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The effect of BTEX compounds on aerobic cometabolism of vinyl chloride by ethylene grown enrichment cultures

Conference ·
OSTI ID:416884
There is mounting field evidence that groundwater contaminated with trichloroethylene (TCE) and tetrachloroethylene (PCE) can be efficiently treated in situ by stimulating anaerobic reductive dechlorination, producing primarily ethylene and/or ethane. However, persistence of vinyl chloride (VC), even at low levels, may result in the need for subsequent aerobic treatment. A recent study by Freedman and Herz (1995) indicated that ethylene and ethane can serve as the primary substrates for aerobic cometabolism of VC, thereby avoiding the need to add an exogenous primary substrate. At many sites where PCE and TCE are found, other organic contaminants are also prevalent in mixtures. Chief among these are BTEX compounds (benzene (BEN), toluene (TOL), ethylbenzene (EBZ) and o-xylene (XYL)). Except for TOL, a limited amount of BTEX biodegradation is typically expected under anaerobic conditions, so most of the BTEX that occurs with PCE and TCE is likely to reach the aerobic zone along with VC, ethylene, and ethane. The objective of this study was to determine the effect of BTEX compounds on aerobic biodegradation of ethylene and VC. In an ethylene-grown enrichment culture, addition of BEN, EBZ, and TOL (6-59 mg/L) inhibited the initial rate of ethylene and VC biodegradation by 75% and 67%, respectively. The lower concentration of XYL added (0.80 mg/L) had a minor effect. As the rate of BEN, EBZ, and TOL biodegradation improved with time, no further inhibition of VC and ethylene consumption was observed. A population of BTEX degrading organisms developed in the ethylene-grown culture, but this did not result in a faster rate of VC or ethylene use. Separately developed BEN- and TOL-grown enrichment cultures confirmed this. Neither aromatic enrichment culture was able to biodegrade VC or ethylene, but both were able to consume all of the other aromatic compounds.
OSTI ID:
416884
Report Number(s):
CONF-951023--
Country of Publication:
United States
Language:
English