent differences revealed in cells-to-enzymes ratios call for further research.© 2012 Society of Chemical Industry

The main goal of wastewater treatment is to obtain high quality effluent. This study proposes a methodology to estimate in real-time the effluent quality in a biological nutrient removal (BNR) sequencing batch reactor (SBR) process.

This is achieved by: (i) detecting the batch quality; and (ii) predicting the classification of the release according to different effluent characteristics. A principal component analysis (PCA) model is built to discern normal or abnormal behavior of the batch release. An index is given to every phase of the process by means of contribution analysis, and a fault signature (FS) is created. The FS in a classification model is associated with a biological removal quality.

The model is applied as a soft-sensor in real-time to new batch releases to obtain a qualitative estimate of the effluent. A correct estimation for the qualitative variables, of above 95%, would provide a reliable tool to estimate BNR performances.© 2012 Society of Chemical Industry

This work analyzes the behaviour of monopolar and bipolar electrochemical reactors with a cylindrical configuration using woven wire meshes as three-dimensional anodes for the production of cuprous oxide.

Calcium gluconate as an additive diminishes cell voltage because of the depolarization of the hydrogen evolution reaction, and it also avoids the reduction of cuprous oxide to metallic copper. The quality of the powders obtained in a bipolar reactor with three-dimensional anodes is similar to that of a monopolar reactor. Powders containing 97% cuprous oxide were obtained at current densities ranging from 21 to 103 mA cm^-2 with current efficiencies near 100%. The bipolar arrangement presents a simpler electrical connection; however, special attention must be paid to some features of construction to minimize the leakage current.

Cylindrical bipolar electrochemical reactors with three-dimensional anodes show a good performance for the production of cuprous oxide powder. © 2012 Society of Chemical Industry

Cyanophycin (CGP) is a sustainable polymer that can be converted to a derivative with reduced arginine content, or to completely biodegradable poly-aspartic acid, which can substitute for non-biodegradable polyacrylates. In nature, it is produced by most cyanobacteria; however, these microbes are not suitable for large-scale production due to slow growth and low polymer content.

Cyanophycin synthetase gene (cphA) from Anabaena variabilis ATCC 29413 was PCR amplified and cloned into Escherichia coli. Different renewable media components, such as soybean meal, potato wastes and corn-derived zein hydrolysate, were evaluated for their feasibility for CGP production at shake flask level. The optimized conditions were then tested in a 7 L bioreactor; a maximum cell weight of 10.2 g L^-1 was obtained. CGP comprised 23 g g^-1 of cell dry matter (CDM) with molecular weight between 21.5 and 31 kDa and was composed of aspartic acid, arginine and lysine in the ratio of 1.05:1:0.2 (mass basis).

The efficient use of renewable biomass for cyanophycin production could achieve competitive price, and in return, promote the use of this platform chemical to produce innovative polymers and materials.© 2012 Society of Chemical Industry

Functionalization of aliphatic biopolymers such as bacterial polyhydroxyalkanoates (PHA) using biologically active hydrophilic moieties like sugars helps to improve the hydrophilicity and biodegradability of the biomaterial.

The effects of reaction variables reaction time, temperature, enzyme concentration and substrate ratio on reaction rate and yield in the synthesis of poly(1'-O-3-hydroxyacyl-sucrose) using Candida antarctica lipase B (EC 3.1.1.3) were studied. Using H₂O₂ as micro-initiator, enzyme-mediated synthesis yielded reaction rate, v^app of 0.076 x 10⁻⁵ mol L⁻¹ s⁻¹. The biodegradability of the functionalized polymer was observed to increase by 1.5 fold compared with the non-functionalized material apart from showing better compostability. Increasing the reaction temperature (>50°C), enzyme concentration (>15 g L⁻¹) and reactant ratio (w/w) of sucrose:PHA (>2) did not increase further the rate or yield. The sucrose-functionalized mcl-PHA was characterized with respect to the non-functionalized material.

Novozym® 435 can be used effectively to synthesize poly(1'-O-3-hydroxyacyl sucrose) in micro-aqueous medium bypassing the need for chemo-synthetic steps. The synthesized biomaterials have potential applications in biomedical and industrial niches.© 2012 Society of Chemical Industry

This study analyzes the effectiveness of gamma irradiation in removing diatrizoate contrast from different water matrices: ultrapure water, surface water, groundwater and wastewater. The use of gamma irradiation for degradation is influenced by coexisting substances in natural waters and wastewaters. The influence of the presence of anions on the degradation of diatrizoate by gamma irradiation was investigated.

