Controlled deposit formation to influence the retention of solutes in reverse osmosis and ultrafiltration

Deposited layers of milk protein reduce the rate of permeation of both lactose and salt ions by compression of the region of the deposited layer adjacent to the membrane into a secondary membrane with solution diffusion properties. The formation of a deposited layer with solution diffusion properties from a macromolecular solution prior to concentrating products such as fruit juices, wine, coffee and tea could be applied for a higher rejection of dissolved and volatile compounds. The stability and the rejection characteristics of deposited layers were studied with a reverse osmosis membrane and a ceramic ultrafiltration membrane with applied pressures up to 6 MPa. The ultrafiltration membrane was used because most of the dissolved low molecular weight compounds pass through. An increase in retention of these compounds depends therefore only on the deposit layer on the membrane.