Reverse Osmosis Brine from Water Reclamation Plant – Cost Effective Process for Treatment and Recovery

The NEWater production in Singapore generates a reverse osmosis (RO) brine with more than 20% of the feed flow, which is a potential untapped source of water. A Capacitive Deionization (CDI) and an integrated pre-treatment process comprised of biological activated carbon (BAC) with an optional second step of ultrafiltration (UF) used in this study were able to provide 80% water recovery from the RO brine. Integrating the RO brine recovery to the NEWater production could potentially achieve more than 95% total water recovery for the NEWater factory. The fouling rate on CDI was relatively lower using UF effluent as compared with BAC-UF effluent. The combined BAC-UF-CDI process was able to provide more than 85% TDS removal. The total organic carbon (TOC) concentration was comparable to the RO feed water while lower cationic and anionic concentrations were achieved. The RO brine treatment process power consumption is estimated at 0.85 kWh/m3.