During the operation of a membrane separation system, organic materials and suspended solids in the incoming water can accumulate on the membrane surface. Fouling from these species impedes the flow of water through and across the membrane.This can result in unacceptably low production,high operating pressure, or an excessivepressure drop in the system. Additionally, dissolved solids in the incoming water can concentrate up to a level where they begin to precipitate on the membrane surface. Scaling from hardness and metal salts, found in most unsoftened water, impedes the flow of water through the membrane. The accumulation of scale next to the membrane surface can increase the amount of dissolved material passing through the membrane, resulting in product water of unacceptable quality. Before the particulate fouling and scale accumulate to a level where product water flow or quality declines, or membrane damage is imminent, removal using offline cleaning is required. Indications of the need for cleaning include a significant decrease in normalized permeate flow, a significant increase in pressure drop across the system (or individual stage), or an increase in the normalized salt passage, such that product quality is unacceptable. Your GE representative can assist you with monitoring your system and determining when cleaning is advised.