Improved Anaerobic Digestion of Food Waste under ammonia stress by Side-Stream Hydrogen Domestication

Anaerobic digestion faces challenges in treating nitrogen-rich food waste. In this study, side-stream hydrogen domestication strategy was employed to improve the ammonia tolerance of AD system. The results revealed that SHD enhanced the methane yield and improved system stability at a high total ammonia nitrogen concentration, while Control stopped producing CH4. Further analysis using enzymes activity assays, flow cytometry, and metagenomics explored the mechanisms underlying ammonia tolerance of R100. SHD profoundly reshaped the microbial community structure, enriching homoacetogens and Methanosaeta-dominated methanogenic archaea. Key metabolic pathways including homoacetogenesis, butyrate degradation, propionate degradation, and methane production were upregulated, accompanied by increased enzymes activity. The gene abundance related to energy-generating pathways such as glycolysis was significantly enhanced, ensuring sufficient Adenosine Triphosphate production. Additionally, the high gene abundance of ion transport systems contributed to the compensation for H+ and K+ losses under ammonia stress. This study provides important insights and practical guidance for developing novel techniques in the field of AD.