Sorting technology for lightweight packaging

1 Problem description

The European Union (EU) is regarded as a model for the functioning recycling of lightweight packaging and the sustainable use of resources. On 11 February 2025, a new EU packaging regulation (PPWR) came into effect, which will replace the old regulation in August next year and then be binding [1]. The aim of the PPWR is to reduce the environmental impact of packaging. By 2030, all packaging in the EU must be recyclable. Within the framework of the extended manufacturer’s responsibility, enterprises and online retailers have to modify the product design and use of packaging materials to increase the recycling and reuse of packaging materials. One of the goals here is to reduce packaging weight and promote recycling. All importers of packaging and packaged products into the EU from non-member countries will have to fulfil new obligations.

Just a quick look at supermarket shelves (Fig. 1) is interesting, to get a picture of the packaging waste we generate with our shopping. And what you see on the shelves forms only a small part of the overall packaging waste as the products first have to be delivered to the supermarkets in larger packaging units. It would seem that product manufacturers design their packaging according to completely different aspects. Besides the actual packaging for stocking the products, the primary factor is an attractive design to maximize purchasing incentive. Before consumer products are launched on the market today, they are thoroughly tested to find out, for example, which attributes and variations trigger the most buying interest. Market-leading companies use, for example, neuromarketing based on the evaluation of brainwaves of test consumers in MRT brain centres.

Increasingly, ecolabels or eco-friendly packaging are used that are intended to show or suggest the manufacturing companies’ closeness to nature or climate neutrality. On packaging, for example, the wood look is not genuine, but just imprinted, cork is imitated with plastic, and packaging only consists of a small percentage of recycled paper or plastic even if the packaging itself claims something else. Products are sometimes packaged two or three times over with additional coatings and layers that not only make recycling difficult but prevent it completely. Oversize packaging misleads about the content, even though this is only allowed to a certain extent. There are, however, plenty of exceptions. One example are sophisticated chocolate boxes with limited content. But even ordinary products mislead with half-empty packaging.

2 Current situation in Europe

What will the EU’s new packaging regulation bring, and what is technically possible and financeable? Fig. 2 shows the per capita packaging generated by the population in the EU and comparable countries. The data come from Eurostat and apply for the year 2022. The year 2022 provides the EU’s current data [2], whereas for many countries, the current data comes from the year 2021 or 2019, and for other countries, the data have to be estimated. According to this, the highest specific consumption is found in Ireland, Italy, and Germany and the lowest in Cyprus, Croatia, and Bulgaria. In our view, the specific data provided for recycling must be considered with great caution. That is largely to do with the definitions. According to the narrow definition, it is meant as a material reuse of the raw materials for new products, in the picture other calculation methods are included, like, for example, waste-to-energy conversion of packaging waste.

Fig. 3 gives an impression of what quantities of packaging waste per capita of the EU population we are dealing, and how the volumes of waste have changed. According to this, the average volumes have steadily increased, from approx. 157.2 kg/per capita in 2011 to 186.5 kg/per capita in 2022. That corresponds to growth of 18.6 % or 84.3 Mta (million tonnes per annum) packaging waste in the EU in 2021 in absolute numbers. Paper and cardboard waste accounted for the largest part over the overall period: in 2022 this reached 40.8 %, followed by plastic waste with 19.4 %, glass waste with 18.8 %, waste wood with 16.0 % and metal waste, including drink cans made of aluminium, with 4.9 % and other materials with 0.2 %. The percentage shares are primarily determined from the volumes of processed lightweight packaging waste (Fig. 4). In the EU, it is currently assumed that around 80.1 % of the waste is recovered, including for waste-to-energy processing, while 65.4 % of this waste is recycled.

Fig. 5 clearly shows again the huge differences in the EU countries based on the example of processing plastic waste from packaging. With the new packaging regulation PPWR, for plastic up to 2025 in the EU an average recycling rate of 55 % should have been achieved, it being expressly defined that the plastic packaging waste should be recycled into new plastic products. As a goal für 2030, in addition, for the total packaging waste a recycling rate of 70 % has been specified. Manufacturers and users of packaging will face formidable challenges. Consumers are called upon to collect much more packaging, to separate it correctly and return it. The processing plants will also face much bigger challenges. In this article, existing and coming high-tech solutions for plant operators, engineers and suppliers are discussed.

