不同细菌分泌物及其反渗透膜污堵特性比较

反渗透(RO)工艺在城市污水再生处理中的应用越来越多,但膜污堵严重影响了该工艺的稳定运行.溶解性微生物产物(SMP)是造成RO膜污堵的最主要的有机物.本文以再生水厂RO膜面分离的两种细菌Pseudomonas sp. AM1-1和Chromobacterium sp.AM1-2的SMP为研究对象,比较了两者SMP的组成成分及其对RO膜的污堵能力.结果发现,在葡萄糖培养基中培养至稳定期后,两者产生的SMP中多糖与蛋白质比例均约为1∶1,AM1-1的SMP中多糖和蛋白质均呈双峰式分布,分布于大于10~5Da和小于10~3Da两个范围;AM1-2的SMP中,多糖分子量呈双峰式分布,主要分布于大于10~6Da的范围,有少量小于10~3Da,蛋白质分子量小于10~3Da.通过RO错流过滤污堵实验装置考察了两种SMP对RO膜的污堵特性,发现SMP中大分子有机物的分子量与SMP的膜污堵潜力密切相关,有机物分子量越大,SMP的膜污堵潜力越高,而多糖和蛋白质的比例并不是决定SMP膜污堵潜力的关键.因此,减少SMP中的大分子量物质(特别是大分子多糖)在RO膜表面的沉积,是缓解SMP造成的RO膜污堵的关键.

Comparation of the soluble microbial products released by different bacteria and their ability in RO membrane fouling

Reverse osmosis(RO) system are widely used in the reclamation of municipal wastewater,but fouling of RO membrane causes serious negative effects on the operation. Soluble microbial products(SMP) is the key organic matter causing the biofouling of RO membrane. In this study we characterized the SMPs of 2 different bacterial strains isolated from the surface of RO membranes used in municipal wastewater treatment plant,namely Pseudomonas sp. AM1-1 and Chromobacterium sp.AM1-2,and further compared the ability of causing RO membrane fouling by these two kinds of SMPs. It was found that the proportion of polysaccharide and protein in the two kinds of SMPs was approximately 1:1. The molecular weight(MW) of polysaccharides and proteins in the SMPs from AM1-1 showed a bimodal distribution,having a MW less than 10³ Da or more than 10⁵ Da. While MW of polysaccharides in the SMPs from AM1-2 also showed a bimodal distribution,but the majority was more than 10⁶ Da and minority was less than 10³ Da. The MW of proteins in the SMP from AM1-2 is less than 10³ Da. The results of lab-scale crossflow fouling experiment show that the higher the MW of organic matters in SMP was,the higher risk of organic fouling would be. The proportion of polysaccharide and protein was not the key factor that affected the RO membrane fouling ability of SMPs. Therefore,reducing the amount of organic matters(especially polysaccharides) with high MW in the surface of RO membrane is the key to reduce the risk of RO membrane fouling caused by SMPs.