纳米材料介导下污泥厌氧消化系统高效降解多环芳烃的机制

Measures should be taken to deal with the huge amount of municipal sewage sludge with serious polycyclic aromatic hydrocarbons (PAHs) pollution in China. Previous research had confirmed that nanomaterials can promote extracellular electron transfer and had a significant effect on the degradation of PAHs. Due to the complexity of environmental conditions of the sewage sludge anaerobic digestion system, the relationship between the extracellular electron transfer process and PAHs degradation has not a clear understanding. The pure culture laboratory and indoor simulation anaerobic digestion experiments will be combined together in this project. Micro-structural analysis, electrochemical analysis combined high-throughput sequencing technology and real-time PCR are used to determine extracellular electron transfer mode via nano-conductive mineral; to analyze possibility of extracellular long distance electron transfer and its impact on PAHs degradation process; to investigate microbial community composition and distribution of anaerobic sludge at the molecular level under nanoparticles condition; to confirm the conductivity and coupling relationship with PAHs degradation process; to clarify the relationship between the extracellular electron transfer process and the degradation of PAHs in the anaerobic sludge via nano-conductive materials. Then the control measures of the biodegradation of PAHs during the sludge anaerobic digestion will also be acqurired. After that, stable isotope and high-throughput metagenome sequencing technique will be employed to investigate the biodegradation pathway of the typical PAHs, and reveal the extracellular electron transfer process of microorganism and its driving mechanism on the biodegradation of PAHs under nanoparticles condition. This study will provide a scientific basis for the degradation of PAHs in the sludge anaerobic digestion treatment process.

城市污泥产生量大且多环芳烃（PAHs）污染严重，迫切需要科学的处理方式。前期研究工作证实纳米材料具有促进胞外电子传递且对PAHs的厌氧降解有显著影响，然而污泥厌氧消化体系极为复杂，至今对污泥厌氧过程中纳米材料介导的微生物胞外电子传递与PAHs降解的耦联关系缺乏深入研究。本项目拟通过实验室纯培养和厌氧消化模拟试验，利用微结构分析、生物电化学分析联合高通量测序和荧光定量PCR等生物技术，探究纳米材料介导下的胞外电子传递模式；在分子水平上研究纳米材料介导下污泥厌氧系统主要微生物种类及分布、导电性及与PAHs降解过程的耦联关系；并在此基础上获得厌氧过程中PAHs降解的调控措施，最后利用稳定性同位素及高通量测序手段，揭示纳米材料介导下污泥厌氧过程中参与降解PAHs的微生物群落特征及其代谢途径，获得纳米材料介导下污泥厌氧系统微生物胞外电子传递过程及对PAHs降解的影响机制，为污泥厌氧消化提供科学依据。

本项目围绕关键的科学问题“纳米材料介导的微生物胞外电子传递及对污泥厌氧消化降解多环芳烃的作用机制”开展研究，主要成果如下：1）获得了污泥中PAHs种类、分布及其与纳米矿物材料之间的吸附特性，在污泥厌氧消化过程中，形成了微生物-PAHs-纳米材料的团聚体。2）阐明了生物纳米FeS及磁性炭强化污泥厌氧产甲烷同步降解芘的机制，解析了Klebsiella sp. LZ6培养系统中添加生物纳米FeS和磁性炭对降解芘及代谢通路的影响，构建了Klebsiella sp. LZ6与Methanosarcina barkeri双菌互营共培养厌氧系统。3）获得了多环芳烃厌氧降解菌种资源并解析了其代谢途径，经鉴定并命名为Pseudomonas aeruginosa sp. LZ2、Klebsiella pneumoniae sp. LZ6、Clostridium sp. LZ20和Clostridium sp. LZ25。4）研究了纳米材料对Klebsiella sp. LZ6和Methanosarcina barkeri降解芘的效果及电子传递特性，生物纳米FeS或磁性炭均能提高Klebsiella sp. LZ6对芘的降解率；采用GC-MS分析了纳米材料介导下Klebsiella sp. LZ6对芘的降解途径；构建了Klebsiella sp. LZ6与Methanosarcina barkeri双菌厌氧产甲烷同步降解芘的系统，探讨了生物纳米FeS及磁性炭介导下的双菌系统降解多环芳烃的机制。5）阐明了电化学强化污泥厌氧产甲烷同步降解菲的效果及机理，构建了微生物电解池与污泥厌氧消化耦合系统，并对系统中阴极材料及外加电压量进行了优化，剖析了外加电压条件下Clostridium sp. LZ25降解菲的分子机制。6）建立了纳米材料介导的污泥厌氧消化中试示范工程。

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