Decision tools for recycling with a focus on fibre reinforced composites

January 19, 2024

A circular economy is an approach to sustain a product value and functions by increasing the lifecycle of products by performing material efficiency engagements such as reuse, remanufacture and recycle wherever feasible. With the rapid growth of composite use in the UK industrial composite sectors, it is important for related companies to adopt the circular economy approach and to manage both manufacturing and end-of-life waste for better sustainability. The current disposal practice is that 98% of composite waste is disposed of in landfill. With the upsurge of waste legislation by both local and international governing bodies, industrial players have to consider recycling. A crucial issue prior to recycling is the separation of components of materials that make up product assemblies. A particular interest for this research is products that contain composite materials. From literature which builds on the Sherwood plot, existing mathematical models for product complexity are based on the mass fraction of constituent materials. This measure was adapted by previous researchers to predict ‘what gets recycled’. However, the research argument is that this measure could be improved by considering the environmental and technological incentive to recycle materials. In this PhD, the material security and recycling technology readiness level were modelled into an integrated measure. The research realises that it is not only product complexity that hinders recycling and that the system and incentives for a circular economy need to be reconsidered. The second part of this research developed decision tools for composite recycling taking into account the waste supply chain, location and other significant factors. The critical success factors of the circular economy such as drivers, sustainers, barriers and waste ownership have also been determined. A questionnaire approach was used to investigate this aspect while the centre of gravity method and weighted sum method were utilised as a scientific approach to propose an alternative location for recycling centres. Hence, the associated reverse supply chain complexity was assessed. An appropriate technique was suggested to reduce the overall distribution network complexity. From the first analysis, an apparent recycling desirability boundary enabling products to be prioritised for recycling was developed. This model and analysis can be used as an information source in developing policies and product recycling priorities. The second part results indicated that the drivers and sustainers for composite recycling were primarily rooted in an obligation to comply with the rules and regulation of environmental protection that are enforced. The end-user was identified to be the best for managing the composite end-of-life waste. New mathematical models were developed that allow strategic placement of recycling centres near to waste resources by minimising the complexity of waste collection while enabling the shortest total driving distance with the lowest total greenhouse gas emission. Moreover, the capacity of the recycling centre is programmed in as constraint to be met. Collectively, the entire findings from this study have brought together considerations on products recycling desirability and complexity of composite reverse supply chain, into a comprehensive and updated assessment. The vision is that the knowledge integration between new models will guide the stakeholders towards the enhancement of the sustainable use of engineered products including composites. In the absence of such approach, the world cannot truly culminate in shaping a better circular economy practices.
Al Amin Mohammed Sultan
Al Amin Mohammed Sultan. (2019). Decision tools for recycling with a focus on fibre reinforced composites. The University of Manchester Department of Mechanical, Aerospace & Civil Engineering.