Understanding and regulation of interspecies electron transfer, including hydrogen-mediated interspecies electron transfer (MIET) and direct interspecies electron transfer (DIET), is crucial for enhancing anaerobic digestion (AD). In this study, MIET and DIET were regulated in a multistage anaerobic hythane reactor (MAHR) via inoculum management, activated carbon (AC) addition, and organic loading rate (OLR) adjustment. The operational stability, organic removal, and methane production can be enhanced, with AC addition in the methane production zone (Mm) (RC and RC). The reactors of RC and RC achieved start-up within 20 days and showed a 20 % and 104 % increase in maximum methane production rates, respectively. Microbial community characteristics confirmed that AC in Mm could facilitate DIET establishment, but its addition in Mh could not. This assertion was supported by the observed tighter and more positive correlation between biofilm conductivity and DIET-related microbes in RC and RC, as opposed to RC and RC. Further, the dual drive of DIET and MIET was revealed through the comprehensive analysis of operational performances and microbial community with the structure equation model. The electron fluxes analysis highlighted a dynamic shift of DIET and MIET in the methanogenic stage with AC addition and OLR variation. The DIET was proved more efficient than MIET in Mm with AC addition and OLR below 40 g COD/L/d, while high OLR (80 g COD/L/d) favored MIET with lower methane production efficiency. The results of this study shed light on the nuanced characteristics of interspecies electron transfer, providing valuable insights for the further design and operation of stage-separated AD.

中文翻译：

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分级厌氧消化系统中的种间电子转移调节：接种策略、活性炭整合和有机负荷率调整的作用


了解和调节种间电子转移，包括氢介导的种间电子转移（MIET）和直接种间电子转移（DIET），对于增强厌氧消化（AD）至关重要。在本研究中，通过接种量管理、活性炭（AC）添加和有机负荷率（OLR）调整，在多级厌氧乙烷反应器（MAHR）中调节MIET和DIET。通过在甲烷生产区 (Mm)（RC 和 RC）添加 AC，可以提高运行稳定性、有机物去除率和甲烷产量。 RC 和 RC 的反应器在 20 天内实现了启动，最大甲烷生产率分别提高了 20% 和 104%。微生物群落特征证实，Mm 中的 AC 可以促进 DIET 建立，但在 Mh 中添加 AC 则不能。与 RC 和 RC 相比，在 RC 和 RC 中观察到的生物膜电导率和饮食相关微生物之间更紧密和更正的相关性支持了这一主张。进一步通过结构方程模型对运行性能和微生物群落进行综合分析，揭示了DIET和MIET的双重驱动。电子通量分析强调了产甲烷阶段 DIET 和 MIET 随 AC 添加和 OLR 变化的动态变化。事实证明，添加 AC 后，DIET 在 Mm 方面比 MIET 更有效，且 OLR 低于 40 g COD/L/d，而高 OLR (80 g COD/L/d) 有利于 MIET，但甲烷生产效率较低。这项研究的结果揭示了种间电子转移的微妙特征，为阶段分离 AD 的进一步设计和操作提供了宝贵的见解。