Water purification in membrane separation rejection of bacteria and virus and factors effecting permeate flux.

阐明膜过滤和分离的特性对了解膜技术在水净化中的可行性和适用性具有重要意义。在本研究中，细菌和病毒的排斥以及混浊和胶体物质的去除进行了研究。研究了影响膜通量的因素。研究结果如下：1）高岭土悬浮液、腐殖酸和E.外压中空纤维微滤膜（孔径为30 nm）对大肠杆菌群的去除率与管式超滤膜（截留分子量为14，000道尔顿）几乎相同。所用中空纤维膜组件的渗透通量在2.5 ~ 6 m/d之间，具有较高的实际应用价值。2）采用乳胶粒在膜表面形成人工滤饼的方法，对影响膜通量的因素进行了实验和理论研究。初始通量下降速率受到显著影响 ...更多信息 通过孔隙度和颗粒大小。因为错流速度决定了反向输运速率。它给出了稳态通量值。当考虑进水的多分散性时，数值计算表明，随着时间的推移，较小的颗粒聚集在膜上形成的滤饼层中。3）孔径为100 nm的新型微滤膜对E. Colt Q_<beta>（ca.尺寸为25 nm）。膜表面形成的滤饼层显著提高了天然池塘水的截留率。通过<beta>超滤膜（分子量为40，000道尔顿，截留尺寸）观察到Q_的显著泄漏。虽然真实的截留率足够高，但由于浓差极化的影响，实际截留率可能会显著降低。4）在此基础上，采用中空纤维膜组件对5万m^3/d的净化装置进行了初步设计。结果表明，在渗透通量保持在0.5m/d的情况下，膜板所需占地面积远小于同等处理能力的二级净化板。在系统中没有进料流的再循环的情况下，操作成本总是变得比传统的操作成本便宜。少

It is important to elucidate the characteristics of membrane filtration and separation to know feasibility and applicability of membrane technology in water purification. In this research, rejection of bacteria and virus was investigated as well as removal of turbid and colloidal materials. Factors affecting permeate flux was also studied. The results obtained are summarized as below.1) The removals of kaolin suspensions, humic substances and E. coli groups by externally pressurized hollow fiber microfiltration membrane (30 nm of pore size) were almost the same as those by tubular ultrafiltration membrane (14, 000 dalton of molecular weight cut off size). The permeate flux of hollow fiber module used ranged from 2.5 to 6 m/d and it was high enough for practical application.2) By using latex particles for artificial cake formation on membrane surface, factors affecting permeate flux were investigated experimentally and theoretically. Initial flux decline rate was significantly affected … More by porosity and particle size. As cross-flow velocity determines back transport rate. It gave steady-state flux value. When polidispersity of influent was considered, numerical, calculation showed that smaller particles accumulated in cake layer formed on membrane with time elapsed. It was because shear effect was increased with increase on particle size enchancing back transport.3) New microfiltration membrane with pore size of 100 nm rejected 90% of E. colt Q_<beta> (ca. 25 nm in size) applied due to adsorption. The cake layer, formed on membrane significantly increased the rejection in natural pond water filtration. Significant leak of Q_<beta> was observed through ultrafiltration membrane (40, 000 dalton of molecular, cut off size). Even though real rejection was high enough, observed rejection might be significantly reduced due to concentration polarization.4) Based on the above results, preliminary design of of a purification plant (capacity 50, 000 m^3/d) was done adopting hollow fiber module as membrane configuration. It was shown that land area required for the membrane plat was much smaller than that for, a conveational purification plat with same capacity, in case the permeate flux was maintained 0.5 m/d. In case no recycling of feed stream is the system, the operational cost becomes always cheaper than that of the conventional one. Less