How a fleet of robots could help solve the Great Lakes’ plastic pollution problem

In the murky waters of Lake Ontario just off the Toronto harbor, a stream of trash inches toward a round, tubular-looking device floating in the water. A piece of white styrofoam bumps up against the device’s lip. Then, in one fluid motion, it tumbles over the edge. With tendrils of marine plants circling the waste, it looks like the styrofoam could have entered a portal to an undersea world. Instead, the device is a gateway to a less mystical — yet vital — destination: the garbage dump.

“It’s basically like a floating trash can,” says Chelsea Rochman, professor of ecology and evolutionary biology at the University of Toronto, who has worked with a team at the university to capture trash in Lake Ontario with bins like these since 2019. Powered from shore, the device, called a Seabin, uses a motor to create a vortex that gently pulls in floating waste from a 160-foot radius and then stores the trash in an attached basket. 

Across the Great Lakes, which stretch from Duluth, Minnesota, to the border between the United States and Canada in northern New York, dozens of Seabins now work alongside stormwater filters in a cross-border project dubbed the Great Lakes Plastic Cleanup. In mid-September, they were also joined by aquatic waste-collection drones and beach-cleaning roving robots — all to remove some of the 22 million pounds of plastic that enter the lakes each year and help researchers like Rochman understand the lakes’ waste problem.

“We know that the amount of litter we have out there needs more power than the people power that we have,” Rochman explains. Though local groups have organized beach cleanups for decades, people can’t remove waste 24 hours a day like the devices can, nor can they pick up the tiny pieces that machines are able to capture.

Standing on the shore of Lake Ontario, with Toronto’s streetcars rattling by, Rochman points out the overflowing municipal trash bin along the sidewalk — one of several sources of the lake’s trash. Municipal sewage systems, industrial spills, stormwater runoff, recreational boating and beach waste, and agricultural debris all wind up in the lakes as well. In one bin, toothbrushes, tampon applicators, dental flossers, shoe strings, eyeglasses, food scraps, and syringes are entwined in the tendrils of marine plants. Between the leaves, tiny flecks of plastic poke out.

In the lakes, which 40 million people rely on as their primary drinking water source, this waste breaks down, turning into microscopic pieces of plastic and debris, which are then eaten by fish, sucked into surrounding water treatment plants, or pulled to shore or out into the ocean. When plastic is consumed by fish, it can release chemicals like dyes and flame retardants, irritating and potentially damaging their digestive systems. In big sport fish, like lake trout or salmon, Rochman expects to find hundreds of pieces of plastic. Microplastics have also been found in drinking water in the region, where many water treatment plants are ill-equipped to filter the tiny pieces out. (The risk of consuming microplastics for humans remains unclear, though researchers continue to investigate the potential problem.) 

Once captured by researchers like Rochman, each piece of trash becomes another data point. Each day during the summer, students haul out the bins to count, classify, and dispose of their contents. “They know how many cigarette butts we collect, how many straws we collect, how many foam containers we collect,” Rochman says. Some days, the catch is more surprising — students have counted slices of deli meat, old shoes, and, once, a coconut in Seabins this summer.

The Seabins capture 28 grams of waste, on average, each day. “It’s going to sound like a small number because plastic is light,” says Rochman. That weight translates to a couple hundred to 2,000 pieces of microplastic, along with multiple pieces of larger waste. This summer, Rochman expects her team to remove the amount of plastic equivalent to 7,000 plastic water bottles — and that’s only in the 12 bins the university oversees, which make up just a fraction of the devices deployed at 45 marinas across the Great Lakes region.

