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ASTM D5511: Anaerobic Biodegradability of Plastic Materials

ASTM D5511 specifies a method of determining the degree and rate of anaerobic biodegradation of plastic materials in high-solids anaerobic conditions. This test method is designed to be applicable to all plastic materials that are not inhibitory to the microorganisms present in anaerobic digesters operating on household waste. ASTM D5511 is equivalent to ISO 15985.

This test method is designed to yield a percentage of conversion of carbon in the sample to carbon in the gaseous form under conditions found in high-solids anaerobic digesters, treating 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, moisture control, and temperature control.

Plastic test pieces are incubated for normally 15 to 30 days at 37 °C (mesophilic conditions) or 52 °C (thermophilic conditions). The degree of breakdown is determined by analyzing the CO2 and CH4 formation.

ASTM D5511 Key Summary

▶ Materials that can be tested:
     ➢ Plastics and many other types of materials;
▶ Test substance dosage: 15-100 g of volatile solids per 1000 g of wet inoculum (at least 20% dry solids);
▶ Inoculum information:
     ➢ derived from a properly operating anaerobic digester functioning with a pretreated household waste as a sole substrate;         ➢ over 20% of dry solids;
     ➢ post-fermentation for 7 days to reduce the organic content in the inoculum;
     ➢ pH between 7.5 and 8.5;
     ➢ Volatile Fatty Acids —Below 1 g/kg wet weight;
     ➢ NH4 -N—Between 0.5 and 2 g/kg wet weight;
▶ Inoculum dosage: 1000 g wet weight per reactor (at least 20% dry solids);
▶ Positive control substance: analytical-grade cellulose;
▶ Reactor size: normally 2-L wide-mouth Erlenmeyer flask;
▶ Number of reactors: 3 for each test substance, plus 3 for blank control, and 3 for reference control;
▶ Test temperature: 37 °C (mesophilic conditions) or 52 °C (thermophilic conditions);
▶ Measurement:
     ➢ at least five measurements of gas volume per week;
     ➢ gas composition at the end of the test;
     ➢ weight loss of each vessel;
     ➢ Room temperature and atmospheric pressure;
▶ Test duration: normally 15-30 days, but the incubation shall be run until no net gas production is noted for at least five days from both the positive control and test substance reactors;
▶ Test validity criteria: 
     ➢ over 70 % of degradation for cellulose (reference) after 30 days;
     ➢ the deviation among the cellulose replicates is less than 20 % of the mean.

Requirement and Applicability

Different testing methods are applicable for materials with different properties. Below is a summary of the applicability of ASTM D5511. Please check our Method Selection Guide to select the most appropriate method for your materials. You can also find the applicability for many other methods on Aropha Resource Center

TestAnalytical methodSample info required *Poorly solubleVolatileAdsorbing
ASTM D5511CO2 and CH4 evolutionOrganic carbon content *++/-+

*"Sample info required" is the information needed to calculate the biodegradation percentages. This must be available for a selected method.
*"Organic carbon content" is the ratio of the organic carbon weight to the weight of the sample. It can be calculated by the sample formula (e.g., acetic acid C2H4O2, carbon content is 12*2/(12*2+1*4+16*2)=40%). Try our Online C% Calculator. If the formula is unknown, we can send the sample out to a third party lab for you for analysis (normally $110 with a 10-day turnaround time).

Aropha Resource Center

To learn more about different types of biodegradation tests, their applicability, biodegradation mechanisms, and many other information such as case studies, publications, and blogs, please check our Aropha Resource Center

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