Improving water quality for inland potable reuse via O3/biologically active filtration followed by UV/advanced oxidation

ABSTRACT Reverse osmosis (RO) prior to a UV-based advanced oxidation process (UV/AOP) is the center of what is known as the full advanced treatment train for potable reuse of wastewater effluent. This study investigated an alternative to RO via the use of ozone/biologically active filtration (O3/BAF) followed by UV/AOP for inland potable reuse, where RO-based processes may not be appropriate due to the challenges associated with brine disposal. This study followed the fate of eight chemical contaminants, chosen based on their physicochemical properties, through an advanced treatment train. Results showed that O3/BAF can effectively remove or degrade five of the contaminants by at least 95%, moderately effectively remove two of them (above 60%), but was ineffective against caffeine, removing less than 30%. UV/AOP using either hydrogen peroxide (H2O2) or hypochlorous acid (HOCl) as the radical promoter was examined as an additional treatment. Both radical promoters were effective for degrading the contaminants, degrading at least 50% of most contaminants. HOCl performed the same or better than H2O2 for all eight selected chemicals. Utilizing O3/BAF not only removed or degraded chemicals effectively, but also improved UV transmittance (UVT) for UV/AOP. Furthermore, despite the use of HOCl, disinfection by-product (DBP) formation was below regulated levels.