Astani Department of Civil and Environmental Engineering, University of Southern California, 3620 South Vermont Avenue, Los Angeles, CA 90089, USA.
Divert, Inc., 23 Bradford Street, Concord, MA 01742, USA; Southern California Gas Company, 555 West Fifth Street, Los Angeles, CA 90013, USA.
Water Res. 2017 Oct 15;123:277-289. doi: 10.1016/j.watres.2017.06.065. Epub 2017 Jun 23.
Despite growing interest in co-digestion and demonstrated process improvements (e.g., enhanced stability and biogas production), few studies have evaluated how co-digestion impacts the anaerobic digestion (AD) microbiome. Three sequential bench-scale respirometry experiments were conducted at thermophilic temperature (50 °C) with various combinations of primary sludge (PS); thickened waste activated sludge (TWAS); fats, oils, and grease (FOG); and food waste (FW). Two additional runs were then performed to evaluate microbial inhibition at higher organic fractions of FOG (30-60% volatile solids loading (VSL; v/v)). Co-digestion of PS, TWAS, FOG, and FW resulted in a 26% increase in methane production relative to digestion of PS and TWAS. A substantial lag time was observed in biogas production for vessels with FOG addition that decreased by more than half in later runs, likely due to adaptation of the microbial community. 30% FOG with 10% FW showed the highest increase in methane production, increasing 53% compared to digestion of PS and TWAS. FOG addition above 50% VSL was found to be inhibitory with and without FW addition and resulted in volatile fatty acid (VFA) accumulation. Methane production was linked with high relative activity and abundance of syntrophic fatty-acid oxidizers alongside hydrogenotrophic methanogens, signaling the importance of interspecies interactions in AD. Specifically, relative activity of Syntrophomonas was significantly correlated with methane production. Further, methane production increased over subsequent runs along with methyl coenzyme M reductase (mcrA) gene expression, a functional gene in methanogens, suggesting temporal adaptation of the microbial community to co-digestion substrate mixtures. The study demonstrated the benefits of co-digestion in terms of performance enhancement and enrichment of key active microbial populations.
尽管人们对共消化越来越感兴趣，并证明了工艺的改进（例如，增强的稳定性和沼气产量），但很少有研究评估共消化对厌氧消化（AD）微生物组的影响。在嗜热温度（50°C）下进行了三个连续的台式呼吸计实验，其中包含各种组合的初沉污泥（PS）；浓缩的废活性污泥（TWAS）；脂肪、油和油脂（FOG）；和食物垃圾（FW）。然后又进行了另外两个运行，以评估更高有机 FOG 分数（挥发性固体负载（VSL）的 30-60%（v/v））对微生物的抑制作用。与 PS 和 TWAS 的消化相比，PS、TWAS、FOG 和 FW 的共消化导致甲烷产量增加了 26%。在添加 FOG 的容器中观察到沼气产量的明显滞后时间，在随后的运行中减少了一半以上，这可能是由于微生物群落的适应。添加 30%FOG 和 10%FW 显示出最高的甲烷产量增加，与 PS 和 TWAS 的消化相比增加了 53%。发现 FOG 添加量超过 50%VSL 会抑制微生物的生长，无论是否添加 FW，都会导致挥发性脂肪酸（VFA）积累。甲烷产量与共生脂肪酸氧化菌和产氢甲烷菌的相对高活性和丰度相关，这表明种间相互作用在 AD 中的重要性。具体而言，Syntrophomonas 的相对活性与甲烷产量显著相关。此外，随着后续运行的进行，甲烷产量增加，同时甲基辅酶 M 还原酶（mcrA）基因表达增加，这是产甲烷菌的一个功能基因，表明微生物群落对共消化底物混合物的时间适应性。该研究表明了共消化在性能增强和关键活性微生物种群富集方面的优势。
