Advanced oxidation processes for treatment of effluents from a detergent industry

Abstract

Ozonation, catalytic ozonation, Fenton’s and heterogeneous Fenton‐like processes were investigated as possible pretreatments of a low biodegradable and highly toxic wastewater produced by a detergent industry. The presence of a Mn–Ce–O catalyst in ozonation enhances the biodegradability and improves the degradation at low pH values. However, a high content of carbonyl compounds adsorbed on the recovered solid indicates some limitations for real‐scale application. A commercial Fe2O3–MnOx catalyst shows higher activity as well as higher stability concerning carbon adsorption, but the leaching of metals is larger than for Mn–Ce–O. Regarding the heterogeneous Fenton‐like route with an Fe–Ce–O catalyst, even though a high activity and stability are attained, the intermediates are less biodegradable than the original compounds, indicating that the resulting effluent cannot be conducted to an activated sludge post‐treatment. The highest enhancement of effluent biodegradability is obtained with the classic homogeneous Fenton’s process, with the BOD5/COD ratio increasing from 0.32 to 0.80. This process was scaled up and the treated effluent is now safely directed to a municipal wastewater treatment plant.