磁活性污泥法调控MBR膜污染机理的研究

Membrane fouling, the major reason for the flux decline and cost increasing in MBR process, has severely hindered the wider application of MBRs. So far, how to mitigate membrane fouling in MBR process is one of the most challenging issues. Due to the recycling characteristics and biomagnetic effects of magnetic activated sludge (MAS) process, it has the potential advantage and good prospects in membrane fouling control in MBRs. Lots of studies have focused on the magnetite mitigating membrane fouling, however, the mechanism is still uncertain. Due to this, this proposal will focus on the microorganisms and their metabolites under biomagnetic effects. Specifically, the main research will always follow the theory of “biomagnetic effects affecting microorganisms, thereby affecting microbial metabolites, consequently affecting membrane fouling process”. The fouling behavior and local flux distribution will be quantitatively monitored real-time with ultrasonic time-domain reflectometry (UTDR) and wavelet signal analysis. Furthermore, the proposal will also attempt to use multidisciplinary research methodologies from environmental engineering, microbiology, and molecular biology to investigate the trends of microbial community, microbial growth and metabolism, mixed sludge liquor in the membrane bioreactors with/without magnetic particles. The mechanism of magnetite mitigating membrane fouling will be illustrated from macroscopic and microscopic perspectives. The new microbial growth and metabolism kinetics model will be established based on mitigating fouling in the new environments of magnetite. All of the work will serve as guidance for application and outreach of this technology.

由膜污染导致的膜通量降低、运行成本增加等问题，严重限制了MBR 的推广，至今仍是MBR应用中的最大障碍。磁活性污泥法由于磁粉可回收、磁生物效应等特点，在MBR膜污染控制方面具有潜在优势和应用前景，已有学者进行了系列报导，但调控机理尚不清楚。本课题拟从磁的生物效应出发，以微生物及其代谢产物为研究对象，以“磁生物效应影响微生物，进而影响微生物代谢产物，继而影响膜污染进程”为研究主线，结合超声时域反射法、小波信号分析等技术实时定量监控膜污染进程及其点通量分布的变化，进一步运用环境工程学、微生物学、分子生物学等多学科交叉结合的研究手段，对比研究有/无磁粉MBR系统的微生物群落演替规律、微生物生长和代谢规律、污泥混合液特性变化规律，揭示磁活性污泥法调控MBR膜污染的机理，构建基于磁生物效应影响膜污染的微生物生长和代谢的动力学模型，为该技术的应用推广提供理论指导。

本项目针对MBR应用中的最大障碍“膜污染”，基于磁活性污泥法磁种可回收、磁生物效应等特点，构建了有/无磁种2套MBR系统对比研究了磁种的引入对污染物去除效能以及膜污染的影响，并通过系统研究其微生物群落演替规律、微生物生长和代谢规律、污泥混合液特性变化规律，由宏观到微观，由理化特性到分子生态学特性，阐明了磁活性污泥法调控MBR膜污染的机理，并通过SPSS统计分析构建了基于磁生物效应影微生物生长和代谢的膜污染模型。研究发现磁种引入后膜清洗周期从28天延长到了48天，并且实验证实磁种的吸附效应、生物混凝效应对膜污染延缓作用不大，膜污染的减缓主要归因于磁生物效应引起的反应器中膜污染先锋物种的减少以及微生物代谢产物中大分子有机物比例的降低（>500 kDa和300-500 kDa的大分子有机物分别减少了24.06%和11.11%）。本研究提供了1种新型实用的MBR膜污染控制方法，并深入解析了磁活性污泥法调控MBR膜污染的机理，为该技术在MBR膜污染控制方面的应用推广提供理论指导与技术支撑。