ISO 23977-2: Aerobic Biodegradability of Plastics in Seawater - Oxygen Consumption (ISO/IEC 17025:2017 Accredited)
ISO 23977-2 is a laboratory test guideline for determining the degree and rate of the aerobic biodegradation level of plastic materials. Biodegradation of plastic materials is determined by measuring the oxygen demand in a closed respirometer when exposed to seawater sampled from coastal areas under laboratory conditions.
The conditions described in this document 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 1 year, but can be extended up to 2 years.
CONCEPT AND PRINCIPLE
ISO 23977-2 determines the biodegradability of a plastic material by measuring oxygen consumption during the biodegradation process in a closed bottle setup (with head space). The degradation percentage is calculated as the ratio of oxygen consumption to the theoretical oxygen demand (ThOD).
This standard 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.
The chemical formula of the test substance and its purity may be known to calculate the ThOD. The material is preferably in powder form with a maximum size of 250 um in diameter to provide better bioavailability for faster biodegradation.
Information on the toxicity of the test substance is helpful in determining the appropriate dosage so that the material does not inhibit bacteria at the concentration tested.
