Stopping the plastic before it gets to the ocean

Baltimore’s ‘Trash Family’, Ocean Cleanup’s ‘Interceptors’, and Amsterdam’s ‘great bubble barrier’ are all ways to cut the amount of plastic trash flowing into the world’s oceans, developed by people who saw a problem and imagined simple, elegant and practical solutions which they then worked to put into effect. 

Back in 2008, when researchers were only starting to look at the problem of plastic pollution in the world’s oceans, Baltimore sailor and engineer John Kellett got tired of seeing a river of trash flow into the city’s inner harbour after it rained. The machine he sketched out, powered by an old-fashioned water wheel, has grown into a family of “Trash Wheels” which catch trash, generate electrical power, attract tourists, and have inspired similar ideas elsewhere.

The Dutch technology nonprofit, Ocean Cleanup, has set the ambitious goal of turning off the tap — the 1,000 of the world’s rivers that send 80% of the plastic pollution into the ocean. It started out to clean up the Great Pacific Garbage Patch, and then worked secretly to tackle the problem at its source – in rivers. Eleven of its solar-powered Interceptor vessels now catch plastic from rivers before it enters the ocean – in Indonesia, Malaysia (2), Viet Nam, Dominican Republic, Jamaica (4) and Los Angeles in the US.

The “Great Bubble Barrier” uses a curtain of bubbles to stop trash flowing into the ocean in two Netherlands cities and soon Portugal and Germany. Its origin story involves an Australian water treatment plant, bubbles in beer, a German ocean engineer, and three Dutch sailors who were tired of seeing trash in the ocean.

Phillip Ehrhorn, a German naval architect and ocean engineer, was visiting an Australian water treatment plant in 2015 when he saw that when water was aerated, small pieces of plastic collected in one corner. He wondered if it might be possible to guide plastic that way in a river.

At the same time, in Amsterdam, beer bubbles inspired sailors Anne Marieke Eveleens, Francis Zoet and Saskia Studer to imagine a curtain of bubbles that sifts out waste but lets fish and boats through. With the help of a €500,000 Postcode Lotteries Green Challenge award and other prizes, they worked on the idea together.

Air is pumped through a tube with holes that is installed on the riverbed, powered where possible by renewable energy. The wall of bubbles pushes plastic to the surface, into a catchment system and ready to be collected. Increased oxygen levels also stimulate the river ecosystem and stop the growth of toxic blue algae.

In 2017, they created a 10-m prototype and, later that year, successfully installed a 180-m pilot in the Ijssel River, which showed that it could divert about 86% of flotsam. 

In 2019, with the Amsterdam municipality and the regional water board, they installed the first long-term Great Bubble Barrier on Amsterdam’s Westerdok canal, aiming to supplement the canal dredging operations. Once collected separately, the bubble barrier waste is analysed by plastics action group Schone Rivieren (Clean rivers).

“The bubble barrier will mean fewer plastics reach the ocean, and is a step towards better regulation of our ecosystem, to the benefit of man, beast and environment,” Marieke van Doorninck, head of sustainability for Amsterdam council, told the Guardian.  Bianca Nijhof, managing director of the Netherlands Water Partnership, who organises the Amsterdam International Water Week conference, said: “This special relationship with water combined with an entrepreneurial mindset mean that innovation is at our core,” said Bianca Nijhof, managing director of the Netherlands Water Partnership, who organises the Amsterdam International Water Week conference. “The bubble barrier is one solution for clean water for all.”

Great Bubble Barrier

The second Bubble Barrier in the Netherlands began in 2018 as an initiative of concerned citizens called Coast Busters, in the municipality of Katwijk. “Every year, more than 1 million pieces of plastic end up in the North Sea at Katwijk,” says Claar-Els, one of the Coast Busters. “That amounts to more than 2 tonnes of plastic which poses a great threat to our ecosystem and our food chain.” 

The Coast Busters got regional backing for a long-term solution via a partnership with the Katwijk municipality and regional water authority Hoogheemraadschap van Rijnland. “The problem is being tackled locally but has a broader effect: plastic pollution from the entire region upstream will be stopped,” says Emile Jaensch of Holland Rijnland. “A perfect example that shows that together – government, partners and residents – can make a difference,” adds Katwijk councillor Jacco Knape.

“Thanks to the bubble screen, we ensure that plants and animals are protected from plastic pollution and therefore contribute to increased biodiversity,” says Waldo von Faber of the Rijnland Water Board. “We are particularly proud to see communities empowered to take action and reaching out to us like the Coast Busters” comments Anne Marieke Eveleens, Co-Founder at The Great Bubble Barrier. “It really shows the power of collaboration to solve plastic pollution.”

The Great Bubble Barrier was a finalist for the 2022 Earthshots Prize and is expanding to Germany and Portugal. The new barrier in Portugal is co-funded by the EU as part of project MAELSTROM, a consortium of 14 European parties which aims to implement innovative and environmentally sustainable technologies to intercept and remove litter from rivers and the seabed. Two of the rivers with the highest levels of plastic pollution in Portugal are in the Porto region.