Comparative Study for Lake Water Remediation: Chemical Coagulation and Electrocoagulation

Water scarcity worldwide has reached the alarming rate and received the greatest attention. The increasing of pressure attributed by world water demand had inspired researchers on use of alternative water sources such as wastewater, a new norm. However, it is a critical need to find out the proper treatment technique to treat the wastewater. In this study, the reclamation and reuse of lake water (wastewater source) was conducted through chemical coagulation and electrocoagulation processes. Aluminium sulphate Al_2(SO_4)_3 was utilized in this study as the coagulant for chemical coagulation process. The dosage of Al_2(SO_4)_3 was manipulated in the range of 2 mg/L – 8 mg/L to investigate the optimal Al_2(SO-4)_3 dosage which brings to greatest removal of chemical oxygen demand (COD), colour, and turbidity from the collected wastewater sample. Whereas, electrocoagulation process was conducted in a lab-scale electrocoagulation reactor with two parallel monopolar aluminium electrodes. The electrocoagulation operation duration and DC power supply to the electrocoagulation reactor were varied in studying the performance of electrocoagulation process. Results obtained from this study depicted that both chemical coagulation and electrocoagulation processes were attractive for the treatment of lake water. However, chemical coagulation presented greater removal efficiency compared to electrocoagulation where it managed to remove COD, colour, and turbidity up to 93.04%, 93.86%, and 93.98%, respectively at the optimal Al_2(SO_4)_3 dosage of 6 mg/L. Sweep coagulation which comprises the adsorption and entrapment of pollutant particles onto aluminium hydroxides was the major mechanism for flocs formation in chemical coagulation process. Besides, the percentage of removal for electrocoagulation process is due to the applied voltage and operation duration. The percentage removal of COD, colour, and turbidity were increased with the increment of DC power supply voltage and pro-longed the operation duration. Results shown that the highest percent of removal is achieved by electrocoagulation reactor operated at 10 V for 45 min in this study, where the percentage of removal for COD, colour, and turbidity was 73.91%, 92.98%, and 71.44%, respectively.