An electrochemical anaerobic dynamic membrane bioreactor for sludge digestion: Enhanced performance, microbial communities and interfacial thermodynamics

• Published in: Separation and purification technology 2025-06, Vol.358, p.130463, Article 130463
• Main Authors: Zhou, Bo, Zheng, Jixing, Niu, Chengxin, Wu, Zhichao, Wang, Zhiwei
• Format: Article
• Language: English
• Subjects: Anaerobic dynamic membrane bioreactor; External voltage; Extracellular electron transfer; Interfacial thermodynamics; Microbial community
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.130463

The formation and fouling control of dynamic membrane (DM) are critical to the performance of anaerobic dynamic membrane bioreactors (AnDMBRs), especially in conditions with high solids concentrations. This study introduced an electro-AnDMBR (EC) for sludge anaerobic digestion over a 120-day period, comparing its performance to a control AnDMBR (CK) without external voltage. The EC system applied a voltage of 0.5 V, resulting in improved filtration performance and enhanced digestion efficiency, with sludge concentrations exceeding 50 g/L. The DM layer in the EC system, influenced by the electric field, was observed to be thinner, more porous, and composed of fewer polysaccharides, proteins, and cells. Calculation based on the extended Derjaguin-Landau-Verwey-Overbeek theory revealed that the alleviated DM fouling in the EC system was due to a 27.9% increase in the energy barrier for sludge-membrane adhesion, facilitated by the electric field’s interaction with modified sludge properties. In addition, the EC system exhibited stronger Lewis acid-base interactions within the sludge flocs, indicative of enhanced hydrogen-bonding interactions and improved electron transfer efficiency. The sludge in the EC system showed a 1.23-fold increase in conductivity and a 2.25-fold increase in capacitance compared to the CK system, along with increased electroactivity of extracellular polymeric substances (EPS), promoting extracellular electron transfer within the microbial communities. Moreover, the application of an electrical field significantly altered the microbial community structure, fostering a more interconnected microbial network and promoting multiple methanogenic pathways, which contributed to the overall enhanced performance of the EC system.