ISO 23977-1: Aerobic Biodegradability of Plastics in Seawater - CO₂ Evolution (ISO/IEC 17025:2017 Accredited)

ISO 23977-1 is an aqueous aerobic biodegradability test that determines the aerobic biodegradability of plastic materials in seawater by measuring CO₂ evolution during biodegradation in a closed system. This test relies on the microorganisms originally present in seawater without the addition of a specific inoculum. The conditions in this study might not always correspond to the optimum conditions for the maximum degree of biodegradation. However, this test method is designed to give an indication of the potential biodegradability of plastic materials.

The test normally lasts for up to 1 year, but can be extended to a maximum of 2 years.

CONCEPT AND PRINCIPLE

ISO 23977-1 describes two variations of a test method for determining the biodegradability of plastic materials by the indigenous population of microorganisms in natural seawater using a static aqueous test system.

The test is performed under mesophilic test conditions for up to two years by incubating plastic materials with either seawater only ("pelagic seawater test") or with seawater to which low amount of sediment has been added (''suspended sediment seawater test"), coming from the same site as that from which the seawater was taken.

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.