Pretreatment and electrically stimulated direct interspecies electron transfer: A synergistic strategy for enhancing methane production from waste activated sludge

초록

Maximum hydrolyzation of waste-activated sludge (WAS) has been reported through various pretreatment (PT) studies. However, uncertainty remains whether electrically stimulated direct interspecies electron transfer (DIET) can enhance bioconversion of pretreated-hydrolyzed WAS and improve methane production in AD. This study first assessed thermal pretreatment (TP) and combined alkaline-thermal pretreatment (ATP) for accelerating WAS hydrolysis, then evaluated whether the resulting hydrolyzed WAS promoted DIET under an applied electrical voltage (EV) of 0.3 V in lab-scale batch reactors. ATP achieved 26.9 % solubilization, compared to 18.9 % for TP. Hydrolyzed WAS combined with EV enhanced methane production in (TP-EV)R and (ATP-EV)R, with the highest yield of 255.1 ± 5.1 mL CH4/g CODr observed in (ATP-EV)R, consistent with DIET promotion among electroactive microorganisms. These findings suggest that pairing pretreated WAS with EV application can enhance AD performance through electro-syntrophic microbial interactions, though the specific mechanistic contribution of DIET requires further isolation in future work. © 2026 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

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