Additives or external voltage are usually applied to promote methane production and organics degradation through the possible means of enhancing direct interspecies electron transfer (DIET), but their effectiveness and explanation are controversial. In this work, external voltage and additives (biochar and zeolite) were applied simultaneously and independently to laboratory-scale anaerobic reactors for further clues of DIET-enhancing mechanism. External voltage was indicated to impede methanogens early, and promote anaerobic process later. Boichar was discovered to benefit only stressed scenarios caused by external voltage or other stresses, but express no significant influence on well-operating ones, which could be attributed to the finding that biochar enriched DIET-capable Methanosarcina and Methanosaeta which are sensitive to stress. Zeolite could not overcome external handicaps with only increase of microbial amounts and diversity but without selectivity. The BET specific areas of biochar (13.6 m²/g) and zeolite (15.1 m²/g) applied in this work are semblable, which excludes the discrepancy in adsorption of inhibitors between the biochar and zeolite. The electron donating capacities (EDC) of biochar and zeolite are, respectively, 0.17 and 0 mmol e⁻/g, while electron accepting capacities (EAC) are similar, revealing that EDC did great benefit to the promotion hence the enrichment of Methanosarcina and Methanosaeta while only containing EAC didn't function significantly. On the contrary, potential H₂-competitors (e.g. Hydrogenophaga) of methanogens could also clone onto biochar that may weaken its DIET benefit for methanogenesis, which was observed in high throughout sequencing. Meanwhile, suspended microbes, which cannot conduct DIET with biochar, were far more extensive than those attached to additives, indicating that biochar also affects microbial activity through other surrounding biochemical connections. The identification of limited application scope of biochar and numerous suspended microbes provides new considerations into the mechanisms of surrounding limitation for biochar application and possible determinants except for DIET.

添加剂或外部电压通常通过可能的增强直接种间电子转移（DIET）的方法施加，以促进甲烷的产生和有机物的降解，但其有效性和解释尚存争议。在这项工作中，将外部电压和添加剂（生物炭和沸石）同时且独立地应用于实验室规模的厌氧反应器，以进一步了解DIET增强机理。已表明外部电压可早期阻止产甲烷菌，并在以后促进厌氧过程。发现Boichar只能使外部电压或其他压力引起的压力情况受益，但对运行良好的情况却没有显着影响，这可能归因于生物炭富含DIET能力的甲烷菌和甲烷的发现。Methanosaeta对压力敏感。仅增加微生物数量和多样性而没有选择性，沸石不能克服外部障碍。这项工作中使用的生物炭（13.6 m ² / g）和沸石（15.1 m ² / g）的BET比表面积是可组装的，这排除了生物炭和沸石之间抑制剂吸附的差异。给电子能力的生物炭的（EDC）和沸石分别是0.17和0毫摩尔ë ^- /克，而电子接受能力（EAC）是相似的，表明EDC促进因此富集没有很大的好处甲烷八叠球菌和Methanosaeta而仅包含EAC的功能并不明显。相反，产甲烷菌的潜在H ₂竞争者（如Hydrogenophaga）也可以克隆到生物炭上，这可能削弱其DIET对产甲烷作用的益处，这在整个测序过程中都很高。同时，不能与生物炭进行DIET的悬浮微生物比附着于添加剂的微生物要广泛得多，这表明生物炭还通过其他周围的生化联系影响微生物活性。鉴定生物炭的有限应用范围和众多悬浮微生物为生物炭应用的周围局限性机理和除DIET以外的可能决定因素提供了新的考虑因素。