To provide a hollow fiber membrane filter which extends operation time by controlling the growth of a cake layer formed on the surface of the hollow fiber membrane in the filtration of raw liquid.
Since a hollow fiber membrane filter is composed of the first filter 1 using hollow fiber membranes for filtering raw liquid as a filter medium, the second filter 20 using hydrophobic hollow fiber membranes 13 for separating air which worked in the first filter 1, and a controller 14 for controlling the flow rate of air to be introduced into the first filter 1, the membrane filter detects bubbling air which is a compressible fluid, the primary side internal pressure of the filter, in accordance with the pressure change of the differential pressure of the filter associated with the capture of of insoluble impurities and controls and a supply flow rate. By using the hydrophobic hollow fiber membrane filter which passes only air to discharge bubbling air from the filter 1, the bubbling air can be discharged selectively. In this way, the growth of a cake layer can be controlled.
SATO MASAHIRO
TOMITA SHUNEI
TOSHIBA CORP