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ABSTRACT: Due to industrial, agricultural, and defense operations, chlorinated solvents, and their natural transformation products, have been found in drinking water, wastewater, and ground water throughout the industrialized world [1]. Further, such compounds represent the most prevalent organic groundwater contaminants in the U.S. [2]. Because many are priority pollutants and/or suspected carcinogens or mutagens, the movement, transformation, and fate of these contaminants in the environment is of interest [3]. For these compounds, in situ bioremediation has the potential to substantially reduce cleanup duration and cost, when compared with traditional pump-and-treat technologies [4].
Environmental Progress 05/1998; 17(2):104 - 110. · 0.92 Impact Factor
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ABSTRACT: When injecting nutrients during active bioremediation, various nutrient addition strategies can be employed in order to remediate the site at minimal expense. In particular, if more than one nutrient is required, a pulse addition strategy can be devised in which these nutrients are added as temporally separated pulses such that the biostimulated portion of the flow field can be maximized. In this manuscript, results of numerical simulations are reported which demonstrate this effect. Previously published kinetic expressions describing microbial growth and carbon tetrachloride degradation under denitrifying conditions are used in these simulations. The simulations indicate that volumetric treatment can be accomplished by injecting long duration nutrient pulses of different nutrients that are separated by a long period where only unamended water is injected. This strategy will cause the nutrient pulses to overlap at a considerable distance from the injection point, while maintaining concentrations that are high enough to ensure significantbiomass growth and contaminant destruction.
Computational Geosciences 08/1997; 1(3):271-288. · 1.35 Impact Factor
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ABSTRACT: The effects of perchloroethylene (PCE) concentration in the range of 0–100 mg/L on methane and acetate production by a methanol-enriched
methanogenic consortia were investigated at 17°C. The results indicate that PCE is more inhibitory to methanogenesis than
to acetogenesis. At concentrations as low as 10 ppm, PCE affects the methanogenic activity of the consortium, and has completely
inhibited this activity at 100 ppm. Conversely, PCE does not begin to inhibit acetogenic activity until the concentration
is above 10 ppm, and has not completely inhibited it even at a PCE concentration of 100 ppm.
Applied Biochemistry and Biotechnology 01/1996; 57-58(1):915-922. · 1.94 Impact Factor
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ABSTRACT: The capability of the simple carbohydrate, glucose, to stimulate aerobic biodegradation of cis-dichloroethylene (cis-DCE) was tested using a river sediment. Greater reductions in cis-DCE were observed in aerobic microcosms incubated with glucose than in either killed controls, bottles incubated with oxygen and no glucose, or bottles containing glucose and no oxygen. Two aquifer sediments from different geographic locations also showed similar trends in dichloroethylene reduction. A sediment-free transfer culture from the original river sediment was further tested for cis-DCE degradation. Results indicate that cis-DCE losses coincide with an increase in chloride-ion concentration. The increase was equivalent to the amount of chloride that would be expected from the measured reduction in dichloroethylene and the release of two chlorides per cis-DCE. The possibility that methanotrophic or ammonia-oxidizing bacteria mediated dichloroethylene destruction was eliminated, because the sediment-free suspension culture showed no evidence of either activity. Hence, it appears that a new type of activity mediated the observed dichloroethylene transformation. The implications of these results on in situ bioremediation of chloroethylenes are discussed.
Water Research.
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ABSTRACT: Anaerobic microcosms of subsurface soils from three location were used to investigate the separate effects of several electron donors on tetrachloroethylene (PCE) dechlorination activity. The substrates tested were methanol, lactate, acetate and sucrose. Various levels of sulfate-reducing, acetogenic, fermentative, and methanogenic activity were observed in all sediments. PCE dechlorination was detected in all microcosms, but the amount of dehalogenation varied by several orders of magnitude. Trichloroethylene as the primary dehalogenation product; however, small amounts of cis-1,2-dichloroethylene, 1,1-dichloroethylene, and vinyl chloride were also detected in several microcosms. Lactate-amended microcosms showed large amounts of dehalogenation in two of the three sediments. One of the two sediments which showed positive activity with lactate also had large amounts of dehalogenation with methanol. Amendment with formate, acetate, or sucrose resulted in only slight dehalogenation in the three sediments. Elevated levels of dehalogenation were not consistently associated with any observable anaerobic metabolisms (sulfate reduction, acetogenesis, fermentation, or methanogensis).
Water Research.
