Biodegradation trichloroethylene

Little CD, AV Palumbo, SE Herbes, ME Lidstrom, RL Tyndall, PJ Gilmour (1988) Trichloroethylene biodegradation by a methane-oxidizing bacterium. Appl Environ Microbiol 54 951-956. 

The results of the EPA SITE demonstration also showed that the cost of methane necessary to support trichloroethylene biodegradation is not excessive in relation to the costs of other technologies available for the removal of trichloroethylene from water. Thus, the Biotrol system may prove to be a cost-effective alternative to more traditional groundwater remediation technologies. 

Typical precautions with trichloroethylene are summarized in Table 5.52. An important factor is that the vapours are much heavier than air they will therefore spread and may accumulate at low levels, particularly in undisturbed areas. Because of its volatility, releases to the environment usually reach the atmosphere. Here it reacts with hydroxyl or other radicals (estimated half-life for reaction with hydroxyl radicals is less than a week) and is not therefore expected to diffuse to the stratosphere to any significant extent. There is some evidence for both aerobic and anaerobic biodegradation of trichloroethylene. 

Since neither biodegradation nor hydrolysis occurs at a rapid rate, most trichloroethylene present in surface waters can be expected to volatilize into the atmosphere. However, because trichloroethylene is denser than and only moderately soluble in water, that which is not immediately volatilized may be expected to submerge and thus be removed from contact with the surface (Doust and Huang 1992). 

Aerobic biodegradation of trichloroethylene occurs by cometabolism with aromatie eompounds (Ensley 1991) and thus requires a cosubstrate such as phenol (Nelson et al. 1987, 1988) or toluene (Fan and Scow 1993). Trichloroethylene degradation by toluene-degrading baeteria has been demonstrated in the presence, but not absence, of toluene (Mu and Scow 1994). Isoprene, a structural analog of trichloroethylene, has also been used as a cosubstrate for triehloroethylene oxidation by some bacteria (Ewers et al. 1990). One source of inhibition of degradation in the absence of cosubstrate may be the toxieity of triehloroethylene itself to indigenous bacteria. 

Fan S, Scow KM. 1993. Biodegradation of trichloroethylene and toluene by indigenous microbial populations in soil. Appl Environ Microbiol 59 1911-1918. 

Mu DY, Scow KM. 1994. Effect of trichloroethylene (TCE) and toluene concentrations on TCE and toluene biodegradation and the population density of TCE and toluene degraders in soil. Appl Environ Microbiol 60 2661-2665. 

Nelson MJK, Montgomery SO, Mahaffey WR, et al. 1987. Biodegradation of trichloroethylene and involvement of an aromatic biodegradative pathway. Appl Environ Microbiol 53 949-954. 

Vanderberg LA, BL Burback, 11 Perry (1995) Biodegradation of trichloroethylene by Mycobacterium vaccae. Can J Microbiol 41 298-301. 

Rhee E, Speece RE. 1992. Maximal biodegradation rates of chloroform and trichloroethylene in anaerobic treatment. Water Sci Technol 25(3) 121-130... 

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,... 

Compound C is an additive designed to enhance the aerobic biodegradation of trichloroethylene (TCE). Compound C is a cometabolite, which allows TCE to be indirectly degraded in situ by... 

Jenal-Wanner, U., and P. L. McCarty, Development and evaluation of semi continuous slurry microcosms to simulate in situ biodegradation of trichloroethylene in contaminated aquifers , Environ. Sci. Technol., 31,2915-2922 (1997). 

Tsien, H.-C., Brusseau, G. A., Hanson, R. S. Wackett, L. P. (1989). Biodegradation of trichloroethylene by Methylosinus trichosporium OB3b. Applied and Environmental Microbiology, 55, 3155-61. 

The biodegradation of trichloroethylene is the most studied since this is probably the most widespread halogenated solvent contaminant. Several substrates drive ttichlorethylene co-oxidation, including methane, propane, propylene, toluene, isopropylbenzene, and ammonia (25). The enzymes that metabolize these substrates have subtly different selectivities with regard to the halogenated solvents, and to date none are capable of co-oxidizing carbon tetrachloride or tetrachloroethylene. Complete mineralization of these compounds can, however, be achieved by sequential anaerobic and aerobic process. Biorem edia tion. 

Bioremediation and thermal desorption are the most frequently selected innovative technologies for NPL sites with SVOCs, which are the second most common contaminants found at NPL sites. Also, SVE has been selected for some of the most volatile SVOCs (e.g., phenols and naphthalenes). Current research efforts are focused on biodegradation of chlorinated aliphatic hydrocarbons, such as trichloroethylene (TCE) and vinyl chloride, which occur at many sites. Thermal desorption most effectively treats PAHs and PCBs, and it may be particularly useful to pretreat organics prior to metal treatment. 

O Neill, W, Nzengung, V, Noakes, J., Bender, J., and Phillips, P., Biodegradation of tetrachloroehtylene and trichloroethylene using mixed-species microbial mats. In Wickramanayake, G.B., and Hinchee, R.E., editors. Bioremediation and Phytoremediation, Batelle, Columbus, WA, pp. 233-237, 1998. 

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