The feasibility of desalting the spent brine from pickled prune processing by electradialysis was studied. Three membrane pairs were tested and one was selected for the process. The limiting current density increased with increasing fluid velocity as well as increasing salt concentration. Increasing current density increased the ion removal rate, the rate of water transport, the power consumption per unit mass of salt removal, and decreased current efficiency. However, the losses of citric acid and benzaldehyde did not increase significantly until the current density was up to 10 mA/cma. The electrodialysis process removed 88% salt from the brine while retaining 80% organic acids and 55% benzaldehyde. -Continued on page 164 Volume 53, No. 7, 79884OURNAL Of FOOD SCYENCE-737

The primary waste water discharged from pilot plant scale sweet potato starch manufacturing was processed by ultrafiltration (UF). The UF permeate was then concentrated by reverse osmosis (RO). Growth of microorganisms in waste water would reduce the flux of UF. When the feed velocity of UF was higher than 2.5 m/set, its positive effect on permeation rate was no longer existent. Relationships between transmembrane pressure and permeate flux were linear at all tested concentrations. UF filtered protein and calcium reduced two-thirds of the biochemical oxygen demand (BOD) and half the chemical oxygen demand (COD) at weight concentration ratio (WCR) of 5. With RO the rest of the components were recovered and BOD and COD were reduced more than 99% and 98%, respectively, at a WCR of 6.