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<p>Anaerobic digesters are typically operated at solids retention times (SRTs) of 20 d or longer to minimize the risk of accidental substrate overloading and biomass washout and to enable the retention of slow-growing methanogens. However, the long-term effects of such disturbances on digester performance and microbiome remain unclear. This study investigates whether short-term pulse disturbances, in the form of temporary SRT reductions causing organic loading rate (OLR) spikes, can enhance microbial resilience and accelerate process stabilisation (recovery) after a press disturbance (prolonged SRT reduction causing an OLR increase). We explored the feasibility of anaerobic digestion at shorter SRTs by introducing one or two pulse SRT disturbances (SRT reduction from 15 to 5 d) in four mesophilic anaerobic digesters treating wastewater sludge, followed by sustained operation (press disturbance) at an SRT of 5 d. Dual pulse disturbances led to faster process recovery compared to digesters receiving a single pulse disturbance (60 d vs. 104 d) with VFAs during the ensuing press disturbance period stabilizing at an average of 308&#xa0;mg COD/L (acetate) and 227&#xa0;mg COD/L (propionate), and biogas methane content reaching an average of 66% within 60 d after the onset of the press disturbance. Microbial community redundancy and resilience, with shifts between the slow-growing, resource-efficient taxa (K-strategists) and fast-growing, opportunistic taxa (r-strategists), were crucial in ensuring minimal disruptions during disturbance and recovery periods. Changes in the relative abundance of taxa that proliferated under stable conditions, namely, the K-strategists <i>Cloacimonadaceae</i> <i>W5</i>, <i>Syntrophomonas</i> spp. and <i>Methanosaeta</i> spp., and the stress tolerant r-strategists <i>Sedimentibacter</i> spp., <i>Christensenellaceae R-7-group</i>, <i>Saccharofermentans</i> spp. and <i>Methanosarcina</i> spp., corresponded with minimal disruptions in process performance during periods of instability. Overall, pulse disturbances may serve as a practical tool for enhancing microbiome resilience in anaerobic digestion, enabling stable performance under fluctuating substrate loading conditions.</p>

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Enhanced resistance and resilience of anaerobic digestion microbiome after single and dual short-term disturbances

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年2月7日

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  • A. F. Mohidin,
  • T. C. A. Ng,
  • E. Santillan,
  • L. Yang,
  • A. Cokro,
  • S. Wuertz

摘要

Anaerobic digesters are typically operated at solids retention times (SRTs) of 20 d or longer to minimize the risk of accidental substrate overloading and biomass washout and to enable the retention of slow-growing methanogens. However, the long-term effects of such disturbances on digester performance and microbiome remain unclear. This study investigates whether short-term pulse disturbances, in the form of temporary SRT reductions causing organic loading rate (OLR) spikes, can enhance microbial resilience and accelerate process stabilisation (recovery) after a press disturbance (prolonged SRT reduction causing an OLR increase). We explored the feasibility of anaerobic digestion at shorter SRTs by introducing one or two pulse SRT disturbances (SRT reduction from 15 to 5 d) in four mesophilic anaerobic digesters treating wastewater sludge, followed by sustained operation (press disturbance) at an SRT of 5 d. Dual pulse disturbances led to faster process recovery compared to digesters receiving a single pulse disturbance (60 d vs. 104 d) with VFAs during the ensuing press disturbance period stabilizing at an average of 308 mg COD/L (acetate) and 227 mg COD/L (propionate), and biogas methane content reaching an average of 66% within 60 d after the onset of the press disturbance. Microbial community redundancy and resilience, with shifts between the slow-growing, resource-efficient taxa (K-strategists) and fast-growing, opportunistic taxa (r-strategists), were crucial in ensuring minimal disruptions during disturbance and recovery periods. Changes in the relative abundance of taxa that proliferated under stable conditions, namely, the K-strategists Cloacimonadaceae W5, Syntrophomonas spp. and Methanosaeta spp., and the stress tolerant r-strategists Sedimentibacter spp., Christensenellaceae R-7-group, Saccharofermentans spp. and Methanosarcina spp., corresponded with minimal disruptions in process performance during periods of instability. Overall, pulse disturbances may serve as a practical tool for enhancing microbiome resilience in anaerobic digestion, enabling stable performance under fluctuating substrate loading conditions.