Reverse osmosis may help blowdown reuse

Abstract

Three types of flat-sheet membranes, including cellulose acetate, aromatic polyamide and NS-100, were evaluated to determine their usefulness in treating cooling tower blowdown. Cellulose acetate and aromatic polyamide membranes, both of which are available commercially, performed satisfactorily for the removal of chemicals from the cooling tower blowdown. Results of this study show that reverse osmosis is a feasible means of treating blowdown for reuse as makeup water in a cooling tower. Although the newly developed NS-100 membrane had a generally satisfactory performance, its deterioration due to the reaction with oxidants, such as chromate etc. , limits its application for the reuse of blowdown. A proposed schematic flow diagram for the reverse osmosis treatment of cooling tower blowdown is also given.