Formation of oxidation byproducts from ozonation of wastewater

Disinfection byproduct (DBP) formation in tertiary wastewater was examined after ozonation (O 3) and advanced oxidation with O 3 and hydrogen peroxide (O 3/H 2O 2). O 3 and O 3/H 2O 2 were applied at multiple dosages to investigate DBP formation during coliform disinfection and trace contaminant oxidation. Results showed O 3 provided superior disinfection of fecal and total coliforms compared to O 3/H 2O 2. Color, UV absorbance, and SUVA were reduced by O 3 and O 3/H 2O 2, offering wastewater utilities a few potential surrogates to monitor disinfection or trace contaminant oxidation. At equivalent O 3 dosages, O 3/H 2O 2 produced greater concentrations of assimilable organic carbon (5–52%), aldehydes (31–47%), and carboxylic acids (12–43%) compared to O 3 alone, indicating that organic DBP formation is largely dependent upon hydroxyl radical exposure. Bromate formation occurred when O 3 dosages exceeded the O 3 demand of the wastewater. Bench-scale tests with free chlorine showed O 3 is capable of reducing total organic halide (TOX) formation potential by at least 20%. In summary, O 3 provided superior disinfection compared to O 3/H 2O 2 while minimizing DBP concentrations. These are important considerations for water reuse, aquifer storage and recovery, and advanced wastewater treatment applications.