Claire Coutris
Research Scientist
Biography
Claire is a research scientist at NIBIO, since 2013. She holds a PhD in Environmental Chemistry and Ecotoxicology from the Norwegian University of Life Sciences (Norway), and a MSc in Ecology and Ecotoxicology from the University of Toulouse (France).
Claire works with soil biology, environmental chemistry, and the fate of emerging contaminants in soils. She conducts toxicity tests on soil microorganisms, invertebrates and plants in mesocosms, with an emphasis on the impact on soil processes. She works on several Norwegian Research Council projects on recycling of waste resources (biogas digestate, sewage sludge, compost) to soils.
Abstract
Since the 1950s, the use of plastics in agriculture has helped solving many challenges related to food production, while its persistence and mismanagement has led to the plastic pollution we face today. A variety of biodegradable plastic products have thus been marketed, with the aim to solve plastic pollution through complete degradation after use. But the environmental conditions for rapid and complete degradation are not necessarily fulfilled, and the possibility that biodegradable plastics may also contribute to plastic pollution must be evaluated. A two-year field experiment with biodegradable mulches (BDMs) based on polybutylene adipate terephthalate (PBAT/starch and PBAT/polylactic acid) buried in several agricultural soils in mesh bags showed that also under colder climatic conditions does degradation occur, involving fragmentation after two months and depolymerization by hydrolysis, as shown by Fourier-transform infrared spectroscopy. The phytopathogenic fungus Rhizoctonia solani was found to be associated with BDM degradation, and the formation of biodegradable microplastics was observed throughout the experimental period. Between 52 and 93 % of the original BDM mass was recovered after two years, suggesting that accumulation is likely to happen in cold climatic regions when BDM is repeatedly used every year. Mass loss followed negative quadratic functions, implying increasing mass loss rates over time. Despite the range of climatic and edaphic factors, with various agricultural practices and vegetable productions at the study locations, the parameters that significantly favored in situ BDM degradation were higher soil organic matter content and temperatures.
Abstract
Food waste collection in Norway is mostly done using plastic bags, made either of polyethylene or, more recently, of biodegradable plastics, which are materials that can be degraded by microorganisms under certain environmental conditions and time frames. Most of the biodegradable plastic bags used in Norway for food waste collection are labelled as compostable, i.e. degradable under composting conditions, but end up in biogas plants and only rarely in composting plants. The present work provides answers to the following questions. First, to what extent are biodegradable plastic bags deteriorated during anaerobic digestion of food waste. Secondly, is the situation different under mesophilic (37°C) and thermophilic (55°C) conditions. Finally, does thermal hydrolysis (THP) pretreatment of food waste containing biodegradable plastic change the results. In tests offering optimal conditions for microorganisms involved in anaerobic digestion, limited deterioration of biodegradable plastics (Mater-Bi® certified as compostable under industrial (ICP) and home (HCP) composting conditions, representative of what is used in Norway for food waste collection for biogas production) was observed, as shown by limited mass loss (14-21 % for ICP and 22-33 % for HCP) and limited changes in the chemical composition after 22 d, a relevant hydraulic retention time for industrial biogas plant operations. Higher mass loss was observed under thermophilic conditions compared to mesophilic conditions. The effect of THP pretreatment of food waste containing biodegradable plastics offered unexpected results: while a small, non-significant increase in mass loss was observed for ICP, THP led to a significantly reduced mass loss for HCP during anaerobic digestion. The biogas process itself was not significantly affected by ICP and HCP present in food waste at a 4 % plastic to food waste ratio. The present research shows that the majority (79-86 % of ICP and 67-78 % of HCP) of biodegradable plastic residues left after initial pretreatment of food waste, will withstand anaerobic conditions, both under mesophilic and thermophilic conditions, also when subjected to THP pretreatment (5 bars, 160°C, 20 min). This strongly suggests that post-treatment of digestate is required to avoid the spread of biodegradable plastics to agricultural soils, for digestates intended for agricultural use.
Authors
Gunhild Bødtker Claire Coutris Eva Marie-Louise Denison Åsa Frostegård Erik J. Joner Bjørn Tore Lunestad Elisabeth Henie Madslien Kaare Magne Nielsen Pål TrosvikAbstract
In this self-tasking scoping review, VKM will map research about the environmental impacts of biodegradable plastics, including biodegradation rates and material persistence in different environments and geographical regions, the influence on microbial ecology and activity, and ecotoxicological effects of materials and associated chemical substances. Related to this is also research associated with the development of methodology, standards, environmental risk assessment, life cycle impact analyses, material sources and properties of biodegradable plastics and products. The aim is to 1) determine the extent of evidence summarised in reviews and original research papers within this emerging research area and 2) map the evidence according to the materials and chemicals studied, types of environments and geographical regions covered, the hypotheses addressed, the type of endpoints assessed and the reported key findings. Systematic literature searches will be performed to identify the summarised evidence, applying APRIO to develop a tailored search protocol that addresses the multi- and cross-disciplinary nature of the research area. We will select and map the identified publications applying Rayyan and sort them into three categories based on their main scientific focus and aim of study: 1) material properties and application, 2) biodegradation and microbial ecology, and 3) ecotoxicology. There will be no geographical restrictions on the search and study selection, but in the data charting process we will highlight findings relevant to Norway and other Nordic countries. The current project adheres to the “Preferred Reporting Items for Systematic Reviews and MetaAnalyses extension for Scoping Reviews (PRISMA-ScR) Checklist” for protocol development and reporting. We will address uncertainties associated with research studies applying EFSA guidelines and their generic list of common types of uncertainty affecting scientific studies and assessments.