Study results indicate that: (1) diatrizoate radiolysis fits pseudo-first-order kinetics; removal of  91.9% of the diatrizoate was achieved at a dose of 1000 Gy; (2) diatrizoate degradation depends on the type of water matrix, with the radiolysis being affected by the presence of anions, as follows: (i) high concentrations of Cl⁻ increase the efficacy of the process; and (ii) low concentrations of markedly decrease the degradation rate, because nitrite ions act as scavengers of , hydroxyl radical and hydrogen radical; (3) TOC values showed that diatrizoate does not mineralize at a dose of 1000 Gy.

Radiolysis degrades diatrizoate by more than 90%; results obtained indicate that it is not mineralized, with TOC values remaining constant in all waters studied. © 2013 Society of Chemical Industry

Biological wastewater treatment by nitrification is widely used; however information on inhibition of nitrification by sulfide is still scarce. The aim of this study was to evaluate the inhibitory effect of different initial sulfide concentrations on ammonium and nitrite oxidizing processes.

In the absence of sulfide, nitrification was completed after 24 h with an ammonium consumption efficiency (E_NH4+) of 100.0 ± 2.1% and an ammonium to nitrate conversion yield (Y_NO3-) of 0.90 ± 0.01 g NO₃^--N g^–1 NH₄⁺-N consumed. At sulfide concentrations lower than 13.5 ± 0.7 mg HS^--S L^–1, E_NH4+ was maintained at 100% after 60 h. At sulfide concentrations ranging from 3.1 to 112.0 mg HS^--S L^–1, the Y_NO3- decreased from 0.9 to 0.3 due to an accumulation of nitrite, whereas specific rates decreased by 51 to 92% for NH₄⁺ consumption and by 77 to 97% for NO₃^- production. The IC₅₀ value (concentration causing 50% inhibition) for ammonium and nitrite oxidation was 2.6 ± 0.3 and 1.2 ± 0.2 mg HS^--S L^–1, respectively.

Sulfide provoked an inhibitory effect on both ammonium and nitrite oxidizing processes, nitrite oxidation being the most affected step. This information is relevant for wastewater treatment, indicating that the presence of sulfide in effluents even at low concentration might strongly alter the nitrifying activity of activated sludge and provoke nitrite accumulation.© 2012 Society of Chemical Industry

Zeolite X is one of the most important synthetic zeolites and has been used extensively. Therefore, to satisfy its high demand the synthesis of zeolite X from inexpensive sources is very desirable. Low-grade bauxite, an inexpensive aluminium and silicon source has been used to synthesize zeolite A. In the present paper, the production of zeolite X from this inexpensive low-grade bauxite is attempted for the first time.

The combination of alkali fusion activation and hydrothermal reaction synthesis provides a successful method to synthesize zeolite X from this low-grade bauxite. The molar ratios of SiO₂/Al₂O₃, Na₂O/SiO₂andH₂O/Na₂O are the most crucial parameters, which determine the phase composition and crystallinity of products. Using sodium silicate solution to adjust SiO₂/Al₂O₃ molar ratio, highly crystallized zeolite X is achieved under the optimized experimental conditions of 2Na₂O: 0.2Al₂O₃: 1SiO₂: 76H₂O at 95°C for 24 h. The synthesized zeolite X was further characterized by SEM, BET, FT-IR, and thermal stability.

The results indicate that the inexpensive raw material can be utilized to synthesize highly-crystallized zeolite X under optimized experimental conditions.

Traditional FT catalysts such as Co and Fe still suffer from carbon-induced deactivation even with alkali promotion. The objective of this study was to examine the effect of Ba addition to carbon-tolerant Mo carbide since it has Pt-like characteristics and is cheaper than noble metals as an FT catalyst.

