Study On The Membranous Material In The Ultrafiltration Prosess For Secondary Effluent

People paid more and more attention on membrane separation techniques because of its virtues: good water quality, low energy consumption, simple operation and easy to reuse. In recent years, the cost of the membrane fell down while its quality improved for the rapid development of the membrane separation techniques. The research and the use of membrane separation techniques in wastewater recycle become a hot point. But there are lots of problems need to be solved in the use of membrane. The thorniest matter which becoming the major obstacle of membrane use in wastewater treatment is the fouling of membrane. The mechanism of fouling is important. This paper studied some different material membranes which have diverse configuration parameters and same nominal pore size, in order to make clear that how configuration parameter dose to membrane fouling. And this research used hydrophilic and hydrophobic organic molecular weight cutoff in the secondary effluent, membrane configuration parameters and membrane fouling explained different filtration phases have different organic removal ratio. Also, this paper compared the membrane configuration parameters before and after membrane fouling, and used it to explain different molecular weight cutoff can cause different fouling type, which can result in different membrane filtration flux decline rate. The results showed that:(i) Different membranes have different configuration parameters, the difference of pore fractal dimension, separation layer thickness and pore ratio comparatively larger than the difference of pore density and pore size distribution.(ii) Membrane configuration parameter affects membrane filtration flux decline rate. Membrane pore clogging do more impact on flux early decline, and that pore size narrowing do more impact to latter flux decline.(iii) There are more hydrophilic organics than hydrophobic organic in the secondaryeffluent. And there are more linear hydrophilic organics larger than 30kDalton.(iv) In early time of filtration, the organic removal ratio of the hydrophobic membrane relate to those factors which can cause pore size narrowing, and the organic removal ratio of the hydrophilic membrane relate to those factors which can cause pore clogging.(v) In latter period of filtration, the organic remove of the hydrophobic membrane depending on the sieve by its material and the organic it adsorbed inside of the membrane, and the deviation of the separation layer thickness have great impact on organic removal ratio. The organic remove of the hydrophilic membrane depending on the sieve by its material and the organic it adsorbed outside of the membrane.(vi) Little weight molecular not only affect the inside adsorption of organic, but also affect the outside adsorption of organic. It can press the organics adsorbed outside of the membrane which can result in sharper roughness of the membrane surface, cause worse membrane fouling and led to faster filtration flux decline.