UCLA

Hydrophobic organic pollutants (HOPs), such as polyaromatic hydrocarbons primarily from automobile exhausts and dissolved organic matter (DOM) are ubiquitous in the aquatic environment. The association between DOM and HOPs as a bound interaction of DOM-HOPs minimizes the bioavailability of free HOPs and their potential health effects. In addition, DOM is also the precursor of disinfection by-products involving the disinfection treatment processes.

It is very important to understand the relationship between free and bound HOPs, disinfection by-products, and DOM in drinking water treatment, stormwater runoff and dry weather flow of aquatic environment. This thesis will explore the binding phenomenon between HOPs and DOM in raw and treated water from water treatment plants, after powdered activated carbon treatment, and in stormwater runoff and dry weather flow.

This thesis also introduced the analytical methodologies for characterizing DOM and the hazardous potential of HOPs and thus understanding their relationship. DOM characteristics were measured for: 1) total concentration of organic carbon by dissolved organic carbon (DOC), 2) aromaticity by UV absorbance and specific UV absorbance (SUVA), and 3) size distribution by ultrafiltration (UF), 4) polarity by polarity rapid assessment method (PRAM), 5) UV and fluorescent chemical components by UV spectrometer and fluorescence excitation-emission matrix (EEM) and fluorescence regional integration (FRI). Hazardous potential of HOPs was measured by fluorescence quenching determined partition coefficient KDOM.

Studies have been completed and showed that monitoring both the free and bound forms of HOPs as well as disinfection by-products (such as, trihalomethanes) and their relationship to DOM during drinking water treatment processes is necessary to better understand drinking water quality and give more effective suggestions to optimize treatment processes. In addition, this work showed the relationship between DOM and HOPs in equilibrium with DOM-HOPs needs definition on a seasonal basis to understand the bioavailability of HOPs in dry weather flow and stormwater runoff events. The determination of free and total HOPs has not been considered in the California "State Implementation Plan" for water quality-based effluent limits of HOPs. A method using a standard probe- perylene has been developed to be able to evaluate these situations on a site specific basis since DOM is site specific.

Key findings of this study were: 1) DOM characteristics are different from site to site and affect pollutants removal and formation. 2) Bulk SUVA shows a positive correlation with Log KDOM (R2=74%). Thus, DOM with more aromatic structure can result in higher binding between HOPs and DOM. 3) DOM with higher concentration, aromaticity, and molecular weight can have more ability to form THMs. 4) Under the conditions studied, PAC (20 mg/L) is an effective method to control both THMs and the hazard potential of HOPs. 5) DOM in urban runoff with higher molecular weight and aromaticity can associate with more HOPs. As a result, the distribution of HOPs affected by DOM in urban runoff needs definition on a seasonal basis and runoff types.