Authors

Abstract

To elucidate the inhibition mechanisms of sludge-grease anaerobic co-digestion (ACoD) and the microbial community succession patterns, this study systematically investigated the process through an enzyme addition strategy. Results demonstrated that compared with sludge mono-digestion, sludge-grease ACoD significantly enhanced methane yield, with the 1.5% mixed fatty acids group achieving a cumulative methane yield of (666.40±30.71) mL/g VS, representing a 179.4% increase over the control group. An addition of 3% unsaturated long-chain fatty acids (LCFAs) was identified as the inhibitory threshold for anaerobic digestion (AD). Both lipase and PECI (Peroxisomal 3,2-trans-enoyl-CoA isomerase) enzyme addition restored methanogenic activity, with the 1% PECI enzyme treatment group achieving a cumulative methane yield of up to 1627.76 mL/g VS, exhibiting the most effective mitigation. However, the addition of both enzymes showed limited improvement in reducing the lag phase of AD. Microbial community analysis revealed that low concentrations of lipase enriched Synergistetes, thereby facilitating the recovery of methanogenic functions, whereas high concentrations suppressed Synergistetes activity. Low concentrations of PECI enzyme promoted Bacteroidetes to dominate the late-stage degradation, while high concentrations maintained stable Synergistetes metabolic activity, thereby effectively circumventing LCFAs toxicity and acid accumulation risks. These findings provide a theoretical basis and technical reference for the engineering application of AD treating lipid-containing organic wastes.

Abstract in Chinese

为明确不饱和长链脂肪酸对污泥-油脂厌氧共消化的抑制机制以及消化过程中微生物群落变化规律不明晰的问题，本研究通过添加不同酶的方法进行探究。污泥-长链脂肪酸厌氧共消化的实验表明，污泥与LCFA厌氧共消化有效提高了甲烷产量，浓度为3%的不饱和长链脂肪酸是厌氧消化的抑制阈值。添加酶的缓解抑制实验表明，添加脂肪水解酶和PECI酶都能恢复产甲烷活性，且PECI酶具有更优的缓解效果。但两种酶添加对厌氧消化滞后期的改善效果有限。微生物分析表明，低浓度脂肪水解酶富集互营菌门促进产甲烷功能恢复，高浓度则抑制互营菌门并限制甲烷产量提升。PECI酶表现更优，中浓度时以拟杆菌门主导后期降解，高浓度时则维持互营菌门的稳定活性，从而规避LCFAs毒性及酸积累问题。本研究可为含油脂废有机弃物厌氧消化的工程应用提供技术参考。