Anaerobic digestion (AD) is a key technology for converting organic matters to methane-rich biogas. However, nutrient imbalance can destabilize the whole digestion. To realize stable operation of AD and improve its efficiency, this work considers a new strategy to control the intermediate concentrations of poor AD under nutrient stress. For this purpose, long-term digestion under different nutrient conditions was investigated. Results showed that the feedstock with a low C/N ratio (= 6) caused VFA accumulation (2072 ± 632 mg/L), leading to the inhibition of methane production. Employing a substrate with a higher C/N ratio (= 11) and/or adding NHHCO (200 mg NH-N/L) could alleviate the VFA inhibition, but excessive dosage of NHHCO would induce ammonia inhibition. Through the established digestion balance between free ammonia nitrogen (FAN) between 0 and 25 mg/L, volatile fatty acid (VFA) 510–2100 mg/L, and alkalinity (ALK) 3300–7800 mg/L, an efficient methane yield of 150–250 mL/g VS was achieved and stable operation of AD under nutrient stress (low C/N ratio) was realized. Metabolic reconstruction between sp. and highlighted that microbial niche balance was developed as a result of digestion balance, which is beneficial for stable operation of AD. These findings improved our understanding of the interaction mechanism between intermediates and microbial niches for stability control in AD.

中文翻译：

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理清微生物生态位平衡和中间体对厌氧消化稳定性和调节的权衡


厌氧消化（AD）是将有机物转化为富含甲烷的沼气的关键技术。然而，营养失衡会破坏整个消化的稳定。为了实现AD的稳定运行并提高其效率，本工作考虑了一种在营养胁迫下控制贫AD中间浓度的新策略。为此，研究了不同营养条​​件下的长期消化。结果表明，低C/N比（= 6）的原料引起VFA积累（2072±632 mg/L），导致甲烷产生受到抑制。采用较高 C/N 比 (= 11) 的底物和/或添加 NHHCO (200 mg NH-N/L) 可以减轻 VFA 抑制，但过量的 NHHCO 会引起氨抑制。通过在游离氨氮 (FAN) 0 至 25 mg/L、挥发性脂肪酸 (VFA) 510–2100 mg/L 和碱度 (ALK) 3300–7800 mg/L 之间建立消化平衡，有效甲烷产量为VS达到了150–250 mL/g，实现了AD在营养胁迫（低C/N比）下的稳定运行。 sp之间的代谢重建。并强调微生物生态位平衡是消化平衡的结果，有利于AD的稳定运行。这些发现提高了我们对 AD 稳定性控制中间体和微生物生态位之间相互作用机制的理解。