ISO 23977-1: 2020 describes two variations of a test method for determining the biodegradability of plastics materials in natural seawater. The test is performed under mesophilic test conditions for up to two years by incubating plastic materials with either seawater only or with seawater to which a low amount of sediment has been added, coming from the same site where the seawater was taken.

The biodegradation is followed by measuring the evolution of carbon dioxide. The level of biodegradation is determined by comparing the amount of carbon dioxide evolved with the theoretical amount and expressed in percentage. The test result is the maximum level of biodegradation, determined from the plateau phase of the biodegradation curve.

BPC Blue is a fully automated biodegradability testing system suitable for ISO 23977. Utilising an in-situ carbon dioxide absorption kit, BPC Blue functions as a closed-respirometer for continuous and on-line measurement of oxygen consumption or depletion caused by aerobic respiration of microorganisms. The instrument is suitable for all test protocols which the measurement principle is based on oxygen demand measurement.