Sulfate reduction can compete for electrons with methane production, thereby reducing methane production. Several factors, such as magnetite addition, carbon sources, and the chemical oxygen demand (COD)/SO42− ratio, can influence the direction of electron flow toward methanogenesis. However, their contributions to methane production remain unclear. In this study, the addition of magnetite significantly enhanced the maximum methane production rate (Rmax). The enrichment of Methanothrix and Methanobacterium in the conductive material groups indicated the establishment of a methanogenesis process through direct interspecies electron transfer (DIET). Although the DIET pathway enhanced Rmax in the conductive material groups, this increase did not translate into a higher methane yield in this study. The contribution of DIET pathway to methane yield was negligible compared with the effect of COD/SO42− ratio and carbon sources. The relative contribution of COD/SO42− ratio exceeded 40 % in directing electron flow.

中文翻译：

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磁铁矿介导的直接种间电子转移在引导电子从含硫酸盐的废水中产生甲烷方面并不起关键作用


硫酸盐还原可以竞争产生甲烷的电子，从而减少甲烷的产生。磁铁矿添加、碳源和化学需氧量 （COD）/SO42− 比率等几个因素会影响电子流向甲烷生成的方向。然而，它们对甲烷产生的贡献仍不清楚。在这项研究中，磁铁矿的添加显著提高了最大甲烷生产率 （Rmax）。导电材料组中甲烷螺菌和甲烷杆菌的富集表明通过直接种间电子转移 （DIET） 建立了甲烷生成过程。尽管 DIET 途径增强了导电材料组中的 Rmax，但在这项研究中，这种增加并没有转化为更高的甲烷产量。与 COD/SO42− 比率和碳源的影响相比，DIET 途径对甲烷产量的贡献可以忽略不计。COD/SO42− 比值在引导电子流方面的相对贡献超过 40%。