Phenol biological degradation

Most of the odours coming from livestock production units are associated with the biological degradation of the animal wastes (35), the feed and the body odour of the animals (1). Volatile fatty acids and phenolic compounds were found to contribute mostly to the strong, typical odour of animal houses by the help of sensory evaluations parallel to the chemical analysis (29), (30). 

Adjustment of sample pH is another effective measure to minimize biological degradation. Afghan et al. (1974) report that Pseudomonas bacteria, responsible for degradation of phenols, is destroyed by both high and low pH values. High pH values increase the chemical oxidation rate of humic substances, and should be avoided (Stevenson, 1982) low pH values can result in precipitation of humic acid if the solution is sufficiently concentrated. Generally, the concentration of humic acid is low and precipitation is not a problem. 

Phenols and cyanides can be biologically degraded or removed by physical-chemical treatment. Normally they are present in such low concentrations that there is no need for targeted pretreatment. Combined treatment in a sufficiently large biological waste water treatment plant is sufficient. 

Electrochemical reduction or oxidation can destroy organic compounds and can frequently render a toxic compound less toxic or harmless or biologically degradeable on the other hand highly toxic compounds, such as chlorinated aromatics, phenols or NCI3 can be formed. 

Wastewater. Phenol is a toxic poUutant to the waterways and has an acute toxicity (- 5 m g/L) to fish. Chlorination of water gives chlorophenols, which impart objectionable odor and taste at 0.01 mg/L. Biochemical degradation is most frequently used to treat wastewater containing phenol. Primary activated sludge, along with secondary biological treatment, reduces phenol content to below 0.1 mg/L (69). 

During fermentation, the betacyanins turned out to be more stable than the betaxanthins, which is assumed to be due to their thermal stability rather than different tendencies of pigments toward microbial degradation. Besides these biological tools, beet extracts may also be purified by column chromatographic techniques. After removal of sugars, salts, and phenolics, the nature-derived color preparation will, however, require E number labeling. ... 

Wisecarver, K. D., and Fan, L. S., Biological Phenol Degradation in a Gas-Liquid-Solid Fluidized Bed Reactor, Biotechnol. Bioeng., 33 1029 (1989)... 

Worden, R. M., and Donaldson, T. L., Dynamics of a Biological Fixed Film for Phenol Degradation in a Fluidized-Bed Bioreactor, Biotechnol. Bioeng., 30 398 (1987)... 

As the following pages of this section will show, there is hardly a new method of analysis which is not immediately tried for the determination of aspirin as such, or in formulations and biological fluids. The analysis of aspirin is intricately interwoven with that of salicylic acid, its precursor and degradation product. From the very first, residual salicylic acid was determined by the convenient reaction with ferric salts — typical for phenols — which give a violet complex with salicylic acid. 

Biological. Bacterial degradation of 2-methylphenol may introduce a hydroxyl group producing 3-methylcatechol (Chapman, 1972). In phenol-acclimated activated sludge, metabolites identified include 3-methylcatechol, 4-methylresorcinol, methylhydroquinone, a-ketobutyric acid, dihydrox-ybenzaldehyde, and trihydroxytoluene (Masunaga et al, 1986). 

Biological. Soil bacteria readily decomposed o-phenylphenol but the products were not identified. By analogy to the degradation of phenol to catechol, o-phenylphenol may be converted to 3-phenylcatechol before degrading to biphenyl. Another pathway may be oxidation by a dioxygenase producing 2-hydroxy-2, 3 -dihydroxybiphenyl (Zbozinek, 1984)... 

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