title: Impact of VOC removal by activated carbon on biodegradation rates of diesel, Syntroleum and biodiesel in contaminated sand.
abstract: The degradation of conventional diesel (D), synthetic diesel (Syntroleum), and pure fish biodiesel (B100) by indigenous microbes was investigated in laboratory microcosms containing contaminated sand. The fate of volatiles and the influence of volatilization on degradation rates were examined by placing activated carbon (AC) in microcosm headspaces to sorb volatiles. Three AC regimes were compared: no activated carbon (NAC), regular weekly AC change (RAC), and frequent AC change (FAC), where the frequency of activated carbon exchange declined from daily to weekly. Generally, the alternative fuels were biodegraded faster than diesel fuel. Hydrocarbon mineralization percentages for the different fuel types over 28days were between 23% (D) and 48% (B100) in the absence of activated carbon, decreased to 12% (D) - 37% (B100) with weekly AC exchange, and were further reduced to 9-22% for more frequent AC change. Sorption of volatiles to AC lowered their availability as a substrate for microbes, reducing respiration. Volatilization was negligible for the biodiesel. A mass balance for the carbon initially present as hydrocarbons in microcosms with activated carbon in the head space was on average 92% closed, with 45-70% remaining in the soil after 4weeks, 9-37% mineralized and up to 12% volatilized. Based on nutrient consumption, up to 29% of the contaminants were likely converted into biomass.
authors.affiliation: Institute of Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman O. 15, Budapest 1022, Hungary; Civil and Environmental Engineering Department, Water and Environmental Research Center, University of Alaska Fairbanks, P.O. Box 755900, Fairbanks, AK 99775-5900, USA.
authors.forename: Agota
authors.initials: A
authors.lastname: Horel
authors.affiliation: Civil and Environmental Engineering Department, Water and Environmental Research Center, University of Alaska Fairbanks, P.O. Box 755900, Fairbanks, AK 99775-5900, USA. Electronic address: sschiewer@alaska.edu.
authors.forename: Silke
authors.initials: S
authors.lastname: Schiewer
mesh_terms: D001673:Biodegradation, Environmental; D056804:Biofuels / Q000032:analysis*; D018533:Biomass; D002245:Carbon Dioxide / Q000032:analysis; D002606:Charcoal / Q000737:chemistry*; D005742:Gasoline / Q000032:analysis*; D059013:Microbial Consortia; D008962:Models, Theoretical; D012989:Soil Pollutants / Q000032:analysis*; D055549:Volatile Organic Compounds / Q000032:analysis*; D014835:Volatilization
chemical_list: D056804:Biofuels; D005742:Gasoline; D012989:Soil Pollutants; D055549:Volatile Organic Compounds; D002245:Carbon Dioxide; D002606:Charcoal
keywords: Activated carbon; Biodegradation; Biodiesel; Degradation rates; Volatilization