Trichloroethane biodegradation

In a model aquatic ecosystem, methoxychlor degraded to ethanol, dihydroxy ethane, dihy-droxyethylene, and unidentified polar metabolites (Metcalf et al, 1971). Kapoor et al. (1970) also studied the biodegradation of methoxychlor in a model ecosystem containing snails, plankton, mosquito larvae, Daphnia magna, and mosquito fish Gambusia affinis). The following metabolites were identified 2-(/5-methoxyphenyl)-2-(p-hydroxyphenyl)-l,l,l-trichloroethane, 2,2-bis (p-hydroxyphenyl) -1,1,1 -trichloroethane, 2,2-bis (p-hydroxyphenyl) -1,1,1 -trichloroethylene,... 

Biological. Vinyl chloride was reported to be a biodegradation product from an anaerobic digester at a wastewater treatment facility (Howard, 1990). Under aerobic conditions. Pseudomonas putida oxidized 1,1,2-trichloroethane to chloroacetic and glyoxylic acids. Simultaneously, 1,1,2-trichloroethane is reduced to vinyl chloride exclusively (Castro and Belser,... 

In a static-culture-flask screening test, 1,1,2-trichloroethane was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum. Biodegradative activity was slow to moderate, concomitant with a significant rate of volatilization (Tabak et al., 1981). 

Hydrolysis can explain the attenuation of contaminant plumes in aquifers where the ratio of rate constant to flow rate is sufficiently high. Thus 1,1,1-trichloroethane (TCA) has been observed to disappear from a mixed halocarbon plume over time, while trichlo-roethene and its biodegradation product 1,2-dichloroethene persist. The hydrolytic loss of organophosphate pesticides in sea water, as determined from both laboratory and field studies, suggests that these compounds will not be long-term contaminants despite runoff into streams and, eventually, the sea (Cotham and Bidleman, 1989). The oceans also can provide a major sink for atmospheric species ranging from carbon tetrachloride to methyl bromide. Loss of methyl bromide in the oceans by a combination of hydrolysis... 

Hydrolysis k = 1.2 M-1 s 1 for reaction at pH 7 and 25°C (Mabey et al. 1983 quoted, Howard et al. 1991) k = 4320 M-1 h-1 for base reaction at pH 9 and 25°C (Mabey et al. 1983 quoted, Howard et al. 1991) abiotic hydrolysis or dehydrohalogenation t,/2 = 384 months (Mabey et al. 1983 quoted, Olsen Davis 1990). Biodegradation aqueous aerobic t,/2 = 672-4320 h, based on acclimated river die-away rate data for 1,1,2,2-tetrachloroethane (Mudder 1981 quoted, Howard et al. 1991), unacclimated seawater (Pearson McConnell 1975 quoted, Howard et al. 1991) and sub-soil grab sample data for a ground water aquifer for 1,1,1-trichloroethane (Wilson et al. 1983 quoted, Howard et al. 1991) aqueous anaerobic t,/2 = 2688-17280 h, based on aerobic biodegradation half-life (Howard et al. 1991). 

Once released to surface water, 1,1,1-trichloroethane is expected to undergo volatilization to the atmosphere. Neither adsorption to sediment nor bioconcentration in aquatic organisms is recognized as an important removal process. Aerobic biodegradation of 1,1,1-trichloroethane can occur in the presence of methane-oxidizing bacteria. If released to groundwater, biodegradation of... 

Most of the released 1,1,2,2-tetrachloroethane enters the atmosphere where it is extremely stable (half-life > 2 years). Some of the chemicals will eventually diffuse into the stratosphere where it will rapidly photodegrade. There is evidence that 1,1,2,2-tetrachloroethane slowly biodegrades. A product of biodegradation under anaerobic conditions is 1,1,2-trichloroethane, a chemical which is resistant to further biodegradation. Under alkaline conditions, 1,1,2,2-tetrachloroethane may be expected to hydrolyze. When disposed of on soil, part of the 1,1,2,2-tetrachloroethane may leach... 

