Application to Bioremediation

Considerable interest has been expressed in the chlorophenol-degrading organism Mycobacterium chlorophenolicum (R. chlorophenolicus) (Apajalahti et al. 1986), partly motivated by its potential for application to bioremediation of chlorophenol-contaminated industrial sites (Haggblom and Valo 1995). 

Sullivan JP, D Dickinson, HA Chase (1998) Methanotrophs, Methylosinus trichosporium OB3b, sMMO, and their application to bioremediation. Crit Rev Microbiol 24 335-373. 

TCE is not able to support the growth of a single organism, but it is susceptible to cooxidation by oxygenases elaborated by organisms dnring growth with structurally unrelated substrates. A review of methanotrophic bacteria (Hanson and Hanson 1996) contains a useful account of their application to bioremediation of TCE-contaminated sites. 

The biotechnological potential of laccases—working with air and producing water as sole by-product—has led to applications from the textile to the pulp and paper industries, from food applications to bioremediation, as well as their use in organic synthesis. 

Lin, G.-H., Sauer, N. E. Cutright, T. J. (1996). Environmental regulations a brief overview of their applications to bioremediation. International Biodeterioration and Biodegradation, 38, 1-8. 

T. Pheiffei, "Case Study of the Eglin Ait Eoice Base Ground Water Bioremediation System," in Innovative Operational Treatment Technologiesfor Application to Supefund Sites Nine Case Studies U.S. Environmental Protection Agency, Washington, D.C., 1990. 

Different mechanisms have therefore clearly emerged and it seems premature to draw general conclusions especially in the application of synthetic and natural surfactants to bioremediation, which is discussed in greater detail in Chapter 14. It is important to note, however, that the production of biosurfactants may not be the only mechanism for facilitating the uptake of substrates with... 

These results may be viewed in the wider context of interactions between potential ligands of multifunctional xenobiotics and metal cations in aquatic environments and the subtle effects of the oxidation level of cations such as Fe. The Fe status of a bacterial culture has an important influence on synthesis of the redox systems of the cell since many of the electron transport proteins contain Fe. This is not generally evaluated systematically, although the degradation of tetrachloromethane by a strain of Pseudomonas sp. under denitrifying conditions clearly illustrated the adverse effect of Fe on the biotransformation of the substrate (Lewis and Crawford 1993 Tatara et al. 1993). This possibility should therefore be taken into account in the application of such organisms to bioremediation programs. 

Apart from its application to the specific problem of groundwater contamination, this procedure offers a potentially valuable procedure for simulating bioremediation of contaminated soils. 

Collectively, these results illustrate the value of this procedure for determining the occurrence of biodegradation and biotransformation in natural environments, and their application to assessing the effectiveness of bioremediation. A number of important limitations should be addressed. 

These results clearly indicate the existence of a number of issues that must be resolved in the application of bioremediation to PAH-contaminated soils, and that caution should be exercised in making generalizations. 

In the application of snch strains to bioremediation of contaminated sites, a nnmber of important considerations shonld be considered. 

Details of the anaerobic degradation of chloroalkanes and chloroalkenes have been discussed in detail in Chapter 7, Part 3, and the application of reductive processes to bioremediation has been examined under denitrifying, sulfidogenic, and methanogenic conditions. An important observation... 

Other factors affecting performance include the presence of toxic material, the redox potential, salinity of the groundwater, light intensity, hydraulic conductivity of the soil, and osmotic potential. The rate of biological treatment is higher for more permeable soils or aquifers. Bioremediation is not applicable to soils with very low permeability, because it would take a long time for the cleanup process unless many more wells were installed, thus raising the cost. 

Oxygenate-degrading microorganisms are typically slow growing and may not be present natively at all sites pilot or treatability studies may be needed to confirm the applicability of bioremediation at a specific site. 

Three cyanide-degrading nitrilases were recently cloned and purified and their kinetic profiles were evaluated in order to better understand their applicability to cyanide bioremediation. CynD from Bacilluspumilus Cl and DyngD from Pseudomonas stutzeri exhibit fairly broad pH profiles with >50% activity retained across pH 5.2 to pH 8.0 while the CHT (NHase) from Gloeocercospora sorghi exhibited a more alkaline pH activity profile with almost all of its activity retained at pH 8.5, slightly lower thermal tolerance, and quite different metal tolerance compared with the two bacterial enzymes [46]. 

The IWA (International Water Association), formerly known as the IWQA, has had several task forces working on model development for various types of processes. I believe that these reactor models have a good potential application for remedial treatment. The subject of the models is extremely complex and too involved for this discussion, as it is a Master s Level course in Environmental Engineering. However, let me indicate that there are several types of models which may have some application to the bioremediation field. The principal models are... 

The ease of the Strecker synthesis from aldehydes makes a-aminonitriles an attractive and important route to a-amino acids. Fortunately, the microbial world offers a number of enzymes for carrying out the necessary conversions, some of them highly stereoselective. Nitrilases catalyze a direct conversion of nitrile into carboxylic acid (Equation (11)), whereas nitrile hydratases catalyze formation of the amide, which can then be hydrolyzed to the carboxylic acid in a second step (Equation (12)). In a recent survey, with a view to bioremediation and synthesis, Brady et al have surveyed the ability of a wide range of bacteria and yeasts to grow on diverse nitriles and amides as sole nitrogen source. This provides a rich source of information on enzymes for future application. 

The technology is not applicable to metallic wastes, building and construction materials, and insoluble inorganic compounds. In liquid phases, lower temperamres decrease reactivity and increase the time required for complete bioremediation. All information is from the vendor and has not been independently verified. 

If this technology is not combined with complementary technologies such as bioremediation or air sparging, it is not applicable to heavier organics such as long-chain hydrocarbons or complex contaminants such as heavy fuels that contain compounds with low vapor pressure. 

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