Probable use of chemical and biochemical detergents to wash polysulphone membranes using in milk ultrafiltration needs a multidisciplinary investigation. By increasing use of these membranes in food processing, washing and recovery of initial permeate flux, in order to use for a longer time from this technology, has much importance. In this research, influence of chemical detergents including EDTA, SDS and NaOH, biochemical including protease and lipase on recovery of permeate flux of ultrafiltration from polysulphone amide with pore size of 20 kD as a function of temperature, pressure, and time were investigated. Optimum amounts of activity of Protease and Lipase in temperature, pH and time of incubation were measured. Results showed that lipase cannot recover permeate flux and usefulness of this enzyme is not comparable with protease. With respect to the results obtained about optimum concentration of enzymes in recovery permeate flux, optimum concentration of chemicals in washing polysulphone membrane including EDTA, SDS, and NaOH were measured. Also, efficiency of optimum rate to mix enzyme, SDS and EDTA to recover flux and chemical used in industry were evaluated. Results showed that biochemicals (enzymes) are able to recover at least 60% of initial flux membranes. This rate for chemicals and under continuous and turbulent flow has been reported to be more than 95%.

Key words: Ultrafiltration, Permeate flux, Pulysulphone membranes, Chemical & biochemical detergents