Large quantities of plastic end up in smoke or in landfills every day instead of being recycled because many companies are unable to sort several different plastics from one another. However, Thomas Trebbien and Andreas Leth Bockhoff—the two mechanical engineers behind the start-up, Trebo—will change all that with their sorting technology that makes it possible to recycle plastics more efficiently.
“We want to solve the problem of mixing plastics and change the way plastics are recycled right now. Instead of focusing on recycling companies with vast amounts of plastic and many different types that can potentially be mixed together, we’re working on developing smaller plants for production companies. This means that we sort where the plastic is generated. Among other things, this eliminates transport costs and ensures that the company has full control over its own plastics,” says Thomas Trebbien.
With Trebo’s technology, companies can thus sort their plastic waste into different fractions—thereby transforming their waste into a valuable resource. The generic term ‘plastic’ covers thousands of specific types—each with different characteristics ranging from hard plastic to paper-thin plastic packaging—two types that are incompatible in the recycling process.
Plastic sorted in liquid
Technologies for sorting plastics are far from new, but Trebo stands out by having developed a sorting machine that uses fluid mechanics. The plastic is first ground into a type of granules. It is then immersed in a liquid where it is subjected to a pre-defined movement set according to such parameters as density, shape, and size to suit the specific plastic mix.
“When plastic particles of different types are subjected to a specific fluid-mechanical movement, they behave differently—for example, one type of plastic will seek to move upwards—another downwards. If the process continues for a sufficiently long time, all the particles will eventually be completely separated into two different layers. Just like in a layer cake,” explains Christian Lundsgaard—partner and development engineer at Trebo.
The sorting process can take anywhere from ten seconds to twenty minutes depending on which and how many types of plastics are included in the mixture. The technology is flexible to different types and mixes because it sorts based on the permeable properties of the plastic.
"Sustainability is paramount for us and at the heart of our business. The unique thing about Trebo is that we have a sustainable solution which at the same time generates great value for businesses"
Entrepreneur Andreas Leth Bockhoff, Trebo
“We’re targeting a wider audience with our technology—partly because we can sort several types of plastic mixes at the same time. Competing technologies can’t do that,” says Andreas Leth Bockhoff.
Once Trebo has tested a specific plastic material flow, it can design a plant that is set exactly according to that mix. Each plant has a very specific setting to fit the flow of material at the production company.
Trebo is currently in the process of patenting its technology. For the time being, however, it is able to issue patents for its sorting technology in Denmark. The company soon hopes to get approval from the Pan-European Patent Office (EPO), so that it can issue patents in all EU countries starting from next year.
Saves money and reduces CO2
Trebo has developed the technology so that it can be easily scaled up and down—depending on the amount of plastic waste a company has. This can be anywhere from about 300 to 500 tonnes a year. Such volumes still make it profitable to sort and recycle plastics with this technology rather than sending it for combustion, which is often also associated with costs.
In addition to cutting costs, companies can also reduce CO2 emissions with a sorting plant because they avoid having to buy new plastics and sending their waste for incineration. Recycling 1 kg of plastic saves 2.4 kg of CO2—equivalent to burning a litre of petrol. This is the rule of thumb for the two entrepreneurs who are motivated by the fact that their technology may mean that more companies will reduce their carbon footprint in the future
“Sustainability is paramount for us and at the heart of our business. The unique thing about Trebo is that we have a sustainable solution which at the same time provides great value for businesses—and here it starts to get interesting,” says Andreas Leth Bockhoff.
Advanced plants can sort the same quantities of plastic, but are very expensive in acquisition and operation. This is one of the reasons why they do not suit production companies that have smaller amounts of plastic waste compared to other larger companies.
For production companies, viewing their plastic waste as a resource requires a change of mindset, say entrepreneurs Thomas Trebbien and Andreas Leth Bockhoff, who are currently in talks with several potential customers. Their work is therefore also about highlighting the benefits that companies can derive from increasing their recycling of plastic through specialized sorting. In this way, the two entrepreneurs are trying to push more production companies towards more sustainable production—and one which at the same time is economically viable.
The idea for the technology behind Trebo came about back in 2016 when Andreas Leth Bockhoff and Thomas Trebbien were both enrolled on DTU’s MSc programme, Design and Innovation. Through a hackathon, they realized how much plastic was being thrown out, sent for combustion, or ended up in the wild.
They immediately started thinking about a solution. Following a meeting with a pharmaceutical company, it became clear that plastic waste is often caused by companies producing products composed of several different plastic types that cannot be sorted properly—and which is therefore often sent for incineration. They also discovered that no one had developed an effective solution for sorting multiple plastic types at the same time—and so they set out to do just that. At DTU, they made their first model—a small tree—which ended up being a springboard for them when they became part of DTU’s innovation hub, Skylab.
“We realized we had a good idea when we joined DTU Skylab. When we presented our project and tree model, one of the managers recommended applying for funding to further develop our project,” says Andreas Leth Bockhoff.
They then sought and received support from Innofounder—part of Innovation Fund Denmark—and since then they have received a total of DKK 1.5 million in funding from various foundations. In 2017, they were ready with their first machine—and the following year they developed a larger prototype. The machine helped win them the title of Student Start-up of the Year at DTU in 2018, which gave them a confidence boost—and today they still think back on their study time as the place where it all started:
“It was crucial that we were studying at DTU while we were developing Trebo. At Skylab, we realized we had the opportunity to make something ourselves and gain insight into how to seek funding for our idea,” says Andreas Leth Bockhoff.
They also stress that it was a great help to get help from specialized DTU researchers vis-a-vis plastics and plastic sorting, which also became the central theme of their MSc thesis. And with funding, they were able to go straight from their thesis to being full-time entrepreneurs at Trebo.
“It’s been a long journey. When we finished our thesis, all we had was a product—we knew nothing about how to run a business or about finding customers. We were also in doubt about what market to enter. So starting a business in this way has been a major learning curve. We’ve really just been thrown into it,” says Thomas Trebbien.
After some years with an office at DTU and production in Hårlev in Denmark’s South Zealand, a million-kroner investment from the venture fund North-East Venture at the end of 2019 has enabled them to move Trebo to an old plastics company in Søborg in central Copenhagen, where they now have an office and production hall.
Future sorting lab
The two entrepreneurs have a clear goal—helping to eliminate all plastic waste at production companies. But despite having come a long way with Trebo since they started in 2016, they know there is still a long way to go:
“We’re constantly at a stage where we need to develop a faster and better process to achieve optimal sorting,” says Andreas Leth Bockhoff.
They are in the process of optimizing the sorting process using artificial intelligence, so that they can better predict which parameters are suitable for different plastic mixtures—and how to subsequently set the machine. They are also working with image recognition to test the quality of the plastic to ensure that the sorting is optimal at all times.
The development work means a lot to the two entrepreneurs, who soon hope they will also be able to land their first contract with a production company to install a Trebo plant as part of their factory. Andreas Leth Bockhoff and Thomas Trebbien cannot predict when this will finally happen, but a champagne bottle is waiting in the fridge for the big day.