The inoculum source plays a crucial role in the anaerobic treatment of wastewaters. Lipids are present in various wastewaters and have a high methanogenic potential, but their hydrolysis results in the production of long chain fatty acids (LCFAs) that are inhibitory to anaerobic microorganisms. Screening of inoculum for the anaerobic treatment of LCFA-containing wastewaters has been performed at mesophilic and thermophilic conditions. However, an evaluation of inocula for producing methane from LCFA-containing wastewater has not yet been conducted at low temperatures and needs to be undertaken. In this study, three inocula (one granular sludge and two municipal digester sludges) were assessed for methane production from LCFA-containing synthetic dairy wastewater (SDW) at low temperatures (10 and 20°C). A methane yield (based on mL-CH₄/g-COD_added) of 86-65% with acetate and 45-20% with SDW was achieved within 10 days using unacclimated granular sludge, whereas the municipal digester sludges produced methane only at 20°C but not at 10°C even after 200 days of incubation. The acetotrophic activity in the inoculum was found to be crucial for methane production from LCFA at low temperatures, highlighting the role of Methanosaeta (acetoclastic archaea) at low temperatures. The presence of bacterial taxa from the family Syntrophaceae (Syntrophus and uncultured taxa) in the inoculum was found to be important for methane production from SDW at 10°C. This study suggests the evaluation of acetotrophic activity and the initial microbial community characteristics by high-throughput amplicon sequencing for selecting the inoculum for producing methane at low temperatures (up to 10°C) from lipid-containing wastewaters.

中文翻译：

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在低温下，对流营养活性促进了LCFA的甲烷生成：从嗜温接种物中筛选。

接种源在废水的厌氧处理中起着至关重要的作用。脂质存在于各种废水中，具有很高的产甲烷潜力，但它们的水解作用会导致产生抑制厌氧微生物的长链脂肪酸（LCFA）。已经在中温和高温条件下筛选了用于厌氧处理含LCFA废水的接种物。但是，尚未在低温下对从含LCFA的废水中生产甲烷的接种物进行评估，因此需要进行评估。在这项研究中，评估了三种接种物（一种颗粒污泥和两种市政消化污泥）在低温（10和20°C）下由含LCFA的合成乳品废水（SDW）产生甲烷的能力。甲烷收率（基于mL-CH₄ / G-COD_加入）的86-65％用乙酸和45-20％用SDW物内使用unacclimated颗粒污泥10天后达到，而市政污泥消化器产生的甲烷仅在20℃下而不是在10℃下甚至孵育200天后。发现接种物中的乙营养活性对于低温下LCFA的甲烷生产至关重要，这突出了甲烷菌（乙酰碎屑古菌）在低温下的作用。浮游纲（Syntrophus）细菌类群的存在接种物中的未培养分类单元）对于SDW在10°C下的甲烷生产非常重要。这项研究建议通过高通量扩增子测序来评估菌体营养活性和初始微生物群落特征，以选择可在低温（最高​​10°C）下从含脂废水中生产甲烷的接种物。