Conductive magnetite (Fe3O4) has been applied into some anaerobic bioprocesses to accelerate direct interspecies electron transfer (DIET), however, Fe3O4 is usually dissolved by iron-reducing bacteria under anaerobic conditions, resulting in the loss of magnetite. Therefore, submicron magnetite particles were added to the sequencing batch reactor (SBR) to build a Fe3O4/SBR system, which could alleviate magnetite dissolution and simultaneously remove tribromophenol (TBP) effectively. The average removal efficiencies of chemical oxygen demand (COD) and TBP in Fe3O4/SBR system were 81% and 91%, respectively, which were 51% and 18% higher than those of the control group without Fe3O4 (SBR system). The enhanced TBP biodegradation was likely related to potential DIET, which was supported by the scanning electron microscopy (SEM) analysis, the increase of dehydrogenase and heme c (fivefold and 1.7-fold), and the enrichment of iron-redoxing bacteria (Geobacter and Thiobacillus). Furthermore, magnetite mainly remained intact in structure as indicated by X-ray diffraction (XRD), which might be ascribed to in situ iron redox cycle and magnetite biosynthesis via Magnetospirillum. Notably, the content of hydrogen peroxide (H2O2) and hydroxyl radical (⋅OH) in Fe3O4/SBR system was 4-5 times higher than that of SBR system. These findings could provide insights into the development of cost-effective strategy for the removal of refractory organic pollutants.

中文翻译：

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通过亚微米磁铁矿增强顺序批处理反应器中三溴酚的去除。

导电磁铁矿（Fe3O4）已用于某些厌氧生物过程中，以促进直接种间电子转移（DIET），但是，Fe3O4通常在厌氧条件下被铁还原细菌溶解，导致磁铁矿损失。因此，将亚微米磁铁矿颗粒添加到顺序分批反应器（SBR）中，以构建Fe3O4 / SBR系统，该系统可减轻磁铁矿溶解并同时有效去除三溴酚（TBP）。Fe3O4 / SBR系统中化学需氧量（COD）和TBP的平均去除效率分别为81％和91％，比不含Fe3O4的对照组（SBR系统）分别高51％和18％。TBP生物降解的增强可能与潜在的DIET有关，这一点得到了扫描电子显微镜（SEM）分析的支持，脱氢酶和血红素c的增加（分别为5倍和1.7倍），以及铁氧化还原细菌（土杆菌和硫杆菌）的富集。此外，磁铁矿主要保持完整的结构，如X射线衍射（XRD）所示，这可能归因于原位铁氧化还原循环和通过磁螺螺旋藻进行磁铁矿的生物合成。值得注意的是，Fe3O4 / SBR体系中过氧化氢（H2O2）和羟基自由基（⋅OH）的含量是SBR体系的4-5倍。这些发现可以为开发去除难治性有机污染物的具有成本效益的策略提供见识。这可能归因于原位铁氧化还原循环和通过磁螺线菌素的磁铁矿生物合成。值得注意的是，Fe3O4 / SBR体系中过氧化氢（H2O2）和羟基自由基（⋅OH）的含量是SBR体系的4-5倍。这些发现可以为开发去除难治性有机污染物的具有成本效益的策略提供见识。这可能归因于原位铁氧化还原循环和通过磁螺线菌素的磁铁矿生物合成。值得注意的是，Fe3O4 / SBR体系中过氧化氢（H2O2）和羟基自由基（⋅OH）的含量是SBR体系的4-5倍。这些发现可以为开发去除难治性有机污染物的具有成本效益的策略提供见识。