| 摘要 |
PROBLEM TO BE SOLVED: To stably filter an ozone-contg. water over a long period by filtering the ozone-contg. water with a polyvinylidene fluoride resin porous membrane with the maximum temp. showing a specified temp. among the peak temps. obtained by differential scanning calorimetry. SOLUTION: In the complete treatment of service water and secondary treated sewage or the treatment of industrial water, waste water, or the like, ozone is added to the raw water to improve the quality, and then the water is treated with a filter membrane. In this case, a material resistant to ozone oxidation, e.g. a polyvinylidene fluoride(PVDF) resin porous membrane, is used as the membrane used in filtration. Further, a membrane with the maximum peak temp. obtained by differential scanning calorimetry showing >=160 deg.C among the PVDF resin porous membranes is used as the filter membrane excellent in ozone oxidation resistance. Namely, a microfilter membrane having 0.1-0.5μm average pore diameter and 60-90% porosity, or the like, are used as the membrane.
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