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Controlling pH in biological depuration of industrial wastewater to enable micropollutant removal using a further advanced oxidation process

Authors

  • Gracia Rivas Ibáñez,

    1. Department of Chemical Engineering, University of Almería, Almería, Spain
    2. CIESOL, Joint Centre of the University of Almería-CIEMAT, Almería, Spain
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  • José Luis Casas López,

    1. Department of Chemical Engineering, University of Almería, Almería, Spain
    2. CIESOL, Joint Centre of the University of Almería-CIEMAT, Almería, Spain
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  • Belén Esteban García,

    1. Department of Chemical Engineering, University of Almería, Almería, Spain
    2. CIESOL, Joint Centre of the University of Almería-CIEMAT, Almería, Spain
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  • José Antonio Sánchez Pérez

    Corresponding author
    1. Department of Chemical Engineering, University of Almería, Almería, Spain
    2. CIESOL, Joint Centre of the University of Almería-CIEMAT, Almería, Spain
    • Correspondence to: J.A. Sánchez Pérez, Department of Chemical Engineering, University of Almería, 04120 Almería, Spain. E-mail: jsanchez@ual.es

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Abstract

BACKGROUND

The accumulation of bicarbonates during the biological treatment of high organic strength wastewater has a negative impact on the remaining micropollutant removal through chemical oxidation due to its scavenging effect on hydroxyl radicals. In this study, a lab-scale sequencing batch reactor (SBR) was operated at circumneutral pH to avoid inorganic carbon accumulation, followed by Fenton and photo-Fenton processes to treat an agro-food industrial effluent with acetamiprid as a model pollutant at 100 µg L−1. A cost analysis of the operation strategy was performed.

RESULTS

The pH control did not affect SBR efficiency (98% organic carbon biodegradation) but gave rise to different inorganic carbon concentrations in the effluents: 75.32, 10.81 and 5.7 mg L−1 at pH 8.0, 7.0 and 6.5, respectively. Both Fenton and photo-Fenton resulted in complete acetamiprid removal at pH 6.5 and 7.0 with high iron dosage (up to 80 mg L−1) but only photo-Fenton achieved this at acidic pH with 20 mg Fe L−1.

CONCLUSION

To remove micropollutant from biotreated wastewater by Fenton processes it is highly recommended to control pH at circumneutral values during the biotreatment. The reactant cost analysis showed a reduction of ∼80% to remove the micropollutant, even with photo-Fenton being carried out at pH 2.8. © 2014 Society of Chemical Industry

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