Detoxification reductive

Detoxification Reduction of a chemical s toxic properties by means of biotransformation processes, to form a more readily excreted or a less toxic chemical than the parent compound. 

Functions -Tl, volume reduction Se, separation De, detoxification St, stor-... 

Chemical treatment is a class of processes in which specific chemicals are added to wastes or to contaminated media in order to achieve detoxification. Depending on the nature of the contaminants, the chemical processes required will include pH adjustment, lysis, oxidation, reduction or a combination of these. Thus, chemical treatment is used to effect a chemical transformation of the waste to an innocuous or less toxic form. In addition, chemical treatment is often used to prepare for or facilitate the treatment of wastes by other technologies. Figure 12 identifies specific treatment processes which perform these functions. 

Daub, M. E., Leisman, G. B., Clark, R. A., and Bowden, E. F. (1992). Reductive detoxification as a mechanism of fungal resistance to singlet oxygen-generating photosensitizers. Proc. Natl. Acad. Sci. USA 89 9588-9592. 

Substitution therapy with methadone or buprenorphine has been veiy successfiil in terms of harm reduction. Some opiate addicts might also benefit from naltrexone treatment. One idea is that patients should undergo rapid opiate detoxification with naltrexone under anaesthesia, which then allows fiuther naltrexone treatment to reduce the likelihood of relapse. However, the mode of action of rapid opiate detoxification is obscure. Moreover, it can be a dangerous procedure and some studies now indicate that this procedure can induce even more severe and long-lasting withdrawal symptoms as well as no improvement in relapse rates than a regular detoxification and psychosocial relapse prevention program. 

When patients elect detoxification from maintenance, a very gradual reduction of dosage is preferred, with careful monitoring of drug craving and withdrawal symptoms. Three to 6 months is recommended for most elective detoxifications. As many as one-third of methadone maintenance clients have been found to have a marked fear of detoxification (Milby et al. 1986). 

Patients requiring detoxification from high or supratherapeutic dosages of benzodiazepines constitute a smaller number of patients, but they are at greater risk for life-threatening discontinuation symptoms, such as seizures, delirium, and psychoses. There has been more experience with inpatient detoxification in this group, but outpatient detoxification is possible if conducted slowly (5% reduction in dose per week), with frequent contact, and in the context of a therapeutic alliance with the patient. Often, such an alliance proves unworkable because the patient s impoverished control results in supplementation from outside sources or early exhaustion of prescribed supplies meant to be tapered. In these cases, as in the cases of patients with a history of seizures, delirium, or psychoses during previous detoxification attempts, inpatient detoxification is indicated. 

He J, KM Ritalakti, MR Aiello, FE Loftier (2003) Complete detoxification of vinyl chloride by an anaerobic enrichment culture and identification of the reductively dechlorinating population as a Dehaloccoides species. Appl Environ Microbiol 69 996-1003. 

It is not currently feasible to achieve a zero discharge of chemical pollutants from metal finishing operations. However, substantial reductions in the type and volume of hazardous chemicals wasted from most metal finishing operations are possible.8 Because end-of-pipe waste detoxification is costly for small- and medium-sized metal finishers, and the cost and liability of residuals disposal have increased for all metal finishers, management and production personnel may be more willing to consider production process modifications to reduce the amount of chemicals lost to waste. 

This section provides guidance for reducing waterborne wastes from metal finishing operations in order to avoid or reduce the need for waste detoxification and the subsequent off-site disposal of detoxification residuals. Waste reduction practices may take the form of5 ... 

There are a number of different mechanisms by which microorganisms resist metal toxicity (Table 11.1). Five mechanisms that microbes use to mediate metal toxicity have been proposed and they include (1) formation of a permeability barrier,21-24 (2) active transport,25-29 (3) sequestration,30-32 (4) enzymatic detoxification,33 34 and (5) reduction in sensitivity.35,36 Microbes may use one or more of these mechanisms to exclude nonessential metals and regulate internal concentrations of essential metals. 

Chemical detoxification uses oxidation, reduction, neutralization, and hydrolysis to reduce the toxicity of the contaminants. The basic theory is similar to that of treating pumped groundwater. 

Since cyclodextrins form complexes with various other substances, including many dyes and surfactants, it is clear that they could be useful in effluent treatment. They are potentially suitable for the reduction or removal of polluting substances either by immobilisation or by solubilisation and extraction and thus can accelerate detoxification [30]. 

Iron 5 X 104 3 X 10 3 Oxygen transport, storage, activation and detoxification, electron transfer, nitrogen fixation, ribose reduction, etc. 

Specific effluents have also been subjected to WRF-mediated remediation studies. Decolourization, dechlorination and detoxification of highly toxic bleach plant effluents derived from the pulp and paper industry have been reported [26-28], while degradation and decolourization of synthetic dyes due to the non-specificity of the LMEs have been widely documented [29, 30], Likewise, treatment of the acidic, phenolic-rich olive oil mill wastewater has shown COD reduction, decolourization and dephenolization [31-34],... 

Table IV also contains results of UV absorption studies of hydroxylation effects on the DNA intercalative binding of ben-zo[a]pyrene metabolites and metabolite model compounds. The most important feature of these results is that hydrolysis of BPDE to BPT causes a four-fold reduction in the intercalation association constant. Of all the BP derivatives studied, the tetrol has the lowest binding constant for intercalation. The small binding constant of the tetrol compared with BPDE, coupled with the DNA catalyzed hydrolysis of BPDE to the tetrol may provide a detoxification pathway for removal of a portion of unreacted intercalated BPDE.

Carvalho MF, Alves CCT, Ferreira MIM, De Marco P, Castro PML (2002) Isolation and initial characterization of a bacterial consortium able to mineralize fluorobenzene. Appl Environ Microbiol 68 102-105 Cheung KH, Gu J-D (2005) Reduction of chromate (Cr042 ) by a Bacillus mag-netarium isolated from marine. World J Microbiol Biotechnol 21 213-219 Cheung KH, Gu J-D (2007) Mechanism of hexavalent chromium detoxification by microorganisms and bioremediation application potential A review. Int Biodeter Biodegr 59 8-15... 

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