Meet the Inventors — Week 09: The world’s rivers are choking on discarded plastic. We meet the Chinese inventors of a new robot, designed to automatically clean some of the world’s most polluted rivers, keeping our oceans plastic free.
The Problem: Plastic, plastic every where but not a drop to drink
Perched on the far eastern end of the ancient Silk Road trade route, the Chinese city of Xi’an was once famed for its network of picturesque waterways and lakes dotted between its imperial palaces. Together they fed into one longest rivers in the world — the mighty Yellow River.
Today, however, the picture is far less pretty. The Yellow River is now one of the major sources of rubbish littering the world’s oceans. An estimated 112,000 tonnes of discarded plastic is carried out to the sea by its current each year — almost 1.5% of all the plastic debris that winds up in the ocean.
Over the past half-century, plastic has become an integral part of our daily life. When discarded appropriately, plastic is an efficient and useful material that can be used to make every day objects cheap and durable — from furniture to grocery bags, vehicle parts to toys.
However, if discarded inappropriately it is a material that can be potentially destructive and harmful to the environment. The main problem is that, because plastic isn’t biodegradable, if it does enter the water system it can linger for generations to come. Some estimates claim that of the almost four million tonnes of waste generated every day, almost 13 percent is plastic. Worse still, when the plastic does start to break down it can release chemicals and so-called “micro-plastics”, that make their way into marine ecosystems.
As a significant amount of this waste comes from human activity in cities, some of the worst water pollution comes from rivers that flow through urban centres.
It was precisely while watching this day-to-day accumulation of rubbish in the ponds, lakes and rivers scattered around Xi’an, that a group of young engineers — Jiannan Zhu, Guo Mengrui, Yuwei Cheng, Zhe Wang and Yidan Qiao — decided to do something about it.
The Solution: Automated cleaning, at your service
Their solution was a swimming robot that can comb lakes and urban waterways to collect litter and debris.
Designed while they were studying at Northwestern Polytechnical University in Xi’an, the Orca Water Cleaning Robot scoops up 20kg of debris before needing to return to shore to have its basket emptied.
Fitted with arms at the front that help to gather the rubbish into its collection basket, the robot can be driven by remote control or sent on a pre-programmed route. The team have also fitted the robot with cameras, ultrasound and radar to allow it to navigate autonomously, avoiding obstacles but gathering up debris floating on, or just beneath the surface.
According to the maximum capacity tests conducted by the team, the robot is capable of collecting up to 50kg of rubbish in an hour in particularly polluted areas of water. Compared to manually fishing out debris — the approach currently used in Xi’an to clean the city’s lakes and rivers — the robot is up to seven times faster.
“Of course, it cannot collect big pieces of debris like a tree, but it can clean up normal rubbish like leaves, discarded food boxes and bottles,” explains Jiannan, one of the team who designed the robot. “The pollution in the water comes from the activities of daily life but it can also come from industrial sources. So, we also have installed sensors that can collect water data from the lakes to predict changes in the water quality and so protect the ecosystem.”
This so-called ‘Water Quality Data Management Platform’ was built after discussions with the water authorities in Xi’an revealed they wanted a way of monitoring the water quality in the lakes and rivers around the city.
Motoring at a sedate one metre per second (2.2mph), the catamaran-style robot can pick up plastic bags, bottles, and other packaging and even skim off blooms of algae that can choke water courses. The team have already tested a prototype of the robot, which is 1.2 metres long and 0.8 metres wide, in five lakes around Xi’an city.
The design saw the group become national winners of the 2018 James Dyson Award in China and they have now launched a company, Orca Smart Technology. They have been working with experts to increase the efficiency and the battery runtime of the robot. Powered by a polymer lithium battery, it currently runs out of juice after about four hours of continuous use.
The Orca team’s solution will compliment more ambitious plastic collection projects such as Ocean Cleanup, which is deploying a 600-metre-long floating barricade that will drift on the currents of the Pacific Ocean, gathering the plastic rubbish that has accumulated there. A three-metre skirt beneath the air-filled floaters will help to trap debris just beneath the surface.
The project, founded in 2013 by Dutch inventor Boyan Slat at the age of 18, is undergoing its final ocean trials before the system will be towed out into to the Great Pacific Garbage Patch, a part of the ocean where the highest concentrations of plastic have accumulated.
While the Orca team are currently attempting to tackle the mess before it spills out into the ocean, they also hope to develop larger robots to work on larger bodies of water.
“Currently, we created a small unmanned surface vessel to mainly focus on urban lakes,” Jiannan says. “We have already designed a bigger one for the rivers and ocean, and we hope to perhaps test that next year.”
But for the Orca team, perhaps the greatest rewards will be felt closer to home.
“We imagine using robotic technology to bring back clean, fresh water sources to urban life,” says Guo, another member of the Orca team.
Words: Richard Gray, journalist
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