Impact of electrooxidation on combined physicochemical and membrane treatment processes: Treatment of high strength chemical industry wastewater

Industrial wastewaters containing high concentrations of organics, particularly of recalcitrant nature, demand a unique type of treatment approaches often requiring two or more processes operated in tandem. In this paper, the effectiveness of combined treatment processes viz., coagulation/flocculation (C/F), electrooxidation (EO) and membrane (M) processes for tackling organic load in a segregated chemical industry wastewater is reported. The wastewater is characterized by strong color, high concentrations of salinity, total kjeldhal nitrogen (TKN) and chemical oxygen demand (COD). Three different combined process; i) UF–RO (CP-I); ii) C/F–EO–UF–RO (CP-II) and iii) C/F–EO1–EO2–UF–RO (CP-III) were investigated. The overall COD and TDS removal efficiencies in that order were: CP-I, 73% and 82%; CP-II, 84% and 85%, and CP-III, 93% and 87%. The percent COD and TDS removals at each stage of the combined process were evaluated and the impact of EO process on the overall performance of the process schemes was discussed. It emerged that intermediate level EO process considerably reduces organic load in the effluent, while large part of TDS removal can be attributed to final RO treatment. Thus, the combined treatment processes appear to be promising for obtaining greater efficiency of organic and salinity load removals.