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点，对于了解膜技术在净水中的可行性和适用性具有重要意义。在本研究中，对细菌和病毒的排斥以及对混浊和胶体物质的去除进行了研究。并对影响渗透通量的因素进行了研究。研究结果如下：1)外加压中空纤维微滤膜(孔径30 nm)对高岭土悬浮液、腐殖质和大肠杆菌的去除效果与管式超滤膜(截留分子量为1.4万道尔顿)基本相同。中空纤维组件的渗透通量为2.5~6m/d，具有较高的实际应用价值。2)利用胶乳颗粒在膜表面形成人造滤饼，对影响渗透通量的因素进行了实验和理论研究。初始通量衰减率对…有显著影响更多的取决于孔隙率和颗粒大小。因为错流速度决定了回输速度。给出了稳态磁通值。当考虑进水的颗粒分散性时，数值计算表明，随着时间的推移，膜上形成的滤饼层中积累了较小的颗粒。3)孔径为100 nm的新型微滤膜因吸附作用而截留了90%的E.colt Q&lt；beta&gt；(约25 nm)。膜上形成的滤饼层显著提高了池塘水自然过滤的截留率。通过超滤膜(40,000道尔顿分子，截断大小)观察到Q_&lt；β&Gt；显著泄漏。在上述结果的基础上，采用中空纤维组件作为膜结构，对一座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，膜板所需的占地面积比相同容量的传送式净化板小得多，在没有进料循环的情况下，运行成本始终低于传统的传送式净化板。较少

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