Composting simulated

As biodegradation test we predominantly used the polyester hydrolysis with lipases. The free acids built during the ester cleavage were monitored via an automatic and improved titration system. Beside the enzyme test we also performed soil burial tests, compost simulations and tests with isolated microorganisms to check whether the results obtained with the lipase can be transferred to natural conditions. 

While the reduced enzymatic susceptibility of the aromatic ester bonds is caused by the interaction of the long chains in the polymer, the chain length itself has no direct influence on the biodegradability above a minimum molar mass. Tests with copolyesters from terephthalic acid, adipic acid and 1,4-butanediol, which were chain extended with hexamethylene-diisocyanate, did not result in a decrease in the biological degradation rate (in a compost simulation test), although the molar mass of the prepolyesters of about 48,000 D was increased to 232,000 D by the chain extension [85]. 

Schoenfeld J, Gelsomino A, Van Overbeek LS, Gorissen A, Smalla K, Van Elsas JD (2003) Effects of compost addition and simulated solarisation on the fate of Ralstonia solanacearum biovar 2 and indigenous bacteria in soil. FEMS Microbiol Ecol 43 63-74. doi 10.1111/j. 1574-6941,2003.tb01046.x... 

Grewal, S. K., Rajeev, S., Sreevatsan, S., and Michel, F. C., Jr. (2006). Persistence of Mycobacterium avium subsp. paratuberculosis and other zoonotic pathogens during simulated composting, manure packing, and liquid storage of dairy manure. Appl. Environ. Microbiol. 72,... 

Kaplan, D. L. Kaplan, A. M. (1982b). Thermophilic biotransformations of 2,4,6-trinitrotoluene under simulated composting conditions. Applied and Environmental Microbiology, 44(3), 757-60. 

Lay et al., 1999 Fan et al., 2002). For example, Fan et al. have successfully used a heat-shocked cow dung compost to convert a simulated organic wastewater into hydrogen gas (Fan et al., 2003). 

Joyce, J.R, Sato, C., Cardenas, R., and SurampaUi, R.Y. 1998. Composting of polycyclic aromatic hydrocarbons in simulated municipal solid waste. Water Environment Research, 70 356-61. 

Starnecker, A. Menner, M. (1996a). Assessment of biodegradability of plastics under simulated composting conditions in a laboratory test system. International Biodeterioration and Biodegradation, 37, 85-92. 

For each of the steps in the flow diagram, Figure 1, standards organizations worldwide have developed very similar and entirely appropriate laboratory simulation methods for testing plastics for use in various environments such as compost, soil, water, etc. Developing plastics may, therefore, be tested and approved as environmentally degradable in a particular environment, such as soil, compost, seawater and freshwater. Based on these methods, specifications have been established for what is and what is not disposable in such sites or use environments. 

Degradation of Biodegradable Polymers in Real and Simulated Composting Conditions... 

Most of the relevant standards developed so far address the compostability of a plastic material from a package in laboratory simulated conditions which... 

PLA bottles (500 mL) were provided from NatureWorks LLC (Blair, NE) with 96% L-lactide and bluetone colorant. The bottles were composted in a commercial compost pile and in laboratory simulated conditions. 

A polymer s compostability is a function of many factors such as pH, temperature, humidity, microorganisms population, and osmotic pressure. Simulated laboratory conditions as described by ASTM D6400 (//), D5338 (7) and ISO 14855 (6) may be an oversimplification of commercial composting systems which do not completely reflect the conditions in the commercial composting facilities. Therefore, further studies are necessary to assure that laboratory studies can duplicate commercial systems. 

The details of the pair potential used in the simulations are given in Table I. This consists of an -trans model of the sec-butyl chloride molecule with six moieties. The intermolecular pair potential is then built up with 36 site-site terms per molecular pair. Each site-site term is compost of two parts Lennard-Jones and charge-charge. In this way, chiral discrimination is built in to the potential in a natural way. The phase-space average R-R (or S-S) potential is different from the equivalent in R-S interactions. The algorithm transforms this into dynamical time-correlation functions. 

Thom KA, Pennington JC, and Hayes CA, 15N NMR investigation of the reduction and binding of TNT in an aerobic bench scale reactor simulating windrow composting, Environ. Sci. Technol., 36, 3797, 2002. 

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