Biodegradation measuring rate

Chapelle, F.H., P.M. Bradley, D.R. Lovley, and D.A. Vroblesky. 1996. Measuring rates of biodegradation in a contaminated aquifer using field and laboratory methods. Ground Water 34, 691-698. 

Surface water t,/2 = 4008-30936 h, based on estimated aqueous aerobic biodegradation half-life (Howard et al. 1991) measured rate constant k < 0.004 M 1 s 1 for direct reaction with ozone in water at pH 2 and 22°C, with t,/2 > 100 d at pH 7 (Yao Haag 1991). 

Biodegradation average rate of biodegradation 71.0 mg COD g- h- based on measurements of COD decrease using activated sludge inoculum with 20-d of adaptation to the substrate (Pitter 1976 quoted. Scow 1982). Biotransformation ... 

Biodegradation average rate of biodegradation 30.0 mg COD g h based on measurements of COD decrease using activated sludge inoculum with 20-d of adaptation to the substrate (Fitter 1976 quoted. Scow 1982) V,(aq. aerobic) = 677 320 h, based on river die-away studies V/aq. anaerobic) = 2400-12000 h, based on degradation rates in microcosm studies simulating anaerobic aquifers (Howard et al. 1991). ti/j(aerobic) = 28 d, t,//anaerobic) = 100 d in natural waters (Capel Larson 1995)... 

Surface water photooxidation ty, = 267 d-64.6 yr, based on measured rate constant for the reaction with hydroxyl radicals in water (Anbar Neta 1967 Dorfman Adams 1973 quoted, Howard et al. 1991) ty, = 48-288 h, based on aqueous aerobic biodegradation half-life (Howard et al. 1991). 

However, as already alluded to, lab-culture data do not always translate into measurable rates in natural or field exposures of PE. Early data on incubating PE in soil show minimal weight loss even over very long periods of exposure. Reported experimental results on PEs (Table 6.5) are consistent with very slow biodegradation. 

ChapeUe, F., P. Bradley, D. Lovley, and D. Vroblesky. 1996. Measuring Rates of Biodegradation in a Contaminated Aquifer Using Field and Laboratory Methods, Ground Water, vol. 34, no. 4, pp. 691— 698. 

Hydrolytic reactions, which are best documented, include saponification of esters, hydrolysis of amides, and hydrolysis of ethers (glycosides). Except for ester saponification, all the other reactions proceed at a measurable rate only by enzymic catalysis. Hydrolytic enzymes are regular constituents of the digestive tract and lysosomes. They are responsible for the biodegradation of polyesters, polyamides (including polypeptides), polysaccharides and, probably, polyurethanes. 

Rate of biodegradation. The rate of attack of microorganisms or enzymes measured by CO2 production relative to that of compounds of similar chemical structure produced in nature which are known not to accumulate in the environment. 

---