Abstract The performance of a single-stage semi-pilot scale reactor in anaerobically digesting food waste was examined and its microbial community composition investigated using high-throughput 16S rRNA gene sequencing. Highest biogas yield (1.01 L/g VSadded), highest removal efficiency for chemical oxygen demand (COD) (95.84%) and volatile solid (VS) (92.7%) were achieved during 124-day HRT. When the hydraulic retention time (HRT) reduced from 124 days to 62 days, ammonia and volatile fatty acids (VFA) concentration in the reactor gradually increased while pH, biogas yield, removal efficiency for VS and COD decreased gradually. This was likely due to the accumulation of volatile fatty acid (VFA), which resulted in scum accumulating in the reactor. The abundance of acid-producing bacteria resulted in the accumulation of VFA in the reactor, which is a critical factor that could explain process failure. Hydrogenotrophic methanogenesis was the main pathway for producing methane from hydrogen and carbon dioxide during the 124-day HRT. The decline in hydrogenotrophic methanogens at 62-day HRT inhibited the decomposition of VFA and accelerated the transfer of the amino acid degradation pathway, which further enhanced VFA accumulation. However, the dominant methanogens failed to degrade the excessive acetate at 41-day HRT. This metabolic discrepancy ultimately led to process deterioration.

中文翻译：

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水力停留时间对厌氧单级半中试规模反应器处理食物垃圾的工艺性能和微生物群落结构的影响

摘要 研究了单级半中试规模反应器在厌氧消化食物垃圾中的性能，并使用高通量 16S rRNA 基因测序研究了其微生物群落组成。在 124 天 HRT 期间实现了最高沼气产量 (1.01 L/g VS added)、化学需氧量 (COD) (95.84%) 和挥发性固体 (VS) (92.7%) 的最高去除效率。当水力停留时间（HRT）从124天减少到62天时，反应器中氨和挥发性脂肪酸（VFA）浓度逐渐升高，而pH值、沼气产率、VS和COD去除率逐渐降低。这可能是由于挥发性脂肪酸 (VFA) 的积累导致了反应器中的浮渣积累。大量产酸细菌导致反应器中 VFA 的积累，这是可以解释过程失败的关键因素。在 124 天的 HRT 期间，氢营养产甲烷是从氢气和二氧化碳生产甲烷的主要途径。62 天 HRT 时氢营养产甲烷菌的减少抑制了 VFA 的分解并加速了氨基酸降解途径的转移，从而进一步增强了 VFA 的积累。然而，在 41 天 HRT 时，主要产甲烷菌未能降解过量的醋酸盐。这种代谢差异最终导致过程恶化。62 天 HRT 氢营养产甲烷菌的减少抑制了 VFA 的分解并加速了氨基酸降解途径的转移，从而进一步增强了 VFA 的积累。然而，在 41 天 HRT 时，主要产甲烷菌未能降解过量的醋酸盐。这种代谢差异最终导致过程恶化。62 天 HRT 氢营养产甲烷菌的减少抑制了 VFA 的分解并加速了氨基酸降解途径的转移，从而进一步增强了 VFA 的积累。然而，在 41 天 HRT 时，主要产甲烷菌未能降解过量的醋酸盐。这种代谢差异最终导致过程恶化。