Micro-aeration strategy for improved biogas yield and in-situ hydrogen sulfide mitigation during high-solids co-digestion of poultry litter.

High-solids anaerobic digestion sustainably converts organic waste into methane-rich biogas and nutrient-rich biomanure, offering dual benefits. This study assessed poultry litter (PL) digestion at 10 %, 30 %, and 60 % total solids (TS) under three setups: (i) PL alone, (ii) co-digestion with food waste hydrolysate (PL + FH) to improve carbon/nitrogen (C/N) ratio, and (iii) in situ desulfurization (St-PL) using sulfur-oxidizing bacteria (SOB) with micro-aeration to reduce H2S. The highest biogas yields were obtained at 30 % TS: 12.4 L (PL + FH), 9.9 L (PL), and 8.9 L (St-PL). Methane content was highest in St-PL (68 %) with H2S removal of 80-92 %. However, slight sulfate accumulation was detected in the digestate, attributed to the metabolic activity of sulfur oxidizing bacteria (SOB). Microbial analysis revealed the dominance of Firmicutes, Bacteroidetes, Methanosaeta, and Methanobacterium. This study demonstrates a scalable strategy in which micro-aeration combined with SOB enhanced methane yield and biogas quality while effectively mitigating H2S during high-solids poultry litter digestion.