Mineralization biodegradability

Biodegradable polymers are polymers that imdergo microbially induced chain scission leading to mineralization. Biodegradable polymers may not been produced from bio-source only, but it can be derived from the petroleum source (Ray and Bousmina, 2005). Efforts... 

Very early in the study of sulfide mineral biodegradation, it was discerned that microbially-regenerated ferric ions constituted a very potent reagent for indirect attack (for literature, see Kuznetsov et al., 1963 Silverman and Ehrlich, 1964 Zajic, 1969). The ubiquitous occurrence of iron in natural situations and the wide range of reactions with sulfide minerals that can occur, combine to make the ferric ion, either as such or in complex form, the most important chemical species involved in indirect attack mechanisms. The general reaction, known to be applicable to a number of sulfide minerals under aerobic conditions (Bryner et al., 1954 Ivanov et al., 1961), may be expressed as ... 

The synergistic potential in mixtures with other surfactants as well as with other functional ingredients The high solubility in aqueous solution The superior biodegradability down to complete mineralization... 

Biodegradation. Under aerobic conditions, biodegradation results in the mineralization of an organic compound to carbon dioxide and water and—if the compound contains nitrogen, sulfur, phosphorus, or chlorine—with the release of ammonium (or nitrite), sulfate, phosphate, or chloride. These inorganic products may then enter well-established geochemical cycles. Under anaerobic conditions, methane may be formed in addition to carbon dioxide, and sulfate may be reduced to sulhde. 

Defined mineral media containing only the substance whose biodegradation is being examined... 

Simkins S, R Mukherjee, M Alexander (1986) Two approaches to modeling kinetics of biodegradation by growing cells and application of a two-compartment model for mineralization kinetics in sewage. Appl Environ Microbiol 51 1153-1160. 

There has been considerable discussion on the mineralization of DDT, and in particular the biodegradation of the intermediate DDE. Cells of Pseudomonas acidovorans strain M3GY have been shown, however, during growth with biphenyl to degrade DDE with the fission of one ring and production of 4-chlorobenzoate (Hay and Eocht 1998). 

It has been shown using (l- " C-ethyl) tetraethyl lead that this was biodegradable, and that the rate of mineralization was adversely affected by the presence of hydrocarbons that are generally simultaneous contaminants (Mulroy and Ou 1998). 

A number of substituted triazines are used as herbicides, and their biodegradation has been discussed in Chapter 10, Part 1. Treatment of soil contaminated with atrazine (2-chloro-4-(ethylamino)-6-isopropylamino-l,3,5-triazine) illustrated a number of significant features. Although the soil that was used had the potential for degradation, a laboratory experiment with Pseudomonas sp. strain ADP that had an established potential for atrazine degradation revealed important limitations. There was a substantial decline in the numbers of Pseudomonas sp. strain ADP and only limited mineralization. Supplementation with citrate or succinate increased the survival of the strain, and successful mineralization was dependent on the preservation of a carbon/nitrogen ratio >10 (Silva et al. 2004). The last would apply generally to substrates with a low C/N ratio such as triazines. 

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