SKIMMED-MILK DEMINERALIZATION BY ELECTRODIALYSIS - CONVENTIONAL VERSUS SELECTIVE MEMBRANES

Electrodialysis (ED) is a membrane technique that is useful in the dem ineralization of dairy products. In this work, experimental results ob tained in batch electrodialysis of skimmed milk are presented. Two kin ds of membranes were used: the first kind were conventional membranes in PVC and the second were monovalent ion selective membranes which ar e now available on the market. This latter type of membrane permits th e transport of monovalent ions but limits the passage of large ions wh ich have a high valency. The limiting current was measured as a functi on of feed flow into the stack. The results obtained when using both t ypes of membranes were compared for elimination rate of K+, Na+, Cl-, Ca2+, Mg2+ and PO43- ions as well as for current efficiency and electr ic power consumption in the separation process.