Ozone-biological activated carbon as a pretreatment process for reverse osmosis brine treatment and recovery

Ozonation was used in this study to improve biodegradability of RO brine from water reclamation facilities. An ozone dosage ranging from 3 to 10 mg O3/L and contact times of 10 and 20 min in batch studies were found to increase the biodegradability (BOD5/TOC ratio) of the RO brine by 1.8–3.5 times. At the same time, total organic carbon (TOC) removal was in the range of 5.3–24.5%. The lab-scale ozone-biological activated carbon (BAC) at an ozone dosage of 6.0 mg O3/L with 20-min contact time was able to achieve 3 times higher TOC removal compared to using BAC alone. Further processing with Capacitive Deionization (CDI) process was able to generate a product water with better water quality than the RO feed water, i.e., with more than 80% ions removal and a lower TOC concentration. The ozone-BAC pretreatment has the potential of reducing fouling in the CDI process.