Membrane fouling mitigation and EPS reduction by CNTs-TiO2-PEDOT modified anode-membrane in Membrane Electro-Bioreactor (MEBR) treating mariculture wastewater

Abstract

Membrane Electro-Bioreactor (MEBR), with dual function of electrochemical in-situ membrane fouling mitigation and pollutants removal by chlorine evolution reaction (CIER), has emerged as a promising technology of treating mariculture wastewater. However, the fouling control mechanism regarding extracellular polymeric substance (EPS) variations and related microbial community is still unclear. In this study, MEBR was developed with conducting anode-membrane modified by CNTs-TiO2-PEDOT for fouling resistant and ammonia/nitrite removal. The CIER electroactivity was enhanced that onset potential negatively shifted from 1.12 to 0.98 V vs. SCE (saturated calomel electrode). Ammonia removal rate (71.49 mgN/(L·day)) was 176.8 % higher and nitrite was significantly reduced in MEBR than MBR at HRT of 45 min. Membrane fouling was mitigated in MEBR that operation duration was extended by 40 % compared with MBR. The EPS of cake layer on the membrane surface rather than the biofilters was found the main fouling contributor. The significant reduction in LB-EPSp (65.4 %) in MEBR (33.8 % in MBR) was the dominant factor contributing to membrane fouling alleviation, which highly depended on the relative abundance of Hyphomonas and Hirschia. This study will be beneficial for fouling control in seawater treatment.