The five plastic hotspots of the high seas – the ocean gyres where marine debris accumulates – tend to get most of the attention, but in the semi-enclosed Mediterranean Sea, the problem of plastic pollution is similarly severe. Estimates show that the Mediterranean, with its heavily populated coastal areas, has among the world’s highest concentrations of larger pieces of plastic debris. In the Baltic Sea, off Europe’s northern coast, microplastics are also rapidly accumulating.
That’s why the European Union is funding the majority of a new $7.1 million (6 million euro) research collaboration to test and scale up new technologies to intercept plastics before they enter the Mediterranean and Baltic seas. The four-year project, called CLAIM (Cleaning Marine Litter by Developing and Applying Innovative Methods), involves 19 research and business partners across 15 countries.
The research effort comes as countries agreed to a non-binding resolution to eliminate ocean plastic pollution at a November meeting of the United Nations Environment Assembly. While the resolution established no timelines or firm targets, the agreement paves a path to explore a legal treaty that will reduce plastic pollution. The European Commission is also in the process of drafting a broader strategy to improve recycling and cut marine litter.
The goal of CLAIM, said project co-coordinate Nikoleta Bellou, a marine biologist at the Hellenic Centre for Marine Research in Greece, is to move technologies to reduce plastic pollution out of laboratories and into real-world use. Wastewater treatment plants were a logical place to start.
Of the 5–12 million metric tons of plastic entering the marine environment in a single year, much of it is microplastics and microfibers, which are washed down sink drains and shed from clothing. These plastics are so small that they’re hard for wastewater treatment plants to filter out using existing technologies.
Researchers are now working to develop better filters to remove microplastics at wastewater plants and will also develop a photocatalytic device intended to degrade even smaller nanoparticles of common plastics like PVC, nylon or polypropylene in the water. While ultraviolet radiation breaks down plastic, it’s usually a very slow process, Bellou said. The photocatalytic device, which is being developed in collaboration with French wastewater treatment operator Waste & Water, will use nanocoatings that can essentially jump-start the reaction. Though the device is still only in the research and development phase, the team aims to get it ready for testing within the project’s time frame. In the far longer term, she believes similar technology could even be used in homes.
Another team partnering with CLAIM is working on a small-scale pyrolyzer, which uses a thermal-chemical process to convert plastics into a combustible gas and recyclable waste. The idea would be to mount the device on boats, which could collect and break down plastic on the go. The team at IRIS, an Italian startup behind the project, says a big benefit is that pyrolysis doesn’t produce dioxins and furans, both toxic compounds that are usually released if plastics are burned. The excess heat and combustible gas produced by the process, called syngas, can be used on the boat and at port to generate electricity or heat water.
The company plans to demonstrate the device on a vessel provided by Greek company New Naval and at a small fishing port in Denmark, said Ilaria Schiavi, an engineering research and business development specialist at IRIS.
New Naval, a company that specializes in equipment for cleaning up oil spills, is also working to test booms – floating barriers – that can be placed near the mouths of rivers or wherever wastewater is released. Deploying various sizes of mesh screens, they’re designed to trap debris already in the water and prevent it from floating further out.
Overall, for every technology being developed through CLAIM, the focus is on proving economic feasibility, social acceptance and encouraging adoption, Bellou said. However, she believes that stronger government policies will eventually be needed before the private sector will truly take on the plastic pollution problem. “There’s always conflict of who’s responsible for what, especially because the seas … don’t have borders,” she said.
Some environmentalists are cautious about embracing the kinds of solutions being tested through CLAIM’s work. Abby Barrows, a microplastics researcher with the nonprofit Adventure Scientists, said the focus on removing plastics from wastewater is important, but she worries about technologies that further enable “continuous management” of plastic pollution, rather than reducing its use in the first place. It’s also important, she said, to think about the energy consumption and potential environmental consequences of new treatment and filtration technologies themselves.
“We all need to be working together toward solutions, [and] cleaning up pollution is part of moving forward, but we also really need to rethink our use of disposable plastic, as well as the design of synthetic textiles,” she said.