The presence of Ba increased the Mo carbide production rate and reduced the activation energy for its formation. The promoted catalyst exhibited higher specific basic site strength and CO₂ uptake for strong basic site than that of the undoped catalyst. Both catalysts exhibited optimal reaction rate at a H₂ mole fraction of 0.75 while CO consumption rate, total olefin-to-paraffin ratio, methane suppression as well as C₅₊ selectivity were improved with Ba addition. The non-standard Anderson–Schulz–Flory (ASF) product distribution observed for the Ba-doped catalyst may be due to the appearance of an additional polymerization site on the catalyst surface located in the BaMoO₄ phase. Chain growth factor was enhanced by up to 93% from 0.43 to 0.83 with the Ba-doped catalyst.

Ba promoter increased chain growth probability by about 93%. The deviation of product distribution from standard ASF plots with 2 chain growth factors for the 3wt%Ba-10%MoC_1-x/Al₂O₃ catalyst was probably due to the presence of different active sites for chain initiation. The result is unprecedented and represents excellent opportunity for industrial exploitation of a new and relatively cheap carbon-resistant catalyst.© 2012 Society of Chemical Industry

The production cost and the material properties of polyhydroxyalkanoate (PHA), a biodegradable plastic are common issues of debate. It has become a constant challenge for researchers to find suitable and relatively cheap carbon substrates. This study has investigated the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)], using a combination of fatty acids and alcohols. The fermentation process described in this study also highlights the potential use of 1-pentanol for the generation of 3HV monomer, in contrast to odd carbon numbered volatile fatty acids, which are known to exert some levels of toxicity towards the cells.

Among the various mixtures of fatty acids and 3HV precursors, the mixture of 0.50 wt% C oleic acid and 0.06 wt% C 1-pentanol was found suitable for the production of this copolymer. It was found that Cupriavidus sp. USMAA2-4 could produce up to 56 wt% of P(3HB-co-3HV) with 8 mol% 3HV monomer units. The 3HV monomer composition was also successfully regulated in the range 3–66 mol% by manipulating the culture conditions. The number average molecular weight of the copolymer produced was in the range 217–351 kDa.

The findings of this study might be used as a platform for scale-up production of 3HV copolymers with different monomer compositions using mixtures of oleic acid and alcohols, namely 1-pentanol for a sustainable production process.© 2012 Society of Chemical Industry

Fundamental studies are reported investigating the electrochemical deposition of cadmium and zinc contained in solutions from a zinc electro-refining plant. This work also analyzes the performance of a filterpress electrochemical reactor used in the recovery of zinc and cadmium from this effluent.

The cathodic polarization curves showed electrochemical processes with mixed control for 304 SS and Al. The cyclic voltammetry studies on stainless steel revealed the presence of metal deposits at low current densities, whereas Zn and Cd were preferentially deposited at high overpotentials. The greatest recovery of cadmium (19%) and zinc (24%) at j_ap = 4 mA cm^-2 was obtained with a 304 SS cathode and t = 180 min. The SEM micrographs of cathode plates confirmed the presence of cadmium and zinc deposits. In addition, EDS analyses revealed that the composition of such deposits depends on the deposition time and the cathode material.

A continuous filterpress electrochemical reactor with 304 SS and Al cathodes exhibited a promising performance level for cadmium and zinc recovery from industrial solutions.

Studies on the degradation and mineralization of tetracycline by means of the electro-Fenton process are lacking in the available literature. Its relevance as a pre-treatment prior to a biological process for the removal of tetracycline was therefore examined.

Degradation followed pseudo-first-order kinetics and the optimal operating conditions were: 0.1 mmol L^-1 catalyst (Fe²⁺) concentration, 300 mA applied current intensity and 25 mg L^-1 tetracycline, leading to total degradation within only 5 min and a mineralization yield of 89 % after 6 h electrolysis. Biodegradability tests were realized with 100 mg L^-1 tetracycline; BOD₅/COD ratio increased from 0.02 to 0.56 after 6 h electrolysis, showing the relevance of the electro-Fenton pre-treatment. However, to keep a significant residual organic content, 2 to 4 h electrolysis time may be more relevant, leading to BOD₅/COD ratio and mineralization yields of 0.33–0.44 and 46–72%, respectively.

Activated sludge cultures of pretreated and non-pretreated tetracycline solutions were carried out for 3 weeks. The overall TOC removal increased from 28% for the non-pretreated tetracycline to 68 and 86% after 2 and 4 h electrolysis, confirming the efficiency of the proposed combined process. © 2012 Society of Chemical Industry