Abstract: Membranes, for example immersed polymeric ultrafiltration or microfiltration membranes, are cleaned by contacting them with a chemical cleaner comprising one or more of a gluconate, a hydrosulfite, a metabisulfite or an acid, for example phosphoric acid. The membranes may have been exposed to organic or inorganic foulants, some of which may have resulted from pretreatment involving adding coagulants, for example coagulants containing iron or aluminum, to water to be treated. Methods for treating a waste cleaning solution were described.