Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China; School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China.
Waste Manag. 2021 May 15;127:10-17. doi: 10.1016/j.wasman.2021.04.022. Epub 2021 Apr 25.
Magnetite, a common mineral that is abundant in the soils and sediments, has been widely documented to enhance the anaerobic digestion of organic wastes, whereas the mechanisms of magnetite promoting interspecies electron transfer are still unclear. In this study, under the conditions (ethanol-type fermentation) employed, magnetite stimulated the secretion of extracellular polymeric substances (EPS). Analysis of three-dimensional excitation emission matrix revealed that these EPS secreted in the presence of magnetite were primarily comprised of the redox-active organic functional groups. Electrochemical analysis showed that the EPS secreted with magnetite had the higher electron-accepting and electron-donating capacity than the EPS without magnetite. Syntrophomonas species capable of extracellularly transferring electron were enriched with supplementing magnetite. Together with the increased abundance of Methanospirillum and Methanobacterium species that could proceed direct interspecies electron transfer (DIET), the anaerobic digestion was likely improved due to the establishment of DIET with supplementing magnetite. As a result, anaerobic digestion of kitchen wastes was evidently enhanced. With decreasing the solid retention time to 30 d, the methane production rate only slightly declined to 18 ± 0.8 mL/g-VSS/d in the magnetite-supplemented digester, while almost no methane was detected in the digester without magnetite.
磁铁矿是一种常见的矿物，在土壤和沉积物中含量丰富，已被广泛证明可以促进有机废物的厌氧消化，而磁铁矿促进种间电子转移的机制仍不清楚。在本研究中，在采用的条件（乙醇型发酵）下，磁铁矿刺激了细胞外聚合物物质（EPS）的分泌。三维激发发射矩阵分析表明，这些在磁铁矿存在下分泌的 EPS 主要由氧化还原活性有机官能团组成。电化学分析表明，与没有磁铁矿的 EPS 相比，分泌有磁铁矿的 EPS 具有更高的电子接受和电子供体能力。能够体外传递电子的互营单胞菌属物种在补充磁铁矿时得到了富集。随着能够进行直接种间电子转移（DIET）的产甲烷菌属和甲烷杆菌属物种丰度的增加，由于补充磁铁矿建立了 DIET，厌氧消化可能得到了改善。结果，厨房废物的厌氧消化得到了明显增强。将固体停留时间减少到 30 d 时，补充磁铁矿的消化器中的甲烷产率仅略微下降到 18 ± 0.8 mL/g-VSS/d，而在没有磁铁矿的消化器中几乎没有检测到甲烷。
