Advanced treatment of biologically pretreated coking wastewater by electrochemical oxidation using Ti/RuO2–IrO2 electrodes

Authors


Correspondence to: Xuwen He, School of Chemical and Environmental Engineering, China University of Mining & Technology. E-mail: hexuwen@sina.com.cn

Abstract

Background

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.

Results

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.

Conclusion

Ti/RuO2–IrO2 anode systems were confirmed to be effective in advanced treatment of biologically pretreated coking wastewater. © 2012 Society of Chemical Industry

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