自组装希瓦氏菌/FeS杂合生物膜协同去除污染物的机理研究

Biotreatment is widely adopted wastewater treatment technique. However, the slow remove rate makes it difficult to treat the persistent organic pollutants, acting as the main bottleneck of biotreatment. When electroactive bacteria is doped with nanomaterials, hybrid biofilm with high electroactivity and catalytic capability can form, which is promising for the next generation of wastewater biotreatment techniques. Meanwhile, the pollutant removal mechanism, especially the synergistic effect of microorganism and nanomaterial, is unclear, with the difficulty left for the rational regulation of removal process. In the prior research, we have successfully developed a self-assembled and highly electroactive Shewanella/FeS hybrid biofilm, which exhibited remarkably improved nitrobenzene removal efficiency. Based on the primary achievement of Shewanella/FeS hybrid biofilm, the proposed project will systematically study the hybrid biofilm formation process and investigate the synergistic reduction characteristic of hybrid biofilm component in pollutant removal. The major catalytic site, electron mediator and electron transfer pathways during reduction will be elucidated, followed by model study to describe the electron distribution of hybrid biofilm. Then the mechanism of how Shewanella and FeS synergistically reduce the pollutant will be brought out. Accordingly, rational regulation strategies will be developed to effectively enhance the pollutant removal efficiency. The proposed research will help to establish the methodology for hybrid biofilm reduction mechanism elucidation and rational regulation, break through the bottleneck of persistent organic pollutants removal with conventional biotreatment techniques, and more importantly, inspire the development of next generation of wastewater biotreatment techniques.

生物处理是应用最广泛的污水处理技术，但其处理难降解有机污染物时去除速率慢，是关键的技术瓶颈。微生物掺杂纳米材料形成的杂合生物膜具有高电活性与催化活性，是具有广泛应用前景的生物处理新技术，但其去除机制，特别是微生物与纳米材料的协同作用不清楚，难以进行理性调控。我们前期已构建自组装希瓦氏菌/FeS杂合生物膜，发现其具有显著增强的电活性和硝基苯去除能力。据此，本项目将以希瓦氏菌/FeS体系为例，系统考察杂合生物膜的形成规律；研究杂合生物膜组分协同催化还原污染物的特性；解析还原过程的主要催化位点，电子媒介与电子传递路径；构建杂合生物膜电子分布模型；阐明希瓦氏菌与FeS协同还原污染物的机理；在此基础上，提出人工理性调控策略，大幅度提高去除效率。该研究将有助于建立杂合生物膜去除机理解析与理性调控的方法，突破传统生物处理去除难降解有机污染物时效率低的瓶颈，为发展高效污水生物处理技术提供新方法和新思路。

微生物掺杂纳米材料形成的杂合生物膜具有高催化活性，是具有广泛应用前景的污染物生物处理新技术。但目前对如何理性设计杂合生物膜研究不足，对其去除机制，特别是微生物与纳米材料的协同作用不清楚。本研究以希瓦氏菌这一模式菌株为研究对象，基于其独特的生物合成FeS纳米颗粒的能力，从FeS生物合成和杂合生物膜自组装调控、胞外电子传递与污染物协同催化去除机制解析等方面展开系统研究。首先，本研究提出并开发了一种基于Fe、S前体还原控制的FeS纳米颗粒生物合成调控策略，实现了不同尺寸和催化活性的FeS纳米颗粒的可控生物合成。进一步，在微生物燃料电池条件下调控FeS的生物合成和自组装过程，构建了FeS定向沉积到细胞间质、外膜及胞外的希瓦氏菌@FeS杂合生物膜，并系统研究了该杂合生物膜的胞外电子传递特性，提出了原位沉积的FeS在希瓦氏菌强化胞外电子传递中的独特机制；基于以上研究，开发协同催化去除污染物的体系，实现了六价铬、对硝基芬、对氯酚等污染物的高效去除，并系统研究了杂合生物膜去除污染物过程中希瓦氏菌与FeS的协同机制，提出了“微生物供电-FeS催化”的协同模式。本研究在纳米材料掺杂的杂合生物膜的理性设计、构建与污染物去除应用取得了较重要的进展，有助于突破传统生物处理效率低的瓶颈，为发展高效污水生物处理技术提供新方法和新思路。