MSCA-COFUND-CLEAR-Doc - PhD Position #CD22-55: In-situ recycling of multiphase post-consumer plastic waste in isolated areas

Context:

More than anywhere else, isolated areas such as islands and remote regions are confronted with residual material management challenges, including post-consumer plastic waste (PCW). The context of these geographically distant environments exacerbates the PCW management problem by acting on two levels: L1) the small quantity of plastics for each chemical nature that can be used as a deposit of materials to be recycled, and L2) the cost increase in handling and transport to large-scale storage centres due to its remoteness. In both cases, it becomes absolutely uneconomic to recycle PCW in a conventional way. It therefore appears advantageous to develop simple mechanical recycling techniques for multi-phase post-consumer PCW that are applicable to remote environments but can be scaled up.

Recycling of PCW:

Conventional recycling of plastic waste generally involves 3 main steps and may involve several partners. The first step is to recover or collect and transport the material to sorting centres where the different types of plastics are separated, compacted into bales, and sent to regeneration factories. The second stage consists in washing, crushing and granulating the plastics. The third stage is the transformation of the recycled granules into semi-finished or finished products.

Conventional sorting is performed manually by combining particle size, ballistic, magnetic and optical processes. However, this sorting method is not without flaws and the nature of the polymers and residual contaminants in the bales is variable. Furthermore, the presence of contaminants and the chemical and thermal degradation of the polymer lead to a reduction in the properties of the recycled pellets compared to the virgin polymer-based pellets. Thus, in the case of heterogeneous and small deposits characteristic of remote environments, the use of these conventional sorting processes makes the recycling of these plastic wastes uneconomic.

It would therefore appear judicious to elaborate a research project on the development of simple recovery techniques that would minimise the sorting and decontamination stages in order to allow the manufacture of finished products adapted to the quality and quantity of the available raw materials, when complying with sanitary regulations. These techniques will allow a reduction in the energy costs associated with the handling of PCW to the management centres.

Proposed project:

The proposed thesis aims to valorise the largest quantity of post-consumer recycled polymers from remote areas by incorporating them when manufacturing building materials such as building claddings and decking. This project will be carried out in collaboration with the municipalities of Iles-de-la-Madeleine (IDLM), Quebec, Canada and Iles du Ponant, France. The specific objectives of this three-year thesis are:

O1) to determine the classes of PCW that enable manufacturing different products. If volumes are not sufficient, an integrative approach without sorting could be preferred (year 1),

O2) identify and quantify the contaminants present in the recycled pellets and study their impact on the process and performance of the PCW (year 1),

O3) develop, if necessary, a simple decontamination line (years 1 and 2),

O4) develop new formulations based on unsorted or poorly sorted recycled polymers (year 2),

O5) develop and characterize industrial materials based on the formulations developed (year 2),

O6) shape building products by simple processes such as extrusion and 3D printing (year 2),

O7) carry out a pilot project as a technological showcase at the IDLM (year 3),

O8) evaluate the sustainability of the applications developed in the island context (years 2 and 3).

The thesis will be carried out within the International Associated Laboratory Eco materials for Infrastructures and Building (LIA-ECOMAT) between the UdeS in Quebec and the University Gustave Eiffel in France. The doctoral student will spend 18 months at CITÉ (the Crossroads of Innovation in Ecological Technologies) at the UdeS and then 18 months in France and will have a double degree (French and Canadian) at the end of his or her thesis.

This is an opportunity to have access to a large team of researchers for the supervision of the doctoral student, as well as laboratories and research equipment that are perfectly suited to the subject of the thesis. Indeed, the CITÉ of the UdeS as well as the Materials and Structure department of the Gustave Eiffel University, have experience and expertise in the field of recycling, shaping and characterization of polymeric materials. This project will allow the PhD student to acquire knowledge in the field of thermoplastic recycling, an important current issue, and to contribute to the circular economy by proposing technical and technological solutions to reduce the amount of waste in remote areas. The candidate will work on a multidisciplinary topic, grow his or her knowledge in materials, processing, multi-scale characterisation and sustainability, all in a leading international team.

Expected benefits:

The economic benefits of this project will be multiple: cost reduction to transport PCW to sorting centres and to import some construction materials that will be locally manufactured from recycled PCW. Given the multi-phase material development approach, the project will have important environmental benefits such as the reduction of the rate of PCW rejection and their sending to landfill sites. In addition, the reduction in energy demand related to the transportation of PCW perfectly meets current requirements in terms of greenhouse gas emissions reduction. Finally, the project will have significant social and societal benefits for the targeted communities. Indeed, local actors will play an active role in the creation of added value for materials currently considered as waste and fitted to local needs.