Continuous flow electrocoagulation process in combination with other treatment processes: A review of current applications and approaches

Abstract

The combination of electrocoagulation (EC) with other treatment techniques is a recent approach to achieve better removal of pollutants. Numerous reported experiments revealed the feasibility of combining EC with various physical, chemical, and biological treatment processes. However, most of the experiments reported the behavior of EC units in batch process, other experiments were more realistic as they were conducted in a continuous flow process. There have been numerous review papers highlighted different points regarding EC, these review papers covered the removal of a specific pollutant, treatment of specific wastewater, operational factors, type of the treatment process that is integrated with EC, or applications of advanced EC. Nevertheless, the type of EC process, batch or continuous, was overlooked in these reviews. This manuscript reviewed the combination of continuous flow EC process with other treatment techniques. The outcomes of this study showed the efficient performance of these combinations to remove various pollutants, however, a potential deterioration of removal efficiency for a certain pollutant might occur especially those pollutants which are removed by post biological nutrients removal. Moreover, real wastewater was used in most of the reviewed studies confirming the applicability of the results and conclusions, on the other hand, the majority of the studies were conducted using bench scale units which may lessen the authenticity of the results. Furthermore, a lack of comprehensive costing studies and kinetic studies of these combinations is noticeable. Finally, the majority of the reviewed papers investigated EC as a pretreatment process, accordingly an obvious gap of EC as a post treatment process should be considered.