Identifying the factors that influence the reactivity of effluent organic matter with hydroxyl radicals.
Advanced oxidation processes (AOPs) are an effective treatment technology for the removal of a variety of organic pollutants in both water and wastewater treatment. However, many background constituents in water are highly reactive towards hydroxyl radicals (HO) and decrease the efficiency of the process towards contaminant oxidation. Up to 95% of the HO scavenging can come from dissolved organic matter (OM). In this study, 28 wastewater effluent samples were analyzed to find correlations between the reactivity of HO with wastewater-derived OM (known as effluent organic matter, EfOM), water quality parameters, treatment train characteristics, and fluorescence-derived data. Rate constants for the reaction between HO and EfOM (kEfOM-HO) were measured using a bench scale UV-based AOP system with methylene blue as an HO probe and confirmed using an electron pulse radiolysis method for a subset of the samples. The EfOM was characterized using a series of physicochemical parameters, including polarity, average molecular size and fluorescence. The kinetic data were analyzed with principal component analysis and Akaike Information Criterion. Four predictors were identified as dominant: chemical oxygen demand, retention onto NH2 extraction medium, fluorescence index, and total organic carbon. These four variables accounted for approximately 62% of the variability in the value of kEfOM-HO The average kEfOM-HO value for EfOM in this study was 2.5 × 10(8) MC(-1) s(-1), which is about 31% lower than the 3.6 × 10(8) MC(-1) s(-1) value determined for natural organic matter isolates and commonly used in AOP modeling.
Department of Civil and Environmental Engineering, University of North Carolina, 9201 University City Blvd., Charlotte, NC 28223, USA; Department of Civil, Environmental and Architectural Engineering, 428 UCB, University of Colorado at Boulder, Boulder, CO 80309, USA. Electronic address: okeen@uncc.edu.
Olya S
OS
Keen
Department of Chemistry and Biochemistry, California State University at Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840, USA.
Garrett
G
McKay
Department of Chemistry and Biochemistry, California State University at Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840, USA.
Stephen P
SP
Mezyk
Department of Civil, Environmental and Architectural Engineering, 428 UCB, University of Colorado at Boulder, Boulder, CO 80309, USA.
Karl G
KG
Linden
Department of Civil, Environmental and Architectural Engineering, 428 UCB, University of Colorado at Boulder, Boulder, CO 80309, USA.
Fernando L
FL
Rosario-Ortiz
D001673:Biodegradation, Environmental; D016166:Free Radical Scavengers / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D008962:Models, Theoretical; D009930:Organic Chemicals / Q000737:chemistry*; D025341:Principal Component Analysis; D011675:Pulse Radiolysis; D013997:Time Factors; D014481:United States; D014865:Waste Disposal, Fluid; D062065:Wastewater; D018508:Water Purification; D060753:Water Quality
D016166:Free Radical Scavengers; D017665:Hydroxyl Radical; D009930:Organic Chemicals; D062065:Wastewater
Advanced oxidation; Effluent organic matter; Hydroxyl radical; Wastewater treatment