CHARACTER AND FATE OF ORGANIC MATTER IN DOMESTIC EFFLUENTS USED FOR INDIRECT POTABLE REUSE USING LC-OCD ANALYSIS

Residual organic carbon is of concern in indirect potable reuse systems. The objective of this study was to investigate the unidentified bulk of reclaimed water organics by applying state of the art characterization techniques. Methods such as fractionation of effluent organic matter (EfOM) onto XAD-resin in conjunction with solid-state 13C-nuclear magnetic resonance spectroscopy (13C-NMR) and size exclusion chromatography with online UV absorbance and organic carbon detection (LC-OCD) were employed. Drinking water samples and hydraulically corresponding reclaimed water samples prior to and after soil-aquifer treatment (SAT) from watersheds in Arizona and Texas were investigated. 13C-NMR spectra of drinking water and reclaimed water after SAT were similar indicating that structure and composition of corresponding isolates (XAD-8 and XAD-4) were dominated by natural organic matter (NOM) and compounds of similar structure. This approach was able to characterize approximately 70% of dissolved organic carbon. LC-OCD analysis allows to examine bulk water samples without sample preparation. This technique generates a continuous gel chromatographic distribution of organic matter. According to chromatograms of drinking water and reclaimed water after SAT samples, EfOM did not differ from drinking water NOM. These results verify the hypothesis that both EfOM and authochtonous NOM derive from the same microbiologic synthesis.