Application of chlorine dioxide (ClO2) to reverse osmosis (RO) membrane for seawater desalination

There are justifiable concerns about reverse osmosis (RO) performance deterioration and carcinogenic byproducts from disinfection in water treatment facilities. Traditional disinfectant chlorine (Cl-2) has been replaced with stable and safe disinfection processes. Chlorine dioxide (ClO2) as an alternative disinfectant has been increasingly adopted in various water treatment facilities. To identify the applicability of ClO2 to RO desalination process, lab-scale experiments were designed by simulating actual oxidant exposure circumstances. In the experiment, Cl-2 or ClO2 solution was injected separately into a working RO system. Our results showed that Cl-2 dosage greatly decreased permeate flux slope. However, instant flux increase of approximately 5% was observed when ClO2 was injected. ATR FT-IR and EDX analysis for exposed membranes showed that Cl-2 deformed amide peaks and attached Cl atom onto the membrane, indicating chlorination. However, none of these results was observed in ClO2 exposure cases. In addition, immediate sodium bisulfite application alleviated flux decrease under Cl-2 chlorination. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.