Accession Number : ADA255696


Title :   Anaerobic Microbial Transformation of Aromatic Hydrocarbons and Mixtures of Aromatic Hydrocarbons and Halogenated Solvents


Descriptive Note : Final rept. 30 Sep 1988-31 Mar 1992


Corporate Author : STANFORD UNIV CA DEPT OF CIVIL ENGINEERING


Personal Author(s) : Edwards, Elizabeth A ; Liang, Li-Nuo ; Grbic-Galic, Dunia


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a255696.pdf


Report Date : 25 Aug 1992


Pagination or Media Count : 151


Abstract : Anaerobic microbial transformation of monoaromatic hydrocarbons (MAH) , chlorinated benzenes (CB), and mixtures of MAH and CB, as well as MAH and chlorinated aliphatic solvents (tetrachloroethylene -- PCE, and carbon tetrachloride -CT) was studied in laboratory microcosms derived from hydrocarbon-contaminated groundwater aquifers. Some MAH, such as toluene and o- xylene, were completely degraded to CO2 and CH4 by mixed methanogenic cultures from a creosote-contaminated aquifer. This degradation was inhibited by the addition of accessory electron acceptors (oxygen, nitrate, sulfate), indicating acclimation of the microbial community to methanogenic conditions. The addition of preferred substrates, such as acetate, propionate, methanol, fatty acids, glucose, casamino acids, pepton, yeast extract, or acetone also inhibited MAH degradation, indicating that the presence of natural organic substrates may preclude anaerobic biodegradation of MAH in situ. Cyclohexane, CT, and high concentrations of toluene and o-xylene had a toxic effect Under sulfate-reducing conditions, several MAH -toluene, all three xylene isomers, and benzene were mineralized to CO2, by microorganisms from a petroleum-contaminated, sulfidogenic aquifer. Whereas-toluene and xylenes were sequentially degraded in a mixture, benzene was degraded only if alone, or slowly transformed in a mixture with toluene. This explains previously reported recalcitrance of benzene under anaerobic conditions. Anaerobic Transformation, Monoaromatic Hydrocarbons, Chlorobenzenes, Carbon Tetrachloride, Tetrachloroethylene, Mixtures, Methanogenic, Sulfate-Reducing.


Descriptors :   *MIXTURES , *HYDROCARBONS , *SOLVENTS , *HALOGENATED HYDROCARBONS , *TRANSFORMATIONS , *MICROORGANISMS , *ANAEROBIC PROCESSES , BENZENE , COMMUNITIES , DEGRADATION , SUBSTRATES , CARBON , OXYGEN , ISOMERS , ELECTRONS , AQUIFERS , METHANOLS , XYLENES , YEASTS , LABORATORIES , CYCLOHEXANES , SULFATES , ELECTRON ACCEPTORS , OILS , ACETONES , CULTURE , ACETATES , GLUCOSE , ACIDS , NITRATES , CRUDE OIL , FATTY ACIDS , BIODETERIORATION , TOLUENES , ADDITION , CARBON TETRACHLORIDE , CREOSOTE , PEPTONES , PROPIONATES


Subject Categories : Biochemistry
      Microbiology
      Organic Chemistry


Distribution Statement : APPROVED FOR PUBLIC RELEASE