【作者】 李莹；

【导师】 张宏伟；

【作者基本信息】 天津大学 ， 环境工程， 2008， 博士

【摘要】 膜生物反应器(MBR)将活性污泥工艺与膜分离工艺相结合,与传统活性污泥工艺相比具有占地面积小、污泥产率低等优点,是近几年来受到普遍重视的新型生物反应器。然而膜污染和高昂的投资费用是影响膜生物反应器进一步推广应用的主要因素。本课题采用浸没式MBR处理城市污水,通过收集自2006年5月启动调试至2007年10月近一年半的运行数据,系统研究了污泥胞外聚合物(EPS)的提取方法、在反应器内的变化特征以及对MBR运行的影响。首先,采用七种方法(热、酸、碱处理等)提取MBR中污泥EPS,研究了这些方法对于污泥EPS的最佳提取条件。在针对MBR中活性污泥EPS的提取方面,综合考虑提取总量、细胞破坏程度以及操作的难易度, EDTA二钠和热提取是最简便有效的两种提取方法。其次,在取样数据的基础上应用克里格插值的方法对数据进行空间插值,并结合Surfer 8.0软件将结果直观地显示出来,具体结论如下:在水平面中,长度方向上EPS总量以及作为主要成份的多糖和蛋白质分布均呈两头高中间低的形式,宽度方向上EPS则呈现出中间高,向两边逐渐递减的趋势,之后在稍远离膜组件的地方又有所回升。在竖直面中,EPS浓度随着深度的增加呈递减的趋势。再次,以稳定运行的试验数据为基础研究了曝气强度、有机负荷和SRT与污泥EPS变化的关系以及污泥EPS对污泥沉降性能的影响。同时发现,膜生物反应器中溶解性EPS的积累会对污泥的MLVSS/MLSS和脱氢酶活性产生不利影响,抑制微生物代谢活性。微生物代谢产物是混合液上清液和出水中的有机污染物中的重要组成部分。最后,通过运行数据从膜的生物污染角度解释了曝气强度、污泥浓度和有机负荷对于微滤膜污染速率的影响,从而得出了减缓膜的生物污染的最佳工况范围。更多还原

【Abstract】 A membrane bioreactor (MBR) combines the activated sludge process with a membrane separation process. Membrane Bioreactor is a comparably new type of biological reactor that has attracted great attention in recent years. The advantages offered by MBR over conventional activated sludge process (ASP) include a small footprint, reduced sludge production and so on. However, membrane fouling and high cost are main factors that prevent MBR from applied further. In this dissertation, submerged membrane bioreactor was used to treat municipal wastewater. Through collecting the operation data from startup from May 2006 to October 2007, the extraction of extracellular polymeric substances (EPS), diversification of EPS and its influence to bioreactor operation were studied.First, the optimum conditions and effectiveness of extraction of EPS from activated sludge in membrane bioreactor were studied under seven conditions, such as thermal, acid, alkaline methods. After giving overall considerations to the accuracy, simplicity, attraction efficacy and the damage to the sludge cell, it was concluded that both thermal treatment and EDTA bi-sodium treatment were effective according to the extraction of extracellular polymeric substances (EPS) from activated sludge in membrane bioreactor (MBR).Second, sampling data was spatial interpolated by Krieger interpolation method, and software Surfer 8.0 was applied to display the results straightly. Experimental results showed that: in level, the gross EPS was higher at both sides but lower in the centre lengthwise. The diversification trend of carbohydrates and protein, which were the main components, was the same. Nevertheless, the gross EPS was higher in the centre, decreased to both sides but increased when slightly far from the membrane module widthwise. In vertical, the gross EPS decreased with the increase of depth.Third, based on experimental data, the relationships of the diversification of EPS with aeration intensity, organic loading and sludge retention time (SRT) as well as their influences on sludge settleability were studied. Moreover, the accumulation of soluble EPS in MBR had adverse effect on sludge MLVSS/MLSS value and dehydrogenase activity, and the microbial metabolism activity was then restrained. The microbial metabolism products were main pollutants of mixture supernatant and effluent. Finally, through operation data, the influences of aeration intensity, sludge concentration and organic loading on microfiltration membrane fouling were explained in terms of membrane biological fouling. Accordingly, the range of optimum operation modes was obtained to lessen membrane biological fouling.更多还原