Pervaporation of pharmaceutical waste streams and synthetic mixtures usingwater selective membranes

The separation characteristics of binary mixtures and complex pharmaceutica l wastes were studied using commercial water selective pervaporation membra nes. Various synthetic alcohol-water (plus salt in some cases) systems and actual waste were utilized for the investigation, The total flux (at 60 deg rees C) for the ethanol-water system decreased from 1.26 to 0.05 kg/m(2)/hr as the feed ethanol concentration increase fi om 35 to 97 wt %. The separa tion factor (water/ethanol) was found to increase by about 100 times for th e same range of concentration. The water isopropanol selectivity was found to be considerably higher than the water/ethanol selectivity. The total flu x (at 60 degrees C) for the isopropanol-water system varied from 0.85 to 0. 48 kg/m(2)/hr as the feed isopropanol concentration was increased from 35 t o 70 wt %. The effect of the presence of salt salt in the feed on the perva poration separation was also studied. There was a noticeable effect only at high concentrations of salt in the alcohol-water feed. Both the total flux and the membrane selectivity were observed to decrease at high salt concen trations. Pervaporation can be used for the volume reduction of pharmaceuti cal wastes. Pervaporation experiments were performed on a complex pharmaceu tical "waste A" at two different temperatures. The total flux (0.9 kg/m(2)/ hr) at 60 degrees C for the waste was observed to be six times the total fl ux at 28 degrees C whereas the TOC (total organic carbon) reduction factor (7.9) at 60 degrees C was found to 2.5 times that at 28 degrees C. A 87 % r emoval of the TOC and COD of the waste stream was observed Pervaporation, u sing water selective membrane, was also performed on a dilute "Waste B" and only 40 % TOC/COD removal was obtained Based on the experimental results a nd operating cost calculations, it can be concluded that pervaporation is i ndeed an attractive strategy for the volume reduction and for simultaneous reduction of organic concentration in the permeate stream.