Ferrate-enhanced electrocoagulation/ultrafiltration system on municipal secondary effluent treatment: Identify synergistic contribution of coagulant and oxidation

Abstract

Herein, we presented a ferrate-enhanced electrocoagulation/ultrafiltration (fECUF) system with three pathways of contaminants removal during the oxidation of Fe(II), realizing superior water production, excellent fouling control, and outstanding environmental risk reduction in municipal wastewater reuse. The system addressed the issue of the rapid inorganic membrane fouling caused by the traditional electrocoagulation processes. The formation of a unique cake layer with a bilayer structure in fECUF was favored to decrease the accumulation of organics and inorganics in membrane pores and maintain the membrane flux. Compared with the UF control system, the fECUF system decreased the transmembrane pressure by 63.13%. Redundancy analysis confirmed that oxidation dominated the removal of humic-like substances and UV254, while oxidation and coagulation synergistically promoted the reduction of DOC, protein-like substances, and trace organics. Also, coagulation contributed to the removal of antibiotics resistance genes (ARGs), which reduced their ability to be widely transmuted by a horizontal gene transfer mechanism. Compared to the UF control system, 4.48–39.76 times higher reduction of four ARGs were obtained in fECUF. Overall, this study has verified the potential advantages of the fECUF system in membrane fouling control and contaminants reduction for water reclamation.