Phosphorus Removal from Wastewater in Johkasou Sewage Treatment Tank by Electro-coagulation

Abstract

—Orthogonal experimental plan was used to explore the effect of aeration rate, electrolysis time, and current density on the total phosphorus (TP) removal of sewage from purification tank (Johkasou). The results showed that the removal efficiencies of total phosphorus in an anode-cathode-anode electrolytic cell increased by from 3.4% to 22.6% than that of an anode-cathode electrolytic cell. For the anode-cathode-anode electrolytic cell, the TP concentration of effluent could reach below 1mg/L (discharge standard for effluent) with a TP removal rate above 95.9% under the condition of electrolysis time of 60 mins or current density of 4 mA·cm -2 . Whereas the anode-cathode electrolytic cell must require a combination with any two of the above three experimental factors at high levels to achieve the discharge standard, and the TP removal rates were more than 92.6%. Aeration improved the phosphorus removal rate in the electrolysis apparatus. Fourier transform infrared spectroscopy (FTIR) analysis showed that the precipitate of electro-coagulation was a mixture of hydroxyl iron phosphate and iron phosphate. The phosphorus of the sewage in the Johkasou could be effectively removed through sludge discharge.