Treatment of mixed industrial wastewater by electrocoagulation and indirect electrochemical oxidation

Abstract

Treatment of mixed industrial wastewater is a challenging task due to its high complexity. This work scrutinizes the electrochemical treatment of mixed industrial wastewater, specifically electrocoagulation and indirect electrochemical oxidation processes through COD and color removal studies. Both processes are found to be more efficient at the wastewater pH. Monopolar connection was found more effective than bipolar connection for the removal of COD and color from wastewater. The monopolar connection removed COD up to 55% and color 56% whereas bipolar connection leads to the removal of 43% and 48% respectively at wastewater pH with an applied voltage 1.5 V in the course of 1 h of electrolysis. In the case of indirect electrochemical oxidation process using graphite electrodes, the COD and color abatement efficiencies of the indirect electrochemical oxidation process were found as 55% and 99.8%, respectively within 1 h of electrolysis conducted at pH 7.7, applied voltage 4 V, and NaCl concentration 1 g L^-1. This work also highlights the importance of the presence of electrolytes in the indirect electrochemical oxidation process as the external addition of sodium chloride significantly enhanced both COD and color elimination efficiency.

Keywords: Active chlorine; COD removal; Color removal; Electrocoagulation; Indirect electrochemical oxidation; Mixed industrial wastewater.