AOX removal from industrial wastewaters using advanced oxidation processes: assessment of a combined chemical–biological oxidation

In this paper, the abatement of adsorbable halogenated organic compounds (AOX) from an industrial wastewater containing relatively high chloride concentrations by a combined chemical and biological oxidation is assessed. For chemical oxidation, the O 3 /UV, H 2 O 2 /UV and photo-Fenton processes are evaluated on pilot scale. Biological oxidation is simulated in a 4 h respirometry experiment with periodic aeration. The results show that a selective degradation of AOX with respect to the matrix compounds (expressed as chemical oxygen demand) could be achieved. For O 3 /UV, lowering the ratio of O 3 dosage to UV intensity leads to a better selectivity for AOX. During O 3 -based experiments, the AOX removal is generally less than during the H 2 O 2 -based experiments. However, after biological oxidation, the AOX levels are comparable. For H 2 O 2 /UV, optimal operating parameters for UV and H 2 O 2 dosage are next determined in a second run with another wastewater sample.