WASHING METHOD OF REVERSE OSMOSIS MEMBRANE MODULE

PROBLEM TO BE SOLVED: To provide a washing method of a reverse osmosis membrane module capable of shortening the washing time of the reverse osmosis membrane module and reducing the additional amount of a medicine when a biological substance adheres to a membrane surface.SOLUTION: A water treatment system 1 which is provided with a reverse osmosis membrane module 5 separating supply water W1 to permeated water W2 and concentrated water W3 and which is a washing method of the reverse osmosis membrane module 5 performed when the reverse osmosis membrane module 5 has a biological contamination tendency includes: a washing auxiliary agent addition step adding a washing auxiliary agent to the reverse osmosis membrane module 5; and an osmotic pressure adjustment step adjusting osmotic pressure in the reverse osmosis membrane module 5 so as to transfer the permeated water W2 from the secondary side of a membrane in the reverse osmosis membrane module 5 toward a primary side after the washing auxiliary agent addition step.SELECTED DRAWING: Figure 6 【課題】生物物質が膜面に付着した場合に、逆浸透膜モジュールの洗浄時間を短縮できると共に、薬剤の添加量を低減できる逆浸透膜モジュールの洗浄方法を提供すること。【解決手段】供給水Ｗ１を透過水Ｗ２と濃縮水Ｗ３とに分離する逆浸透膜モジュール５を備える水処理システム１において、逆浸透膜モジュール５について生物汚染傾向である場合に行われる逆浸透膜モジュール５の洗浄方法であって、逆浸透膜モジュール５に洗浄補助剤を添加する洗浄補助剤添加工程と、洗浄補助剤添加工程の後に、逆浸透膜モジュール５の膜の二次側から一次側に向けて透過水Ｗ２の移動が生じるように、逆浸透膜モジュール５の浸透圧を調整する浸透圧調整工程と、を含む。【選択図】図６