Microfiltration, ultrafiltration, and reverse osmosis are gaining application in the water treatment market.  In order to maintain the efficiencies of these filtration systems, regular membrane cleanings have a significant impact on process operations.  Citric acid is primarily used to remove scales and metal dioxides from the fouled membranes. Citric acid is very effective in dissolving iron oxide precipitates by complexation.  Also, some of organic compounds and proteins can be hydrolyzed.