基于表面改性复合膜的异向传质生物膜胞内储存物质驱动同步脱氮除磷研究

Membrane aerated biofilm technology, because of its high oxygen utilization, counter-diffusion characteristics and low stripping loss of volatile organic compounds, was received extensive attention in the field of water and wastewater treatment. Wherein the gas permeable membrane used as the diffuser for bubbleless aeration as well as the carrier for biofilm growth, which mass transfer of oxygen, microbial adhesion properties have a significant impact on system performance. PVDF hollow fiber composite membrane with excellent oxygen mass transfer performance, biocompatibility and stability will be prepared by surface modification for membrane aerated biofilm System. And the effects of surface properties of the composite membrane on different bacterial adhesion, growth and detachment will be investigated and biofilm management will be emphasized. An anaerobic-aerobic sequencing batch membrane aerated biofilm system, base on the surface-modified composite membrane, will be developed to achieve simultaneous removal of organics, nitrogen and phosphorus. Efficient organics, nitrogen and phosphate removal performance depend on the cooperation and reasonable distribution of different microorganisms in the membrane aerated biofilm system, as well as coexistence and excellent mass transfer of muiti-microenvironment in the biofilm system. Simultaneous nitrification, denitrification and phosphorus removal behavior driven by intracellular storage polymers of counter-diffusion biofilm will be discussed by microbial communities distribution and mass transfer characteristics analysis of biofilm attached on the surface-modified composite membrane.

膜曝气生物膜技术因其氧利用率高、异相传质特性、挥发性污染物气提损失小等优点在水污染控制领域得到广泛关注，其中膜组件作为无泡曝气及生物膜附着的载体，其氧气传质、微生物附着特性对系统性能具有重要的影响。本课题对自制PVDF疏水性中空纤维微孔膜进行表面改性，制备适用于膜曝气过程的氧气传质性能、生物亲和性、稳定性良好的中空纤维复合膜，并对其表面特性对于不同功能菌群附着、生长及脱落的影响及系统中生物膜控制策略进行研究。以表面改性复合膜为基础，在厌氧-好氧膜曝气生物膜系统中实现基于胞内储存物质的有机物、氮、磷的同步高效去除。系统良好的同步脱氮除磷效果的获得有赖于不同功能菌群在生物膜中的合理空间分布与多种菌群的共同作用，以及在生物膜内部创造一个多种微环境的小生态系统与各微环境之间良好的物质传递。本课题通过生物膜功能解析及传质特征研究，揭示异向传质生物膜基于胞内储存物质同步硝化反硝化反硝化除磷机理。

膜生物膜反应器（Membrane Biofilm Reactor，MBfR，又称为膜曝气生物反应器）是将高效膜曝气与生物处理相结合的新型水污染控制技术，在MBfR中，膜作为氧气传质及生物膜附着的双重载体，其性能对系统的快速启动及稳定运行具有至关重要的作用，目前适用于MBfR的商品化膜尚不多见。课题采用非溶剂致相分离法制备PVDF疏水性中空纤维微孔膜，针对MBfR研究中疏水性微孔膜供氧能力不足、耐污染性较差等问题，采用界面聚合法（以壳聚糖和均苯三甲酰氯为水、油两相单体）及自聚合法（以左旋多巴、多巴胺为自聚合单体）对原膜进行表面改性，均获得了氧传质性能优于原膜（氧总转移系数分别为原膜1.7-2.1倍）的复合膜。原膜及改性膜MBfR系统均能够实现较好的有机物及同步营养物质去除，但改性膜MBfR系统中微生物初始附着速度、附着数量及生物膜稳定性均高于原膜，显示改性膜MBfR系统在快速启动、稳定高效运行方面的优势。针对MBfR实际应用中的膜污染问题，选取典型有机污染物牛血清白蛋白、腐殖酸和海藻酸钠，研究原膜及改性复合膜的膜污染特性，并运用XDLVO理论定量解析三种污染物与原膜和改性膜之间的界面相互作用机制，评价不同界面相互作用对膜污染的贡献。以表面改性复合膜为基础构建MBfR系统，实现有机物及氮磷等营养物质的同步去除，探究MBfR中外源碳源及胞内储存物质碳源同步硝化反硝化特性，结合MBfR中异向传质生物膜微生物种群分布特征，解析MBfR系统有机物及营养物质同步去除机理。