Performance analysis of a continuous-flow single-channel reactor for surface water treatment using electrocoagulation process

Abstract

A Continuous-Flow Single-Channel (CFSC) reactor made of vertical flow channels was used for the treatment of surface water by Electrocoagulation (EC). The effects of different CFSC reactor configurations based on the number of Pair of Working Electrodes (PWE) were analysed by considering transport phenomena within the reactor, which including mixing time and theoretical minimal residence time of electro-dissolved electrodes inside the reactor (tmin). The main objective of this study is to prove that the widespread conclusion which stipulates that increasing the number of electrodes improves the performance of the EC process is not true for all reactor’s geometries. Since the pairs of electrodes are placed in the up-flow channel, the PWE’s number is interpreted as the number of Working Up-Flow Channel (WUFC) in the reactor. The results show that the increase in the WUFC’s number (m WUFC) in the CFSC reactor leads to a higher electrodes’ consumption and a lower tmin. The latter is due to the PWEs’ close location to the reactor’s outlet, resulting in a waste of electro-dissolved aluminium, as it does not fully contribute to destabilizing the suspended particles; rather, it promotes secondary pollution by increasing the residual aluminium concentration in treated water. The CFSC reactor configuration with m WUFC = 4 reduces the electrodes’ consumption and operating cost by approximately 28.1% and 14%, respectively. It also increases the mixing time (higher tmin value) and enhances turbidity removal by about 4% compared to the CFSC reactor configuration with m WUFC = 10 for the same energy consumption.