ORIGINAL RESEARCH Evaluation of the biodegradability of fluorescent dissolved organic matter via biological filtration Melanie Vines | Leigh G. Terry Department of Civil, Construction, and Environmental Engineering, University of Alabama, Tuscaloosa, Alabama Correspondence Leigh G. Terry, Department of Civil, Construction, and Environmental Engineering, University of Alabama, Box 870205, Tuscaloosa, AL 35487, USA. Email: leigh.terry@ua.edu Funding information University of Alabama Office of Research and Economic Development Associate Editor: Graham A. Gagnon Abstract Fluorescence spectroscopy to evaluate the removal of dissolved organic matter (DOM) via biofiltration under varying operational and water quality conditions was investigated in this study. Three feedwaters (lake, river, and wastewater effluent) were examined at three temperatures (6, 22, and 28  C) and three empty bed contact times (EBCTs; 5, 15, and 30 min) to simulate seasonal and operational variations experienced by utilities. Parallel factor (PARAFAC) analy- sis was used to characterize the fluorescing DOM and to determine the compo- nent removal. Three components were found in the lake and river feedwaters, and four components were found in the wastewater effluent. In natural source waters, protein-like components were removed most effectively via biofiltration. In the wastewater effluent, a humic-like component common in nutrient-rich waters was removed most effectively, and the protein-like component was removed second most effectively. Increased EBCT and temperature increased the removal efficiency of bulk DOM and the protein-like components. KEYWORDS biofiltration, DOC, drinking water treatment, fluorescence spectroscopy, PARAFAC, TOC 1 | INTRODUCTION Natural organic matter (NOM) is found in virtually all sur- face waters and consists of a complex, heterogeneous mix- ture of compounds. NOM in surface waters can be categorized based on its origin as follows: (a) NOM derived in the watershed from vegetative debris and then trans- ported into the water body is often referred to as humic- like, terrestrial, or allochtonous material (Coble, 1996); (b) NOM derived from microbial processes within the water body is often referred to as protein-like, microbial, or autochtonous material (Coble, 1996); and (c) NOM derived from wastewater treatment plant effluent is referred to as effluent organic matter (EfOM) (Nam & Amy, 2008; Yang, Peleato, Legge, & Andrews, 2019) and can be synthetic organic chemicals from anthropogenic sources, recalcitrant NOM derived in the watershed, and soluble microbial products derived during wastewater treatment biological processes (Drewes & Fox, 1999). Dissolved organic matter (DOM), NOM that passes through a 0.45 μm filter (Zsolnay, 2003), is often a concern for drinking water treat- ment utilities as DOM can react with disinfectants (e.g., chlorine) in drinking water systems to form toxic dis- infection byproducts (DBPs), cause biological regrowth within the distribution system, or constitute a specific harmful or concerning pollutant (Terry & Summers, 2018). Biological regrowth within a system can lead to distribution pipe corrosion (Broo, Berghult, & Hedberg, 1999) and decrease the disinfectant residual throughout the distribu- tion system (Jacangelo, Demarco, Owen, & Randtke, 1995). Understanding the character of DOM is advantageous to understanding reactions occurring within the water treatment plant and the distribution system. DOM is often measured via bulk metrics such as dissolved organic Received: 9 June 2020 Revised: 4 August 2020 Accepted: 13 August 2020 DOI: 10.1002/aws2.1201 AWWA Wat Sci. 2020;e1201. wileyonlinelibrary.com/journal/aws © 2020 American Water Works Association 1 of 14 https://doi.org/10.1002/aws2.1201