Development and application of wastewater treatment system using membrane separation

本研究项目旨在发展膜分离固液分离废水处理工艺。膜过滤的特点：采用平板式超滤膜和微滤膜，考察了活性污泥曝气池与膜组件连接时的过滤阻力和出水水质。滤液的质量与膜的孔径大小无关。滤速与曝气池中的MLSS无关，对膜孔径不敏感。曝气池中可观察到大分子有机物的积累。中空纤维膜在好氧废水处理中的应用：中空纤维膜的孔径为0。将1微米直接淹没到Actiat…的实验室曝气池中更多的ED污泥法。流出物是通过这个膜吸入的。连续抽吸造成滤池堵塞，而间歇抽吸的引入解决了这一问题。运行近一年，MLSS高达4万mg/L左右，但很高的生物量降低了溶解氧水平，COD的去除也显著下降。中空纤维膜只要间歇运行，应用前景广阔。(3)膜分离在厌氧工艺中的应用：采用平板式膜与混流型厌氧反应器相结合。该系统实现了常规厌氧工艺所不能实现的生物质长停留时间。以牛奶为合成底物的试验表明，MLSS最高可达15,000 mg/L，且出水水质优良，产气量高。过滤通量逐渐下降，但通过清洗膜可以恢复膜。该系统对生活污水污泥进行了处理。在最佳运行时间为10天时，膜法比常规工艺多产甲烷20-40%。采用聚乙烯醇(PVA)对厌氧菌进行了固定化试验。所制得的微球在相当长的时间内稳定，固定化后的培养可以提高细菌的生物活性。较少

This research project aims at the development of wastewater treatment process in with employing membrane separation for solid-liquid separatikon. This project especially focused on practical aspects and the following results were obtained.(1) Charecteristics of membrane filtration: Uitra membrane and micro membrene in flat type was used to examine the filtration resistance and filtrate water quality when aeration tank of activated sludge was connected with membrane module. Filtrate quality did not at all depend on pore size of membrane. Filtration rate was independent from MLSS in aeration tank, and was not sensitive to pore size of membrane. Accumulation of organic materials of high molecular weight was observed in aeration tank. Molecular weight distribution was examined with gel chromatography.(2) Application of hollow fiber membrane to aerobic wastewater treatment: Hollow fiber membrene of pore-size of 0. 1 micron was directly submerged into laboratoryscale aeration tank of activat … More ed sludge process. Effluent was suctioned through this membrane. Continuous suctioning caused filter clogging problem, while introducing the intermittent suction solved this problem. Successful operation was achieved for nearly one year with MLSS as high as about 40,000 mg/L. However, very high biomass dropped dissolved oxygen level, and COD removal decreased significantly. Application of hollow fiber membrene is very promising as long as intermittent operation is done.(3) Application of membrane separation to anaerobic process: A flat type of membrane was used in combination with mixed-flow type anaerobic reactor. This system enabled long biomass residence time which can not be achieved in conventional anaerobic process. The experiment using milk as a synthetic substrate showad that MLSS reached as high as 15,000 mg/L, and good methane production with excellent effluent was achieved. Filtration flux decreased gradually but the membrene was recovered by cleaning the membrane. Domestic sewage sludge was gtreated in this system. Membrane process can produce 20-40% more methane than conventional process at betention time of 10 days. Immobilization of anaerobic bacteria by using polyvinyl alcohol (PVA) was examined. The obtained beads were stable for reasonably long period, and incubation after the immobilization could raise the biological activity of bacteria. Less