Electrocoagulation applications for industrial wastewaters: a critical review

Abstract

Cost-effective methods are required to treat a wide range of wastewater pollutants in a diverse range of conditions. As compared with traditional treatment methods, electrocoagulation provides a relatively compact and robust treatment alternative in which sacrificial metal anodes initiate electrochemical reactions that provide active metal cations for coagulation and flocculation. The inherent advantage of electrocoagulation is that no coagulants have to be added to the wastewater and hence the salinity of the water does not increase after treatment. Electrocoagulation is a complex process involving a multitude of pollutant removal mechanisms operating synergistically. Although numerous publications have appeared in the recent past, the lack of a holistic and systematic approach has resulted in the design of several treatment units without considering the complexity of the system and process control mechanisms. Due to the fact that electrocoagulation is thought to be an enigmatic, promising treatment technology and a cost-effective solution for sustainable water management in the future, it will become increasingly important to provide a deeper insight into the pollutant removal mechanisms involved, kinetic modelling and reactor design. Considering the abovementioned facts, in this paper, industrial wastewater electrocoagulation applications have been reviewed with special emphasis placed on the major reaction mechanisms involved in these applications. Evaluation was based on specific pollutant parameters of the sector as well as operation costs including solid waste management, sacrificial electrode materials and electrical energy requirements.