Kewalo Harbor is one of the Hawaiian capital’s busiest waterways. Each day, dozens of charter, diving and fishing boats filled with people – mostly tourists – motor in and out. Next to the harbor is Ala Moana Beach Park, a popular swimming, surfing and picnic spot. With all those people in and around the harbor comes a lot of trash. Kewalo Harbor, along with other aquatic tourism hotspots, is experiencing serious problems with pollution.
Most of the debris is plastic, but petroleum spills and paint, which chips off boat hulls, also poses a hazard to wildlife, people and vessels. That’s why an increasing number of natural resource managers, including those at Kewalo, have turned to skimmers as a potential solution. Some are custom-made, like Baltimore’s solar- and hydro-powered “Mr. Trash Wheel,” while others are commercial products, such as the electric-powered Marina Trash Skimmer. But experts say that while using skimmers and holding cleanups to pull plastic trash out of aquatic ecosystems can be helpful, it can mask the real solution to pollution, potentially creating bigger problems in the long run.
“I support cleanup efforts, but the problem with cleanup is that it doesn’t really solve the problem,” said Sherri “Sam” Mason, a chemist at the State University of New York at Fredonia, who studies plastic pollution in the Great Lakes. “The real solution is to slow or halt the production and use of plastic and toxic materials.”
Aquatic skimmers are simple devices that can collect debris as water currents flow through them or pull in debris in with a pump. Skimmers collect and store debris in a container, which is sometimes equipped with a filter to absorb liquid toxins. Skimmer debris containers and filters need to be cleaned frequently – as often as several times a day – to be effective.
That can be a deterrent to their use, according to skimmer manufacturers and users, including Pete Ceglinski, chief executive and co-founder of Seabin. The Australian company has developed a small circular pump-powered skimmer called the Seabin. The skimmer is not yet commercially available, but the company has so far installed 11 Seabins in six locations around the world. But Ceglinski predicts high demand for the product once it hits the market, noting the company has received more than 40,000 emails from people inquiring about purchasing a Seabin.
“For now, the Seabin needs to be installed on a floating dock in a marina, and in a strategic location where the pollution congregates – this is the only main challenge,” said Ceglinski, who is testing a new type of debris catch bag made of recycled plastic before bringing the Seabin to market. “The Seabin itself is plug and play.”
Ceglinski said that when installed properly in the right place, a Seabin can collect 2.2lbs to 3.3lbs (1kg-1.5kg) of trash daily, and around half a ton of debris annually. The device also skims petroleum from the water and picks up tiny broken-up bits of plastic, called microplastic, as small as 2mm.
According to Mason, harbors are a good place to install debris skimmers, as opposed to using them in large open water bodies like the ocean. For instance, 23-year-old Dutch inventor Boylan Slat plans to install a fleet of floating booms to concentrate trash into collection bins in the heavily polluted North Pacific Gyre, which some scientists say is “a waste of effort.”
“Skimmers would benefit harbors most, because the closer you are to the source of debris – which is people on land – the easier it is to clean it up,” said Mason. “In the ocean, debris gets spread out and breaks up into small pieces that are harder to separate from living things.”
It appears that even in harbors, debris skimmers’ effectiveness depends on the conditions at the location where it’s installed. Harbormaster John Eveleth oversaw the installation of a Marina Trash Skimmer – which looks like a partly submerged dumpster – in Kewalo Harbor last summer. He said it took a while to determine the right place to situate the large device in the busy harbor, but once he found a spot, “the skimmer worked beautifully … until it didn’t.”
Eveleth said the device functioned well for a few weeks, but wave action from boats coming in and out of the harbor and natural tide movement made it much less effective over time. So he and other harbor administrators decided to pull it out of the water and the device now sits in storage.
Mason said she’s heard many stories of skimmer successes and failures. Despite some innovative new products, like Seabin and the Baltimore trash wheel, she said resources to further develop skimmer devices might be better used to investigate new types of biodegradable materials to replace plastic so that plastic pollution is stopped at the source.
“Imagine you go into bathroom and see that your bathtub is overflowing with water,” said Mason. “Is your first instinct to mop up the water or turn off tap? We need to turn off tap. Cleanup efforts are not changing behaviors, they’re telling people they can keep doing what they’re doing and someone else will clean up their mess.”
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