To provide a low cost, easily washable and highly reliable spiral type membrane element, and a method for operating a spiral type membrane module.
The spiral type membrane element 1 is constituted by covering a spiral-shaped membrane element consisting of a plurality of independent or continuous envelope-like membranes wound on the outer peripheral surface of a water collection tube 2 via raw water spacers with a separation membrane and further covering the resultant assembly with an outer peripheral part flow path material. The preferred flow rate of transmission water at filtering by the spiral type membrane element 1 is 0.5-2.0 m3/m2/day and the preferred filtering time is 10-300 minutes. Also, the preferred flow rate of washing water at washing is 1.0-4.0 m3/m2/day and the preferred washing time is 10-300 seconds. In such a range, the ratio of the passing water quantity at filtering to the passing water quantity at back-washing is set to be ≤600.
KAWASHIMA TOSHIYUKI
HISADA HAJIME
