New insight into DOC and DON in a drinking water biological aerated filter (BAF) by multimethod and correlation analysis of 3D-EEM

Abstract

To get insight into the components and variations of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in a lab-scale drinking water biological aerated filter (BAF), the concentrations and three-dimensional excitation–emission matrix (3D-EEM) spectrum of DOC and DON were determined and analyzed; peak identification, fluorescence regional integration (FRI) analysis and a parallel factor (PARAFAC) model were applied to analyze the 3D-EEM spectrum. Fluorescent DOC in the BAF mainly existed in the form of humic acids and fulvic acids, and fluorescent DON mainly existed in tryptophan protein form. Protein-like substances accounted for more than 60% of fluorescent organic matter through FRI analysis. Tyrosine and tryptophan-like proteins, and fulvic acid-like substances were effectively removed through the BAF process, while humic acids remained almost unchanged. The results of peak identification, FRI analysis, and PARAFAC model were consistent with each other, especially for FRI and PARAFAC. It is manifest that the FRI technique and PARAFAC model are effective tools for 3D-EEM spectrum analysis. The FRI technique proved to be more suitable to characterize DOC and DON in this study than peak identification and the PARAFAC model.