Performance of selected anion exchange resins for the treatment of a high DOC content surface water

The objective of this study was first to compare the performance of four strong anion exchange resins (AERs) (MIEX® from Orica Pty Ltd, DOWEX-11® and DOWEX-MSA® from DOW chemical and IRA-938® from Rohm and Haas) for their application in drinking water treatment (natural organic matter (NOM), mineral anions (nitrate, sulfate and bromide) and pesticide removal) using bench-scale experimental procedures on a high DOC content surface water. The efficiency of MIEX® for NOM and mineral anions removal was furthermore evaluated using bench-scale dose-response experiments on raw, clarified and post-ozonated waters. NOM removal was assessed using the measurement of dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254) and the use of high-performance size exclusion chromatography with UV (HPSEC/UV) and fluorescence detection (HPSEC/FLUO). The MIEX® and IRA938® anionic resins exhibit a faster removal of NOM and mineral anions compared to the DOWEX11® and MSA® AERs. All the resins were found to be very effective with similar performances after 30 to 45 min of contact time. As expected, only limited sorption of atrazine and isoproturon (C0=1 μg/L) occurred with MIEX®, DOWEX11® and MSA® AERs. MIEX® resin proved to be very efficient in eliminating NOM of high-molecular weight but also a large part of the smallest UV absorbing organic compounds which were refractory to coagulation/flocculation treatment. Remaining DOC levels after 30 min of contact with MIEX® were found similar in raw water, clarified water and even post-ozonated water implying no DOC benefit can be gained by employing conventional treatment prior to MIEX® treatment. Removal of bromide (initial concentration 110 μg/L) was also observed and ranged from 30% to 65% for resin dose increasing from 2 to 8 mL/L.