Anaerobic cathodic dynamic membrane bioreactor for high-strength organic wastewater treatment: Potential for fouling control and enhanced methanogenesis

Anaerobic dynamic membrane bioreactor (AnDMBR) technology is gaining attention as a cost-effective and sustainable solution for treating organic wastewater, achieving high treatment and filtration efficiencies without the need for costly filter material. However, challenges related to the maintenance and fouling of dynamic membrane (DM) hinder its practical application. This study examined the potential of electrochemically assisted AnDMBR (e-AnDMBR) in treating high-strength organic wastewater under negative external voltages varying from 0 to -1.2 V applied to the cathodic DM. A voltage of -0.8 V was most effective in enhancing methane production and reducing DM fouling, with a 10 % increase in methane yield and a 21 % decrease in the transmembrane pressure increase rate, making it the optimal applied voltage for reactor performance and stability. This performance enhancement was attributed to the formation and maintenance of stable DM and the development of electro-syntrophic microbial communities, potentially accelerating methanogenesis and contributing to overall process stability. However, a more negative voltage of -1.2 V triggered adverse electrochemical effects, including reduced methanogenic activity and accelerated DM fouling due to chemical precipitation. Specifically, Methanosarcinales, whose members are capable of electrotrophic methanogenesis, dominated the DM and mixed liquor archaeal communities at -0.8 V, and the dominance shifted to strictly hydrogenotrophic Methanobrevibacter at -1.2 V. These results suggest that e-AnDMBRs with cathodic DM offer a promising approach for sustainable high-rate anaerobic treatment of high-strength organic wastewater, with the application of optimal voltage being crucial. This study underscores the critical influence of applied voltage on both reactor performance and microbial ecology, providing valuable insights for advancing e-AnDMBR technology and its application.