Organic degradation

Others would extend the fertiliser concept to the simultaneous addition of readily biodegradable substrates along with the fertiliser nutrients to stimulate the growth of contaminant-degrading organisms most rapidly, and to aid in the rapid utilisation of the fertiliser nutrients before they might be leached from the contaminated area. The specific requirements for the most efficacious substrates is an area of current research. 

Others would include the addition of materials aimed at increa sing the bioavailabiUty of the contaminant to the degrading organisms. The most studied compounds are surfactants, but cations have been reported to increase the bioavailabiUty of some organic compounds, and sorbents and clays are also considered. The dispersion of spilled oil on water by the appHcation of dispersants is perhaps the major commercial use of this idea. 

A major concern when remediating wood-treatment sites is that pentachlorophenol was often used in combination with metal salts, and these compounds, such as chromated copper—arsenate, are potent inhibitors of at least some pentachlorophenol degrading organisms (49). Sites with significant levels of such inorganics may not be suitable candidates for bioremediation. 

The selector process is apphcable for readily degradable wastewaters it also requires upstream controls. In a selector, degradable organics are removed by the doc formers by biosorption and therefore are not available as a food source for the filaments. 

Organic matter All of the degradable organics. Living material containing carbon compounds. Used as food by microorganisms. 

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). 

Use of analogs of the substrate, for example, biphenyl for PCB-degrading organisms... 

Substrates that are related to those naturally available to the degrading organism, but unrelated to that of the contaminant has been exploited only occasionally ... 

Systematic studies on the degradation of 4-nitrophenol (Spain et al. 1984) showed that the rates of adaptation in a natural system were comparable to those observed in a laboratory test system and were associated with an increase in the number of degrading organisms by up to 1000-fold. 

Many contaminants contain nitrogen, phosphorus, or sulfur, and degradative organisms may utilize one or more of these leaving the major part of the substrate intact. This is particularly important for munitions-related compounds with a high N/C ratio, when the addition of carbon sources may lead to the favorable development of anaerobic or facultatively anaerobic microorganisms. 

The use of toluene to induce oxygenation of haloalkanes has been discussed in Chapter 7, Part 3, and probes for toluene-2-monooxygenase have been used to evaluate the potential nnmber of TCE-degrading organisms in an aquifer (Fries et al. 1997b). In this study, repetitive extragenic palindromic PCR (REP-PCR) (de Bruijn 1992) of isolates was used to classify their metabolic capability. 

Adverse effect of readily degraded surfactants that diminish the oxygen concentration available to the substrate-degrading organisms... 

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