To stop plastic reaching the ocean, a start-up in Ecuador is using a conveyor belt to skim off and remove plastic from rivers – and working to stop polluters adding plastic to rivers in the first place.
Plastic bottles, sports balls, and what look like the wheels from a toy pram float down the San Pedro River that runs through Quito, Ecuador. They are on their way towards the Pacific Ocean, on a downstream journey repeated all over the world as plastic waste is flushed through rivers into the seas.
However, this particular patch of plastic waste is about to have its journey cut short. It is brought to a stop by a floating barrier in the water, part of a local plastic clean-up technology called the Azure system, which collects plastic from rivers.
Created by the tech start-up Ichthion, the Azure system's simple design has the capacity to stop and collect around 80 tonnes of plastic per day. At this particular point in the San Pedro River, the most it's collected in a day has been 1.5 tonnes of plastic and synthetic fabrics – that's roughly the same weight as a female hippopotamus.
"What you take out of rivers, what you find along the riverbanks… the majority of this will all end up in the ocean," says Inty Grønneberg, founder and chief executive of Ichthion, a name derived from ichthyology, the study of fish. "Our idea is to prevent ocean-bound plastic."
Plastic pollution in the open sea is a growing concern. It can harm turtles, strangle sea lions, or be consumed by birds or fish, which could also end up in the human food chain. Scientists are also increasingly concerned that microplastics can cause irreversible toxicity within aquatic ecosystems. Research shows that up to 80% of this plastic is carried out to sea via rivers, mainly due to the mismanagement of waste on land.
But a growing number of innovators, like Grønneberg, are trying to stop this flow.
The Azure system is a boom device that stretches across the river to stop objects floating on the surface. It extends down 60cm (2ft) into the water, allowing fish and other organisms to move freely below, and is placed at an angle allowing the natural water flow to direct all debris into one corner of the riverbank.
A manual operator in the water then guides the debris onto a mobile conveyor belt that dumps the plastic into a large container on shore, where it is sorted for recycling and trash destined for landfill.
But Ichthion doesn't only pick up debris in the river, it also tries to stop it from arriving there in the first place by documenting and generating data about what is collected. This way they can better identify the source of the garbage, whether it be mounds of industrial waste from factories, or bags of household trash that indicates a problem with the municipal garbage system. The data allows them to work with municipalities, businesses and communities to stop the problem.
"We know very little about the contamination problem," says Grønneberg. "But if you only look at what you extract, it won't stop. So that's why extraction is important, but prevention based on data is more important."
Currently, the team collects the data manually, but they are also training an artificial intelligence system to identify a variety of plastics to take over this process. Grønneberg also plans to use drone images of the river upstream to identify the debris before it arrives.
The majority of what Ichthion collects from Ecuadorian rivers is plastic bottles, which come from local communities. This is why getting local communities involved is also essential to generate long-term change, says Yessica Benavides, Ichthion co-founder and vice president of strategic relations. So far, local people have been involved through activities like community clean-up days, awareness campaigns and hiring locals to operate the Azure system.
Ichthion isn't the only organisation working on plastic removal from rivers. There's a variety of designs from robots, receptacles and booms, some more expensive and more effective than others.
Jordyn Wolfand, assistant professor of civil and environmental engineering at the University of Portland in the US, evaluated over 40 plastic clean-up systems for rivers. The most effective, she says, were the ones that understood the specific problems and needs of each site, not any one design in particular.
"Litter patterns and litter accumulation is so site-specific that there really isn't a best approach," she told BBC Future Planet. One way that technologies do tend to be more effective though, Wolfand adds, is when they're implemented farther upstream, closer to the source of pollution.
Even when you have a design that's good at removing plastic from a river, there are more challenges ahead.
The Bubble Barrier, a plastic removal technology based in the Netherlands, is one design that understood early on the importance of not interfering with ship traffic if it wanted to be used in European rivers.
They came up with a bubble curtain created by pumping a constant stream of air through a perforated tube that lies on the bottom of the river. The bubbles create an upward current that lifts submerged debris to the surface, while the natural flow of the river directs it to the river bank where it is collected. Because there is no physical barrier, it doesn't hinder the passage of ships or fish.
