Membrane-Based Dairy Separation: A Comparison of Nanofiltration and Electrodialysis

摘要

Two membrane technologies are compared for the separation of potentially valuable lactose and calcium from a currently underutilised dairy stream, i.e. whey ultrafiltration permeate. Nanofiltration, a pressure driven separation through a porous membrane, is able to simultaneously concentrate and demineralise this stream, giving up to 70% reduction in unwanted monovalent salts. Electrodialysis, an electrically driven separation of ions through ion exchange or porous membranes, is able to demineralise whey permeate to higher levels, but has lower selectivity between mono- and divalent ions. The technologies are evaluated with regard to membrane perm-selectivity, efficiency, cost and suitability to the given separation, based upon research presented in the literature. It is concluded that nanofiltration offers the most potential for separation between undesirable monovalent ions and valuable divalent ions and lactose, while electrodialysis is more suitable for higher levels of demineralisation where a purer lactose product is required.