Treehugger Tuesday

From the website Mother Nature Network:

Ocean Cleanup mission takes aim at rivers
Mary Jo DiLonardo
October 28, 2019, 4:04 p.m.

Boyan Slat's plastic-free dream is taking shape.

The group behind the mission to rid our oceans of plastic has opened a second front in the war by pulling plastic from the world's most polluted waterways before it gets to the ocean.

The Ocean Cleanup team unveiled a group of Interceptors, which are currently in operation on two rivers in Malaysia and Indonesia. By their estimate, roughly 80% of the world's plastic reaches the ocean through 1,000 rivers. The goal is to clean up those rivers by 2025, pulling in roughly 50,000 kilograms of plastic a day with each river Interceptor.

"To truly rid the oceans of plastic, we need to both clean up the legacy and close the tap, preventing more plastic from reaching the oceans in the first place," said founder Boyan Slat.

The river element was unveiled less than a month after the team successfully collected plastic in the ocean after a rocky few months.

The ocean element is back on track

"Our ocean cleanup system is now finally catching plastic, from one-ton ghost nets to tiny microplastics! Also, anyone missing a wheel?" announced Slat. It was a buoyant moment for a project that has had its ups and downs.

Slat became the poster boy for entrepreneurship when he quit university and launched the project at 18. He had come up with the idea after diving in Greece as a teenager, recognizing the scope of the problem — and coming up with a potential solution. He has been the face of the project ever since, through good times and bad.

The Ocean Cleanup was redeployed in June after spending four months in the shop and has been in testing mode for the last few months. The second deployment was a quieter affair than the first, when the much-lauded cleanup system began trolling the Great Pacific Garbage Patch to collect plastic waste. However, the Ocean Cleanup was forced to return to port in Hawaii just a few months after being launched because the passive floating system was catching plastic, but it wasn't necessarily retaining it and an 18-meter end section had broken away from the main frame.

Undeterred by their critics, the team behind the Ocean Cleanup said the mishap was all part of the process.

The basic principle behind the iterative design process is to test, learn, and repeat until you have a proven concept. We do not know with certainty that these proposed options will solve the issues we have encountered. In fact, there may still be further unknowns, as is the nature when doing something that has never been done before. What we do know, is that every day we are not yet operational the plastic pollution problem is not getting better.

How it works (and why it didn't before)

Ocean Cleanup is a Netherlands-based group of about 80 engineers, researchers, scientists and computational modelers. Dubbed 001/B or Wilson, it consists of a 2,000-foot (600 meter) U-shaped boom with an attached woven skirt. It acts like a floating artificial coastline. The boom prevents plastic from flowing over it, while the skirt stops debris from escaping underneath it. It's set up to collect everything from big items like massive fishing nets as well as microplastics, all without disturbing marine life below.

It was the system's finally realized ability to capture the tiniest of plastic pieces that signaled the team had rounded the corner.

"After beginning this journey seven years ago, this first year of testing in the unforgivable environment of the high seas strongly indicates that our vision is attainable and that the beginning of our mission to rid the ocean of plastic garbage, which has accumulated for decades, is within our sights," Slat said in a news release and the video above.

However, with the Ocean Cleanup's success comes a new question: If you clean up the plastic, are your endangering the health of the neuston, an ecosystem that lives at the top surface of the water? This question about the neuston — which is comprised of bacteria, protozoans, certain species of fish, jellyfish, sea anemones, vellela and crabs — has come up several times this year, as the linked story explains. In response, the Ocean Cleanup has been communicating with the biologist who originally raised the question and that they are adjusting the system and its environmental impact as they go. (There's some continued back-and-forth on Twitter on the best way to do this.)

Learning from mistakes

The bumps and ongoing adjustments are part of the process. In fact, it was the problem that sent them back to port in December that helped them solve a deeper issue. The offshore crew noticed on Dec. 29 that the section was detached and after some debate, determined that the boom must return to port because both end sections contained sensors and satellite communication had been compromised.

Late last year, the boom was struggling in places to hold on to plastic that it gathered.

"It has been four weeks since we deployed System 001 in the Great Pacific Garbage Patch (GPGP). In this time, we have observed that plastic is exiting the system once it is collected, so we are currently working on causes and solutions to remedy this," Slat wrote on the group's website in late November. "Because this is our beta system, and this is the first deployment of any ocean cleanup system, we have been preparing ourselves for surprises."

"Although we are not harvesting plastic yet, based on the current results, we are positive we are close to making it work," Slat said at the time.

One reason the system didn't work as hoped has to do with speed. To catch the plastic, the system typically has to move faster — or in some cases, slower — than the plastic it's hoping to catch, Slat said. The fix put in place — one inspired by sailing — ensured that the the system will not travel at the same speed as the plastic.

There are still obstacles to be overcome and problems to be solved, but the team is making progress and building momentum as this BrightVibes video explains: