Sustainable Solutions for Plastics
ASTM D5511
Standard Test Method for Determining Anaerobic Biodegradation* of Plastic Materials Under High-Solids Anaerobic-Digestion Conditions
Significance and Use (This test method is equivalent to ISO 15985)
Biodegradation of a plastic within a high-solids anaerobic digestion unit is an important phenomenon because it will affect the decomposition of other waste materials enclosed by the plastic and the resulting quality and appearance of the digestate after an anaerobic digestion process. Biodegradation of plastics could allow for the safe disposal of these plastics through aerobic and anaerobic solid-waste-treatment plants. This procedure has been developed to permit the determination of the rate and degree of anaerobic biodegradability of plastic products when placed in a high-solids anaerobic digester for the production of digestate from municipal solid waste.
This test method may also resemble some conditions in biologically active landfills where the gas generated is recovered and biogas production is actively promoted by inoculation (for example, codeposition of anaerobic sewage sludge, anaerobic leachate recirculation), moisture control (for example, leachate recirculation), and temperature control (for example, short-term injection of oxygen, heating of recirculated leachate)
Limitations
Because there is a wide variation in the construction and operation of anaerobic-digestion systems and because regulatory requirements for composting systems vary, this procedure is not intended to simulate the environment of any particular high-solids anaerobic-digestion system. However, it is expected to resemble the environment of a high-solids anaerobic-digestion process operated under optimum conditions. More specifically, the procedure is intended to create a standard laboratory environment that will permit a rapid and reproducible determination of the anaerobic biodegradability under high-solids digestion conditions.
Claims of performance shall be limited to the numerical result obtained in the test and not be used for unqualified “biodegradable” claims. Reports shall clearly state the percentage of net gaseous carbon generation for both the test and reference samples at the completion of the test. Furthermore, results shall not be extrapolated past the actual duration of the test.
* Biodegradation rates of EcoPure®-treated plastic materials measured according to the ASTM D5511 test method are generally conducted using above 30% solids content. Solids content in naturally wetter landfills range from 55% to 65%, while the driest landfills may reach 93%. Actual biodegradation rates will vary in biologically-active landfills according to the type of plastic used, the product configuration, and the solid content, temperature and moisture levels of the landfill.