Fouling behaviors are different at various negative potentials in electrochemical anaerobic membrane bioreactors with conductive ceramic membranes

Abstract

Membrane fouling remains a critical challenge to the practical application of anaerobic membrane bioreactor (AnMBR). To address this challenge, a conductive ceramic membrane was prepared for fouling control in AnMBR. By using the conductive membranes, the anti-fouling performances were enhanced about 3 times at potentials below -1.0 V vs Ag/AgCl compared to the conventional AnMBR. The particle size distributions and the electric field calculations suggest that such an enhancement was mainly attributed to the increased particle sizes of foulants in the supernatant and the electric field forces. Moreover, the scanning electron microscope and confocal laser scanning microscope results show that the conductive membrane at -1.0 V could increase the porosity of the gel layer on the surface, whereas the conductive membrane at -2.0 V could inhibit the activity of adhering bacteria. Surprisingly, membrane fouling of electrically-assisted AnMBR (AnEMBR) at -0.5 V was increased, which was attributed to a dense biofilm-like structure formation. Such a result is contrary to the conventional cognition that negative potential could mitigate the membrane fouling. Overall, this work supplements the understanding of the anti-fouling effects of the electric field in AnEMBR, and provides supplementary information for the engineering application of AnEMBR.

Keywords: Anti-fouling mechanisms; Conductive ceramic membrane; Electrochemical anaerobic membrane bioreactor (AnEMBR); Membrane fouling; Methane production.