How companies clean the world's most polluted river

How companies clean the world’s most polluted river

Each year, millions of tons of plastic waste flows into the ocean, much of it coming from about 1,000 highly polluted rivers. And with total waste production expected to increase by more than 75% by 2050, the problem will only get worse.

Businesses around the world have turned their attention to the problem of river litter, building various levees, fences, and wheels that help contain and remove waste as it flows downstream.

Styles range from solar-powered garbage-collecting barges to stainless-steel fences, and different rivers will require different methods.

Here’s how three companies, Clearwater Mills, Ocean Cleanup, and AlphaMERS dealt with the problem.

Clearwater Mills Trash Wheels

Baltimore’s trash wheels, which debuted in 2014, are one of the original efforts to tackle river waste. Built by Clearwater Mills, company founder John Kellett was inspired to design the wheels after years of seeing trash pouring into Baltimore Harbor after severe storms.

“We have Mr. Trash Wheel, Captain Trash Wheel, Professor Trash Wheel and Gwynnda the Good Wheel of the West here in Baltimore,” Kellett said, citing the names of the holographic wheels that have become a social media celebrity in the city.

Mr. Trash Wheel of Baltimore devours trash and debris after a big storm.

Baltimore Waterfront Partnership

Here’s how it works: V-shaped containment arms are positioned across the river, with rubber skirts extending about two feet below the water’s surface. This catches the trash floating down the river and guides it toward the “mouth” of the spinning water wheel, which is powered by the river’s current and the solar panels connected to it. The rotation of the wheel drives a conveyor belt that lifts garbage and debris from the river and deposits it in a garbage can. Attached cameras allow the team to monitor how full trash containers are.

“When that trash can is full, we have another floating barge to bring in with an empty trash can,” Kellett said. “Take it out full, put it in the empty one and keep collecting trash.”

The four wheels picked up a total of about 2,000 tons of trash and debris. Sticks and papers make up the bulk of this weight because the plastic is so light, but the total amount includes about 1.5 million plastic bottles, 1.4 million foam containers, and 12.6 million cigarette butts. Everything is then incinerated in a waste-to-energy facility.

Additional trash wheels are planned in Texas, California and even Panama, where local nonprofit Marea Verde has teamed up with Clearwater Mills to build the family’s fifth wheel, called Wanda Díaz. The project is funded by the Benioff Ocean Initiative and the Coca-Cola Foundation, which together support a range of river clean-up projects around the world.

ocean cleaning

Ocean Cleanup is probably best known for its efforts to clean up the Great Pacific Garbage Patch, an endeavor that young company founder Boyan Slat started in 2013 after his TED talk on the topic went viral. The company is now pursuing a dual focus as it has also built a series of river cleaning technologies.

“Our goal is to rid the oceans of plastic, and the reason we’re looking at rivers is because we think it’s the fastest and most cost-effective way to prevent more plastic from being released into the ocean,” Slat said.

The company’s first river cleaner, called the Interceptor Original, launched in 2019. It’s an all-solar-powered barge that works like garbage wheels in Baltimore, on a larger scale. Sitting at the mouth of a river, he directs the trash onto a conveyor belt and automatically distributes the waste through six giant dumps.

Ocean Cleanup’s Interceptor Original is running on Rio Ozama in the Dominican Republic in summer 2020.

ocean cleaning

But because this giant interceptor doesn’t fit into smaller rivers, the team developed another solution, a free-standing floating bulkhead for picking up waste, and a small, portable conveyor belt that scoops up trash and transfers it to a trash can on the beach. This system is currently being deployed in Kingston Harbor, Jamaica, where Slat says the rivers are too narrow for the Interceptor Original.

And for the most waste-choked rivers, there’s Trashfence. The concept is simple. A 26-foot-high steel fence is fixed to the river bed and stops the flow of rubbish during a heavy storm. Once the water level recedes, the excavators remove the waste. But the onslaught of garbage in one of the world’s most polluted rivers in Guatemala has proven too severe for version 1.0.

“The strength of the litter was so high that the litter fence unfortunately failed,” Slat said. “So we are now working on the second edition which we hope will be ready for the next rainy season.”

Eight ocean-cleaning interceptors are currently installed in Indonesia, Malaysia, Vietnam, the Dominican Republic and Jamaica. Slat expects to have about 20 installed by next year, including one in Los Angeles.


India-based AlphaMERS makes another version of a simple river barrier and has 34 facilities in eight different cities across the country. It’s much smaller than the Ocean Cleanup’s Trashfence, and isn’t built for the same heavy-duty waste stream, but it’s still a pretty heavy duty job. Made of stainless steel mesh, the AlphaMERS fence floats 2 feet above the water and dives about 16 inches below.

“The hydrodynamics and hydrostatics are very simple but excellent for the job,” said AlphaMERS founder DC Sekhar. “And it’s very tough, heavy duty with steel chains holding it down on both sides. So it’s able to withstand the monsoon flows immediately after it rains.”

Sekhar says his pontoon fence excels at stopping trash in rivers with fast currents, while boom-and-skirt designs may fail when they pick up currents, because water would instead run over the bulkhead, bringing trash with it.

AlphaMERS floating barrier picks up trash as it flows downstream


Eight floating bulkheads were deployed at various points along the Kom River in Chennai in 2017. Sekhar says they captured about 2,400 tons of plastic in their first year of operation.

The bulkheads were set at an angle to direct the trash toward the riverbank, where prospectors have traditionally picked up trash from the rivers. AlphaMERS uses conveyor belts instead, just like Clearwater Mills and Ocean Cleanup.

“One end of it is floating and one end is on the ground,” Sakhar said of the conveyor belts. “Now it is powered by electric power and portable generators. But very soon we will be running it with the flow of river water.”

The future of waste

These organizations share the same goal of removing as much waste from our lives as possible, but they all also understand that river cleaning systems are not the ultimate solution.

“One of the things we’re looking at is that there’s no need for trash wheels,” Kellett said. “When we tackle the problem upstream to the point where no garbage gets into our waterway and we don’t need a rubbish wheel.”

Getting there will be challenging and will depend on a combination of better waste infrastructure, more sustainable packaging, lower consumption, and public awareness about proper disposal.

Middle-income countries such as the Philippines, India and Malaysia contribute the most to ocean waste. Residents have enough money to buy a lot of packaged goods, but the waste collection infrastructure is underdeveloped.

Sandy Wattemberg, CEO of the nonprofit Marea Verde, is excited that her organization brought the Wanda Díaz trash wheel to Panama and is optimistic about its future performance.

So we hope this will be a very big success for our country.”

“Having these technologies and these types of projects is not the answer. We need to change our habits. We need to look for long-term solutions that allow us to have a cleaner and healthier environment because these types of projects help us create awareness and help us mitigate in the long run. Short and medium term. But at the end of the day, this is not something sustainable. We cannot run thousands of projects like this forever.”

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