Chemical industry wastewater treatment by coagulation combined with Fenton and photo-Fenton processes

Abstract

BACKGROUND Chemical industry wastewater is challenging to treat because of the various chemicals they contain. In this study, the treatment of chemical industry wastewater, which produces a wide variety of chemical aids, such as foam control agents, and silicones used in the textile, food and cosmetics industries, by coagulation combined with Fenton or photo-Fenton oxidation processes was investigated. In coagulation studies, optimum pH and coagulant dose were determined with polyaluminum chloride (PAC), polyaluminum chloride hydroxide sulfate (PACS) and FeCl3 coagulants, while Fe2+, H2O2, pH and oxidation time were optimized in Fenton studies.RESULTS In the coagulation, higher wastewater treatment was achieved with PAC compared to PACS and FeCl3 coagulants, and 62.6% chemical oxygen demand (COD) and 44.3% total organic carbon (TOC) removal were obtained at 500 mg L-1 PAC and pH 8. In the coagulation and Fenton oxidation, 92.4% COD, 79.7% TOC, 99.8% turbidity, and 96.7% total soluble solids (TSS) were achieved. The application of photo-Fenton oxidation instead of Fenton oxidation did not cause a significant change in chemical industry wastewater. The cost of chemical industry wastewater treatment by coagulation and Fenton oxidation was calculated as $19.16 m(-3), and the cost per kilogram of CODremoved was determined as $2.89 kg(-1).CONCLUSION In chemical industry wastewater treatment, high TSS and turbidity removal can be achieved by coagulation with PAC, and the wastewater load subjected to Fenton oxidation can be reduced. Efficient wastewater treatment was provided by Fenton oxidation after coagulation. The application of the photo-Fenton oxidation process instead of Fenton oxidation did not show the expected effect. However, toxicity studies should be performed in treated wastewater using coagulation-Fenton oxidation processes in future studies.