Division of Environment and Natural Resources
DGRADE - Constraints to degradation of biodegradable plastics in terrestrial systems
End: sep 2023
Start: jan 2020
There is an increasing interest in plastics, both as a resource and as a pollutant. Climate change and environmental concerns have boosted the development of biodegradable plastics, spanning from disposable food containers to waste bags and agricultural mulch films. But how fast do these products degrade in Nordic soils and waste streams?
| Status | Active |
| Start - end date | 01.01.2020 - 30.09.2023 |
| Division | Division of Environment and Natural Resources |
| Department | Bioresources and Recycling Technologies |
| Partners | NIBIO, NORSUS, Green Dot Norway, SIMAS IKS, Norsk Landbruksrådgiving, Agri Råd. |
| Total budget | 6480000 |
| Funding source | Norwegian Research Council and Handelens Miljøfond (Grant number 303560) |
There is an increasing interest in plastics, both as a resource and as a pollutant. Although a lot of emphasis is placed on recycling, the use of recycled plastics is still low in Europe. In this context, climate change and environmental concerns have boosted the development of various types of biodegradable plastics.
The use of biodegradable plastics spans from disposable containers for food/drink, serviceware and wipes, via waste bags for food waste collected for biogas production, to agricultural films used to cover soil during vegetable production. Waste and recycling companies are poorly prepared for such a transition, as is the public, which struggles in keeping a profusion of products and their waste separation apart. In addition, biodegradable plastics may not degrade so quickly and completely that the products disappear in nature, and the label may encourage people think otherwise, enhancing littering.
Non-degradable bio-based polymers (such as bio-PET, bio-PE, etc.) are outside the scope of this project. The ambiguous term "bioplastics" should be avoided, as the prefix "bio" doesn't indicate whether it stands for biodegradable or bio-based.
Our three main objectives
- Firstly, we wanted to know how fast biodegradable mulch films used in agriculture are degraded in cold climatic regions like Norway. There is public concern that degradation may not occur fast enough, and that macro- and microplastics could accumulate in soils.
- Secondly, we wanted to describe the fate of biodegradable plastics, such as compostable waste bags, glasses and cutlery, during composting and biogas production. It is important to verify that the intended end-of-life treatments are not a source of plastics to the environment.
- Finally, we wanted to describe the environmental costs/benefits of biodegradable plastics and provide a life-cycle perspective in both agriculture and waste streams.
Ultimately, the project helped providing the recycling and composting sector with the information needed to make sound decisions on questions regarding these materials, and provide farmers with advice on which type of biodegradable plastic products to use for specific purposes and conditions.
Work packages
Results achieved
- Degradation in soil (WP2)
Before this project, the fate of biodegradable plastic mulch in soil was unknown under Nordic conditions. It has now been established that degradation occurs, albeit at a slower pace, with worse-case scenarios for complete degradation in Norwegian soils lying between 2.5 and 9 years, depending on climatic conditions, soil properties and agricultural practices. Beside higher soil temperature, higher soil organic matter content has been shown to accelerate degradation.
Scientific article "In situ degradation of biodegradable plastic mulch in Nordic agricultural soils"
- Degradation in waste streams (WP3)
The project has demonstrated through a full-scale experiment conducted at an industrial composting plant that compostable plastic products, such as polylactic acid (PLA) glasses, are successfully degraded within the time frame of the composting process. Metagenomics analysis during the whole composting process also demonstrated that the main actors of degradation are fungi, naturally present in compost.
For biodegradable plastics entering biogas production, on the other end, we demonstrated that the biodegradable plastic bags used in Norway for food waste collection were only marginally degraded during biogas process, even after thermal hydrolysis pretreatment and high temperature conditions. So, unless biogas digestate is further treated to remove biodegradable plastic residues, the application of digestate will lead to accumulation of plastics in agricultural soils.
NIBIO report on degradation during biogas production
- Life cycle analysis (WP4)
We showed that biodegradable mulch was not necessarily the most environmentally friendly alternative compared to e.g. conventional polyethylene mulch, and uncovered important knowledge gaps related to biodegradable plastic production. LCA also showed that food waste collection in paper bags results in a lower climatic impact compared to food waste collection in biodegradable and conventional plastic bags and is the only option removing the risk for plastic pollution.
A short summary of the results (in Norwegian)
Forum Landbruksplast made a short video (3 min, in Norwegian) summarizing the project's results.
For special interested (and Norwegian speakers), we have also recorded the final seminar, where all topics and results are presented and discussed. This (over 4 hour-long) video is available upon request.
Publications in the project
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Claire CoutrisAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Erik J. JonerAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Conference lecture – Plast og mikroplast i jord: hvilke utfordringer står vi overfor?
Claire Coutris
Authors
Claire CoutrisAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Erik J. JonerAbstract
No abstract has been registered
