DOM removal by flocculation process: Fluorescence excitation–emission matrix spectroscopy (EEMs) characterization

Abstract

DOM is often utilized as a control parameter in the design of water treatment process as well as others such as water treatment efficiency and formation of disinfection byproducts (DBPs), of which removal and characterization have received wide attention. Fluorescence excitation–emission matrix spectroscopy (EEMs) for DOM characterization in flocculation process at present is not well known. It is for this reason that the EEMs in this study was employed to characterize the Missouri River DOM removal by the flocculation process. The results showed that four underlying components extracted from the EEMs of DOM by parallel factor (PARAFAC) were humic acid-like (A), fulvic acid-like (B), protein-like (C) and unidentified component (D), while the Missouri River DOM was dominated by A, B and C. Flocculation was effective for the hydrophobic organic compound A followed by the hydrophilic organic compounds B and C, whereas the smallest molecular size compound C was hard to treat. Further study illustrated that for flocculation at pH 7, higher DOC and THM removal efficiencies were obtained, and that the correlations of DOM components with DOC and THM removal efficiencies were significant, thus indicating that the EEMs-PARAFAC offers a robust analytical method for assessing DOM removal efficiency in the flocculation process.