The separate and synergistic role of biochar and electric field to facilitate mesophilic anaerobic digestion of food waste slurry
Gaojun Wang, Bo Zhang, Changxi Sun, Lu Chen +3
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Abstract
This study investigated the separate and coupling strategies of biochar addition or/and electric field stimulation on anaerobic digestion (AD) of food waste slurry (FWS). Both biochar and electric field stimulation accelerated AD start-up, and the coupling strategy promoted volatile fatty acids (VFA) oxidation and methanogenesis, leading to a 34.1 % increase in accumulated methane yield during a 50-day operation period. Microbial characterization analysis revealed that biochar primarily upregulated the secretion of protein-like compounds in tightly-bound extracellular polymeric substances, and the electroactive matrix involving bulk sludge and biochar was likely established to mediate syntrophic methanogenesis through extracellular electron transfer (EET). Comparatively, electric field mainly governed the electrochemical behaviors and microbial community evolution of the electrode biofilm, which boosting the electrochemical activity of both anode and cathode, and increasing the cell viability of cathodic biofilm. It also selectively enriched Syntrophomonas in the anode and filamentous Methanospirillum in the cathode, which contributed to syntrophic methanogenesis in the electric stimulation groups. Overall, the outcome of this research underlined the different roles of biochar and electric field in boosting methanogenesis, and confirmed the synergistic benefits of the coupling stimulation strategy. • Biochar addition coupling electric stimulation facilitates accumulated CH 4 production by 34.1 % • Regulatory roles of biochar and electric field to boost methanogenesis are distinguished. • Biochar stimulates protein-like EPS secretion of bulk sludge to mediate EET-based methanogenesis. • The electric field harnesses cathodic biofilm formation by enriching filamentous Methanospirillum .
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Identifiers
- Journal
- Journal of Water Process Engineering
- Year
- 2024