3 Technical requirements

There are two basic preconditions for the recyclability of lightweight packaging. First packaging must be designed such that recycling is technically possible at all. That means that it is imperative not to use packaging consisting of incompatible materials or overly complex material mixes (e.g. made of multilayer plastics that cannot be separated). Second, the recycling of packaging waste requires an effective collection system and corresponding sorting systems nationwide. Even the most recyclable packaging is useless without an affordable and suitable infrastructure for collection, sorting, and processing. Fig. 6 provides an impression of how the infrastructure of ARA (Altstoff Recycling Austria) is designed, and which collection and recycling rates have so far been achieved and are planned for the future. For an 80/80/80/ solution, only 51.2 % of the materials generated are reutilized, including thermal processes.

For the recycling of drinks containers, in Europe and other countries, deposit-driven return systems (DRS) have been established and worked effectively for a long time. Such a system could be transferred to other products to create incentives for consumers to make the collection and return of packaging worth it for them personally. Für deposit bottles, well-developed deposit return systems achieve collection rates of more than 90 % [3]. The percentage of drinks containers in the total waste in regions with deposit systems is 66 % lower than in regions without deposit systems. In Europe, deposit systems reach an average collection rate of 87 % for PET bottles for recycling, compared with other recycling systems, which average just 50 % (Fig. 7). In the USA, 72 % returnable containers are collected für recycling, compared with 27 % for non-returnable containers.

There is no one concept for collection, processing, and recycling of packaging. Here we want to address only fully automatic solutions. The most important technical differences are in how far the packaging is specific and is delivered either as a colourful mix of materials or as a specific plastic waste or similar. We also want to factor out municipal solid waste (MSW), which contains packaging waste as single constituents, and exclusively address the specific applications and the sorting of the materials. To be able to automatically sort the different types of plastic/polymers, aluminium, tin plate, or composite materials, like, for example, drink cartons, different technical systems are necessary, such as shredders, drum screens, air sifters, eddy current and metal separators, and specific sorting processes.

Fig. 8 shows an illustration of a sorting plant at Indaver in Belgium. Here, LVP packaging waste is sorted into no fewer than 16 fractions. The arrangement of the machines guarantees a particularly high quality of the end-products. The feed material passes a bag opener and a drum screen for the removal of small parts like bottles and screw tops. Magnets and eddy current separators are used to recover any metals. Air sifters separate plastic films from the packaging waste. Delabellers remove labels. Infrared separators then sort the films by type and density. The heart of the sorting plant are optical separators. They separate the plastics with the help of a combined material and colour identification. In this way, the materials are separated in line with the high standards required by the recycling industry. After a subsequent final manual check, the recovered fractions are pressed into bales.

4 Sorting technology

The leading plant engineering companies offer tailored sorting concepts and solutions, which are specially designed to meet the challenges involved in sorting of low-value packaging. With the EU’s recycling goals for packaging waste and to improve the quality and value of the sorted fractions, the requirements for quality and condition of the sorting plants are also rising. This pertains especially to the different plastic fractions that must be separated. If it is not possible to separate the plastics by different polymers and in some cases certain colours, the materials are not suitable for downstream recycling, but, for example, are only in some cases suited for pyrolysis plants or have to be sent to waste-to-energy plants. The requirements for the sorting qualities and yields of the sorted fractions are therefore increasing to enable their targeted sale.

The actual sorting of the packaging waste in paper, plastic, aluminium, tin, or composite materials is no longer the problem (Fig. 9). The challenge is sorting by plastic types and colours. For PET bottles and trays, progress has been made over a relatively long time, one problem is the much greater soiling of the trays. What has already been achieved for PET so far is now also to be realized for materials made of polyolefins (PO), polypropylene (PP) and polyethylene (PE) and here especially films, bags, carrier bags and bottles made of LDPE and HDPE as well as beakers and bowls made of polystyrene (PS). The recovery of black packaging containing recoverables (e.g. plant pots made of polyolefins, PE/PP) is another challenge. The goal is to recover the individual fractions with high purities of 95 % and more to enable the production of high-value recyclates (PCR).

