The structure of the deposit formed on the membrane during the concentration of milk by reverse osmosis

Abstract

Summary Concentration of milk by reverse osmosis is severely hindered by the formation of deposits on the membrane. Electron micrographs of this deposit show a thin (11nm) continuous electron-dense layer adjacent to the membrane. An electronlucent zone (10–15nm thick) separates this layer from the main bulk of the deposit which is 30 μm thick and consists largely of granules with some vesicles in a diffuse matrix. The density of packing of the granules increases with proximity to the membrane. Their appearance, size and digestion with pronase suggest that these are milk protein granules. The order and nature of these various layers could explain the pattern of flux decline.