Three-dimensional fluorescence or excitation-emission matrix (EEM) spectroscopy is a rapid and widely-used bulk characterization method applied to dissolved organic matter (DOM) from aquatic, atmospheric, and engineered wastewater systems impacting receiving environments. Our group critically evaluated EEM analysis tools of i) fluorescence regional integration (FRI), ii) peak picking of peaks A, C, T, and B assignments, iii) fluorescence indices and iv) parallel factor analysis (PARAFAC) to characterize leachable DOM from wastewater biosolids treated by waste stabilization techniques of lime treatment (LT), anaerobic digestion (AnD), and aerobic digestion (AeD) before agricultural land application. We found that different waste treatment technologies generated contrasting types of water-leachable DOM characterized by DOC, high-performance size exclusion chromatography (HP-SEC) and fluorescence spectroscopy. Biologically digested biosolids-DOM contained higher molecular weight DOM of 1360 Da and red-shifted fulvic-like and humic acid-like associated fluorophores (em: &gt;400 nm) attributable to significant molecular transformations during the sludge stabilization process. Fluorescence spectroscopy measured in DOM sampled across full-scale sludge treatment trains also confirmed development of uncharacterized fluorophore maxima. Although we found significant DOM transformations occurred due to treatment, the metrics of FRI, fluorescence indices, or peak identification previously defined for relative fluorophore maxima of aquatic DOM did not capture biosolids-DOM fluorophore maxima. From this analysis, we discuss strategies to interpret and define quantitative, boundary-based EEM methods for anthropogenic DOM of unique chemical compositions. PARAFAC was successfully applied to biosolid-DOM EEMs and three unique EEM-PARAFAC models of LT, AnD, or AeD stabilized DOM are also proposed.  The last part of this work will discuss the application of 3-D fluorescence spectroscopy to measure chemical interactions of variable biosolids-DOM pools with the emerging contaminants 2-4 dichlorophenol and triclocarban, also measured in solid residual leachates. Our goals are to (i) inform impact assessments of leachates and (ii) consider best practices for EEM analysis that are broadly applicable to DOM of contrasting, anthropogenic origins.

Challenges with traditional fluorescence quantitation metrics for anthropogenic DOM: Case for re-examining approaches and definitions on unique pools of leachable biosolids organic matter

2019 Fall National Meeting

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