(CNN) – What do old televisions, traffic signs, motorcycle helmets, windsurfers, and Christmas trees have in common? They were all caught floating in Amsterdam’s Westerdok canal… by a curtain of bubbles.
The “Bubble Barrier” or “bubble barrier” was developed as a simple way to stop plastic pollution flowing from canals into the ocean. An air compressor sends air through a perforated tube that runs diagonally across the bottom of the channel, creating a stream of bubbles that traps the debris and leads it to a catchment system.
According to Philip Ehrhorn, co-founder and CTO of The Great Bubble Barrier, the Dutch social company that created the system, it traps 86% of the trash that would otherwise go to the IJssel River and the North Sea.
At the request of the municipality of Amsterdam and the regional water authority, the bubble barrier was installed in October 2019 in less than five hours.
Ehrhorn says the idea is to trap the plastic without having a physical barrier like a net or a plume blocking the river, which could disrupt aquatic life or interfere with shipping.
The residues are brought to the surface and led to a collection system.
To minimize noise, the compressor is located 50 meters from the barrier, in a reused shipping container, and is powered by renewable energy from Amsterdam.
Ehrhorn says that while the bubble curtain can trap plastics up to one millimeter in size, the capture system only holds objects 10 millimeters or more. Drifting small aquatic species can become trapped in the bubble curtain current, Ehrhorn says, but can eventually pass through the catchment system. He adds that an independent third party is currently evaluating the movement of the fish around the bubble barrier.
“Like a jacuzzi”
Ehrhorn, of German origin and with a background in naval architecture and ocean engineering, first devised the “Bubble Barrier” when he spent a semester in Australia studying environmental engineering. At a wastewater treatment plant, he saw oxygen bubbles being used to break down organic matter.
“It was like a hot tub,” says Ehrhorn. “And what I observed is that some of the plastic that people had flushed down the toilet was accumulating in a corner.” This observation gave rise to his thesis and, later, to the technology behind the “Bubble Barrier”
Unbeknownst to Ehrhorn, three women from the Netherlands were working on the same idea in Amsterdam. Anne Marieke Eveleens, Saskia Studer and Francis Zoet were in a bar discussing plastic pollution one night when they observed the bubbles in their beer glasses and were inspired.
By chance, a friend of Ehrhorn’s saw his presentation video for a contest calling for solutions to eliminate plastic from the environment.
“We connected and found we had the same vision and mission,” Ehrhorn recalls. “So I submitted my thesis and moved to the Netherlands the next day.” Together, the four turned a simple idea into a pilot project for the bubble barrier on the river IJssel in Amsterdam.
The plastic problem
It is believed that up to 80% of plastic of the oceans comes from rivers and coasts. According to Ehrhorn, much of the plastic in Amsterdam’s Westerdok canal comes from garbage bags that residents leave outside their homes. If the bags break, the wind and rain can wash the trash into the gutter.
Around the world, 11 million metric tons of plastic waste reaches the oceans each year, where it can suffocate and trap some aquatic species. Plastic debris less than five millimeters long, known as microplastics, can also affect marine life. Microplastics, which are often mistaken for food, are ingested and have been found in zooplankton, fish, invertebrates, and mammalian digestive systems.
Seabird conservation ecologist Stephanie B. Borrelle is BirdLife International’s Regional Coordinator for the Pacific and Sea. Your investigation on plastic pollution has revealed that, even with “ambitious commitments currently set by governments,” we could release 53 million metric tons of plastic waste into the world’s freshwater and marine ecosystems by 2030.
As a member of the Working Group on Plastic Pollution Emissions, a team of “scientists, policy experts and conservation professionals,” Borrelle has also investigated the so-called “Bubble Barrier.”
“It was very interesting for us to study it, especially because other types of barriers placed in aquatic environments can be a bit problematic because of the way they interact with ecological functioning and the animals that move through that system,” he says.
Borrelle has some reservations about the technology; He wonders how well the system would be suitable for wide rivers and developing economies, with a pump that needs continuous electricity and occasional maintenance, and notes that the bubbles might not lift heavy pieces of plastic.
“In addition, if there is a lot of traffic, the accumulation of plastic will be affected,” says Borrelle, adding that ships passing through the barrier could drag the plastic.
“There are certain limitations, but, in my opinion, it is an important part of the tools we have to deal with the plastic that is already in the environment,” he says. “The thing about plastic pollution is that there is no single solution to fix it. Once it’s in the environment, it’s about trying to eliminate it from every possible angle. “
At the moment, The Great Bubble Barrier team is working with the Amsterdam water authority and the NGO Plastic Soup Foundation to analyze what type of plastic has been captured and identify its sources, to help develop new policies around waste. plastics.
The Amsterdam water authority empties the 1.8 by 2 meter basket from the catchment system three times a week. The content is sent to a waste processor for sorting, and the appropriate materials are recycled. Ehrhorn says that due to the pandemic, they have not been able to measure the amount of plastic their “Bubble Barrier” has trapped to date.
The for-profit company plans to install more bubble barriers in the Netherlands, Portugal and Indonesia. The company claims that the cost of installation and energy use depend on the location and flow of the river.
In addition to removing plastic from our oceans, the system could help change attitudes. Since the waste within the catchment system is easy for passers-by to see, Ehrhorn believes that it helps people realize the amount of waste that ends up in our waters; thus, the barrier also acts as an educational tool to discourage waste and litter.
“It focuses on trash that would otherwise flow unseen and even under water,” he says. «It literally brings out [aquello] that otherwise would never be seen.