Optimizing BTEX biodegradation under denitrifying conditions
Leaking underground storage tanks are a major source of ground water contamination by petroleum hydrocarbons. Gasoline and other fuels contain benzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX), which are hazardous compounds, regulated by the U.S. Environmental Protection Agency (EPA). Laboratory tests were conducted to determine optimum conditions for benzene, toluene, ethylbenzene, and xylene (collectively known as BTEX) biodegradation by aquifer microorganisms under denitrifying conditions. Microcosms, constructed with aquifer samples from Traverse City, Michigan, were amended with selected concentrations of nutrients and one or more hydrocarbons. Toluene, ethylbenzene, m-xylene, and p-xylene, were degraded to below 5 micrograms/L when present as sole source substrates; stoichiometric calculations indicated that nitrate removal was sufficient to account for 70 to 80% of the compounds being mineralized. o-Xylene was recalcitrant when present as a sole source substrate, but was slowly degraded in the presence of the other hydrocarbons. Benzene was not degraded within one year, regardless of whether it was available as a sole source substrate or in combination with toluene, phenol, or catechol. Pre-exposure to low levels of BTEX and nutrients had variable effects, as did the addition of different concentrations of ammonia and phosphate. Nitrate concentrations as high as 500 mg/L NO3-N were slightly inhibitory. These data indicate that nitrate-mediated biodegradation of BTEX at Traverse City can occur under a variety of environmental conditions with rates relatively independent of nutrient concentrations. However, the data reaffirm that benzene is recalcitrant under strictly anaerobic conditions in these samples.
- Research Organization:
- Environmental Protection Agency, Ada, OK (United States). Robert S. Kerr Environmental Research Lab.
- OSTI ID:
- 5927857
- Report Number(s):
- PB-92-124262/XAB
- Resource Relation:
- Other Information: Pub. in Environmental Toxicology and Chemistry, v10 p1437-144, 1991
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BENZENE
BIODEGRADATION
GROUND WATER
CONTAMINATION
MICHIGAN
WATER POLLUTION
PETROLEUM
UNDERGROUND STORAGE
TOLUENE
XYLENES
AQUIFERS
DENITRIFICATION
ENVIRONMENTAL TRANSPORT
LEAKS
MICROORGANISMS
PETROLEUM PRODUCTS
REMEDIAL ACTION
ALKYLATED AROMATICS
AROMATICS
CHEMICAL REACTIONS
DECOMPOSITION
DEVELOPED COUNTRIES
ENERGY SOURCES
FEDERAL REGION V
FOSSIL FUELS
FUELS
HYDROCARBONS
HYDROGEN COMPOUNDS
MASS TRANSFER
NORTH AMERICA
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
POLLUTION
STORAGE
USA
WATER
020900* - Petroleum- Environmental Aspects
540350 - Environment
Aquatic- Site Resource & Use Studies- (1990-)
560300 - Chemicals Metabolism & Toxicology