COMPARATIVE-STUDIES ON WATER AND WASTE-WATER TREATMENT BY REVERSE-OSMOSIS

The process of water and wastewater desalination by reverse osmosis in a full scale system was investigated. The system was the terminal part of a reclamation plant, in which water is recovered from tanning effluent. Permeate volume flux and pressure are related to the temperature of water and wastewater; volume flux is related to pressure; pressure and retention of dissolved solids are related to dissolved solids concentration in the feed. The membranes after two years of operation showed a relatively low ability of retaining dissolved solids (especially monovalent ions) which ranged from 65% to 79% for Cl-. The retention value, much lower than anticipated (95 %), indicates that there is progressive aging of the membranes and hydrolysis of cellulose acetate.