Microorganisms Break Down Biodegradable Bioplastics
Good news for those who are interested in biodegradable bioplastics. Researchers from ETH Zurich and the Swiss Federal Institute of Aquatic Science and Technology (EAWAG, in German, Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz) conducted a multidisciplinary research and found that microorganisms break down biodegradable bioplastics. This creates new opportunities for waste sorting and plastic waste management in the future, because society becomes even more aware that biodegradable bioplastics can be used in the areas where it makes sense or where there is a risk that plastic would end up in the nature, e.g., in agriculture. The researchers showed that microorganisms in the soil use metabolic carbon from PBAT polymers made from compostable biodegradable bioplastic to produce energy. One of the side products of this process is microbial biomass which is a part of the natural cycle.
The time it takes for biodegradable bioplastic to fully compost depends on multiple factors. Composting includes digestion of the organic matter by microbes in the soil that turn it into carbon dioxide (CO2), water and biomass. The microbes require moist, oxygen, and adequate temperature for composting. Composting takes longer in cold weather, however, if tree leaves compost at lower temperatures, biodegradable bags will also do. Microbial activity is lower in dry or poor soil than in the soil that is rich in nutrients.
“This clarifies that nothing remains after biodegradation besides water, CO2 and biomass,“ says Hasso von Pogrell, Managing Director of European Bioplastics e.V.. “With this study, two concerns that are constantly being raised about biodegradable plastics have been rebutted – the doubt that microorganisms fully metabolize certified biodegradable plastics and the concern that the oil-based part of the polymer will not biodegrade completely.“
What are polymers?
A polymer is a compound consisting of a multitude of identical or comparable molecules. The tested biodegradable PBAT is a mixture of fossil matter and biomass from renewable materials which is used for manufacturing biodegradable, certified compostable bio-waste bags (according to EN 13432).