Systemic methods of resource-efficient management
The Green Deal marks an important move by the EU to do more in terms of sustainability: The EU Member States want to be climate-neutral by 2050. One important element of this is the circular economy, which entails turning waste back into recyclable materials. Sounds like a good idea, but it usually requires practical measures to convert materials. Waste materials are only really recyclable if they are easy and inexpensive to process and convert back into usable products. The extent to which waste is also of value after use basically depends on the quality of waste materials and the methods used to process them. Resource Technology and Management, the Steinbeis Transfer Center in Halle, is working on a number of issues relating to recycling, renewable raw materials, and regenerative energy systems.
A genuine zero-waste strategy keeps a variety of factors in mind – how products are developed, how they are made, but even before that: how they can be recycled after use. It must be possible to estimate the effort required to reprocess materials, and this should be one factor that is considered when designing products.
Under the German Packaging Act, 63% of packaging plastics must be recycled by 2022. Currently, however, more than half of all collected plastic waste is still recycled for energy production or simply exported. This means that each year, roughly 5.35 million metric tons of post-consumer plastic waste is collected. 2.06 million tons of these materials enter the recycling chain. This does not mean that they are used to produce new materials, however. After exports, some of which end up in unknown places, 1.33 million tons of post-consumer waste goes to recycling companies each year. They use the materials to produce 1.02 million tons of recyclates (materials or objects made from recycled materials).
It’s worth mentioning PET bottle recycling at this point. Because bottles are collected through the store recycling system in Germany and sorted by type, almost 100% of PET bottles can be processed into recyclates. The same applies to post-industrial waste (e.g. offcuts from production lines), providing access to a further 0.93 million tons of recyclates. Achieving the high recycling rates of dedicated PET waste bottle systems is impossible for most forms of post-consumer waste, such as household waste collected through the German “yellow garbage can” program.
Because of the large number of impurities – from use, collection, or plastic being comprised of an unmanageable mixture of substances – it is difficult to produce clearly defined, single-variety recyclates. It takes a great deal of effort to sort and clean waste, yet processes still result in large volumes of residual materials that cannot be recycled. In certain areas – such as packaging that comes into contact with food and products subject to tight technical requirements or warranty issues – it is rare for recyclates obtained from waste to be considered for use in materials.
Currently, one option for sidestepping this is chemical recycling, which makes it possible to convert contaminated plastic waste into virgin plastic. Even ignoring this option in the recycling rates stipulated under the German Packaging Act, many companies are trying to adopt international approaches to thermochemical processes.
So is chemical recycling a universal solution?
As part of a study funded by the German Federal Environmental Foundation (DBU), Merseburg University of Applied Sciences has been examining these issues in collaboration with Resource Technology and Management, the Steinbeis Transfer Center. The project team examined two processes in order to investigate the extent to which they also deliver good products using real waste.
The study highlighted major technological challenges. Among other things, interference is caused by all kinds of deposits, corrosion, and waste processing. Processes are significantly more complex than mechanical recycling, and technical and commercial risk should not be underestimated. Experiments showed that even low impurity levels can have a major impact on the chemical recycling process, jeopardizing the economic viability of operating a plant based on thermochemical conversion.
In addition to robust, technical processes, the actual composition of plastic waste will also play a decisive role in establishing a resource-efficient circular economy and achieving economic viability. In the same way that single-variety plastic waste makes it easier to achieve effective mechanical recycling and produce high-quality regranulate, being able to determine the makeup of plastic waste makes it possible to operate chemical recycling efficiently.
Access to (ideally pure) plastic waste streams for mechanical and chemical recycling can be improved by ensuring products are produced according to design requirements aimed at enabling efficient recycling (design for recycling [3, 4]) and by ensuring waste is subsequently collected and sorted as extensively and as carefully as possible. There are also other measures that would help promote the Circular Economy (e.g. [5, 6]).
The Steinbeis experts were not surprised by the results of the study – they are generally applicable to any aspect of doing business and saving resources. If you run an orderly household and keep things neat and tidy, it’s a lot less effort looking for things and cleaning them when you need them. If it’s easy to distinguish one item from another and keep items separate, ideally it just takes one motion of the hand to reuse things. This is a trite comparison based on everyday life, but it is tremendously important when it comes to establishing a circular economy.
Under certain circumstances, recycling rates can be improved by adapting existing product and process requirements, such as changing the appearance of products or functional aspects, by optimizing cost structures in manufacturing, or by offering the convenience of one-for-all garbage cans.
On a fundamental level:
- The simpler a product in terms of fabrication (few components or substances) and the easier it is to take products apart according to component type, the easier it is and the less effort is required to clean, separate, and reuse them
- The higher the quality of waste, the more effectively residual value can be preserved through recycling
- Reusing materials, for example through repair and deposit systems, is preferable to recycling (waste hierarchy)
- The easier it is for consumers to distinguish between and dispose of different types of waste and the more incentives there are to do so properly (money-back programs), the fewer materials are disposed of incorrectly or illegally
- The more accurately materials are collected and/or sorted by type, the more uniformly materials can be processed, traded, and made available to recyclers and processors in order to establish closed-loop material cycles
Recycling and production companies can thus confidently draw on a broad and defined selection of materials in order to make more recyclable products out of materials again, as is basically already the case with PET bottle recycling. This would mark an important step in achieving a genuine circular economy.
As part of the study conducted for the DBU, Merseburg University of Applied Sciences and the Resource Technology and Management Steinbeis Transfer Center have published a list of recommendations for the chemical recycling process in Steinbeis Edition:
Mathias Seitz, Valentin Cepus, Markus Klätte, Dirk Thamm, Martin Pohl
Evaluation under Real Conditions of Thermal-Chemical Depolymerization Technologies (Decomposition Processes) for Recycling of Plastic Waste
2020 | E-book (pdf) | ISBN 978-3-95663-234-1 | free
Available at www.steinbeis-edition.de/shop
Prof. Dr.-Ing. Mathias Seitz (author)
Freelance project manager
Steinbeis Transfer Center Resource Technology and Management (Halle)