Treatment of an agrochemical wastewater by combined coagulation and Fenton oxidation

BACKGROUND: Growing environmental concern about the presence of pesticides in water demands their removal, particularly in industrial wastewater effluents. These streams are characterized by high content of organic colloidal matter. Physicochemical treatments based on the combination of coagulation-flocculation processes have been well studied. An integral treatment of a non-biodegradable agrochemical wastewater has been tackled by physicochemical treatment with polyferric chloride (PFC) followed by a homogeneous Fenton oxidation process. RESULTS: The potential coagulation and flocculation properties of PFC were evaluated for PFC solutions of different OH/Fe molar ratios. TOC removal of 81% was obtained in the coagulation-flocculation pre-treatment under the best operating conditions. The Fenton process with moderate dosage of hydrogen peroxide and 90 degrees C also provided an extra 37% TOC reduction. The sludge from the physicochemical process was successfully activated with KOH at 750 degrees C, obtaining a highly microporous material of 1240 m(2) g(-1) of surface area. CONCLUSION: This work proposes a cost-effective approach to the treatment of a non-biodegradable agrochemical wastewater, achieving overall TOC reduction of 88%. The iron-containing sludge generated in the primary physicochemical treatment when treated by thermal treatment provides a promising adsorbent. (C) 2014 Society of Chemical Industry