Two weeks ago, TF1 took a closer look at fruit and vegetable bags in its “Le 20 H vous répond” feature. Intended to clarify the issue for viewers, the segment only served to reinforce the confusion surrounding notions of bioplastics.
Indeed, by presenting biobased bags as non-biodegradable, the journalists unwittingly mixed up the origin of the material with its end-of-life. Indeed, a biobased material is not necessarily biodegradable and vice versa, the two notions being quite distinct.
Biodegradability is a feature specific to certain materials, referring to their chemical structure and not to their origin. It is the subject of standardized tests attesting to their ability to biodegrade under certain conditions.
The term “biobased” refers only to the origin of the raw materials used, in this case from different biomasses.
So don’t expect biobased polymers to degrade automatically in compost!
The other part of the report focuses on the efficiency of home composting. It’s worth noting that since January 1, 2017, only paper or biobased and domestically compostable plastic bags (in accordance with standard NF T 51-800) can be distributed outside cash registers in France (fruit and vegetables, cheese by the slice, meat, fish, etc.).
The ability of these plastic bags to be composted at home is assessed by French standard NF T51-800 according to three main criteria: disintegration, biodegradation and effect on compost quality.
A number of studies have been critical of the results of composting these bags, implying that the quality of the compost could be reduced and lead to pollution. However, these conclusions need to be considered with caution. In fact, a study by ADEME (Domestic and industrial composting of domestically compostable plastic and paper bags – June 2019) shows that if good composting practices are applied, namely:
- composting must be carried out in closed composters.
- bags must be deposited open, single-layered and filled with kitchen and table biowaste.
- Composters must be managed in accordance with ADEME best practices (weekly stirring for one month, then every 1-2 months, humidity control).
- the average ambient temperature over the first three months of composting must be close to the standard: outside temperature of 25°C ± 5°C.
This will ensure that the bags biodegrade within the expected timeframe, without disturbing the quality of the compost. Beyond the choice of an appropriate material, part of the success of the process therefore lies in the implementation of good composting practices at home.
Don’t hesitate to contact us if you have any questions or would like to find out more about biobased and/or biodegradable plastics. We also offer several training modules to answer all your questions on these complex subjects.