Recycling packaging materials 513 cleaning efficiency of the recycling process was determined with a challenge test. As a result only HDPE related compounds such as oligomers could be detected in the recycled polymer after deep-cleansing. In addition an online sniffing device based on so-called electronic nos as integrated into the recycling process. This sniffing device is able to detect potential migrants such as solvents or other volatile substances, which might be introduced into the recycling process. Based on the challenge test results, upper limits for the concentration of volatile substances could be defined so that any HDPE lots with higher levels can be detected, and separated for being reused in non-food packaging areas. These higher recycling efforts over-compensated the principal lower material suitability of HDPE for closed loop recycling in comparison to PET Another point of interest is, that the project was started in Northern Ireland at a small market scale which is under good control. The HDPE milk bottles were provided by only two bottle manufacturers, which are integrated into the project By reading the bar code the vendors are able to separate bottles from these two manufacturing companies from other milk bottles which are rejected. Therefore, only milk bottles from bottle suppliers and filling companies which support the project are directed to the bottle-to-bottle recycling process. The recycling company, in principle, is therefore in a position to react on negative impacts of applied clues, label, colours etc. and can control its recyclate production 23.6 Future trends For PET, a low diffusivity polymer, closed-loop recycling is now established in several countries all over the world. The HDPE study described in Section 23.5.2 shows that the combination of source control, efficient process technology and quality control using modern sniffing devices enables manufacturing companies also to re-use packaging plastics in direct food contact which have a higher diffusivity than PET. However, it must be realised that compared to PET recycling of polyolefines will always be of much more specific character i. e. limited to a certain first application and a relatively narrow and overseeable recovery system if it is intended to reuse the plastic for sensitive applications such as direct food contact. On the other hand recycling of polyolefine plastic crates into new ones for relatively insensitive applications, such as transport containers for fresh fruits or vegetables, is a less challenging issue and can therefore be dealt with in a more general way Current and future technological improvements and further developments in recovery, sorting and recycling technologies will be an important basis for the expected increasing market shares of recycled polymers in the packagin Accompanied by increasing knowledge of possible post-consumer contaminant levels and further improving developments in analytical control systems, e.g complete inline control of recyclate production, using appropriate sniffing devices, will enable the potential risk of exposure to the consumer of unwantedcleaning efficiency of the recycling process was determined with a challenge test. As a result only HDPE related compounds such as oligomers could be detected in the recycled polymer after deep-cleansing. In addition an online sniffing device based on so-called electronic noses was integrated into the recycling process. This sniffing device is able to detect potential migrants, such as solvents or other volatile substances, which might be introduced into the recycling process. Based on the challenge test results, upper limits for the concentration of volatile substances could be defined so that any HDPE lots with higher levels can be detected, and separated for being reused in non-food packaging areas. These higher recycling efforts over-compensated the principal lower material suitability of HDPE for closed loop recycling in comparison to PET. Another point of interest is, that the project was started in Northern Ireland at a small market scale which is under good control. The HDPE milk bottles were provided by only two bottle manufacturers, which are integrated into the project. By reading the bar code the vendors are able to separate bottles from these two manufacturing companies from other milk bottles which are rejected. Therefore, only milk bottles from bottle suppliers and filling companies which support the project are directed to the bottle-to-bottle recycling process. The recycling company, in principle, is therefore in a position to react on negative impacts of applied clues, label, colours etc. and can control its recyclate production. 23.6 Future trends For PET, a low diffusivity polymer, closed-loop recycling is now established in several countries all over the world. The HDPE study described in Section 23.5.2 shows that the combination of source control, efficient process technology and quality control using modern sniffing devices enables manufacturing companies also to re-use packaging plastics in direct food contact which have a higher diffusivity than PET. However, it must be realised that compared to PET recycling of polyolefines will always be of much more specific character i.e. limited to a certain first application and a relatively narrow and overseeable recovery system if it is intended to reuse the plastic for sensitive applications such as direct food contact. On the other hand recycling of polyolefine plastic crates into new ones for relatively insensitive applications, such as transport containers for fresh fruits or vegetables, is a less challenging issue and can therefore be dealt with in a more general way. Current and future technological improvements and further developments in recovery, sorting and recycling technologies will be an important basis for the expected increasing market shares of recycled polymers in the packaging area. Accompanied by increasing knowledge of possible post-consumer contaminant levels and further improving developments in analytical control systems, e.g. complete inline control of recyclate production, using appropriate sniffing devices, will enable the potential risk of exposure to the consumer of unwanted Recycling packaging materials 513