ASTM D6691 - Aerobic Biodegradability of Plastics in Seawater - CO₂ Evolution (ISO/IEC 17025:2017 Accredited)

ASTM D6691 is an aqueous aerobic biodegradability test that determines the degree and rate of aerobic biodegradation of plastic materials in seawater by measuring CO₂ evolution. This test relies on the pre-grown population of at least ten aerobic marine microorganisms of known genera or the indigenous population existing in natural seawater. The test method is conducted under controlled laboratory conditions.

This test method is applicable to all polymer materials containing at least 20% carbon that are not inhibitory to the microorganisms present in a marine environment. 

The test normally lasts for 10-90 days, but it is acceptable for the experiment to be
terminated in advance when cumulative CO₂ production plateaus or extended if no biodegradation has occurred in a specific time.

CONCEPT AND PRINCIPLE

ASTM D6691 is an aqueous aerobic biodegradability test that determines the degree and rate of aerobic biodegradation of plastic materials in seawater.

Biodegradation is followed by measuring the evolution of CO₂ using a suitable, analytical method. The level of biodegradation is determined by comparing the amount of CO₂ evolved with the theoretical amount of evolved CO₂ (ThCO₂) and expressed in percentage. The test result is the maximum level of biodegradation, determined from the plateau phase of the biodegradation curve.