title: A combined chemical and biological approach to transforming and mineralizing PAHs in runoff water.
abstract: The water quality of lakes, rivers and streams associated with metropolitan areas is declining from increased inputs of urban runoff that contain polycyclic aromatic hydrocarbons (PAHs). Our objective was to transform and mineralize PAHs in runoff using a combined chemical and biological approach. Using (14)C-labeled phenanthrene, (14)C-benzo(a)pyrene and a mixture of 16 PAHs, we found that ozone transformed all PAHs in a H2O matrix within minutes but complete mineralization to CO2 took several weeks. When urban runoff water (7.6 mg CL(-1)) replaced H2O as the background matrix, some delays in degradation rates were observed but transforming a mixture of PAHs was still complete within 10 min. Comparing the biodegradability of the ozonated products to the parent structures in unsaturated soil microcosms showed that the 3-ring phenanthrene was more biodegradable (as evidence by (14)CO2 released) than its ozonated products but for the 5-ring benzo(a)pyrene, the products produced by ozone were much more biodegradable (22% vs. 3% mineralized). For phenanthrene, we identified diphenaldehyde as the initial degradation product produced from ozonation. By continuing to pump the ozonated products ((14)C-labeled diphenaldehyde or ozone-treated benzo(a)pyrene) onto glass beads coated with microorganisms, we verified that biological mineralization could be achieved in a flow-through system and mineralization rates improved with acclimation of the microbial population (i.e., time and exposure to the substrate). These results support a combined ozone and biological approach to treating PAHs in urban runoff water.
authors.affiliation: School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915, USA; Department of Veterinary Technology, Faculty of Veterinary Technology, Kasetsart University, Bangkok 10900, Thailand. Electronic address: cvtcns@ku.ac.th.
authors.forename: Chainarong
authors.initials: C
authors.lastname: Sakulthaew
authors.affiliation: School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915, USA. Electronic address: scomfort1@unl.edu.
authors.forename: Steve
authors.initials: S
authors.lastname: Comfort
authors.affiliation: Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-6105, USA; School of Environmental Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand. Electronic address: chanat@sut.ac.th.
authors.forename: Chanat
authors.initials: C
authors.lastname: Chokejaroenrat
authors.affiliation: Department of Chemistry, Albion College, Albion, MI 49224, USA. Electronic address: charris@albion.edu.
authors.forename: Clifford
authors.initials: C
authors.lastname: Harris
authors.affiliation: Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-6105, USA. Electronic address: xli4@unl.edu.
authors.forename: Xu
authors.initials: X
authors.lastname: Li
mesh_terms: D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D005618:Fresh Water / Q000032:analysis / Q000382:microbiology; D010126:Ozone / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D014507:Urbanization; D062065:Wastewater / Q000737:chemistry* / Q000382:microbiology; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D060753:Water Quality
chemical_list: D010126:Ozone; D011084:Polycyclic Aromatic Hydrocarbons; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Benzo(a)pyrene; Bioremediation; Ozone; PAHs; Phenanthrene