Fluorescence properties of effluent organic matter and role of mineral adsorption in soil aquifer treatment

The objective of this research is to develop and apply fluorescence methods to characterize the properties of organic matter in drinking water, wastewater treatment plant effluent, and recharged groundwater. To complement ongoing mechanistic studies for major effluent organic matter (EOM) biodegraded during soil aquifer treatment (SAT), adsorption of EOM fractions on iron oxide was also studied.; A simple procedure was recommended to measure fluorescence for bulk water samples—pH = 3, dissolved organic carbon (DOC) = 1 mg/L, dilution with 0.01 M KCl, and 290nm cut-off—that minimizes the need to correct spectra for inner-filter absorbance effects and to avoid secondary order water scattering.; A quantitative method, fluorescence zone integration (FZI), was developed to analyze excitation-emission matrix (EEM) data. This method utilized all fluorescence data points and integrated fluorescence in each zone with similar organic compounds. FZI quantified substituted aromatic carbon and amino acids in major EOM fractions. A rank order from high to low in terms of unit total EEM integration (DT) was observed: hydrophobic neutrals (HPO-N) > hydrophobic acids (HPO-A) > hydrophobic bases (HPO-B) > hydrophilic acids (HPI-A) > hydrophilic neutrals (HPI-N).; The fluorescence techniques were applied to field and laboratory SAT systems and watershed study. Fluorescence analysis quantified a decrease of proteinaceous materials and the formation of soluble microbial products (SMPs) and humic substances for short-term SAT. Fluorescence complemented UVA254 by indicating the presence of waste origins present within the vicinity of SAT system and tracking the refractory drinking water DOM, which was not retained on the soil, but was present in the recharged effluent during SAT process.; Adsorptions of EOM fractions on iron oxide indicated that aromatic moieties were preferentially adsorbed. Only a fixed percentage (20 to 40%) of the neutrals and bases EOM fractions adsorbed regardless of iron oxide dose. These results were in accord with natural fractionation of EOM during the long-term SAT process.