Biodegradation of vinyl chloride

Danko AS, M Luo, CE Bagwell, RL Brigmon, DL Freedman (2004) Involvement of linear plasmids in aerobic biodegradation of vinyl chloride. Appl Environ Microbiol 70 6092-6097. 

Barrio-Lage, G.A., Parsons, F.Z., Narbaitz, R.M., Lorenzo, P.A., and Archer, H.E. Enhanced anaerobic biodegradation of vinyl chloride in gronnd water. Environ. Toxicol. Chem., 9(4) 403-415, 1990. 

Bradley, P.M. and Chapelle, F.H. Role for acetotrophic methanogens in methanogenic biodegradation of vinyl chloride. Environ. ScL TechnoL, 33(9) 3473-3476, 1999. 

Davis, J.W. and Carpenter, C.L. Aerobic biodegradation of vinyl chloride in gronndwater samples, Appl Environ. Microbiol, 56 (12) 3878-3880, 1990. 

Ground water t,/2 = 1344-69000 h, based on estimated unacclimated aqueous aerobic biodegradation half-life (Howard et al. 1991) and an estimated half-life for anaerobic biodegradation of vinyl chloride from a ground water field study of chlorinated ethenes (Silka Wallen 1988 quoted, Howard et al. 1991). 

Bradley PM, Chapelle FH, Wilson JT (1998) Field and laboratory evidence for intrinsic biodegradation of vinyl chloride contamination in a Fe(III)-reducing aquifer. J Contam Hydrol 31 111-127... 

FIGURE 14.2 Aerobic biodegradation of vinyl chloride (modified from KieUiom, 2000). 

For many years, the only established mechanism for biodegradation of vinyl chloride was reductive dechlorination to ethylene and ethane. The rate of reductive dechlorination of vinyl chloride is slower than that of dichloroethylene therefore vinyl chloride should be expected to accumulate in ground water plumes (2). Contrary to this expectation, trichloroethylene and dichloroethylene disappear in many plumes without the accumulation of vinyl chloride, ethylene, or ethane. In recent years, it has been recognized that bacteria in aquifers can use a variety of electron acceptors to oxidize cis-dichloroethylene or vinyl chloride to carbon dioxide. Microbial Degradation of cis-dichloroethylene has... 

Mattes TE, NV Coleman, JC Spain, JM Gossett (2005) Physiological and molecular genetic analysis of vinyl chloride and ethene biodegradation in Nocardioides sp. strain JS614. Archiv Microbiol 183 95-106. 

Soil. In a methanogenic aquifer material, /ra/ 5-l, 2-dichloroethylene biodegraded to vinyl chloride (Wilson et al., 1986). Under anoxic conditions ra/ 5-l,2-dichloroethylene, when subjected to indigenous microbes in uncontaminated sediments, degraded to vinyl chloride (Barrio-Lage et al., 1986). tra/ 5-l,2-Dichloroethylene showed slow to moderate degradation concomitant with the rate of volatilization in a static-culture flask-screening test (settled domestic wastewater inoculum) conducted at 25 °C. At concentrations of 5 and 10 mg/L, percent losses after 4 wk of incubation were 95 and 93, respectively. The amount lost due to volatilization was 26 to 33% after 10 d (Tabak et al, 1981). 

Figure 19.9. Electrochemically enhanced microbial reductive dechlorination of perchloro-ethene (PCE) and oxidative degradation of vinyl chloride (VC). Stimulated biodegradation is indicated by a chloride increase during electrochemical treatment.

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... 

Values of Henry s Law constants for selected chlorinated solvents are given in Table 23.1.2. As indicated in the table, values of H for chlorinated eompounds also vary over several orders of magnitude. Chlorinated solvents have low Henry s Law eonstants, with the exception of vinyl chloride. Volatilization of chlorinated solvents compounds from ground water is a relatively slow process that generally can be negleeted when modeling biodegradation. 

It is at times desired that vinyl articles biodegrade—or at least vanish into a landfill. Reports to date suggest that vinyl articles are immortal in landfills. Even with use of aliphatic plasticizers, degradation is limited to cracking and fracture. There are no reports of catalysts for depolymerization under landfill conditions comparable to the effects of cobalt and manganese catalysts used with landfillable polyolefin products such as trash bags. In the case of vinyl, such catalytic action would be unacceptable if accompanied by formation of vinyl chloride monomer or evolution of HCl. 

Coleman NV, JC Spain (2003) Epoxyalkane coenzyme M transferase in the ethene and vinyl chloride biodegradation pathways of Mycobacterium strain JS60. J Bacterial 185 5536-5546. 

Particularly the chlorinated compounds have enjoyed range of applications vinyl chloride (chloro-ethene) as monomer for the production of PVC, tetra- and trichloroethenes as solvents for degreasing, and the insecticides l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and isomers of hexachlorocyclohexane (HCH) (benzene hexachloride). The biodegradation of fluorinated aliphatic compounds is generally different from the outlines that have emerged from investigations on their chlorinated, brominated, and even iodinated analogues. They are therefore treated separately in Part 4 of this chapter. 

Tetrachoroethylene (perchloroethylene, PCE) is the only chlorinated ethene that resists aerobic biodegradation. This compound can be dechlorinated to less- or nonchlorinated ethenes only under anaerobic conditions. This process, known as reductive dehalogenation, was initially thought to be a co-metabolic activity. Recently, however, it was shown that some bacteria species can use PCE as terminal electron acceptor in their basic metabolism i.e., they couple their growth with the reductive dechlorination of PCE.35 Reductive dehalogenation is a promising method for the remediation of PCE-contaminated sites, provided that the process is well controlled to prevent the buildup of even more toxic intermediates, such as the vinyl chloride, a proven carcinogen. 

Vinyl chloride is the least-oxidized chlorinated aliphatic hydrocarbon, and may serve as an electron donor. A vinyl chloride molecule consists of more hydrogen atoms relative to chloride atoms (3 to 1) thus, reductive dechlorination is not favorable to biodegradation. However, under aerobic conditions, vinyl chloride can serve as an electron donor with oxygen as an electron acceptor. 

LDPE), polypropylene (PP), poly(vinyl chloride) (PVC), and polyethylene tere-phthalate (PET) [48], completely new areas of application are preferred in which biodegradability is required for admission, such as applications in the medical field [50, 51]. The reason for this is obvious. When new materials enter the market, they are in competition with aheady established materials. In the case of PUB, due to its temperature stability, a competition with poly(olefin)s arises for all applications in which biodegradabUity is not required by law (Fig. 12). 

The BAT system operates based on principles of aerobic cometabolism. In cometabohsm, enzymes that the microbes produce in the process of consuming one particular compound (e.g., phenol) have the collateral effect of transforming another compound that normally resists biodegradation (e.g., chlorinated ethenes, especially lesser chlorinated ethenes such as dichloroethene or vinyl chloride). The BAT system operates under these principles by sorbing the chlorinated compounds from a vapor stream onto powdered activated carbon (PAC) where they are cometabolically transformed into a combination of end products, including new biomass, carbon dioxide, inorganic salts, and various acids. 

Vinyl chloride (VC) is the monomer from which the common polymer, polyvinyl chloride, is produced. Hence, VC is produced on a very large scale. Not surprisingly, occasional releases of the rather toxic VC to the environment occur. What initial biodegradation product would you expect from VC if it were released into an oxic environment ... 

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