Other Compost Biodegradation Tests

Another, more drastic approach to improve the precision of CO2 measurement and ascertain that CO2 derived from a test material is effectively determined, involves the use of radiolabelled test material. An aerobic, aquatic composting test procedure in which the production of C02 is measured by absorption and liquid scintillation counting has been published as ASTM D6340-98(2007) - Standard test methods for determining aerobic biodegradation of radiolabelled plastic materials in an aqueous or compost environment. 

Two challenges related to this test are the cost and difficulty (or even feasibility) to radiolabelling each and every carbon atom of the test item. In addition, this method does not allow a precise measurement of biomass produced from the sample. 

Besides norms for tests in which the biodegradation is measured directly by quantifying CO2 production or O2 consumption, some exposure tests have also been standardised, e.g., ASTM D5509-96 and ASTM D5512-96. In these tests, plastic test items are exposed to composting conditions which are precisely defined. After a certain period of incubation a loss of property is measured, such as weight, MW, tensile strength, tear resistance and so on. It may be clear that these parameters are only secondary 

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AIB-Vingotte International has a biodegradable home compost test certification for plastic products that references EN 13432 performance specification and other ISO biodegradable test methods. Biodegradation in soil environments is based on International OK Biodegradable Soil standards. Table 8.7 lists the biodegradation standards for home composing. 

Regulated heavy metal testing measures the concentrations of regulated heavy metals or other toxic and hazardous substances in the compost soil at the end of the biodegradation testing. The concentrations of regulated heavy metals or other toxic and hazardous substances must be less than 0.1% of the dry weight of the plastic material. 

Definitions. Standardization of definitions, test methods, and performance criteria are required for degradable, biodegradable, and compostable plastics (as for other plastics), to allow product stewardship, to enable regulatory programs, and to support consumer confidence. In the United States these responsibilities lie with the American Society for Testing and Materials (ASTM). 

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