Assessing the utility of some technological trains for water recovery fromacid and metal salt solutions

Studies on high-quality water recovery from mineral acid (HCl, H2SO4, HNO3/ HF) and iron salt solutions were presented. Water was recovered via three t reatment trains involving electrodialysis (ED) and cation exchange in vario us combinations: System I: EDI + ED2; System 2. ED1 + cation exchange + ED2 ; and System 3: cation exchange + EDI + ED2. Water recovered via System 3 d isplayed the highest quality: its conductivity varied from 2 muS/cm (recove ry from HCl solution) to 49 muS/cm (recovery from H2SO4 solution). It was f ound, however, that pre-decationization raised the deionized water consumpt ion for the rinsing of the ion exchanger, thus decreasing the efficiency of water recovery as compared to System 1 or System 2. That is why, the cost of water recovery via System 3 is relatively high. Water can be also recove red via System 1 or System 2. System 2 provided water of slightly better pa rameters: water contained trace amount of iron salt and its conductivity va ried from 4 muS/cm (water from HCl solution) to 61 muS/cm (wafer from H2SO4 solution). The calculated cost of water production via System 2 is almost the same as that in System I. (C) 2001 Elsevier Science B.V. All rights res erved.