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Transition of microbial communities and degradation pathways in anaerobic digestion at decreasing retention time
New Biotechnology ( IF 4.5 ) Pub Date : 2021-01-01 , DOI: 10.1016/j.nbt.2020.07.005
Miriam Peces 1 , Sergi Astals 2 , Paul D Jensen 3 , William P Clarke 4
Affiliation  

Tuning of operational variables is a common practice to control the anaerobic digestion process and, in advanced applications, to promote the accumulation of fermentation products. However, process variables are interrelated. In this study, the hydraulic retention time (HRT) was decoupled from the organic loading rate (OLR) in order to isolate the effect of HRT as a selective pressure on: process performance, metabolic rates (hydrolytic, acetogenic, and methanogenic) and the microbial community. Four mesophilic anaerobic digesters were subjected to a sequential decrease in HRT from 15 to 8, 4 and 2 days while keeping the OLR constant at chemical oxygen demand of 1 gCOD L r-1 d-1. The results showed that HRT alone was insufficient to wash out methanogens from the digesters, which in turn prevented the accumulation of volatile fatty acids (VFA). Methanosaeta was the dominant genus in the four digesters at all HRTs. Metabolic rates showed that process performance was controlled by hydrolysis, with a clear shift in acetogenic rates, from butyrate and propionate degradation to ethanol degradation at 4 and 2d HRT. The change in acetogenic pathways was attributed to a shift in the fermentation pathways co-current with changes in fermentative bacteria. At 2d HRT, biofilm was formed on the walls and paddles of the digesters, probably as a survival strategy. Most of the taxa in the biofilm were also present in the digester media. Overall, it is the combination of HRT combined with other operational parameters which promotes the washout of methanogens and the accumulation of VFA.

中文翻译:

在减少保留时间下厌氧消化中微生物群落和降解途径的转变

调整操作变量是控制厌氧消化过程的常见做法,在高级应用中,可以促进发酵产物的积累。然而,过程变量是相互关联的。在本研究中,水力停留时间 (HRT) 与有机负荷率 (OLR) 分离,以分离 HRT 作为选择压力对以下方面的影响:工艺性能、代谢率(水解、产乙酸和产甲烷)和微生物群落。四个中温厌氧消化器的 HRT 从 15 天到 8 天、4 天和 2 天依次降低,同时在 1 gCOD L r-1 d-1 的化学需氧量下保持 OLR 恒定。结果表明,单独的 HRT 不足以从消化器中清除产甲烷菌,这反过来又阻止了挥发性脂肪酸 (VFA) 的积累。Methanosaeta 是所有 HRT 的四个消化器中的优势属。代谢速率表明,工艺性能受水解控制,产乙酸速率发生明显变化,在 4 天和 2 天 HRT 从丁酸盐和丙酸盐降解到乙醇降解。产乙酸途径的变化归因于发酵途径的转变与发酵细菌的变化同时发生。在第 2 天 HRT 时,在消化器的壁和桨叶上形成了生物膜,这可能是一种生存策略。生物膜中的大多数分类群也存在于消化器介质中。总的来说,正是 HRT 与其他操作参数相结合,促进了产甲烷菌的清除和 VFA 的积累。代谢速率表明,工艺性能受水解控制,产乙酸速率发生明显变化,在 4 天和 2 天 HRT 从丁酸盐和丙酸盐降解到乙醇降解。产乙酸途径的变化归因于发酵途径的转变与发酵细菌的变化同时发生。在第 2 天 HRT 时,在消化器的壁和桨叶上形成了生物膜,这可能是一种生存策略。生物膜中的大多数分类群也存在于消化器介质中。总的来说,正是 HRT 与其他操作参数相结合,促进了产甲烷菌的清除和 VFA 的积累。代谢速率表明,工艺性能受水解控制,产乙酸速率发生明显变化,在 4 天和 2 天 HRT 从丁酸盐和丙酸盐降解到乙醇降解。产乙酸途径的变化归因于发酵途径的转变与发酵细菌的变化同时发生。在第 2 天 HRT 时,在消化器的壁和桨叶上形成了生物膜,这可能是一种生存策略。生物膜中的大多数分类群也存在于消化器介质中。总的来说,正是 HRT 与其他操作参数相结合,促进了产甲烷菌的清除和 VFA 的积累。产乙酸途径的变化归因于发酵途径的转变与发酵细菌的变化同时发生。在第 2 天 HRT 时,在消化器的壁和桨叶上形成了生物膜,这可能是一种生存策略。生物膜中的大多数分类群也存在于消化器介质中。总的来说,正是 HRT 与其他操作参数相结合,促进了产甲烷菌的清除和 VFA 的积累。产乙酸途径的变化归因于发酵途径的转变与发酵细菌的变化同时发生。在第 2 天 HRT 时,在消化器的壁和桨叶上形成了生物膜,这可能是一种生存策略。生物膜中的大多数分类群也存在于消化器介质中。总的来说,正是 HRT 与其他操作参数相结合,促进了产甲烷菌的清除和 VFA 的积累。
更新日期:2021-01-01
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