Large volumes of post-consumer plastic waste from packaging, household items and other applications still carry unpleasant, pungent odours even after sorting and wet washing. These odorous substances can migrate into the polymer matrix during a product's life cycle and are not reliably removed by conventional recycling steps, which limits the use of recyclate in higher-value applications. To address this, Next Generation Recyclingmaschinen GmbH and Kreyenborg GmbH & Co. KG have agreed a strategic collaboration focused on reducing odours and emissions through a multi-stage, modular and energy-efficient process. The partners combine NGR's experience in processing mixed plastic waste streams with Kreyenborg's heat-treatment expertise to deliver a treatment sequence designed to enhance pellet quality and expand the applicability of post-consumer recyclate in sectors such as packaging, automotive and consumer goods.
Cleaning in the melt phase
The process starts with regranulation based on NGR's C:GRAN cascade technology. An initial cleaning action occurs in the cutter compactor, where warm exhaust air from the cylinder cooling system flows through preheated material. An optional degassing zone can be integrated before the melt filter to remove volatile contaminants. The subsequent melt filter removes solid particles from the melt stream. After filtration, the melt enters a high-performance degassing zone within a cascade extruder. This power venting section acts as a surface generator and, together with an efficient vacuum system, enables maximum degassing performance aimed at extracting volatile impurities as thoroughly as possible. After the cascade, the melt is granulated and the pellets are conveyed to Kreyenborg's IR-Fresh Conditioner for post-treatment.
Thermal-physical post-cleaning
In the second step, remaining low-molecular impurities are removed in a thermal-physical process within the IR-Fresh Conditioner. The dedicated container maintains the material in the optimal temperature window for decontamination while a stream of hot air supports the removal of volatiles. Precise control of process parameters has delivered consistent deodorization and decontamination results in numerous tests on different material streams. For particularly stubborn volatile contaminants, the ground material can also be pre-treated before extrusion. Kreyenborg's infrared technology rapidly brings the material to the target temperature for the respective plastic. Continuous rotation of the IR drum provides a homogeneous mass flow with a defined dwell time based on a first-in, first-out principle, and integrated rotation and mixing elements ensure constant surface exchange. This pre-treatment, combined with the IR-Fresh Conditioner, significantly enhances odour removal in a short residence time and contributes to overall energy efficiency.
Market use and testing
The joint objective is the production of high-quality granulates with reduced odour and emissions. "The combination of our technologies enables a substantial improvement in pellet quality and opens up new markets for recycled plastics," said Marcus Vogt, Technical Sales Manager at Kreyenborg. Stefan Lehner, PCR Product Manager at NGR, views the collaboration as a step that supports the circular economy and its increasing requirements. According to the partners, the system is already operating successfully in the market. Trials with customer materials can be arranged to demonstrate performance and measure results.
C:GRAN - cascade with 'Power venting section' + Kreyenborg conditioner
