Electrocoagulation Process as a Consolidated Technology in the Treatment of Industrial Effluents and as a Promising Process in the Treatment of Effluents Generated by Car Washes: A Brief Review

Abstract

Electrocoagulation (EC) is an efficient treatment method that involves the electrodissolution of anodes, the formation of coagulants in situ, and the production of hydrogen at the cathode, facilitating the removal of pollutants by flotation. Industry in general aims to reduce the contaminant load, expressed as chemical oxygen demand (COD), and EC effluent treatment is particularly effective in this process. The development of EC processes has been an efficient alternative for the treatment of effluents with high pollutant loads, such as tannery, pulp and paper, textile, beverage, and food industries, and many demonstrate the potential for application in car wash effluent. This study presents a review of the use of EC for the treatment of various effluents containing COD, OGs, surfactants, color, and turbidity, but with a greater focus on the vehicle washing sector. It also discusses the factors that influence the efficiency of EC and the main discussions of the authors. Presently, the investigations of studies already carried out show that the performance of the EC process is dependent on many relationships and factors, such as the type of material constituting the electrode, the electric potential difference, the electric current density, the distance between electrodes, the surface area of the electrodes, the pH, the initial concentration of contaminants, the conductivity and the treatment time. The review demonstrated that the EC process has been employed in the treatment of many types of effluents and with relatively high efficiency rates, in general, between 60.0% and up to 90.0%, aiming at the reduction of the COD indexes, the reduction from 60.0% up to 99.0% of color content, the 87.0% reduction of chromium. In turn, for turbidity, it varied on average from 44.0 to 99.0%. For other parameters such as MBAS and OGs, in most studies, the reduction exceeded 90.0%.