Electrocoagulation Treatment of Wet Flue-Gas Desulfurization Wastewater Using Iron-Based Electrodes: Influence of Operating Parameters and Optimization

The aim of this study was to evaluate the performance of electrocoagulation (EC) in treating wastewater from wet flue-gas desulfurization (WFGD). The effects of initial pH, electrolysis time, applied voltage and inter-electrode distance on turbidity and on the removal of heavy metals were examined. The experimental results revealed that the initial pH of 9.0 was optimal for the treatment. There were decreases in the turbidity (99.2%), Cu 2+ (99.3%), Fe 2+ (99.9%), Ni 2+ (98.9%) and Zn 2+ (97.8%) with an electrolysis time of 40 min at an applied voltage of 20 V and an inter-electrode distance of 4 cm in the presence of Fe-Fe electrodes. By comparison, EC required a lower initial pH than chemical coagulation (FeSO 4 ) to achieve an improved removal efficiency for heavy metals and turbidity. The percentage of Fe b species, zeta potential and floc size in the EC process correlated well to the removal of heavy metals and turbidity. The process was also determined to be effective for a reduction in conductivity (75.6% removal).