电场辅助生物驱动还原硝基酚的强化机制及菌群结构解析

Anaerobic reduction is an important step of bioremediation for nitro-aromatic compounds, however, conventional anaeobic reduction process exists insufficient in some aspects, such as low efficiency and unstability. There has been growing interest in the development of bioelectrochemistry method, because it integrates the advantages of biological treatment, electrolytic dissociation and electrochemical oxidation/reduction process. In this project, bioelectrochemistry system is proposed for the improvement of anaerobic nitrophenol-treating system, which is up-flow anaerobic sludge bed (UASB in short). Biological reduction system assisted by electric field (also known as UASB-BES system) will be constructed with enhanced co-metabolic reduction of nitrophenols achieved in the presence of electric field. Enrichment of bacterial community, which is highly efficient, will be achieved through potential control. The relationship between the enhancement mechanism and bacterial community structure will be analyzed through the reveal of bacterial community structure in the cathode of the reductive system. The relationship between the molecular stucture of nitrophenols and degradation permance or dominant community, will be ascertained throuth the analysis of reduction performance and community variation. The performance of UASB-BES coupled system for the treatment of nitrophenol containing industrial wastewater will be evaluated, while cost effectiveness，progressiveness and feasibility of the technology will be assessed. The technical reserve will be provided by this study for the application of bioelectrochemistry method in the field of industry.

厌氧还原过程是生物降解硝基芳香族化合物的重要环节，但常规的厌氧还原工艺存在处理效率低、难以稳定运行等不足。生物电化学技术因综合了生物处理、电解和电化学氧化/还原等废水处理过程的优势而备受关注。本项目拟采用生物电化学技术（BES）改进硝基酚废水厌氧处理体系- - 上流式厌氧污泥床（UASB），构建电场辅助生物驱动硝基酚还原体系（UASB -BES体系），实现硝基酚在外加电场条件下的强化共代谢还原。通过电位调控实现阴极高效菌群的定向富集；分析还原体系阴极区的菌体群落结构，解析硝基酚的强化还原机制与菌体群落结构之间的内在联系；分析以不同结构的硝基酚为底物时的还原效能以及阴极区域生物群落结构的变化情况，建立硝基酚结构与降解性能、优势群落分布之间的联系；考察UASB -BES耦合体系处理含硝基酚的实际工业废水的效能，对工艺经济性、先进性及可行性进行评价。为生物电化学处理技术的实际工业应用提供技术储备。

本项目采用生物电化学技术（BES）改进硝基酚废水厌氧处理体系--上流式厌氧污泥床（UASB），构建了电场辅助生物驱动硝基芳香族化合物（NACs）还原体系（UASB-BES体系），实现了NACs在外加电场条件下的强化共代谢还原。通过电位调控实现了阴极高效菌群的定向富集；分析了还原体系阴极区的菌体群落结构，解析了NACs的强化还原与菌体群落结构之间的内在联系；分析以不同结构的硝基酚为底物时的还原效能以及阴极区域生物群落结构的变化情况，建立硝基酚结构与降解性能、优势群落分布之间的联系；考察了UASB-BES耦合体系的工艺经济性、先进性及可行性。结果表明：相比对照UASB系统，UASB-BES耦合体系中NACs的去除得到了明显加强，随着外加电流密度从0增加到4.71 A m-3，对硝基苯酚（PNP）的去除速率和还原产物对氨基苯酚（PAP）的生成速率可分别从6.16±0.11 mol m-3 d-1和4.21±0.29 mol m-3 d-1增加到6.77±0.00 mol m-3 d-1和6.11±0.28 mol m-3 d-1。UASB-BES耦合体系中生物相丰度明显高于对照UASB系统，还原相关种属、具有电化学活性的微生物种属以及发酵相关种属均可在电场作用下得到明显富集。三种不同结构的硝基酚（邻硝基酚（ONP）、间硝基酚（MNP）、对硝基酚（PNP））在UASB-BES系统中还原的难易程度为ONP > MNP > PNP。随着不同结构的硝基酚变化，所对应的微生物群落的丰富度符合ONP > MNP > PNP的顺序，部分核心菌属始终在阴极生物膜内占优，其他优势微生物群落随硝基酚结构变化而改变。UASB-BES耦合体系中，生物产气过程可得到明显抑制，从而降低了外加碳源成本；耦合系统外加电能消耗低于0.02 kWh mol-1 NP，仅仅为传统电化学过程的1%以下；耦合系统避免了昂贵的质子/离子交换膜的使用，有利于降低构造成本，从而有利于工程放大。相比传统UASB系统，UASB-BES耦合体系在废水中NACs的去除方面具有广阔的应用前景。