Fe3O4-C纳米耦合体抑制膜生物反应器膜污染的机理研究

Abstract: Membrane Bioreactor (MBR) is a promising wastewater treatment technology. But membrane fouling, which occurred during operation, has increased the running cost. Current studies dealing with membrane fouling have mainly focused on the addition of flocculants, which would facilitate the formation of flocs and reduce secretion of EPS and SMP. But the presence of flocculants could also reduce the activity of microorganisms, while flocculation effect would reduce over time. In recent years, magnetic nano-materials have been used in studies to facilitate electron transport, increase SMP and EPS utilization by microorganisms to reduce membrane fouling. However, the flocculation effect of magnetic nano-materials was not satisfaction, which suppressed formation of flocs. A novel nanometer magnetic powder material wrapped by carbon source (coupling of Fe3O4 and C) was brought up in this project to strengthen flocculation effect of nanometer magnetic powder. After modification, carbon surface would provide substrate for microorganisms, promote bio-flocculation. Stable granular structure would thus be formed, and the possibility of membrane pore blocking would be reduced. Modified nanometer magnetic powder can also provide carbon source for denitrifying bacteria inside the granules, which would increase nitrogen removal effect to a higher level. This project intends to clarify the mechanism of membrane fouling reduction in submerged MBR by conducting researches focusing on the impact of modified nanometer magnetic material on bioactivity and microbial community structure, as well as to provide scientific basis for further development of Fe3O4-C coupling body.

摘要：膜生物反应器（MBR）是一项富有前景的废水处理技术。但运行过程中的膜污染问题大大增加了运行成本。目前研究主要通过投加絮凝剂促进絮团形成，降低EPS及SMP分泌，从而缓解膜污染。但絮凝剂的投加会降低微生物活性，且絮凝效果随运行时间逐渐降低。近年来已有研究利用纳米磁粉促进微生物种间电子传递，强化微生物利用SMP和EPS效率的特点来缓解膜污染。但研究发现，纳米磁粉絮凝效果较差。项目提出开发由碳源包覆的新型纳米磁粉（Fe3O4-C纳米耦合体）材料，强化纳米磁粉絮凝效果。改性后表层碳源能提供微生物生长所需基质，促进微生物附着和絮凝，进而形成稳定的颗粒状结构，降低堵塞膜孔几率。同时，改性磁粉能为颗粒内部反硝化菌提供碳源，增强脱氮效果。项目拟通过改性磁粉材料对生物活性及微生物种群结构的影响研究，明确改性磁粉材料对浸没式MBR中膜污染减缓的机制研究，为Fe3O4-C纳米耦合体的开发提供科学依据。

膜生物反应器（MBR）技术在污水处理和回用领域极具竞争力，然而膜污染是制约其广泛应用的瓶颈性问题。本项目从控制MBR膜污染出发，提出应用由碳源包覆的新型纳米磁粉（Fe3O4-C纳米耦合体）材料控制MBR膜污染的新策略。结合材料表征、污泥混合液特性指标、膜污染物分析和微生物群落结构分析等，系统开展改性磁粉对MBR运行效能的影响，阐明其减缓膜污染的机理。项目研究结果如下：（1）经不同碳源（纤维素、淀粉、壳聚糖和生物质炭）改性的磁粉材料，不仅具有磁粉颗粒的结构和性质，而且还能增大材料的比表面积，降低材料表面的Zeta电位，有利于污泥絮体发生团聚；（2）通过MBR连续试验发现，投加改性磁粉有利于微生物在其表面的附着，提高系统对污染物的去除作用，同时通过分析改性磁粉表面的可利用性碳源，探究其对促进污染物去除的作用机制；（3）通过探究改性磁粉对污泥混合液特性的影响发现，改性磁粉能够通过促进微生物脱氢酶活性提高，降低混合液中SMP浓度，进而有效减缓膜污染；（4）探明了投加改性磁粉材料对微生物群落多样性的影响，从分子生物学角度阐明其控制膜污染的机理。综上所述，投加改性磁粉能够有效减缓膜污染，对MBR技术的推广应用具有重要意义。