Chemical disinfection is the cornerstone of safe drinking water. However, the use of chemical disinfection results in the unintentional formation of disinfection by-products (DBPs), an outcome of reactions between the disinfectant and natural organic matter (NOM) present in the native (raw) water. DBPs are suspected carcinogens, and as such, have been regulated by the U.S. Environmental Protection Agency (USEPA) under the Safe Drinking Water Act (SDWA). This document reports the results of a study that investigated the use of chlorine dioxide pre-oxidation for the reduction of DBP precursors, and subsequently, DBP formation potential (FP). To determine the effectiveness of the chlorine dioxide pre-oxidation process, two surface waters were studied: raw water from Lake Claire (Orlando, FL) and raw water from the East Maui Watershed (Makawao, HI). Lake Claire water contains approximately 11-12 mg/L of NOM and 35 mg/L as CaCO3 of alkalinity, while the Maui source water typically ranges between 7-8 mg/L of NOM with 2-10 mg/L as CaCO3 of alkalinity. Two chlorine dioxide doses were investigated (0.75 mg/L and 1.5 mg/L) and compared to a control to quantify the effectiveness of this advanced pre-treatment oxidation process. Water collected at each site was subject to the following treatment process: oxidation, coagulation, flocculation, sedimentation, ultrafiltration, and disinfection with free chlorine. Disinfection by-product formation potential (DBPFP) analysis showed that ClO2 pre-oxidation, in general, increased the 7-day DBPFP of the East Maui water, and decreased the 7-day DBPFP of the Lake Claire source water. For the Lake Claire water at the higher ClO2 dose, total trihalomethanes (TTHM) were decreased by 37 percent and the five regulated haloacetic acids (HAA5) by 23 percent. For the East Maui source water at the higher ClO2 dose, TTHM’s were increased by 53 percent and HAA5’s by 60 percent. Future research should determine the effect of alkalinity on DBPFP, which could be the reason why chlorine dioxide pre-oxidation caused one water source’s DBPFP to decrease and the other to increase.
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Duranceau, Steven J.
Bachelor of Science in Environmental Engineering (B.S.Env.E.)
College of Engineering and Computer Science
Civil, Environmental, and Construction Engineering
Dissertations, Academic -- Engineering and Computer Science; Engineering and Computer Science -- Dissertations, Academic
Length of Campus-only Access
Honors in the Major Thesis
Rodriguez, Angela, "A Laboratory Scale Assessment of the Effect of Chlorine Dioxide Pre-Oxidation on Disinfection By-Product Formation for Two Surface Water Supplies" (2015). HIM 1990-2015. 1739.