Five years ago, Claar-els van Delft noticed plastic trash on the beach in Katwijk, a small Dutch coastal town where the Oude Rijn (Old Rhine) flows into the North Sea.
"There's all sorts of plastic trash around the estuary, everything from tampon applicators to brush bristles to potato chip bags to drinks packaging," said Van Delft, co-founder of the local group Coast Busters. He believes the trash isn't discarded by tourists or drifting into the sea, but rather comes from the nearby estuary.
In 2018, the local community launched an action to block marine plastic, gaining support from neighboring governments and residents, as well as commercial sponsorship. In July 2022, Katwijk successfully completed its first community-led bubble barrier, using bubbles and water flow to intercept trash in the river. This was also the first bubble barrier to be installed within one kilometer of a river's entrance to the sea, effectively serving as a last line of defense before trash reaches the sea.
Bubble Pusher - garbage in the river is concentrated and does not affect shipping
Bubble walls are not new. They've been used in the past to reduce the spread of oil spills at sea, and the offshore wind industry has also employed them to reduce noise levels. This time, they're being applied to collect marine debris.
"By placing perforated pipes at the bottom of the river and pumping compressed air through them, bubbles are generated. As these bubbles rise, they push plastic fragments to the surface. Combined with the water flow, these fragments are concentrated together," explained Philip Ehrhorn, technical director of the Dutch startup The Great Bubble Barrier.
The Big Bubble Interceptor team used this concept to win the 2018 Postcode Lottery Green Challenge and completed its first permanent experimental station on an Amsterdam canal in 2019.
Source: Environmental Information Center (https://e-info.org.tw/node/234789)
