MIEX-UF一体式耦合工艺中超滤膜生物污染的控制研究

发布时间：2018-07-03 05:37

本文选题：膜生物污染 + 超滤　；参考：《天津工业大学》2017年硕士论文

【摘要】：超滤(UF)工艺的发展为饮用水处理提供了一个新的发展方向。但膜污染控制仍然是UF技术应用中的瓶颈问题。其中生物污染对膜的破坏性最为严重,其污染也最难控制。磁性离子交换树脂(MIEX)作为水处理中常用的吸附材料,与膜组合工艺被不少研究者所关注。本课题研究对比了单独UF、MIEX-UF分体式和MIEX-UF 一体式三种工艺,系统考察了多周期运行工况下对不可逆污染的控制效果以及控制机理上的差异。本试验以水体中常见的铜绿假单胞菌作为代表菌种,研究去除EPS的活细菌、未去除EPS的活细菌以及死细菌对超滤过程的膜生物污染,进行三种工艺超滤实验,研究MIEX对于减缓膜生物污染的控制效果。利用激光共聚焦显微镜(CLSM)观察细菌、蛋白质和多糖在膜表面的累计情况。在此基础上对MIEX-UF一体式组合工艺控制膜生物污染机理进行了深入系统的解析。在单独UF过程中,根据单周期运行时间,得出死细菌菌液造成的膜生物污染最严重,其次是未去除EPS的活细菌,较轻的是去除EPS的活细菌。细菌死亡后会释放大量的胞内聚合物,其中包括一些腐殖质、各种聚糖脂以及其他微生物的代谢产物,而这些物质导致在膜表面形成一层具备微生物生存条件的生物膜,从而造成严重的膜生物污染。考察MIEX对膜生物污染的控制效果,结果表明MIEX的投加明显提高工艺运行时间,对于去除EPS的活细菌、未去除EPS的活细菌和死细菌三种不同的污染物,MIEX-UF膜过滤时间较单独UF分别延长了 38.1%、80.0%、181.8%,MIEX-UF 一体式工艺较单独UF工艺能明显减缓膜生物污染。在MIEX去除细菌的过程中,EPS及细菌分泌的胞内聚合物起重要作用。MIEX对死细菌的去除率最大为42.51%,其次是未去除EPS的活细菌为39.26%,对去除EPS的活细菌去除率最低为26.58%。EPS的荷电性影响MIEX对细菌的去除。这是由于细菌分泌的物质中有大量的蛋白质和多糖,蛋白质带负电率先吸附到树脂表面,是增大细菌与树脂间的作用力。考察不同Zeta电位的菌液与最大去除率之间的关系,得出随着电负性的增加,MIEX对细菌的去除效率也在增加。MIEX是阴离子型交换树脂,溶液的电负性越大,越容易与MIEX上的Cl-发生离子交换而被去除。对于三种菌液,MIEX控制膜生物污染中贡献最大的都是M1EX颗粒在膜表面形成动态膜,分别占膜生物污染控制总贡献比例的63%、58%和45%。MIEX-UF 一体式工艺运行过程中,通过微观界面作用力分析,"MIEX-污染物""PVDF-污染物"界面作用力使得MIEX与有机物间更强的亲和力致使有机物穿过MIEX颗粒动态膜时会被MIEX优先捕获,从而减少到达膜面及膜孔的微生物和EPS的量,有效的缓解膜生物污染。
[Abstract]:The development of ultrafiltration (UF) process provides a new direction for drinking water treatment. However, membrane fouling control is still a bottleneck in UF technology application. Among them, biological pollution is the most destructive to the membrane, and its pollution is also the most difficult to control. Magnetic ion exchange resin (miex) is a commonly used adsorption material in water treatment. In this paper, three separate and integrated UFU MIEX-UF processes are studied and compared, and the control effect and control mechanism of irreversible pollution under multi-cycle operation conditions are systematically investigated. In this experiment, Pseudomonas aeruginosa, which is common in water, was used as the representative strain to study the membrane biofiltration of EPS removal bacteria, live bacteria without EPS removal and dead bacteria in ultrafiltration process. The control effect of miex on reducing membrane biological pollution was studied. The accumulation of bacteria, proteins and polysaccharides on the membrane surface was observed by laser confocal microscopy (CLSM). On this basis, the mechanism of membrane biological pollution control by MIEX-UF integrated process was analyzed systematically. In the process of single UF, according to the operating time of single cycle, it was concluded that the biofilm fouling caused by dead bacteria liquid was the most serious, followed by live bacteria without EPS removal and livebacteria with less EPS removal. When bacteria die, they release large amounts of intracellular polymers, including humus, glycans, and other microbial metabolites that lead to the formation of a microbial biofilm on the surface of the membrane. As a result, the membrane is polluted seriously. The control effect of miex on membrane biological fouling was investigated. The results showed that miex could significantly increase the operation time of the process and remove the living bacteria from EPS. The membrane filtration time of live bacteria and dead bacteria without EPS removal was 38.1% longer than that of UF alone, respectively. The MIEX-UF integrated process could significantly reduce the membrane biological pollution compared with the UF process alone. EPS and intracellular Polymers secreted by bacteria play an important role in the process of removing bacteria. MiEX has the highest removal rate of dead bacteria, followed by live bacteria that do not remove EPS, and the lowest removal rate of live bacteria that remove EPS is 26.58.EPS Electricity affects the removal of bacteria by miex. This is because there are a large number of proteins and polysaccharides in the substances secreted by bacteria, and the protein is first adsorbed on the resin surface with negative charge, which increases the interaction force between the bacteria and the resin. The relationship between the bacterial solution with different Zeta potential and the maximum removal rate was investigated. It was concluded that the removal efficiency of bacteria was also increased with the increase of electronegativity. Miex was anion exchange resin, and the electronegativity of the solution was higher. The easier it is to exchange ions with Cl- on miex, the less likely it is to be removed. The most important contribution of M1EX particles to the control of membrane biological pollution was the formation of dynamic membrane on the membrane surface, which accounted for 63% and 58% of the total contribution to the control of membrane biological pollution, respectively, and 45. MIEX-UF in the process of integrated process operation, and the results showed that M1EX particles formed a dynamic membrane on the membrane surface, which accounted for 63% or 58% of the total contribution to the control of membrane biological pollution. Through microcosmic interface force analysis, the interaction force between "miEX-pollutant" and "PVDF-pollutant" makes mix and organic matter stronger affinity so that organic matter will be preferentially captured by miex when it passes through mix particle dynamic membrane. In order to reduce the amount of microbes and EPS reaching the membrane surface and pore, effectively alleviate the membrane biological pollution.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU991.2

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