From the northern shores of Lake Superior in Thunder Bay, Ontario, to the harbor of Buffalo, New York, just a short drive from Niagara Falls, Seabins like the ones in the Toronto harborfront are deployed at 44 other locations, typically in operation from May to November. These bins are monitored not by researchers but by marina owners or local organizations. Partners at the participating sites weigh and dispose of the bins’ contents as they fill up and perform full waste characterizing audits five to 10 times each year. Many marinas also have catch basin baskets installed, called LittaTraps, that sit inside stormwater drains to capture waste before it enters the lake system. Between 2020 and 2021, the project’s technology captured over 74,000 pieces of trash, a number that the team expects will increase as they continue outreach to marinas and municipalities in the region.

In September, a waste collecting drone and beach-cleaning robot also joined the project’s fleet of trash catching technology. The devices, built by French waste capture technology company The Searial Cleaners, collect waste from lakes and beaches, working both via remote control and autonomously. The roving robots are also key public engagement tools, says Claire Touvier, the company’s chief executive. “That’s why this robot needed to be sexy and cool and fun, and to also have a cool name — these are extremely efficient tools when it comes to raising awareness,” she says.

Still, the technology remains a reactive approach. Robots can help clean up the lakes, but human choices about how much plastic to produce, consume, and throw out are at the core of the Great Lakes’ trash problem. Changing them will be key to any long-term solution, says Melissa De Young, policy and programs director at the Canadian nonprofit Pollution Probe, one of the project’s main funders. “We’re doing what we can to remove plastic from the water, but we know that the technologies alone are not going to solve the problem,” she explains. “The data that we’re collecting is really critical because it provides, first, an understanding of the extent of the problem.”

If large macroplastics wind up in capture devices in a certain area, for example, that can indicate communities nearby may lack easy access to disposal facilities or may be uninformed on why proper waste disposal is important. Alternatively, if small plastic pieces used to build other products, called preproduction pellets, or nurdles, are more common, that can indicate that somewhere upstream, a manufacturer may be improperly disposing of its trash.

The captured waste then informs the group’s approach to local solutions, whether that means starting a new educational campaign, meeting with policymakers, or advocating for new industry mandates. Last year, the team consulted on a new Ontario law that requires the foam used to build floating docks for cottages and marinas to be fully enclosed so it does not break down into the water. The group has also contributed to proposed legislation to include mandates for filters on washing machines to prevent microfibers from entering the sewage system in Ontario and stronger laws regarding preproduction plastic disposal in Illinois.

“When we go to government policymakers, when we go to industry in the region, when we go to others to say, ‘Listen, we’ve got a problem here and we need to fix it,’ having that localized data, having that regional data, really aids us in those conversations in terms of capturing people’s attention and really motivating them to do something,” says Mark Fisher, head of the Council for the Great Lakes, a binational organization that also funds the project.

Other researchers in the region are hopeful about the new technology in the lakes, too. No initiative is going to be able to pick up 22 million pounds of plastic out of the Great Lakes every year, but a project that can motivate public and political action can have magnifying results, explains Timothy Hoellein, a biology professor at Loyola University Chicago who has worked on separate lake cleanup projects but is not involved in this one. When it comes to the Seabins, “Their individual footprint is pretty small,” Hoellein says. “But on a collective basis, it could really make a difference.”

As the strategy garners success in the region, its lessons have begun to reach far beyond the Great Lakes’ shores. Rochman and the team at the University of Toronto have partnered with the nonprofit environmental group Ocean Conservancy to found the International Trash Trap Network, which works with groups from Fiji to Florida to help create more trash trapping strategies. Wherever trash traps capture waste, data collection follows. 

It’s all part of the goal of achieving a future where freshwater sources, like the Great Lakes, are no longer dumping zones for waste, Rochman says. “We don’t want to have to have trash traps in the water forever,” she adds. 

But for now and for the foreseeable future, the lakes’ waste problem persists, and so the floating trash cans continue to spin their waste-capturing vortexes. Back on Lake Ontario, a small piece of purple plastic — perhaps an old surgical glove or part of a food wrapper — edges toward the Seabin and falls in. It’s another piece of plastic captured from the lakes, with millions more to go.