Degradation under Anaerobic Conditions

Whilst a large munber of investigations have been published for the degradation of plastics in the presence of oxygen, there is very little data on anaerobic biodegradation. 

In the same work, a munber of anaerobic individual microbial strains degrading PHA, PCL and a polyester from 1,3-propanediol and adipic acid (SP3 6) were isolated and identified. BTA-copolyesters were attacked by the individual strains only when the content of terephthalic acid did not exceed 20 mol%. Here it can be supposed that these organisms predominately attack the quite long aliphatic domains in these copolyesters. 

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Tetratchloroethylene has been detected in the food chain as a contaminant its volatility prevents significant bioaccumulation but some transfer to aquatic sediments is possible. At low concentrations it is slowly degraded under anaerobic conditions. 

From the published reports, there are few aromatic amines found that can be mineralized under anaerobic conditions, such as naphthalene amines, which can be utilized as the sole organic carbon source by bacterial cultures [58]. Furthermore, it was reported that 2-aminonaphthyl sulfonate can be degraded or used as sulfur source by pure cultures [59, 60]. In many reports, however, it was found that sulfo-nated aromatic amines cannot be degraded under anaerobic conditions [61]. 

It is much clear from literature that most of the azo dyes are recalcitrant to aerobic degradation but can be degraded under anaerobic condition. Hence anaerobic... 

The available information about surfactant degradation under anaerobic conditions is restricted to anionic and non-ionic surfactants. Anaerobic biodegradation is strongly dependent on the chemical structure of the compound, the presence of a sufficient amount of anaerobically degrading microorganisms and a fulfilment of their growth requirements. 

When all necessary nutrient supply systems are in balance and functioning properly, aerobic biological remediation can be relatively rapid. Gasoline components have been observed to have a half-life of days to months under well-controlled field conditions. Chemicals such as tetrachloroethylene that are best degraded under anaerobic conditions require significantly more time. Published half-lives for similar chlorinated solvents under field conditions are on the order of 300-day half-lives. Several computer programs are available that calculate the probable life expectancy of remedial projects. For best results, these programs require input of real field data. 

Halogenated aliphatics can be partially or completely degraded under anaerobic conditions through a transformation reaction called reductive de-halogenation. Often a co-metabolic degradation step, reductive dehalogenation... 

Like aliphatic hydrocarbons, aromatic compounds can be completely degraded under anaerobic conditions if the aromatic is oxygenated. Recent evidence also... 

CASRN 118-91-2 molecular formula C7H5CIO2 FW 156.57 Biological. Suflita et al. (1982) reported that 2-chlorobenzoic acid degraded under anaerobic conditions by a stable methanogenic bacterial consortium enriched from sludge. The primary... 

Other studies reporting benzene degradation under anaerobic conditions are similarly difficult to interpret. For instance, Ghosh Sun (1992) observed a loss of l6mg/l benzene over a 44 day period in a bioreactor that did not exhibit a detectable lag period prior to the onset of benzene removal. We can only presume that the bioreactor was not methanogenic as the ambient pH was 5.2-5.5, but no exogenously supplied electron acceptor was available. In this study, the abiotic loss observed in a single control bottle accounted for 50% of the total mass of benzene. 

Ball, H. A. Reinhard, M. (1996). Monoaromatic hydrocarbon degradation under anaerobic conditions at Seal Beach, California Laboratory studies. Environmental Toxicology and Chemistry (in press). 

Clearly, the rate of production of plant material must exceed its rate of decay if peat is to form, but this is ef-fectively a function of the water table. Waterlogging and stagnation allow anoxia to develop rapidly due to the activity of the decomposers and, as noted in Section 3.3.3c, woody tissues are far less readily degraded under anaerobic conditions. 

Phenylurea herbicides are also degraded under anaerobic conditions. N-(3,4-Dichlorophenyil)-N -dimethylurea (Diuron) and Linuron have shown to be dechlorinated in anaerobic sediments with elimination of the chlorine atom in the pam position [220, 221]. 

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