Formation of oxidation byproducts from ozonation of wastewater

Disinfection byproduct (DBP) formation in tertiary wastewater was examined after ozonation (O3) and advanced oxidation with O3 and hydrogen peroxide (O3/H2O2). O3 and O3/H2O2 were applied at multiple dosages to investigate DBP formation during coliform disinfection and trace contaminant oxidation. Results showed O3 provided superior disinfection of fecal and total coliforms compared to O3/H2O2. Color, UV absorbance, and SUVA were reduced by O3 and O3/H2O2, offering wastewater utilities a few potential surrogates to monitor disinfection or trace contaminant oxidation. At equivalent O3 dosages, O3/H2O2 produced greater concentrations of assimilable organic carbon (5–52%), aldehydes (31–47%), and carboxylic acids (12–43%) compared to O3 alone, indicating that organic DBP formation is largely dependent upon hydroxyl radical exposure. Bromate formation occurred when O3 dosages exceeded the O3 demand of the wastewater. Bench-scale tests with free chlorine showed O3 is capable of reducing total organic halide (TOX) formation potential by at least 20%. In summary, O3 provided superior disinfection compared to O3/H2O2 while minimizing DBP concentrations. These are important considerations for water reuse, aquifer storage and recovery, and advanced wastewater treatment applications.