| The impact of pre-oxidation and subsequent chlorination, as well as pre-oxidation in combination with alum coagulation, intermediate oxidation, and filtration on the formation and speciation of subsequent chlorination disinfection by-products in the San Francisco Bay delta water was examined. Bench scale experiments designed to enhance DBP formation were conducted on two delta waters, and it was found that pre-oxidation with ozone and chlorine dioxide may have the potential to reduce subsequent chlorination DBP formation. Treatment processes representative of current Bay utilities were conducted at bench scale on one delta water. Bromide was spiked to represent extreme salt water intrusion. Chlorine dioxide had a limited impact on DBP formation. Ozone was most effective for controlling THM formation, however it resulted in higher HAA formation when compared to no pre-oxidation. However, elevated levels of bromate and bromine-containing DBPs are a concern when treating waters with high ambient bromide levels. |
