COD removal from high salinity petrochemical wastewater using Photo-assisted peroxi-coagulation

Abstract

Photo-assisted peroxi-coagulation (PPC) was investigated for treatment of high TDS (total dissolved solids) wastewater. The most important characteristics of the studied wastewater were high TDS of around 16428 mg L-1 and BOD5/COD ratio of 0.07. Effective operating parameters, including initial pH values of 3-8, reaction time of 60-240 min, electrode distance values of 2-6 cm, and voltage values of 0.5-3 V were investigated in batch mode experiments. Optimum conditions were obtained at pH = 3, voltage = 1.5 V, electrode distance = 2 cm, and reaction time = 420 min, corresponding to 89.44 % COD removal, which meets the Iran environmental discharge legislation (COD = 100 mg L-1). Kinetic analysis showed that pseudo first-order kinetic model was best fitted (R2 = 0.97). GC mass chromatograms before and after treatment showed degradation of complex compounds to more simple constituents.