Study On The Ultrafiltration Membrane Separation Property Affected By Raw Water Quality Changes

In recent years, utilisation of Ultrafilration membrane technology on watertreatment has been developed rapidly, and become the most promising treatmenttechnology of water treatment. Membrane manufacturing technology developmentcontinued, PVC alloy hollow fiber membrane is the more popular membrane in recentyears. In order to applied to engineering practice had a good result, that need in-depthanalysis the membrane fouling process.In this study, we took membrane filtration raw water with a variety of water qualitythat configured based on surface water quality changes. Determination of the membraneflux decay process, analyze the performance of membrane filtration by raw waterquality changes, material in surface water can be divided into insolubility of particulatematter and dissolved organic matter, we used Kaolin and humic acid configuration ofraw water to simulate the surface water in this study, that can be better control changesof the water quality, turbidity measured Kaolin and UV254measured humic acid.Through configuration raw water that exists only turbidity and then filtration,determination of membrane of flux attenuation by turbidity changes; throughconfiguration raw water that exists turbidity and organic matter and then filtration,organic concentration is constant, determination of membrane flux attenuation byturbidity changes; through configuration raw water that exists organic matter only andthen filtration, determination of membrane flux decay by organic matter concentrationchanges; though configuration raw water that exists organic matter and turbidity andthen filtration, turbidity level is constant, determination of membrane flux attenuationby organic matter concentration changes. With numerous tests and the results arein-depth analysis, have the following conclusions:When organic matter does not exist, increase in raw water turbidity will be reducedthe membrane flux, cause the membrane filtration property declined, but the effect isnot obvious, its impact on the property of membrane filtration can not be consideredwith the small changes in turbidity.When the raw water does not exist organics, turbidity could be polluted theUltrafiltration membrane in a certain degree, but the pollution is not very serious. Mostof the membrane flux can be restored by aeration, aeration after the membrane flux, theaverage response rate in more than98%. When the raw water does not exist organics, Ultrafiltration membrane surface cakelayer formation process is divided into three stages: The first stage is the suspendedmaterial rapid adsorption by membrane surface. The second stage is the steady growthof cake layer. The third stage is compaction of cake layer.When the raw water existence of organic matter, the increase of raw water turbiditycan be improve the effect of membrane filtration to some extent, delay the attenuationof membrane flux. But the effect will be significant only the turbidity have a bigchanges.Raw water by coagulation can improve turbidity, increasing the particle size ofsuspended particulate matter, can significantly enhance the UF removal rate, and caneffectively alleviate the pollution of organic ultrafiltration membrane.Raw water filtered in the condition of only have organic matter, when the content ofUV254in water is reached0.065cm-1, membrane filtration removal efficiency of13.85%to20.00%; when the content of UV254in water is reached0.12cm-1, membranefiltration removal efficiency of11.67%to15.00%; when the content of UV254in wateris reached0.20cm-1, membrane filtration removal efficiency of6.50%to8.50%; itmeans the removal rate of Ultrafiltration membrane on organic matter is not veryhigh.Membrane resistance produced by organic matter have a fast growth rate in theinitial phase, the membrane resistance is almost no change after a period of time, but thecontent of organic matter have an increasing trend that after membrane filtration. Itsexplained that the membrane removal of organic matter is not rely on physical screening,and the filter only have removal efficiency in the initial period. Ultrafiltrationmembrane removal of organic matter mainly depend on the membrane pore and surfaceadsorption, and the combination of the two were closely, difficult to be removed withthe backwash and aeration.In the case of the same turbidity, organic matter content changes have a greaterimpact on membrane flux. As UV254concentration increase, the rate of decline ofmembrane flux is faster, and the membrane flux recovery capability after aeration isdecline.