There are described some applications of membrane separation, e.g. reverse osmosis in the treatment of sugar beat press water. recovery of salt from waste brine at a sugar decolorization plant or microfiltration and ultratiltration of raw sugar juice, as an alternative to chemical purification process. The last case is completed by original experimental work. Samples were treated with cross flow micro- and ultrafiltration on ceramic membranes having porosity 20 and 50 nm. The changes in the content Of Sucrose, invert sugar and lactic acid were observed, resulting in increasing the juice purity from the initial value 89% to the final value 91-92%. In addition, permeate can be a subject for direct crystallisation after thickening to produce the final product. Retentate purity decreased to 87-88%. For nanotiltration tests (NF) there has been designed a special stainless steel cross-flow dynamic cell for pressures up to 4 MPa. The preliminary NF tests were focused on testing different commercial flat polymeric membranes (Hydronautics-Nitto Denko, Osmonics-Desal). (C) 2002 Elsevier Science B.V. All rights reserved.