Abstract: The present invention relates to a method of recovering lactose from a lactose-containing liquid source comprising providing a lactose-containing liquid source, crystallising the lactose in the lactose-containing liquid source to generate one or more lactose-containing liquid streams, recovering a lactose-containing extract from the one or more lactose-containing liquid streams by subjecting the one or more lactose-containing liquid streams to filtration to remove cells, proteins, polypeptides, polysaccharides, lipid, ions or salts. The method also includes processing the lactose-containing liquid streams using at least nanofiltration, ultrafiltration and/or centrifugal separation and recycling the lactose-containing extract into the lactose-containing liquid source.