Abstract

Recovery from stress is an important property for anaerobic digestion (AD). Although AD is quite adaptable with regard to waste composition, new substrates added to stable systems may cause process decline. We tested whether crude glycerol would cause stress to a thermophilic AD microbiome previously stabilized long-term on a low C/N ratio feedstock. Three-percent (v/v) crude glycerol was added to the basal substrate (poultry litter) for two hydraulic retention time (HRT) periods. This caused stress where biogas volume and methane percentage dramatically decreased and VFA levels increased. When the basal substrate was resumed, secondary inhibition occurred, resulting in even greater stress (biogas production ceased, methane 3.6%). Unassisted recovery of system processes required eight HRT periods. In contrast, crude glycerol applied at a lower organic loading rate did not cause inhibition. Crude glycerol caused changes in dominance in the microbial community (16S rRNA pyrotags). Although process resilience was slow, the recovery of digester functions occurred in conjunction with the recovery of community structure, particularly putative syntrophic acetate-oxidizing bacteria.

Key points

• Crude glycerol caused stress in thermophilic co-digestion with poultry litter.

• Unassisted resilience of digester functions (methane) required 8 HRT.

• Syntrophic acetate-oxidizing bacteria implicated for keystone resilience functions.

中文翻译：

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嗜热消化池中粗甘油诱导的压力：微生物群落发散和弹性，但过程恢复缓慢

摘要

从压力中恢复是厌氧消化（AD）的重要属性。尽管AD在废物成分方面非常适用，但添加到稳定系统中的新基材可能会导致工艺下降。我们测试了粗甘油是否会导致对嗜热性AD微生物组产生压力，该微生物先前已在低C / N比原料下长期稳定下来。在两个水力停留时间（HRT）期间，将3％（v / v）的粗甘油添加到基础基质（家禽垫料）中。这引起了压力，其中沼气量和甲烷百分比急剧下降，VFA水平升高。当恢复基础底物时，发生二次抑制，导致更大的压力（沼气停止产生，甲烷3.6％）。系统过程的无辅助恢复需要八个HRT周期。相反，以较低的有机负荷率施用的粗甘油没有引起抑制作用。粗甘油引起微生物群落（16S rRNA pyrotags）的优势变化。尽管过程复原力较慢，但消化器功能的恢复与群落结构的恢复同时发生，特别是假定的腐殖酸-乙酸氧化细菌。

关键点

•粗甘油与家禽垫料共消化时引起应激。

•沼气池功能（甲烷）的无辅助弹性需要8 HRT。

•腐殖酸氧化细菌与梯形抗逆功能有关。