Improvement of sludge characteristics and mitigation of membrane fouling in the treatment of pesticide wastewater by electrochemical anaerobic membrane bioreactor

Abstract

Electrochemical anaerobic membrane bioreactor attracted attention due to stable treatment quality with low footprint, and draw solute has significant effect on the sludge characteristics and membrane fouling performance. In this pilot-scale study, an electrochemical anaerobic membrane bioreactor (E-AnMBR) was proposed for treating pesticide wastewater at different hydraulic retention times (HRTs), demonstrating that E-AnMBR was superior on improvement of sludge characteristics and mitigation of membrane fouling, compared with the conventional anaerobic membrane bioreactor (C-AnMBR). E-AnMBR reduced sludge yield by 41.2 ± 6.7% and the SVI was significantly decreased by 32.5±13.8%. The accumulation of VFA in E-AnMBR was slighter than that of C-AnMBR, and the minimum average VFA was 255±6 mg/L. The methane yield of E-AnMBR (0.22–0.29 L CH4/g CODremoved) was 1.2–1.4 times than that of C-AnMBR. The EPS contents in suspended and attached sludge of E-AnMBR were significantly reduced by 41.8 ± 3.3% and 77.4 ± 14.5% than that of C-AnMBR, respectively. These results suggested that E-AnMBR has lower sludge disposal pressure, higher stability and methane recovery potential. Not only that, E-AnMBR successfully reduced membrane resistance, delaying the fouling rate by 31.0–38.5%. Finally, the linear relationship between EPS characteristics and membrane pollution was determined.