title: Reactivity of effluent organic matter (EfOM) with hydroxyl radical as a function of molecular weight.
abstract: The application of advanced oxidation processes (AOPs) for the treatment of wastewater is hindered by scavenging of the hydroxyl radical (HO*) by effluent organic matter (EfOM). This scavenging is directly proportional to the second-order reaction rate constant between EfOM and HO* (kEfOM-HO*). To understand the kinetics of this reaction as a function of the subcomponents of EfOM, four wastewater samples were fractionated by ultrafiltration into distinct apparent molecular weight (AMW) fractions (<1, <3, <5, and <10 kDa), and their kEfOM-HO* values were quantified. In general, the values for k(EfOM-HO*) decreased as the AMW increased. The values of k(EfOM-HO*) for the bulk waters varied between 6.32 and 14.1x10(8) MC(-1)s(-1) (units of per molar carbon concentration per second). In the case of the <1 kDa fraction, the values of kEfOM-HO* varied from 14.3 to 35.0x10(8) MC(-1)s(-1), or approximately 2.31(+/-0.24) times that of the corresponding bulk waters. For the <3 kDa, <5 kDa, and <10 kDa fractions, the k(EfOM-HO*) values were 1.83(+/-0.25), 1.32(+/-0.23), and 1.26(+/-0.35) times that of the bulk waters, respectively. Based on the obtained results, the variability and general magnitude of the kEfOM-HO* values were attributed to the production and reactivity of soluble microbial products (SMP), a major component of EfOM. Two samples collected at a wastewater treatment facility with different treatment variables had different kEfOM-HO* values, indicating that wastewater treatment processes will impact overall HO* scavenging by EfOM and should be considered during the implementation of AOPs.
authors.affiliation: Department of Civil, Environmental and Architectural Engineering, 428 UCB, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Mei Mei
authors.initials: MM
authors.lastname: Dong
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Mezyk
authors.forename: Fernando L
authors.initials: FL
authors.lastname: Rosario-Ortiz
mesh_terms: D005591:Chemical Fractionation; D017665:Hydroxyl Radical / Q000737:chemistry*; D008970:Molecular Weight; D009930:Organic Chemicals / Q000737:chemistry*; D010084:Oxidation-Reduction; D052638:Particulate Matter / Q000737:chemistry*; D014462:Ultrafiltration; D014865:Waste Disposal, Fluid / Q000379:methods; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D009930:Organic Chemicals; D052638:Particulate Matter; D014874:Water Pollutants, Chemical; D014867:Water; D017665:Hydroxyl Radical