Date of Graduation

8-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Civil Engineering

Advisor

Julian L. Fairey

Committee Member

Rodney D. Williams

Second Committee Member

Jamie A. Hestekin

Third Committee Member

David M. Miller

Keywords

Applied sciences, Asymmetric flow field-flow fractionation, Dissolved organic matter, Drinking water, Enhanced coagulation, Fluorescence parafac, Magnetic ion exchange resin, Trihalomethanes

Abstract

Methods were developed for application of asymmetric flow field-flow fractionation (AF4) and fluorescence parallel factor (PARAFAC) analysis to raw and treated samples from drinking water sources to improve characterizations of dissolved organic matter (DOM) and discover DOM properties correlated to disinfection byproduct (DBP) formation potential (FP). Raw water samples were collected from a reservoir, adjusted to pH 6, 7, and 8 and subjected to (1) jar tests using aluminum sulfate (alum) and (2) treatment with magnetic ion exchange (MIEX®) resin. Both treatments were followed by DBPFP tests at pH 7. AF4 was used to size DOM in raw and alum treated samples at pH 6 and 8. AF4 fractograms showed that DOM removal was more effective at pH 6 than at pH 8, and preferential removal of larger-sized DOM occurred at pH 6 but not at pH 8.

A fluorescence-PARAFAC model was constructed using excitation-emission matrices (EEMs) from all samples. A strong linear correlation (r2 = 0.87) between chloroform FP and a humic-like PARAFAC component (C1) was developed. This correlation was a significant improvement over the correlation (r2 = 0.03) between chloroform FP and specific ultraviolet absorbance at 254 nm (SUVA254), a DBPFP surrogate commonly used in drinking water treatment plants to optimize DOM removal processes. This indicated that chloroform FP-C1 correlations were not treatment-specific.

Alum coagulation at pH 6, 7, and 8 and DBPFP tests at pH 7 were performed on a set of raw waters from eleven drinking water treatment plants from across the United States. AF4 was used to size DOM before and after alum coagulation, and showed similar results to the earlier study, i.e., increased removal at pH 6 compared to pH 8. A fluorescence-PARAFAC model was constructed and total trihalomethane (TTHM) FP was strongly correlated (r2 = 0.91) to C1 for eight water sources. TTHMFP-SUVA254 correlations for ten locations were weak (r2 = 0.15), which indicated that C1 was an improved DBPFP surrogate relative to SUVA254 and could be used as a surrogate to select and optimize DBP precursor removal processes.

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