Removing PAHs from urban runoff water by combining ozonation and carbon nano-onions.
Ozone (O3) is a chemical oxidant capable of transforming polycyclic aromatic hydrocarbons (PAHs) in urban runoff within minutes but complete oxidation to CO2 can take days to weeks. We developed and tested a flow-through system that used ozone to quickly transform PAHs in a runoff stream and then removed the ozone-transformed PAHs via adsorption to carbon nano-onions (CNOs). To quantify the efficacy of this approach, (14)C-labeled phenanthrene and benzo(a)pyrene, as well as a mixture of 16 unlabeled PAHs were used as test compounds. These PAHs were pumped from a reservoir into a flow-through reactor that continuously ozonated the solution. Outflow from the reactor then went to a chamber that contained CNOs to adsorb the ozone-transformed PAHs and allowed clean water to pass. By adding a microbial consortium to the CNOs following adsorption, we observed that bacteria were able to degrade the adsorbed products and release more soluble, biodegradable products back into solution. Control treatments confirmed that parent PAH structures (i.e., non-ozonated) were not biologically degraded following CNO adsorption and that O3-transformed PAHs were not released from the CNOs in the absence of bacteria. These results support the combined use of ozone, carbon nano-onions with subsequent biological degradation as a means of removing PAHs from urban runoff or a commercial waste stream.
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.
Chainarong
C
Sakulthaew
School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915, USA. Electronic address: scomfort1@unl.edu.
Steve D
SD
Comfort
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.
Chanat
C
Chokejaroenrat
Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-6105, USA. Electronic address: xli4@unl.edu.
Xu
X
Li
Department of Chemistry, Albion College, Albion, MI 49224, USA. Electronic address: charris@albion.edu.
Clifford E
CE
Harris
D000327:Adsorption; D001673:Biodegradation, Environmental; D002244:Carbon / Q000737:chemistry*; D037741:Fullerenes / Q000737:chemistry; D006108:Graphite / Q000737:chemistry; D059013:Microbial Consortia; D053758:Nanoparticles / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000737:chemistry; D013499:Surface Properties; D014507:Urbanization; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
D037741:Fullerenes; D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; D010126:Ozone; D002244:Carbon; D006108:Graphite
Bioremediation; Carbon nano-onions; Ozone; PAHs; Urban runoff