With the example of sorting solutions from Steinert (Fig. 10), the complexity of the requirements can be clearly recognized. The Unisort PR EVO 5.0 and the Unisort Film Evo 5.0 model generations are here the standard machines for plastics sorting and stand for high operational reliability and availability. A new technology (Active Object Control) from UniSort Machines controls the behaviour of the material on the belt conveyor and, in combination with intelligent sensor-based technology, guarantees high capacity and sorting reliability at a belt speed up to 4.5 m/s. This is available for working widths of 1000 mm, 1400 mm, 2000 mm, and 2800 mm. Artificial intelligence (AI) technology enables sorting on a higher level based on other optically scanned characteristic properties like impurities. At Steinert, colour and near-infrared sensors (NIR) are combined with Hyper Spectral Imaging (HSI) technology.

A similar AI technology is applied by TOMRA (Fig. 11). The Autosort™ technology uses learning-based object identification for the automation of complex sorting applications and outperforms conventional optical methods. Modern sensors with near-infrared technology (NIR) differentiate between food-grade and non-food-grade materials. This leads to a higher material purity and reduces the manual sorting requirement. With the Autosort™ Flake sorting system (Fig. 12) from TOMRA, flakes can be sorted by polymer, colour, and transparency. The flexible set-up enables easy configuration for various plastic applications, including the separation of PET and PO flakes into high-grade PP and PE fractions. With this, contaminated mixed plastics can be processed to high-purity fractions for saleable recyclates.

5 Typical plants

5.1 PreZero, sorting plant, Eitting/Germany

In 2022, the environment service provider PreZero started up operation of a state-of-the-art sorting plant for lightweight packaging in Eitting. PreZero is a company in the Schwarz Group, which is investing around € 40 mill. in the plant. At the facility just outside of Munich, 0.12 Mta lightweight packaging from the yellow bin bag collection is processed (Fig. 13). In the sorting process, state-of-the-art technology from Stadler Anlagenbau is used. The collected packaging material is sorted into a total of 18 different fractions. These include plastic types, polypropylene, polyethylene terephthalate (PET), polyethylene and polystyrene. Unlike at other plants, the respective fractions can additionally be sorted by colour. With the help of black scans, black plastics are identified, which cannot be sorted in conventional plants. The plant is in operation around the clock on 365 days a year.

5.2 Hündgen Entsorgung, sorting plant, Swisttal/Germany

Handling an annual waste volume of 270 000 t, Hündgen Entsorgung in Swisttal near Bonn is one of the biggest single sites for processing lightweight packaging. With a new innovative sorting plant (Fig. 14), the family-owned company has responded to the stricter packaging regulation. The sorting systems use state-of-the-art technology and increase the yield of unmixed, material recoverables and plastics. The hourly processing rate is 15 t lightweight packaging with capacity for further increases. With the UniSort line from Steinert, the lightweight packaging is separated with the help of near-infrared technology into the different groups of recoverables. These include polyethylene, polypropylene, polystyrene, and black plastics. Moreover, PET bottles and trays, drinks cartons as well as PE/PP films, paper, cardboard, and card and mixed plastics are also separated.

5.3 Indaver, sorting centre in Willebroek/Belgium

At its recycling centre in Willebroek, Indaver sorts selectively collected household packaging waste, better known as LVP packaging, metal packaging and drink cartons. This waste includes all forms of plastic packaging like bottles, containers, hard plastic packaging, bowls and plastic films, metal packaging like tins, aluminium trays, drink cans, spray bottles and drink cartons. For the collection and recycling of packaging waste in Belgium, FOST plus is responsible. Indaver operates the sorting centre (Fig. 15), which processes 65 000 t LVP annually. With optical sensors, the waste is separated into a total of 16 fractions, 11 of these pertain to various polymers and colour variants and five different other packaging materials. Aluminium plastic bags (crisp bags) can be separated but cannot yet be recycled.

