| 摘要 |
PROBLEM TO BE SOLVED: To smoothly operate a membrane filter even under negative pressure and to apply optical suction pressure to the membrane filter by generating a differential pressure across the membrane in the membrane filter through a vacuum can and a water separator and adjusting the differential pressure across the membrane above and below the water surface in a pressure adjusting tank. SOLUTION: When a prescribed presser of -P is formed in a vacuum can 7, a water head H is generated between the water surface L1 inside the can and the water surface L2 outside the can according to the difference between atmospheric pressure and pressure inside the can. In this state, adjustment negative pressure -ΔP corresponding to a water head h2 from the opening position of a lead pipe 11 in the vacuum can 7 to the water surface outside the can extends to a water separator 9, and this adjustment negative pressure -ΔP is used as driving force to generate a differential pressure Pd across the membrane in a membrane filter 3. This differential pressure Pd is the difference between the adjustment negative pressure -ΔP plus positive pressure corresponding to a water head h3 from the water surface L3 inside the water separator 9 to the water surface L4 inside a membrane immersion tank 2 and atmospheric pressure. This between-membrane differential pressure Pd is used as driving force to perform membrane filtration and to subject raw water to solid-liquid separation.
|
