| 摘要 |
<p>PROBLEM TO BE SOLVED: To stably remove solid particles having high adhesiveness over a long period of time by setting the jet quantity of gas in backwashing so that a value calculated by dividing vol. per one pulse by a jet time and the area of the filter membrane of a part to which the gas is jetted becomes a specific range. SOLUTION: In a filter 4, a valve 19 is opened and the compressed gas stored in a head tank 17 is jetted from a backwashing nozzle 15 in a pulse like manner through a valve group 18 and the solid particles accumulated on the primary side of a filter element 8 is shaken down from a filter membrane. As the filter element, one characterized by that the ratio of the surface area on the primary side of the filter membrane to the apparent outer surface area is 1-5 is used generally. When the quantity of gas jetted in a pulse like manner is too little, backwashing effect is not obtained and, when too much, deformation is generated in the filter membrane. Therefore, a value calculated by dividing vol. per one pulse by a jet time and the area of the filter element of a part to which the gas is jetted is pref. 0.07-0.2m/sec.</p> |
