title: Biosurfactant-enhanced bioremediation of aged polycyclic aromatic hydrocarbons (PAHs) in creosote contaminated soil.
abstract: The potential for biological treatment of an environment contaminated by complex petrochemical contaminants was evaluated using creosote contaminated soil in ex situ bio-slurry reactors. The efficacy of biosurfactant application and stimulation of in situ biosurfactant production was investigated. The biosurfactant produced was purified and characterised using Fourier transform infrared (FTIR) spectroscopy. Biosurfactant enhanced degradation of PAHs was 86.5% (with addition of biosurfactant) and 57% in controls with no biosurfactant and nutrient amendments after incubation for 45 days. A slight decrease in degradation rate observed in the simultaneous biosurfactant and nutrient, NH4NO3 and KH2PO4, supplemented microcosm can be attributed to preferential microbial consumption of the biosurfactant supplemented. The overall removal of PAHs was determined to be mass transport limited since the dissolution rate caused by the biosurfactant enhanced the bioavailability of the PAHs to the microorganisms. The consortium culture was predominated by the aromatic ring-cleaving species Bacillus stratosphericus, Bacillus subtilis, Bacillus megaterium, and Pseudomonas aeruginosa.
authors.affiliation: Water Utilisation and Environmental Engineering Division, Department of Chemical Engineering, University of Pretoria, Pretoria 0002, South Africa.
authors.forename: Fisseha Andualem
authors.initials: FA
authors.lastname: Bezza
authors.affiliation: Water Utilisation and Environmental Engineering Division, Department of Chemical Engineering, University of Pretoria, Pretoria 0002, South Africa. Electronic address: Evans.Chirwa@up.ac.za.
authors.forename: Evans M Nkhalambayausi
authors.initials: EM
authors.lastname: Chirwa
mesh_terms: D001407:Bacillus / Q000254:growth & development / Q000378:metabolism; D001673:Biodegradation, Environmental; D001682:Biological Availability; D003407:Creosote / Q000032:analysis* / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D013501:Surface-Active Agents / Q000737:chemistry / Q000378:metabolism
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants; D013501:Surface-Active Agents; D003407:Creosote
keywords: Bio-slurry reactor; Biosurfactant; Creosote degradation; In situ biosurfactant production