Carpet waste recycling plant pilot for polypropylene

A consortium of internationally-based companies and organisations has secured European funding for the ISOPREP project which aims to recycle the polypropylene element found in synthetic carpet waste into a much higher quality polypropylene output that can subsequently be used in the manufacture of premium polypropylene-based products.

The ten partners in the multi-disciplinary consortium – the Advanced Resins and Coatings Innovation Centre (a strategic partnership between London South Bank University and TWI), Floteks, Fraunhofer IBP, the Institute of Process and Particle Engineering – Tu Graz, Sabanci University, Rotaject Systems, Bioniqs, Axion Recycling Ltd., the Centre for Nanotechnology and Smart Materials, and TWI – are located across Europe in Turkey, Germany, Austria, Portugal and the UK. The overall project is being coordinated by TWI.

Polypropylene is used extensively in products ranging from food and drink packaging through to carpets, electronics, automobile interiors and even bank notes. However, it is a non-sustainable polymer which contributes to non-biodegradable plastic waste, and with just 1% of polypropylene currently being recycled, the rest is going to landfill and polluting the land and sea. Any recycling of polypropylene is currently carried out mechanically and the result is an inferior plastic that is only suitable for use in low grade products.

Instead, the ISOPREP project aims to exploit a novel, patented ionic solvent, originally developed under the HiPerPol project funded by Innovate UK, to selectively solubilise the polypropylene element of waste carpet. When applied to waste carpet, also known as carpet feedstock, the solvent breaks it down, removing any dyes, colours and impurities from the material in the process and outputs virgin quality polypropylene which can be freshly manufactured into high quality, end user products. Consequently, this has huge potential for recycling as synthetic carpet can constitute as much as 100% polypropylene.

Previously, the solvent’s application has been restricted to controlled use under laboratory conditions. However, it will now be employed in a real-life scenario, based at partner TWI’s premises in Cambridge, UK where a pilot recycling plant with the capacity to process one tonne of synthetic carpet waste is being built. Following the delivery of two tonnes of carpet feedstock to TWI, a core recycling system is being created that will breakdown the waste into small shreds. Once processed, the patented solvent will be applied to the feedstock in order to dissolve the polypropylene, the output from which will be fresh, commercially viable polypropylene that can be used in the manufacture of premium quality products.

The ultimate aim of the ISOPREP project is to demonstrate that the solvent-based recycling approach, initially validated under laboratory conditions only, can be successfully scaled up into a process that has industry-wide application in the longer term.

Geraldine Durand, Director of the Advanced Resins and Coatings Innovation Centre said “The combination of the patented solvent application, the new polypropylene dissolving method and the first-of-its-kind carpet feedstock recycling plant will offer a number of environmental positives including a reduction in CO2 emissions and the quantity of fossil fuel used in the manufacture of new polypropylene products, as well as a decrease in the amount of polypropylene going to landfill.” “In summary, this cost effective and environmentally friendly method of recycling polypropylene has clear benefits that should make it attractive to industry” she added.

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