Effective treatment of high-concentration brewery wastewater through anaerobic digestion (AD) has always been a challenging issue. Enhancing direct interspecies electron transfer (DIET) was demonstrated to increase methane production during AD under high organic loading rate (OLR). Herein, the feasibility of enhancing DIET with the addition of riboflavin-loaded granular activated carbon (RF-GAC) as well as co-addition with Methanosarcina barkeri (Rf-GAC+M.barkeri) was investigated (M.barkeri is well-known to be capable of DIET with electroactive bacteria). During the whole process, the Rf-GAC and the Rf-GAC+M.barkeri group both achieved average COD removal rates above 97 %, which was 14 % higher than that of the control. The average methane production in the Rf-GAC group and the Rf-GAC+M.barkeri group respectively reached 0.334 ± 0.02 L(stp)/g COD and 0.345 ± 0.02 L(stp)/g COD, 1.35 and 1.39 times higher than the 0.247 ± 0.03 L(stp)/g COD reached by the control. The control reactor deteriorated at an OLR of 12 kg COD/(m³·d), whereas the Rf-GAC and the Rf-GAC+M.barkeri group maintained stable as the OLR reached as high as 17.5 kg COD/(m³·d) and the volatile fatty acids concentration was consistently below 10 mM. The RF-GAC performed better than Rf-GAC+M.barkeri in enriching Methanothrix, whose relative abundance was 60.6 % in the former group. Metabolic pathway analysis revealed the addition of RF-GAC upregulated genes related to DIET in Methanothrix species, including hdrA and fpoD. Furthermore, Methanothrix remained the dominant archaea even continuously inoculating pure strains of M.barkeri during the entire operational period. Pure culture experiments proved that GAC inhibited M.barkeri growth. The results of this study can be optimized for practical application of AD treating high-concentration brewery wastewater.

中文翻译：

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在连续接种 Methanosarcina barkeri 的情况下，通过载有核黄素的颗粒活性炭在高浓度啤酒厂废水的厌氧消化中富集 Methanothrix 物种


通过厌氧消化 （AD） 有效处理高浓度啤酒厂废水一直是一个具有挑战性的问题。在高有机负载率 （OLR） 下，增强直接种间电子转移 （DIET） 可以增加 AD 期间的甲烷产生。在此，研究了通过添加载核黄素的颗粒活性炭 （RF-GAC） 以及与 Methanosarcina barkeri （Rf-GAC+M.barkeri） 共添加来增强 DIET 的可行性（众所周知，M.barkeri 能够与电活性细菌进行 DIET）。在整个过程中，Rf-GAC 和 Rf-GAC+M.barkeri 组的平均 COD 去除率均在 97 % 以上，比对照高 14 %。Rf-GAC 组和 Rf-GAC+M.barkeri 组的平均甲烷产量分别达到 0.334 ± 0.02 L（stp）/g COD 和 0.345 ± 0.02 L（stp）/g COD，分别是对照达到的 0.247 ± 0.03 L（stp）/g COD 的 1.35 和 1.39 倍。对照反应器在 12 kg COD/（m³·d） 的 OLR 下变质，而 Rf-GAC 和 Rf-GAC+M.barkeri 组在 OLR 高达 17.5 kg COD/（m³·d） 且挥发性脂肪酸浓度始终低于 10 mM 时保持稳定。RF-GAC 在富集甲烷丝菌方面表现优于 Rf-GAC+M.barkeri，前一组甲烷丝菌的相对丰度为 60.6 %。代谢途径分析显示，在甲烷丝菌物种中，RF-GAC 的添加上调了与 DIET 相关的基因，包括 hdrA 和 fpoD。此外，甲烷丝菌仍然是占主导地位的古细菌，甚至不断接种 M 的纯菌株。Barkeri 在整个运营期间。纯培养实验证明 GAC 抑制了 M.barkeri 的生长。本研究结果可以针对 AD 处理高浓度啤酒厂废水的实际应用进行优化。