"For the first time we can get a view of what's really flowing down our rivers," says Philip Ehrhorn, chief technology operator and co-found of the Bubble Barrier. This is essential to stop debris from arriving in the first place, he adds.
Their 60m-long (200ft) barrier in Amsterdam collects roughly 80kg (176lb) dry weight of plastic per month, says Ehrhorn – that's about 80 large plastic bags of waste. But while it may be effective, the bubble curtain can cost tens of thousands of dollars per year to operate, as it requires a lot of energy to maintain the air compressor and provide a consistent curtain of bubbles. For countries in the Global South, this may be prohibitive.
The Azure system was created with cost in mind, says Grønneberg. The conveyor belt that extracts the plastic from the water is mobile, which means not every river barrier needs its own extraction machine. The system can simply be moved from one barrier to the next. It is also only turned on for brief periods of the day or week to collect the accumulated trash, which keeps operating costs at a minimum. They also try to give jobs to local community members.
Such solutions are especially needed in countries in the Global South facing growing mounds of waste. Ecuador has its own garbage crisis with overflowing landfills and open dumps, but it also receives plastic waste from abroad. Between 2018 and 2022, Ecuador imported over 48,000 tonnes of plastic waste from 42 countries, mainly the United States, says the local advocacy group Zero Garbage Alliance.
Earlier in 2024, the Ecuadorian government also approved a free trade deal with China that contains a clause allowing China to send its waste to Ecuador. This will include plastics, among a variety of other difficult-to-process waste.
"This is a very serious problem," says Grønneberg, adding what can't be recycled often ends up in local landfills and rivers.
But some say clean-up efforts come with their own drawbacks. In a 2023 comment paper, a group of academics outlined a number of concerns with these technologies.
Win Cowger, one of the paper's authors and a research scientist at the Moore Institute for Plastic Pollution Research in California, is concerned about the environmental impact of plastic-catching barriers in rivers in the long term, especially if their use becomes widespread. They could stop organisms, sediments and all sorts of natural organic matter from flowing downriver, which are all important for coastal marine environments to thrive and prevent coastal erosion, he says.
Grønneberg says that during the design phase for the Azure system he worked closely with scientists to minimise impact on the river ecosystem, such as making sure their barrier doesn't reach the riverbed. And not all organic matter flowing in rivers is good, he adds. The majority of greenery they collect in their barrier systems is water hyacinth, an invasive species that reduces the oxygen level in rivers, releases methane when it rots and multiplies quickly, he says.
But not all clean-up methods take this approach. Cowger and his co-authors note claims of greenwashing by some firms in the industry, such as tech companies that are accused of promoting clean-up instead of reducing production, and the plastic producers who may endorse these technologies. Focusing too much on clean-up alone can distract from more effective long-term solutions, the authors write.
"These actions, a lot of times are a front for plastic producers to say look we're doing something, we're cleaning up the ocean or the rivers," says Cowger, which allows these companies to continue producing.
By far the most crucial solution, says Cowger, is to reduce the amount of plastics produced every year, guided and enforced by policies. He adds that some amount of clean-up is necessary. "We should be using the most environmentally friendly techniques," says Cowger, but "where are we going to dedicate most of our energy? We have limited resources, limited time to do stuff to make a difference."
Grønneberg says that up until now Ichthion has not received any funding from plastic-producing companies, and its focus on tracing how plastic enters rivers is an essential part of its work, alongside clean-up efforts. The Bubble Barrier has received a small unsolicited donation from one plastic producer in the past, but has no current or ongoing partnerships with plastic producers, a spokesperson says.
Grønneberg believes tackling the production of plastics is one of several problems to address. It's also an issue of poor or non-existent waste management systems in places like Ecuador and other developing countries, he says, arguing the best way to address that is by generating data and working to change these systems.
Standing on the banks of the San Pedro River, Grønneberg points out the Azure barrier wasn't designed to be permanently installed in any river, and the organisation's work is also part of the effort to stop plastic from arriving there in the first place.
And in the end, he comes to a similar view to Cowger. "The solution is to avoid consumption," he says. "That's fundamental."
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