Impacts of biogas residual biochar on anaerobic digestion of food waste with different organic loading rate: Methanogenic performance and metabolic pathways

초록

This study investigated the effects of different doses of biogas residue biochar (BRB) (5 g /L and 10 g/L) on the methanogenic performance and metabolic pathways during anaerobic digestion (AD) of food waste (FW) under a wide range of organic loading rate (OLR) (5, 10, 20, and 30 g volatile solid (VS)/L) conditions. The results indicated the cumulative methane yield was highest (375 +/- 8.40 mL/g VS) at an OLR of 10 g VS/L when no BRB was added, while suffered significant inhibition at higher OLRs (>10 g VS/L) due to volatile fatty acid (VFA) accumulation. BRB addition (5 g/L) significantly facilitated methane production by first enhancing organic matter degradation and VFA content (days 1---10), and then accelerating VFA consumption (days 18---50), with these beneficial effects becoming progressively more pronounced at higher OLRs (>5 g VS/L) in this study. Microbial and metabolic analysis revealed key microbial communities included Aminobacterium, Proteiniphilum, Clostridium_sensu_stricto_1, Syntrophomonas, and Methanosarcina were enriched, and methanol and methylamine/ dimethylamine/trimethylamine methanogenic pathways were enhanced under high OLR conditions with BRB addition. This study provides metabolic flexibility for maintaining stable methane production in response to high OLR while offering a closed-loop solution for digestate valorization.

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