Ajayi Olutooni B, Arnold William A, Wright Natasha, Guest Jeremy S, Novak Paige J
Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, MN, United States.
Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, United States.
Front Microbiol. 2025 May 14;16:1583463. doi: 10.3389/fmicb.2025.1583463. eCollection 2025.
Two-stage anaerobic digestion (AD) systems provide treatment for high strength wastewater with high stability and performance. Encapsulation technology can intensify AD to facilitate the separation of the solids retention time from the hydraulic retention time (HRT), offering lower HRTs, smaller reactors, and high effluent quality. To support successful deployment, however, the encapsulated community must contain all the needed microorganisms for successful treatment and be flexible enough to treat a variety of wastewaters. Here, a two-stage system was investigated in which microbial cultures were enriched on various high-strength wastewaters in suspended flow-through systems to determine how feed type influenced performance and microbial community structure. The hypothesis was that specific genera, or so-called "keystone species" would positively correlate to organic carbon degradation for a given feed, enabling construction of a well-functioning community for encapsulation. Results showed that the number of total bacteria (as 16S rRNA gene copies) did not correlate to soluble chemical oxygen demand (sCOD) removal, indicating that the community structure and/or members were important for good performance. Results also showed that feed type strongly influenced carbon removal and microbial community structure for 1st-stage fermenting communities, but not 2nd-stage methanogenic communities. In this study, the "core" community members were defined as organisms common to all of either the 1st- or 2nd-stage reactors irrespective of the feed they received and were present in at least 50% of the samples throughout the entire experiment. "Unique" community members were specific to a single feed, and hence, only present in either the 1st- or 2nd-stage reactors receiving that feed. In both 1st- and 2nd-stage communities, only one core genera and no unique genera were positively and significantly correlated to sCOD removal. Verification experiments performed with encapsulated communities showed that organisms identified in flow-through system and correlated with carbon degradation, though not significantly, seemed to be important for performance. Our results suggest that one cannot construct a community containing specific populations in lieu of enrichment. Nevertheless, a single diverse encapsulated anaerobic community should provide good (>80%) carbon removal when fed a variety of influents, if time is provided for enrichment after deployment.
两级厌氧消化（AD）系统可为高强度废水提供具有高稳定性和性能的处理。包封技术可以强化厌氧消化，促进固体停留时间与水力停留时间（HRT）的分离，从而实现更短的HRT、更小的反应器以及更高的出水水质。然而，为了支持该技术的成功应用，包封的微生物群落必须包含成功处理所需的所有微生物，并且要有足够的灵活性来处理各种废水。在此，研究了一种两级系统，其中微生物培养物在悬浮流通系统中以各种高强度废水进行富集，以确定进料类型如何影响性能和微生物群落结构。假设是特定的属，即所谓的“关键物种”，将与给定进料的有机碳降解呈正相关，从而能够构建一个功能良好的用于包封的群落。结果表明，细菌总数（以16S rRNA基因拷贝数计）与可溶性化学需氧量（sCOD）的去除没有相关性，这表明群落结构和/或成员对于良好的性能很重要。结果还表明，进料类型对一级发酵群落的碳去除和微生物群落结构有强烈影响，但对二级产甲烷群落没有影响。在本研究中，“核心”群落成员被定义为一级或二级反应器中所有样品共有的生物体，无论它们接收何种进料，并且在整个实验过程中至少50%的样品中存在。“独特”群落成员特定于单一进料，因此仅存在于接收该进料的一级或二级反应器中。在一级和二级群落中，只有一个核心属且没有独特属与sCOD去除呈正相关且显著相关。对包封群落进行的验证实验表明，在流通系统中鉴定出的与碳降解相关的生物体，虽然相关性不显著，但似乎对性能很重要。我们的结果表明，不能构建一个包含特定种群而不进行富集的群落。然而，如果在部署后提供富集时间，单一多样的包封厌氧群落当进料各种进水时应能实现良好（>80%）的碳去除。
