Biodegradation process Biological

Biological Activity Evolution Profile Through the Biodegradation Process. 236... 

Biodegradative Processes and Biological Waste Treatment Ana sis and Control... 

The same facts apply to biodegradative processes Five years ago, little was known about the enzymology of lignin biodegradation, and the molecular biology of cellulases was in its infancy. Advances have since been made in leaps and bounds these advances are fully discussed within this volume. 

IT Corporation (IT) developed a two-stage photolytic and biological soil detoxification process to treat soils contaminated with polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-/7-dioxin (TCDD). The photolysis/biodegradation process has been evaluated under the U.S. 

PROBABLE FATE photolysis photooxidation m atmosphere, photooxidation half-life in air 3.4-33.7 hrs, reacts with photochemically produced hydroxyl radicals with a half-life of 0.001 hr oxidation occurs slowly hydrolysis not an important process volatilization principle transport mechanism, expected to volatilize quickly from dry soil, volatilization half-life from a model river 10 days sorption not an important process biological processes biotrans-formation occurs, biodegradation is slow at low concentrations reversible hydration to beta-hydroxypropionaldehyde, half-life 21 days... 

PROBABLE FATE photolysis-, aqueous photolysis is not expected to be important, reaction with photochemically produced hydroxyl radicals has a half-life of 13.44 hr, direct photolysis is not expected to be important since it should not adsorb wavelengths >290 nm oxidation photooxidation is not expected to be important, photooxidation only in atmosphere, photooxidation half-life in air 9.65 hrs-4.02 days hydrolysis very slow, maybe significant, hydrolysis of carbon-chloride bonds, release to water results in hydrolysis with a half-life of 40 days when released to soil, it may hydrolyze hydrolyzed slowly in aqueous dimethylformamide at pH 7, first-order hydrolytic half-life 22yrs volatilization expected to volatilize if released to water, volatilization half-lives from lakes, rivers, and streams 3.5, 4.4, and 180.5 days respectively sorption not an important process biological processes biodegrades in water after several weeks of acclimation, biodegradation not important under natural conditions, no bioaccumulation noted... 

PROBABLE FATE photolysis the dissolved portion of the compound may undergo rapid photolysis to quinones, atmospheric and aqueous photolytic half-lives 6 hrs-32.6 days, may be subject to direct photolysis in the atmosphere, reaction with photochemically produced hydroxyl radicals has a half-life of 1.00 days oxidation rapid oxidation by chlorine and/or ozone may compete for dissolved DBA, photooxidation half-life in air 0.428-4.28 hrs hydrolysis not an important process volatilization probably too slow to be important, rate uncertain sorption strong adsorption by suspended solids, especially organic particulates, should be the principal transport process biological processes bioaccumulation is short-term, metabolization and microbial biodegradation are the principal fates... 

PROBABLE FATE photolysis no direct photolysis, indirect photolysis too slow to be environmentally important, photooxidation half-life in water 2.4-12.2 yrs, photooxidation half-life in air 7.4 hrs-2.5 days oxidation not important, reaction with photochemically produced hydroxyl radicals gives a half-life of 18 hrs hydrolysis hydrolysis (only in surface waters) believed to be too slow to be important, first-order hydrolytic half-life 10 yrs volatilization not expected to be an important transport process sorption sorption onto particulates and com-plexation with organics are dominant transport processes biological processes bioaccumulated in many organisms, biodegraded rapidly in natural soil, some biotransformation, all biological processes are important fates... 

PROBABLE FATE photolysis, probably occurs slowly will react with photochemically produced hydroxyl radicals with a half-life of 31 days oxidation resistant to autooxidation by peroxy radical in water, oxidized by hydroxy radicals in atmosphere hydrolysis unimportant process first-order hydroxyl half-life >879 yrs volatilization volatilizes at a relatively rapid rate volatilization half-life <24 hr sorption probably absorbed by organic materials adsorption to sediment is a major environmental fate process biological processes bioaccumulates more than ehlorobenzene, too resistant to biodegradation to compete with volatilization will wash out in rain water... 

PROBABLE FATE photolysis direct photolysis in water expected to be slow oxidation photooxidation in the troposphere is probably the predominant fate process hydrolysis slow hydrolysis to 3-cloroallyl alcohol occurs, may be important process, first order hydrolytic half-life 5.5 days-11.3 days volatilization volatilization to the atmosphere should be a major transport process biological processes biodegradation is possible evaporation from water 25°C of 1 ppm solution is 50% after 31 min., and 90% after 98 min about 95% ends up in air the rest ends up in water... 

PROBABLE FATE photolysis not an important process oxidation probably not an important process hydrolysis too slow to be important volatilization may be an important process sorption is an important process biological processes bioaccumulation is an important process, biodegradation in anaerobic systems, but not in aerobic systems... 

The biodegradation processes of both xenobiotics such as aromatic compounds, plastics, such as poly(vinyl alcohol), polyesters, poly-(ethylene), and nylon, as weU as pol5mciers with biological origin, and blends of both types have been reviewed (3). S5mthetic materials with groups susceptible to hydrolytic microbial attack have also been dealt with. 

This chapter overviews the literature regarding the biodegradation processes of bioactive calcium phosphate ceramics from the viewpoint of in vitro physico-chemical dissolution processes and in vivolin vitro biological degradation processes. 

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