Design of a continuous-flow single-channel reactor using optimal experimental data from batch reactor for turbidity removal by electrocoagulation

Abstract

Electrocoagulation was used for turbidity removal from surface water in an internal loop airlift batch reactor. The turbidity removal efficiency of 72.05 % and energy consumption of 0.210 kW h/m3 were achieved using initial conductivity of 1,494 μS/cm, applied voltage of 5 V, treatment time of 6.5 min and inter-electrode distance of 14 mm as optimal experimental conditions. These optimal experimental data were used to design a continuous-flow single-channel (CFSC) reactor for surface water treatment by Electrocoagulation. Furthermore, experimental study under previous optimal experimental data was carried out in the CFSC reactor and the performance of two reactors was compared. Then, hydrodynamic behaviour of the CFSC reactor was studied using Residence Time Distribution (RTD). According to the results, the amount of electro-dissolved aluminum and the energy consumption were lower in the CFSC reactor than in batch system. Despite these decreases, turbidity removal efficiency was more effective in the CFSC reactor than in batch reactor. This performance is attributed to the high mixing level within the reactor as well as the reuse of the tiny flocs for particles destabilization. According to the RTD results, the hydrodynamic behaviour of the CFSC reactor shows neither short-circuiting nor dead zones, but presents small deviation from plug flow. Dispersion models were used to characterize flow within the CFSC reactor. As a result, tanks-in-series model with J = 59 and axial dispersion model with Peclet = 116 are determined as models corresponding to the hydrodynamic behaviour of the CFSC reactor.