Performance evaluation of electrocoagulation process for removal of heavy metals from wastewater using aluminum electrodes under variable operating conditions

Abstract

Heavy metals are commonly found in agricultural and industrial wastewater. Because of their high toxicity and negative effects on human health, their removal from wastewater is of great importance. Electrocoagulation is a promising technology for the removal of heavy metals. The removal of heavy metals, namely, lead, cadmium, zinc, chromium, nickel, manganese, and copper as individual elements and in mixtures of synthetic and real wastewater by electrocoagulation, was studied using aluminum electrodes as anodes and stainless steel electrodes as cathodes in monopolar connections for different reaction times and current densities. The results show that the removal percentages of individual elements were 100% for lead after 20 min at 5 mA/cm2, 98% for cadmium after 40 min at 15 mA/cm2, 98% for zinc after 40 min at 5 mA/cm2, 100% for nickel after 40 min at 5 mA/cm2, 98% for chromium after 60 min at 5 mA/cm2, 98% for manganese after 60 min at 15 mA/cm2, and 100% for copper at 40 min at 5 mA/cm2. The results of wastewater mixtures showed similar removal patterns but lower removal values than those for individual elements. Pseudo-second-order kinetic model best describes the kinetics of the removal of the heavy metals investigated.