Trichloroethane will enter the atmosphere from its use in the manufacture of vinylidene chloride and its use as a solvent. Once in the atmosphere, 1,1,2-trichloroethane will photodegrade slowly by reaction with hydroxyl radicals (half-life 24 to 50 days in unpolluted atmospheres and within a few days in polluted atmospheres). The soil partition coefficient of 1,2-trichloroethane is low and it will readily leach in the case of eventual, very slow biodegradation. Bioconcentration is not a significant process. It will also be discharged in wastewater associated with these uses and in... 

ORIGIN/INDUSTRY SOURCES/USES not a natural product formed by the anaerobic biodegradation of trichloroethylene and by the hydrolysis of 1,1,1-trichloroethane manufacturer of polyvinylidene copolymers and methyl chloroform flexible films for food packing (Saran and Velon wraps) flame retardant coatings for fiber and carpet backing in pipes coating for steel pipes adhesive applications... 

BIOLOGICAL PROPERTIES slowly biodegrades some biodegradation when evaporation is very slow and the body of water is rich in microorganisms (i.e. eutropic lake) 1,1,1-trichloroethane is a product of biodegradation under anaerobic conditions the log of the BCF in fish is 0.9-1 slightly enduring in water, half-life 2-20 days aerobic half-life 4 weeks-6 months anaerobic half-life 7 days-4 weeks T.O.C. in water 0.5 ppm... 

Trichloroethane has been shown to be formed during the anaerobic biodegradation of... 

No information on the release of 1,1,2-trichloroethane to soil was found in the available literature. It is anticipated that process residues and sludge containing this chemical may be landfilled (Jackson et al. 1984). In an experiment designed to simulate the anaerobic conditions for biodegradation in landfills, 1,1,2-trichloroethane was found to be a biodegradation product of 1,1,2,2-tetrachloroethane (Hallen et al. 1986). Therefore 1,1,2-trichloroethane may be produced in landfills or other anaerobic environments (e.g. groundwater) that have been contaminated with 1,1,2,2-tetrachloroethane. 

In an attempt to simulate the anaerobic conditions for biodegradation in landfills, experiments were performed under anoxic conditions using inocula from anaerobic digester units of wastewater treatment facilities that were not acclimated to industrial solvents. After 1 week of incubation with 10 jg/L of 1,1,2-trichloroethane, 0.44 pg/g of vinyl chloride was formed, the highest level observed from any of the chlorinated ethanes or ethenes studied (Hallen et al. 1986). In further experiments when the concentration of inoculum was increased, 4.3 and 5.8 pg/g of vinyl chloride was formed after 1 and 2 weeks, respectively. The degradation reactions observed not only include reductive dehalogenation but the transformation of chlorinated ethanes into ethenes. It is interesting to note... 

Environmental Fate. Further investigation would resolve the discrepancies in the data for anaerobic degradation of 1,1,2-trichloroethane. Additional studies are needed to characterize the nature of the transformation and to clarify whether biotic, abiotic, or catalyzed abiotic reactions are involved. Will these reactions generally occur under environmental conditions A determination of the half-life in representative groundwater and sediment-water systems would be useful. From the available evidence, biodegradation in aerobic systems appears unlikely, although additional studies, particulary in soil, are desireable and would clarify this point. 

In another invention, a modifier is introduced to increase the adhesion of asphalt/wa-ter emulsions to aggregates. Emulsified asphalt is not so deleterious to the environment but its performance suffers from aggregate delamination. In yet another recent invention, terpene solvent, which is a naturally occurring (but never in this high concentration), biodegradable material, was used to replace the mineral spirits, xylene, trichloroethane, toluene, or methyl ethyl ketone normally used in cutback formulations (cutback asphalt is a dispersion of asphalt in a suitable solvent to reduce viscosity and allow for cold application). The two other patents discuss inventions leading to an improvement of high and low temperature properties of asphalt with no special impact on reduction of solvents used. 

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