5.4 Interzero, recycling centre in Marl/Germany

In Germany, Interzero currently operates five of the ten largest sorting plants for lightweight packaging (LVP) and mixes of recoverables. At these plants, the company specializing in environmental and process engineering sorts around 33 % of the lightweight packaging generated across Germany with a total sorting capacity of 0.81 Mta. This is the biggest sorting capacity of any company in Europe. The Marl site (Fig. 16) has a plant capacity of 0.2 Mta. There, primarily plastic packaging made of polyethylene (PE) and polypropylene (PP) is processed to unmixed recyclates. The finished regranulate Procyclen can be individually adapted to meet the requirements of customers from the plastics processing industry, In the various recycling plants, a wide range of fractions and polyolefins are processed to unmixed recyclates. The focus here is on LDPE, HDPE, PP, PET, and EPS.

5.5 Vaersa, Sorting plant Alzira/Spain

In Aluzira, near Valencia, Vaersa, a publicly owned enterprise, operates one of the biggest sorting plants for lightweight packaging in Spain. Following a complete modernization and switch to largely automatic operation in 2024, it proved possible to increase the plant capacity from 3 t/h to 8 t/h. The rebuilt compact processing line (Fig. 17) now offers state-of-the-art sorting technology without any compromise in respect of operation, capacity, and efficiency of the plant. The sorting process takes place in two sorting cabins and ballistic separators, magnetic and eddy current separators for the ferrous and non-ferrous fractions as well as optical separators that identify recoverables. The output material is separated into the fractions PET, HDPE, film, Tetra Pak, mixed plastics, ferrous and non-ferrous metals. At the end of the process, the recovered materials are pressed into bales and transported to recycling operations.

5.6 RE Plano, sorting plant in Bochum/Germany

RE Plano, a subsidiary of the Remondis Group, is aiming to replicate the good results achieved in the recycling of PET for the materials polyethylene (PE, HD-PE) and polypropylene (PP). At the plant in Bochum, an AI-based sorting technology supplied by Steinert is paving the way for new closed-loop applications for the especially difficult-to-sort plastic fractions. To operate the plant cost-effectively, it is important to sort plastic fractions that often remain unseparated because it is difficult to distinguish between them, like white and natural-coloured plastics as well as single and multi-layered packaging, by type and colour of the plastic. The AI-based technology combines colour and near-infrared sensors (NIR) with Hyper Spectral Imaging (HSI) technology. Here, fractions with purities in excess of 97 % have been achieved, these are pressed into bales (Fig. 18) and then processed to recyclates.

5.7 Henkel, product laboratory in Dusseldorf/Germany

As an internationally renowned manufacturer of brand products for the consumer goods and adhesives industry, Henkel is pressing ahead with improving the sortability of its packaging. In its test laboratory, the company has installed a TOMRA Autosort^TM scanner (Fig. 19) to test future packaging prior to the introduction on the market in order to ascertain whether they exhibit useful properties for easy sorting and recycling. The scanner is equipped with a near-infrared and a VIS sensor. With the help of this combination of sensors, the machine recognizes not only the type of material of the product, e.g. plastics like PP, PET, HDPE, or paper, but also the colour of the packaging, which can be crucial for effective sorting. The system has so far been installed in around 100 countries worldwide and enables Henkel, to obtain results quickly and easily for the selection of packaging.

6 Outlook

Despite stringent requirements for lightweight packaging, the EU is still far from achieving high rates for the reuse of waste and a real recycling economy. Worldwide, the situation is better only in few countries, e.g. in Japan. One of the biggest problems is the inadequate recyclability of many types of packaging along with nationwide collection rates that are still too low. This is to be improved considerably by 2030 with the new EU packaging regulation. There is, however, only little in the regulation regarding the sorting plants needed to reach the ambitious goals for the specified sorting volumes and qualities. The plants can only be operated cost-effectively if sufficient fractions of sorted material with purity contents of over 95 % are reached [4]. The plant engineering companies are offering solutions to achieve this level, but that costs money and, in our view, it would be necessary for policy makers to create more clear financial incentives to enable their realization.