‘Incredibly promising’: the bubble barrier extracting plastic from a Dutch river

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Five years ago, Claire-Els van Delft began to suspect that the plastic waste at the beach in Katwijk in the Netherlands came not from visitors, or the sea, but from a nearby river mouth.

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“We started picking up garbage and we saw, near the river entrance, pieces coming from fresh water – all kinds of plastic,” she says. “The tampon sheath, the brushed bristles, but the crisp package, the beverage package, everything.”

Sure enough, when the volunteers looked through an oil drum filled with water from the Aude Rijn river, they saw tiny plastic particles in the middle of the muck. “We saw so much pollution, we were shocked,” says Van Delft, co-founder of the local charity. Coast Busters,

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How Bubble Barrier Works

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Fast forward to July 2022, and Katwijk is the site of the world’s first river”bubble barrier“- an experimental concept where a 120-metre stream of rising bubbles, as well as a stream of water, pushes plastic waste aside to be collected.

“We place a perforated tube at an angle to the bottom of the waterway, and then pump compressed air through: the rising air bubbles create an upward stream that propels the plastic from the water column to the surface and then back to the surface.” will lift – together with the flow of the river – it is all pushed aside,” explains Philipp Ehrhorn, chief technology officer at Dutch startup The Great Bubble Barrier. “Here, we get the flow from the pumping station, or the wind can even push the waste into the catchment system.”

Driven by a team of keen sailors, surfers and water enthusiasts, the company won an international Postcode Lottery Green Challenge In 2018 and the following year launched its first permanent pilot in a canal in Amsterdam. Such is the promise of the trial that it has convinced the Rijnland Water Board, 12 municipalities and the Holland Rijnland and Zuid-Holland regions as well as coast busters and local fundraisers to invest €470,000 for its construction . river bubble barrier.

Plastics removed from waterways are sorted as part of the barrier bubble study. Photograph: Cynthia Van Elk / The Great Bubble Barrier

Jaco Nape, deputy mayor of Katwijk Municipality, said he saw the local plastic problem with his own eyes when he was invited to clean up litter on the beach. “Plastic pollution is a growing problem around the world, affecting communities as well as the environment, [and] Unfortunately Katwijk is no exception,” he says. “We see plastic pollution by visitors to the beach, leaving wrappers and other plastics behind, but we’re the last stop before all the plastic collected along the Aude Rijn. are also. flowing into the sea, With this bubble barrier, we can stop those plastics.”

Bass Knapp, an executive board member of the Regionland Water Board, believes the bubble barrier will not stop fish migration, and is investing €42,000 a year to drive it. “We conducted a test which showed that in the pumping station, only one of the 233 pieces of plastic larger than 1 mm is removed from the water. [by its filter]”But with the bubble barrier, we expect between 86% and 90% of the plastic pollution to be removed. One test was incredibly promising. It’s one of our biggest river estuaries,” he says. , and a really good place to put a promising pilot to work trying to reduce ocean-going plastic.”

Anne Marieke Avalance, co-founder of The Great Bubble Barrier, is working on scaling up the technology, discussing a potential barrier in an estuary in Portugal and another project in Southeast Asia. “One of the requests we sometimes get is for a big international port like Rotterdam – there, it’s 20 meters deep but that’s [currently] Out of scope,” she admits. “It’s also difficult if there are a lot of ships, and they’re dredging several times a year.”

But many believe the technology still has real promise for specific scenarios. Dr Frans Bushman, a researcher at the independent Institute for Environmental Hydrodynamics at Deltares, has tested the barrier in Amsterdam using about 1,000 tagged tangerines. “We released them at several points and counted how many were caught,” he says. “It was up to 90% from the catchment system side; Sometimes on the other hand we saw that it was quite low, probably because there is a place where the intensity of the bubble is not that high, and some tangerines were passing by. ,

He adds that objects that were completely floating could be blown over the bubble barrier by air, making it less effective, but he believes it is still a “promising technology”. . [with] great potential”.

The concept of the Great Bubble Barrier is in operation in Amsterdam.
The concept of the Great Bubble Barrier is in operation in Amsterdam. Photograph: The Great Bubble Barrier

However, some researchers suggest that The plastic of the river does not necessarily end in the seaalthough they can still harm ecosystems and human livelihood. River systems also differ, says Tim van Emerick, assistant professor in Wageningen University’s Hydrology and Quantitative Water Management Group. “When thinking about rivers globally, imagine how widely they can vary, from narrow canals in Amsterdam and Leiden to great deltas like the Mekong,” he explains. “Most technical solutions, such as bubble barriers, only cover a range of them, emphasizing that there will always be a need for a solution portfolio. Of course, consuming less plastic and polluting doesn’t matter. Where you go, and that can really have the biggest impact.”

Back in Katwijk, there are plans to build a visitor and education center next to the bubble barrier to make this happen, and expectations are running high. Under the summer sun, a stream of gentle bubbles breaks the surface of the river, like a jacuzzi. “We were looking forward,” says Van Delft, quite seriously, “to come to the opening in a swimsuit!”


Source: www.theguardian.com

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