Will this solar-powered device clean the world’s most polluted rivers?

Dutch nonprofit The Ocean Cleanup has unveiled a river-cleaning invention called the Interceptor, which aims to stem the flood of plastic entering the ocean in five years.

the interceptor polluter river
The Interceptor at work in the Dominican Republic in Santo Domingo. A similar prototype is now being tested in Jakarta, Indonesia. Image: The Ocean Cleanup

It had rained all morning across Jakarta on the first Tuesday in February. The rivers in the Indonesian capital quickly filled up, carrying all kinds of debris toward the Java Sea. In one of the city’s largest waterways, a Dutch-made device was trapping some of the trash to prevent it from washing out into the ocean.

The Interceptor 001 had been shipped to Jakarta in early 2019 by its inventor, the Rotterdam, Netherlands-based nonprofit organisation The Ocean Cleanup (TOC). The prototype has been on a trial run since May 2019 near the mouth of the Cengkareng drain, which connects the city’s notoriously garbage-laden Angke River to the Java Sea.

Jakarta’s prototype is the first generation of a device that TOC aims to deploy in 1,000 of the world’s most polluted rivers in just five years. The organisation estimates these waterways are responsible for carrying 80 per cent of ocean trash out to sea, with the remaining 20 per cent of marine trash coming from around 30,000 other rivers.

There are two Interceptors currently installed, the second on the Klang River in Kuala Lumpur, Malaysia. According to Chris Worp, TOC’s managing director, the group plans to deploy another Interceptor to the Rio Ozama in the Dominican Republic this month, and a fourth to southern Vietnam.

Donors from all over the world have invested millions of dollars in TOC to help the organisation accomplish what it says are “ambitious” and “novel” solutions to the scourge of oceangoing trash. But the process has not been smooth. Mongabay visited the prototype in Jakarta in February and found issues with the device. Now, TOC is facing allegations that it copied the design of another successful river cleanup device patented more than a decade ago.

Competing designs?

The river-cleaning project is part of The Ocean Cleanup’s overall goal to reduce the amount of trash in the ocean. CEO Boyan Slat founded the organisation in 2013 to create an open-ocean device that would remove all plastic in the Great Pacific Garbage Patch in five years. After many iterations and much media attention and criticism from scientists, a 160-meter (525-foot) test design collected and retained ocean plastic for the first time in October last year.

Over the course of the project, many scientists encouraged the organisation to focus its efforts on rivers, where they said a cleanup device would be more effective. TOC took heed in 2015, when it began developing the Interceptor.

The Interceptor is powered by solar panels atop its white exterior shell. Each device’s unique number is painted on one of its long sleek sides, facing to the banks of the river. At water level, a long waste barrier protrudes upstream, allowing the force of the current to push trash toward the device’s mouth.

There, a conveyor belt lifts debris out of the water and deposits it onto a platform inside the device that shuttles trash to one of six dumpsters. Once the containers are full, a local team takes them to shore to be emptied.

The latest Interceptor design can extract 50,000 kilograms (110,000 pounds) of plastic per day — double that under “optimal conditions” — and can hold 50 cubic meters (1,770 cubic feet) of garbage, according to TOC’s website. The prototype in Jakarta has about one-fourth to one-fifth that capacity, and holds the trash in small crates instead of dumpsters. As a result, it needs to be maintained and emptied more frequently.

During the Interceptor’s splashy unveiling event last October in Rotterdam, Slat called it the first “integrated system that you can bring anywhere in the world and install within days.”

That’s just not so, according to John Kellett, founder and president of Clearwater Mills LLC. In 2014, Kellett installed a device called the Waterwheel Powered Trash Interceptor in the Jones River in Baltimore, Maryland. This device, dubbed “Mr. Trash Wheel,” uses booms to funnel trash to its mouth and a conveyor belt to lift trash out of the water.

A key difference from TOC’s Interceptor is that a water wheel powers the conveyor belt and solar-powered water pumps keep the wheel going when the current is weak. Due to its success, Baltimore now has three trash wheels, and Clearwater Mills is working in California, Texas and Panama to bring its design worldwide.

“They were aware of our efforts, experience and success when they developed their river device in secret and publicly dismissed it while borrowing heavily from our technology,” Kellett told Mongabay of TOC.

In an email addressing these claims that Kellett shared with Mongabay, he informed TOC that Clearwater Mills had patented its device’s design more than a decade ago. Kellett also told TOC that he thought their changes “make it more expensive, less effective and harder to maintain.”

“We would love to see that the resources and efforts allocated to this global crisis are used effectively and that we are not duplicating efforts or working at cross purposes,” he told Mongabay.

Worp acknowledged that the two devices share similar elements, but said TOC started its design from scratch. “It would be like saying one car is the same as all the others,” he said. “We obviously know about the other systems that are out there, but we’ve really taken this from a different angle to find a scalable, high capacity, high efficiency solution.”

According to Kellett, TOC has approached some of the organisations that Clearwater Mills is working with outside Baltimore to offer them an Interceptor instead. Worp denied this, and told Mongabay that his team doesn’t see any other solutions as competitive.

Getting the public involved in trash

For both organisations, finding a solution to river pollution goes beyond the cleanup devices.

“They’re providing an opportunity to educate the public and inspire people to become part of the solution,” Kellett said of the three devices his company deployed in Baltimore, which have spurred countless local environmental activities and educational programs.

According to Worp, several school groups have visited the Interceptor prototype in Jakarta. Community engagement is important to The Ocean Cleanup because it ultimately relies on local organisations to operate and maintain the devices.

Some scientists are skeptical about TOC’s goal of targeting so many rivers in vastly different parts of the world. Andrew Gray, a hydrologist at the University of California, Riverside, studies small mountainous watersheds that expel a large amount of sediment to the ocean during strong storms. These storms can be destructive to any man-made device, he said.

“[These storms] that are probably discharging most of the plastics, are the kinds of events that you’re not going to have a trash boom up because the hydrodynamics are far too aggressive,” he said.

Gray also said the Interceptor would need to be incredibly versatile to accommodate a variety of river sizes.

Win Cowger, a graduate student in Gray’s lab, pointed out the unpredictability of natural systems.

“Whenever you apply one solution — one device — to a broad range of ecosystems and a broad range of circumstances, it tends to have some implications that you might not have expected,” he said.

Rainy days in Jakarta

Early this year, Jakarta experienced one of its worst flooding disasters in recent years. Torrential rain, with a record-breaking intensity, showered Greater Jakarta for almost 16 hours through New Year’s Eve and into New Year’s Day. Most of the city’s rivers flooded their surroundings. The Interceptor was found damaged after its waste barrier broke loose.

The water volume in the Cengkareng drain increased significantly, but never overflowed its banks, according to Muhammad Khusen, the leader of a waste-collecting worker group in the subdistrict where the Interceptor is located. He said it was the river’s strong current that damaged the device’s waste barrier, but TOC engineers were able to repair it the following day.

When Mongabay visited the device a few weeks later, in February, the rains were constant, albeit less intense than at the start of the year. While the Interceptor was undamaged, waste had piled up on the barrier and clogged up the device’s opening.

Workers were using long poles to try to break up the clog, which included a lot of large organic material like branches, bamboo and banana tree trunks, and feed the debris bit by bit into the Interceptor.

A team of three workers has been assigned to collect the trash and maintain the device every day, Khusen said. But on the day of Mongabay’s visit, he had to call in reinforcements. As many as 10 workers were on hand throughout the afternoon to help clean up the collected debris after an earlier attempt failed to get much done. When the workers went home at 3 p.m., only about 20 per cent of the trapped debris had been taken out. 


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