The deposition of organic matter on the membrane surface, which causes inefficiencies. Fouling can take the form of many classifications, such as organic fouling which describes the relationship between biofouling and organic colloidal fouling. Foulants that present more problems include proteins and polysaccharides which occur in very small macromolecular and colloidal configuration. Periods of backwash sees low-pressure membranes with certain degrees of hydraulic reversibility that is not optional for high-pressure membranes. Ultimately, the productivity of the cleaning chemicals is hampered by the suitability of membrane materials with cleaning agents. Coagulants used during the pretreatment phase are capable of decreasing organic fouling.