| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 94 === The effects of operating conditions, such as aeration intensity, filtration pressure, membrane pore size and step increase pressure, on the filtration rate, cake formation and membrane blocking in submerged membrane filtration are studied. Two inorganic membranes with mean pore size of 0.17μm and 0.45μm, respectively, are used to filter PMMA particles with a mean diameter of 5μm. The experimental results show that the filtration resistances of cake and membrane blocking play the major roles on the overall filtration resistance, but the resistance due to membrane blocking is dominant. The filtration rate increases with the increase of aeration flux because of the reduction of cake formation. In addition, the filtration rate can also be enhanced significantly by the method of step-increase of filtration pressure. It is because both membrane blocking and cake formation are reduced by using this method. The membrane blocking and particle deposition are observed by SEM analysis. The structure of the inorganic membranes is not isotropic, the occurrence of membrane blocking is because of the existence of large pores. The model analysis of experimental results show that the complete blocking and the intermediate blocking occur in the pores of 0.17 μm and 0.45 μm membranes, respectively, at the beginning of filtration. However, the blocking models change to cake filtration after a period of time.
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