Faculty of Environmental Engineering, The University of Kitakyushu, 1-1, Hibikino, Wakamatsu, Kitakyushu, Japan.
School of Municipal and Environmental Engineering, Shandong Jianzhu University, Fengming Rd., Lingang Development Zone, Jinan, China.
Water Res. 2020 Jul 15;179:115883. doi: 10.1016/j.watres.2020.115883. Epub 2020 May 3.
Acidic failure is relatively common in anaerobic digesters that receive readily biodegradable food wastes at high loading. Under low pH conditions, the activity of methanogenic biomass decreases resulting in complete failure of the digestion process. In this experimental study, we demonstrated that one of the causes for the digester failure under low pH conditions is due to accelerated decay of methanogenic biomass. When enriched acetate degrading methanogens were exposed to a low pH environment (pH = 5.1 with phosphoric acid) in a batch experiment without external substrate, the specific decay rate was observed to increase as much as 10 times of that at pH 7.0. The specific decay rate for formate degrader was also found to increase under low pH conditions whilst the fermentative microorganisms in the cultures appeared to be tolerant to low pH conditions. A Propidium Mono-Azide-quantitative Polymerase Chain Reaction (PMA-qPCR) analysis revealed that the archaeal biomass dominated by methanogens dropped by 71-79% from the initial concentration after 6 days of the acidic batch experiment whilst the bacterial biomass dominating acidogens decreased by only 25%. The decrease in the number of living cells in the batch experiments at different pH was monitored with time to determine a correlation between decay rate and incubation pH.
酸性失效在接收高负荷易生物降解食物废物的厌氧消化器中相对常见。在低 pH 值条件下，产甲烷生物量的活性降低，导致消化过程完全失效。在这项实验研究中，我们证明了低 pH 值条件下消化器失效的原因之一是产甲烷生物量的加速衰减。在没有外部底物的批处理实验中，当富集的乙酸降解产甲烷菌暴露于低 pH 环境（pH = 5.1，用磷酸）时，观察到比在 pH 7.0 时的特定衰减率增加了多达 10 倍。在低 pH 条件下也发现了甲酸降解菌的特定衰减率增加，而培养物中的发酵微生物似乎对低 pH 条件具有耐受性。吖啶橙单偶氮定量聚合酶链反应（PMA-qPCR）分析表明，在酸性批处理实验进行 6 天后，由产甲烷菌主导的古菌生物量从初始浓度下降了 71-79%，而主导产酸菌的细菌生物量仅下降了 25%。随着时间的推移，监测不同 pH 值批次实验中活细胞数量的减少，以确定衰减率与孵育 pH 值之间的相关性。
