When planning a membrane cleaning, it is important to consider the order in which the required cleaners should be used. In general, remove biological growth and colloidal silt first (using surfactants)
A second cleaning (acid) removes the metals and scale from the membrane. Layers, such as silica and barium sulfate which tend to exist at the lower level of the stratum (closest to or directly on the membrane), may be removed in a final procedure (EDTA).
During the cleaner re circulation and rinsing procedures, pressures should be reduced so permeation is avoided. By reducing pressures, the membrane foulants are no longer being forced toward the membrane by the water flowing through it. Instead, foulants may move away from the membrane surface, into solution and out of the membrane element