不同进料频率对丙酸产甲烷菌群富集的影响

Effects of Different Feeding Frequencies on the Enrichment of Propionic Acid Methanogenic Bacterial Flora

    摘要
  • 摘要: 针对厨余垃圾在低频进料模式下进行厌氧消化过程中易积累丙酸导致系统失稳的问题，以丙酸钠为唯一碳源，在不同进料频率(R1、R2、R3和R4四组试验，分别为每天、每2 d、3 d和4.5 d进出料100、200、300和450 mL)下采用半连续进料模式驯化富集丙酸产甲烷菌群，探究不同进料频率对厌氧消化系统运行过程中产气量、TAN浓度、挥发性脂肪酸等组分变化以及微生物群落结构的影响；同时利用修正的Gompertz模型分析不同进料频率下厌氧消化系统累计产甲烷动力学特性。结果表明：每3 d进料频率系统能够克服较大的丙酸负荷〔1.5 g/(L·d)期间〕冲击，平均日产甲烷量为409.82 mL，优于其他进料频率。比较各组模拟的动力学特性发现，在参数研究范围内，丙酸厌氧消化系统迟滞时间随着进料频率的升高而减小。不同进料频率下微生物群落结构分析表明，在第60天时R1、R2、R3和R4四组中具有丙酸氧化功能的菌属的相对丰度从5.19%分别增至13.55%、13.64%、9.31%和8.41%，氢养型产甲烷菌Methanoculleus在R1、R2、R3和R4四组厌氧消化系统中的相对丰度分别为33.63%、29.96%、41.77%和41.47%。研究显示，与每天进料频率的厌氧消化系统相比，每2 d、每3 d和每4.5 d进料频率的系统在较大丙酸瞬时负荷冲击下均有效地促进了丙酸产甲烷菌群的富集和保留，且综合评估后，每2天或每3天进料系统的促进效果较优。

     

    Abstract: Given the issue that food waste tends to accumulate propionic acid during anaerobic digestion in low-frequency feeding modes, leading to system instability, this study used sodium propionate as the sole carbon source to domesticate and enrich propionic acid methanogenic bacteria in a semi-continuous feeding mode. Different feeding frequencies (100, 200, 300 and 450 mL/d, daily, every 2, 3 and 4.5 days, respectively) were employed. The results showed that the anaerobic digestion system enriched propionic acid methanogens with a semi-continuous feeding mode with 100, 200, 300 and 450 mL of feed every 2, 3 and 4.5 d. The effects of different feeding frequencies on the changes in gas production, TAN concentration, volatile fatty acid, and other components as well as the structure of the microbial community were investigated. The system effectively handled a large propionic acid load (1.5 g/(L·d) period), with an average daily methane production of 409.82 mL, outperforming other feeding frequencies. Comparing the kinetic characteristics of each group, the hysteresis time of the propionic acid anaerobic digestion system decreased with increasing feed frequency within the tested parameters. Analysis of microbial community structure revealed that the relative abundance of genera responsible for propionic acid oxidation increased from 5.19% to 13.55%, 13.64%, 9.31% and 8.41% in groups of R1, R2, R3 and R4, respectively, by day 60. The relative abundance of the hydrogenotrophic methanogenic bacterium Methanoculleus was also assessed, with Methanoculleus hydrophilicus showing relative abundances of 33.63%, 29.96%, 41.77% and 41.47% in R1, R2, R3 and R4 anaerobic groups, respectively. The study demonstrates that the anaerobic digestion systems with feeding frequencies of 2, 3 and 4.5 days effective promote the enrichment and retention of propionic acid methanogens under larger transient propionic acid loads compared to daily feeding, and the promotion of the feed system every 2 or 3 days was superior after a comprehensive evaluation.

     

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