1. As the leader of the task on organic recycling and composting performance, Normec OWS plays a crucial role in assessing the biodegradability of FDCA-containing polyesters and blends. Could you elaborate on the methodologies used by Normec OWS to evaluate biodegradation under controlled composting conditions? How do these results inform the optimization of polyester recipes for improved biodegradability?
The requirements for industrially compostable products are specified in the harmonized European norm EN 13432. This defines 4 main requirements:
- 2 on environmental safety: no hazardous elements and heavy metals and no effect on compost quality, including ecotoxicity testing) and
- 2 on degradation: complete biodegradation (= mineralization into CO2) of the carbon in the material and disintegration (= physically falling apart) during a composting process
In first instance the biodegradation of the developed products under controlled composting conditions is evaluated according to ISO 14855 by Normec OWS. In this test the test material is mixed with mature compost and incubated in the dark at 58°C. The evolved CO2 is measured to determine the biodegradation. The biodegradation rate and levels are communicated to BASF to allow modification to speed up of decrease the biodegradation rate by changing the polymer structure.
Apart from industrial compostability also home compostability will be examined. In the latter the high temperature levels above 60°C as occuring during industrial composting are not achieved and this impact must be investigated.
2. Normec OWS is involved in testing biodegradation in soil environments in collaboration with ETHZ, BASF, and other partners. Could you explain the specific tests conducted by Normec OWS to assess the biodegradability of polyesters and blends in soil? How do these tests contribute to understanding the environmental fate of the materials developed in the project?
First, ETHZ will execute hydrolytic tests to allow a fast screening of the biodegradability of the developed polymers. The further developed materials will be tested for biodegradation in soil by partners ETHZ and BASF in line with the international standard ISO 23517 for soil biodegradable mulch films. The biodegradation tests will not only include lab trials, but also field incubation studies, while partner HYDRA will perform mesocosm experiments. Potentially residuals polyesters will be extracted to assess the fate of these residues and the amount of plastic that is incorporated in biomass.
3. In the task on biodegradation tests in aquatic environments, Normec OWS collaborates with HYDRA, ETHZ, and BASF to study the biodegradation of polymers under various freshwater and marine conditions. What methodologies does Normec OWS employ to evaluate biodegradation in aquatic environments? How do these tests address the challenges of assessing biodegradability in water ecosystems?
HDYRA will study the biodegradation behaviour of the FDCA-based polymer in selected oxic and anoxic freshwater and marine conditions. Not only in the lab, but also in the field and by mesocosm studies. Additionally, ETHZ will perform extraction processes of the residual polymer from the different degradation trials to determine the fate of the residuals.
4. Normec OWS is also responsible for conducting ecotoxicity tests on degradation residuals in both soil and aquatic environments. Could you describe the approach Normec OWS takes to assess the potential ecological impacts of degradation residuals? How do these tests ensure the safety of the developed materials for the environment and organisms inhabiting these ecosystems?
The potential polymer residuals, present in compost, soil and aquatic environment after biodegradation, will be evaluated for ecotoxicity and compared to control reactors to which no test item was added at start of the biodegradation process. A broad range of organisms will be evaluated from bacteria to algae, plants, worms, Daphnia, marine species, … to evaluate the ecotoxicological impact. Together with the biodegradation characteristic, this will allow the development of environmentally safe products.