| 摘要 |
PROBLEM TO BE SOLVED: To prevent the decomposition of a separating membrane during the discontinuation of the operation of a machine and not to lower the membrane performance at the time of restarting the operation by containing a HINOKI (Japanese cypress) family plant extraction component in filter treatment water when the filter treatment water is passed through a separating membrane. SOLUTION: When the water treatment is carried out for a separating membrane such as a hollow yarn membrane, pollutants are accumulated in a membrane surface following the progress of filtration. At that time, cleaning is carried out by passing filter treating water, and a HINOKI (Japanese cypress) family plant extraction component such as hinokithiol is contained in the filter treating water. The proliferation of microbes such as heat-resistant bacteria, lactic-acid bacillus and the like is controlled by the hinoki family plant extraction component, and the growth is prevented to the extremely low concentration. The decomposition of the membrane, therefore, is prevented during the discontinuation of the operation of a machine, and the operation can be, restarted immediately. A separating membrane used herein is a hollow yarn membrane, namely an ultra-filter membrane or a precision filter membrane provided with the pore diameter, the outer diameter, the inner diameter and the membrane thicknes of respectively 1-10μm, 100-2,000μm, 50-100μm and 20-500μm. The HINOKI family plant extraction component is hinokithiol, and the extraction component concentration is 1-1,000ppm.
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