INNOVATION | ODOUR REDUCTION
the thinking behind the research: “VOCs in plastic waste are normally related to organic matter degradation which leads to different volatile acids as volatile fatty acids. In this regard, micro-organ- isms can use these substances as carbon source and energy, so they can degrade them, which means that micro-organisms can help to reduce odour from plastic waste.” Focusing on the odours from waste dairy
Above: Researchers at Aimplas, in Spain, have investigated a variety of techniques to remove
contaminants and odours from recycled plastics
The steam technology process has attracted
interest from five companies. Their identity is subject to confidentiality but she says they include: engi- neering groups that build machinery for mechanical recycling of plastics; multinational recycling compa- nies that already have experience in recycling PET for high-grade applications and now want to move into polyolefin recycling; plus groups that produce virgin plastics and chemicals and now want to invest in recycling technologies that allow the upcycling of post-consumer polyolefins. Aimplas, based in Spain, is another research institute that is active in odour reduction in plastics recycling. Its research work has investigated a variety of techniques to remove contaminants and odours from recycled plastics, from improved washing techniques to the use of supercritical carbon dioxide to remove VOCs during extrusion (see Plastics Recycling World May-June 2019). This year has seen the start of the second stage of the ENZPLAST project, which is investigating the use of enzymes for different applications in the plastics sector. In the context of recycling, ENZPLAST2 is developing a procedure to use micro-organisms to eliminate odours from dairy packaging. Initial results indicate a reduction in the odour intensity of recycled PE from dairy packaging. Pablo Ferrero, researcher at Aimplas, explains
Right: Luigi Bandera is focusing its response to the growing demand for plastics recycling solutions under the name RevoTech
30 PLASTICS RECYCLING WORLD | May/June 2020
www.plasticsrecyclingworld.com
packaging, he says: “First, Aimplas isolated micro-organisms degrading the compounds generating odour, using culture media where the unique carbon source was compounds generating odour. Then, plastic was contaminated with these compounds generating odour and this contami- nated plastic was exposed to the isolated micro- organisms. Samples of contaminated plastic exposed to micro-organisms were taken at different times and a reduction in the odour intensity was found along time. This indicates that micro-organ- isms and biotechnology can help to reduce and eliminate odour from plastic waste.” Machinery companies are demonstrating how degassing extruder technology can be utilised in the fight to control recyclate odours, often with the aid of a secondary process. Film and sheet extru- sion technology group Luigi Bandera is focusing its response to growing demand for plastics recycling solutions under the name RevoTech, which features its HVTSE (Highly Vented Twin Screw Extrusion) equipment as a key technology. At K2019, it showcased production of PET food-grade rigid film from PET recycled flakes in which HVTSE co-rotating twin-screw extruders are complement- ed by its patented Pure high-vacuum purification systems (Plastics Recycling World March/April 2020). The RevoTech approach can also be used with recycled polyolefins, with benefits that include high odour control. Andrea Carraro, Senior Sales Manager, says
Bandera’s RevoTech approach for recycled polyole- fins involves a microwave-based technology after
IMAGE: AIMPLAS
IMAGE: BANDERA
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