INNOVATION | ODOUR REDUCTION


Right: Odour- less recyclate using Star- linger odour reduction technology


Eva Verdejo, Head of


Sustainability and Industrial Recovery Department at Aimplas


sensory evaluation of other polyolefins such as PP and LDPE, with the ultimate aim to develop appro- priate avoidance and minimisation strategies,” she says. “The next step is to re-evaluate customised washing and recycling processes with regards to odour minimisation. Furthermore, we are develop- ing novel analytical procedures to detect and monitor in-line odour emission, which can be implemented by process quality control systems.” According to Eva Verdejo, Head of Sustainability and Industrial Recovery Department at Aimplas, the Spain-based research organisation, odour reduc- tion or elimination in plastics recycling is of critical importance. Innovative technological solutions to odour problems should be provided in order to achieve the high-quality recycling targets foreseen in the plastics circular economy strategy of the European Commission. “Odour elimination is going to be highly important both for waste materials with a high organic filler content and for high added- value applications, such as in the automotive sector,” she says. “In these cases, getting odour reduction to within acceptable limits may result in a considerable increase in the selling price, a higher percentage of recycled material in the final part and, of course, compliance with the regulations. “One of the most important aspects is to provide a permanent solution at the right price for the different demands required by a particular applica- tion, and based on the characteristics of the original waste material. Consequently, it is impor- tant to provide a solution for recycled material whether it is in pellet or ground material form. The equipment used for each type is different, as well as the applied techniques. However, depending on the requirement of the final application, the results of odour reduction will be successful or not.” Aimplas is working on providing customised solutions in order to reduce odour problems in recycled materials – with different techniques depending on the particular application. Examples include: oxidation of organic compounds by means of ozone (applied directly over the material or in aqueous media); extraction of substances with supercritical fluids in extruders, such as CO2


and


water; and extraction through degasification in twin screw extruders. In addition, techniques are being combined with each other and with the incorpora- tion of specific additives to obtain synergistic results. These technologies have been developed within specific projects such as LIFE EXTRUCLEAN, in which odour reductions of up to 70-80% for the recycling of packaging containing hazardous waste were obtained. Other projects for particular compa- nies have also achieved significant reductions,


18 PLASTICS RECYCLING WORLD | July/August 2018


ranging from 60-95% depending on the substance, plastics material and the initial contamination level. Aimplas adds that future developments will see


further process optimisation to make them more effective at lower cost. This includes complemen- tary systems for both continuous and discontinuous odour removal, providing different solutions for niche applications. Recycling technology groups have also been working on the problem of odour. Starlinger has developed new technology in odour reduction which can be specified with its plastics recycling lines. The company says that in order to be fit for reuse in production, recycled material needs to match the quality of virgin resin. The removal of well-known contaminants such as ink is only the beginning; any migrated substances or residues of monomers or decomposition products have to be eliminated as well. For materials that are prone to suffer from unpleasant smells, for example, polyolefin containers that were filled with deter- gents, cleaners, or cosmetics, but also polyolefin film with organic contamination, Starlinger has developed a technology that neutralises odours on a permanent basis. The technology turns smelly material like


detergent bottles into odour-reduced pellets that meet high quality standards. Starlinger’s method works without the use of additives; the smell is not just masked, but permanently removed through eliminating the substances causing it. The proce-


www.plasticsrecyclingworld.com


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