Aerobic biodegradability of plastic materials in soil
ISO 17556:2019 specifies a method for determining the ultimate aerobic biodegradability of plastic materials in soil by measuring the oxygen demand in a closed respirometer or the amount of carbon dioxide evolved. The plastic material, which is the sole source of carbon and energy, is mixed with the soil. The mixture is allowed to stand in a flask over a period of time during the which the amount of oxygen consumed (BOD) or the amount of carbon dioxide evolved is determined. Provided the CO2 evolved is absorbed, the BOD can be determined, for example, by measuring the amount of oxygen required to maintain a constant gas volume in a respirometer flask, or by measuring either automatically or manually the change in volume or pressure (or a combination of the two). Alternatively, the amount of CO2 evolved is measured at intervals dependent on the biodegradation kinetics of the test substance by passing CO2-free air over the soil and then determining the CO2 content of the air. The level of biodegradation, expressed as a percentage, is determined by comparing the BOD with the theoretical oxygen demand or by comparing the amount of CO2 evolved with the theoretical amount. The normal test period is six months. The test may be shortened or extended until the plateau phase is reached, but the total test period shall not exceed two years.
Gas Endeavour® can be easily coupled with our patented in-situ carbon dioxide absorption kit to function as a fully automated closed-respirometer for continuous and on-line measurement of oxygen consumption or depletion caused by aerobic respiration of microorganisms. The apparatus is suitable for all test protocols which the measurement principle can be based on oxygen demand (BOD) measurement.
Read more about ISO 17556 at iso.org.