高温微生物电催化同步矿化氟代硝基苯类化合物作用机制

Fluoro-nitrobenzene derivatives have less biodegradability and higher ecology toxic than chloro-nitrobenzene derivatives, which are lack of economic and effective treatment methods. Based on the previous research findings, the performance of simultaneous mineralization of fluoro-nitrobenzene derivatives was observed in thermophilic microbial electrocatalysis system. However, the mechanisms of simultaneous mineralization were less understood yet. Thermophilic microbes, a key component of the thermophilic microbial electrocatalysis reactor, would be enriched from different sources. The mineralization ability of various fluoro-nitrobenzene derivatives were investigated in using thermophilic microbial electrocatalysis system. The key metabolic reactions, coupling mechanisms of mineralization and electron transfer mechanisms were explored by electrochemical, microbiology and quantum chemistry means in the process of simultaneous mineralization of fluoro-nitrobenzene derivatives using thermophilic microbial electrocatalysis system. Furthermore, the formation process of biofilm, population structure and dynamics，and expression of the key enzymes are studied, which could disclose microbial mechanism of simultaneous mineralization. Not only can the results mentioned above deepen and broaden the understanding of coupling relationship between microbial metabolism and electrochemical catalysis as well as enlarge wastewater treatment theory and technology, but it also can provide new insight in persistent toxic organic wastewater treatment. Moreover, it can guarantee the sound development of organic fluorine chemical industry.

氟代硝基苯类化合物是一类比氯代硝基苯类化合物生物降解性更差、毒性更大的有机污染物，尚缺乏经济、有效的处理手段。申请人尝试性研究发现，嗜热微生物结合电催化系统能够高效实现氟代硝基苯化合物同步矿化，但目前对该系统的同步矿化机理尚未有研究报道。本项目通过富集不同源的嗜热功能微生物，构建高温微生物电催化系统；在考察系统对典型氟代硝基苯解毒及同步矿化性能的基础上，结合电化学、微生物学及量子化学等手段，探明氟代硝基苯的关键代谢步骤、耦合矿化方式及电子传递机制等化学降解机理；从生物膜形成过程、种群结构动态及关键酶系表达等层面揭示氟代硝基苯同步矿化的微生物降解机理。项目不仅能进一步加深和拓展人们对微生物代谢和电化学催化之间的耦合关系认识，丰富废水处理理论和技术，还可为难降解有毒有机废水处理技术的开发提供一个新的思路，为有机氟化工等新兴产业的健康发展提供技术保障。

氟代硝基苯类化合物是一类新兴的难降解有毒有机污染物，具有“三致性”和“脂溶性”，尚缺乏经济、有效的处理手段。本项目考察了不同接种源污泥、电极材料、盐度、工况参数对氟代硝基苯降解性能的影响，发现以永太科技公司污水处理系统的污泥作为接种源，系统能够100%去除p-FNB，脱氟率达到82.1%。选用不锈钢和石墨作为电极材料对氟代硝基苯的处理性能要显著优于钛。NaCl浓度从0g/L上升到40g/L，高温微生物电催化系统的脱氟性能抑制率为42.2%，而生物系统的脱氟反应被100%抑制，表明高温微生物电催化系统中的微生物有更好的盐度耐受能力。扩大化系统处理p-FNB过程中的最优工艺参数为：初始p-FNB浓度0.8 mmol L-1,碳氮比8.6和外加槽压1.8V。此外还发现外加槽压下，电极生物膜和悬浮污泥都能够在25h内完全去除p-FNB，脱氟效率分别为54.7%和53.1%，这些结果表明电极生物膜和悬浮污泥对p-FNB的降解具有相似的贡献。同时在考察系统对典型氟代硝基苯解毒及同步矿化性能的基础上，结合非线性循环曲线、GC-MS及量子化学等手段，探明氟代硝基苯还原成氟代苯胺是其降解矿化的关键，以及在高温微生物电催化系统中氟代硝基苯的代谢途径，同时总结出了生物阴极还原和生物阳极氧化脱氟的协同代谢机制。从电子传递角度探明微生物只能以氧气作为电子受体才能降解氟代硝基苯，而在仅提供电子供体的条件下氟代硝基苯可以实现还原转化为氟代苯胺，但是无法实现脱氟。此外，本项目还从微生物群落结构及关键酶系表达等微生物机理角度揭示了高温生物电催化系统可以提高微生物酶活并富集具有降解氟代硝基苯的功能微生物。