Year Established: 2013 Start Date: 2013-03-01 End Date: 2014-02-28
Total Federal Funds: $17,502 Total Non-Federal Funds: $35,003
Principal Investigators: Wen Zhang, Julian Fairey
Abstract: Drinking water treatment plants (DWTPs) in the United States are facing a great challenge to achieve compliance with the Stage 2 Disinfection/Disinfection Byproduct (DBP) rule. Two DWTPs in Arkansas - the Beaver Water District (Lowell, AR) and Central Arkansas Water (Little Rock, AR) are in the process of changing the primary disinfectant from free chlorine (HOCl/OCl-) to chlorine dioxide (ClO2) to curb formation of trihalomethanes (THMs) and haloacetic acids (HAAs). However, other DBPs are now being considered for regulation, including compounds within the highly toxic nitrosamine family, which can form in drinking waters in highest concentrations during chloramination. Due to the difference in hydrophobicity, precursor removal processes used to curb THM and HAA formation (e.g., enhanced coagulation) may be ineffective for removal nitrosamine precursors. Limited evidence has shown the impact of source water, treatment process (biofiltration) and chemical additives (coagulant aids) on nitrosamine formation. The objective of the proposed research project is to assess the relative contribution of the various nitrosamine precursors in drinking water systems. Total nitrosamine formation potential (TONOFP) with chloramines will be measured on a diverse group of drinking water sources, wastewater effluents, biofilms, and coagulant aids to determine the principal precursors of nitrosamines in DWTPs. TONO is measured by chemiluminescence following conversion of all nitrosamine species to nitrogen oxide. The source water selected for the experiments include raw water samples from the Beaver Water District (Lowell, AR), Mohawk Water Treatment Plant (Tulsa, OK) and A.B. Jewell Water Treatment Plant (Tulsa, OK), and wastewater effluent from West Side Wastewater Treatment Plant (Fayetteville, AR). Biofilter medium samples will be taken from these three DWTPs to assess the potential of biofilms as a source of precursors for nitrosamine formation. And lastly, one coagulant aid, polyDADMAC, will be evaluated with alum for TONOFP. By identifying the nitrosamine precursors, this project will advance the science of nitrosamine research and benefit the water utilities to curb DBP formation and make informed decisions regarding disinfection regimes.