AWWA JAW57267

Researchers have recommended application of ozonation and biofiltration to aid coagulation in removing disinfection byproduct (DBP) precursors, but data on the efficacy of such combined processes have been limited. This study was conducted to investigate the effectiveness of combined processes, and variations on them, using a raw water with high alkalinity and low total organic carbon (TOC). The authors evaluated nine treatment simulations, all incorporating coagulation, ozonation, and biofiltration in the treatment train. Variations in the treatment trains studied included the point of ozonation with respect to coagulation, the ozone dosage required for various disinfection objectives, the pH of coagulation, ozonation, and biofiltration, and the type of biofiltration media. According to the data, the combination of ozonation, coagulation, and biofiltration proved successful in significantly reducing trihalomethane and haloacetic acid formation potential. The point of ozonation did not affect the overall treatment of water with low TOC and high alkalinity. In addition, study results supported previous work by showing the correlation between the reduction of DBP formation potential and the reduction of ultraviolet absorbance. These findings should help water utilities better understand how ozonation and biofiltration can be coupled with coagulation to comply with requirements of the Disinfectants/Disinfection Byproducts Rule. In addition to yielding a significant quantity of data, the work also provided a protocol for future research with similar objectives. This study is the first part of a larger project examining the effectiveness of coagulation, ozonation, and biofiltration using waters with different water quality characteristics. Includes 32 references, tables, figures.