| abstract |
The method for washing a microfiltration membrane or ultrafiltration membrane of the present invention comprises a step of bringing the microfiltration membrane or ultrafiltration membrane into contact with hydroxyl radicals. The method of the present invention is particularly suitable for an oxidation resistant film such as a Halar in which bio-fouling or organic fouling has occurred. For example, hydroxyl radicals are generated from an aqueous ionic solution of a transition metal (eg, molybdenum, chromium, cobalt, copper or tungsten, but more preferably iron) and hydrogen peroxide under acidic conditions. The method of the present invention is particularly suitable for hollow fiber membranes, in which liquid flows into the walls of vertical hollow fiber membranes due to oxygen bubbles generated during the reaction, and water is pushed out from the upper part of the lumen. If a filter cake is present on the ultrafiltration membrane, the oxygen bubbles will cause the solution to self-stir such that such filter cake is destroyed. |