PETpla.net Insider 06+07 / 2014

MATERIAL / RECYCLING 22 PET planet insider Vol. 15 No. 06+07/14 www.petpla.net MATERIAL / RECYCLING 22 customers can point to a closed-cycle system. This is firstly sustainable, and secondly it’s cost- efficient, because we can also pay reasonable prices. On the other hand, Stute uses the mate- rial for producing new preforms, thus practising resource-economy as well as obtaining a finan- cial benefit.” Washing processes The in-house recycling system consists of a washing module and a decontamination module, both of them in rack construction. All decon- tamination processes have to be preceded by a washing process, so as to obtain clean flakes as the material. It is here that label residues, glue, sand and other soluble soiling are washed off:  Bottles are ground in the washing module to create flakes.  Flakes are then pre-washed at low tempera- tures, mechanically pre-cleaned using jetting and friction. The washing water involved is fil- tered, and can be re-circulated for using again.  Label residues and adhesives are detached in a caustic washer, so that no dirt or glue remains on the surface of the flakes. A Parsifal filtration system continuously treats the soiled caustic in two stages, so that it can be used again at a consistent level of quality.  In a sink-or-swim process a density separator separates the lighter PO cap materials from the heavier PET flakes.  In a multi-stage post-washing step, the flakes are rinsed with hot water. The energy of the hot water is used several times over, thanks to cascades, with each cascade temperature zone being treated again using membrane filtration.  After being washed, the flakes are mechani- cally and thermally dried by a hot-air blower. Bottle-to-bottle decontamination module In order to achieve food-grade quality, the material has to be decontaminated in accordance with international standards. In Krones’ Vacuum- Supercleaning process, the entire PET input The density separator, in a sink-or-swim process, separates the lighter PO cap materials from the heavier PET flakes.