Scientific basis
The project, entitled “Continued biodegradation of fragments of certified compostable plastic films in the soil under real conditions”, is intended to provide reliable data on the further degradation of such materials in the soil. The aim is to record the behaviour of compostable plastic films after treatment in organic waste plants more precisely and to evaluate them on a scientifically sound basis.
Classification in the biological cycle
Certified compostable organic waste collection bags are used in many households for the separate collection of kitchen waste. In Austria, very lightweight plastic carrier bags have had to be compostable since 2020. They are initially used for loose fruit and vegetables, can then be used to store food and later be used for the collection of organic waste.
In Germany, compostable organic waste bags for the collection and disposal of organic waste are generally permissible, provided that no deviating requirements of the public waste management authorities apply and the requirements of the Biowaste Ordinance are complied with. This includes, among other things, the bags degrading in composting plants within six weeks of treatment and disintegrating into fragments smaller than two millimeters. Proof is provided by an independent certification procedure, such as “DINplus Biowaste Bags” based on the DIN EN 13432 standard.
Examination under practical conditions
The research project aims to clarify whether film fragments that may remain in the compost are further biodegraded under real conditions in the soil. In addition, the metabolism by soil microorganisms is to be quantified.
To this end, certified industrially compostable films are treated in regular plant operation in two biowaste treatment plants. A composting plant in Austria and a fermentation plant with downstream composting in Germany are involved. The composts produced in this way, which contain corresponding fragments, are then spread on soils. Samples will be taken regularly over an expected period of 24 months to track the further degradation of the remaining particles.
Partners from academia and practice
Institutions from science, material production and biowaste treatment are involved in the project. Participating research partners are institutes of the University of Vienna, the University of Natural Resources and Life Sciences, Vienna and the Swiss Federal Institute of Technology Zurich. The project is sponsored by the Austrian Microplastic-Free Alliance and the German Natural Circular Economy Initiative. An interdisciplinary advisory board made up of experts from waste management, compost and soil management as well as from science and politics accompanies the project.
The project aims to provide insights into how fragments of certified compostable plastic films behave along the process chain from composting to soil input. This is intended to create a scientific basis for the evaluation of their further biodegradation in the soil.
