Full-Scale Evaluation of In Situ Cometabolic Degradation of Trichloroethylene in Groundwater through Toluene Injection

Groundwater contaminated with 500−1200 μg/L trichloroethylene (TCE) was treated in situ over a 410-day period by cometabolic biodegradation through injection of 7−13.4 mg/L toluene, oxygen, and hydrogen peroxide in groundwater circulated between two contaminated aquifers through two treatment wells...

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Bibliographic Details
Published in:	Environmental science & technology Vol. 32; no. 1; pp. 88 - 100
Main Authors:	McCarty, Perry L, Goltz, Mark N, Hopkins, Gary D, Dolan, Mark E, Allan, Jason P, Kawakami, Brett T, Carrothers, T. J
Format:	Journal Article
Language:	English
Published:	Washington, DC American Chemical Society 01-01-1998
Subjects:	Applied sciences Aquifers Biodegradation Chemistry Chlorine compounds Contamination Earth sciences Earth, ocean, space Engineering and environment geology. Geothermics environmental degradation Exact sciences and technology Groundwater Groundwater pollution Groundwaters Hydrogen peroxide Isotopes natural resources Natural water pollution Oxygen Pollution Pollution, environment geology Toluene waste management water management water resources Water treatment and pollution Water wells Biodegradation Oxygen Decontamination Chlorine Organic compounds Toluene Water pollution Injection well Hydrogen Peroxides Ground water Ethylene(trichloro)
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Summary:	Groundwater contaminated with 500−1200 μg/L trichloroethylene (TCE) was treated in situ over a 410-day period by cometabolic biodegradation through injection of 7−13.4 mg/L toluene, oxygen, and hydrogen peroxide in groundwater circulated between two contaminated aquifers through two treatment wells located 10 m apart. One well pumped contaminated groundwater from the 8 m thick upper aquifer to the 5 m thick lower aquifer, while the other pumped contaminated water from the lower to the upper aquifers using flow rates of 25−38 L/min, effecting groundwater circulation between them. Following 18 days of periodic toluene injection to develop an active biological population, continuous pulses of toluene were added. Over 312 days, an average 87 ± 8% TCE removal was obtained in the upper aquifer with each pass through the treatment well. In the lower aquifer, removals were 83 ± 16% over the last 79 days when peroxide addition was reduced. Treatment reduced TCE in the regional groundwater plumes from about 1000 μg/L in new water entering the 480 m2 monitored treatment zone to an average of 18−24 μg/L in groundwater leaving the treatment zone, indicating total TCE removal of 97−98%. Pumping heads for groundwater recirculation were less than 6 m. Toluene was removed by 99.98% through biodegradation to an average of 1.1 ± 1.6 μg/L at the 22 m × 22 m boundaries of the study zone, well below the goal of 20 μg/L maximum.
Bibliography:	istex:BAF6C0C946393EAB4EDCFB0DFB41CF9094F392EF Abstract published in Advance ACS Abstracts, November 15, 1997. ark:/67375/TPS-C0LQLVPS-Z ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0013-936X 1520-5851
DOI:	10.1021/es970322b