Up to 12.7 million tons of waste makes its way into the world’s oceans each year, forming massive “plastic islands” in oceanic gyres and devastating birds and marine life in the process.

Cleanup, in which plastics are currently collected at sea, stored and shipped to shore for disposal, is estimated to take from 50 to 130 years with annual costs expected by some at nearly US $37 million. In the meantime, the trash is degrading faster than it can be gathered, disintegrating into harmful and even more difficult to mitigate microscopic forms.

Now a team of researchers from Massachusetts in the United States is suggesting a new approach: self-powered cleanup vessels that turn the trash they harvest from the seas into the fuel they use for the job.

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The “blue diesel”-powered ships could reduce the amount of fuel and roundtrips needed to remove ocean waste, the researchers write in a paper published in the Proceedings of the National Academy of Sciences of the United States of America.

The researchers, representing Harvard University, the Woods Hole Oceanographic Institution and the Worcester Polytechnic Institute, suggest using high temperatures and high pressure in a process called hydrothermal liquefaction to depolymerize the plastics into a harnessable energy, creating self-powered cleanup that eliminates the need to refuel or unload plastic waste and potentially reduces total cleanup times.

Of course, it isn’t enough to clean up the oceans faster and with less fuel waste. The world needs to address the amount of garbage that makes it into the oceans in the first place, the researchers write. “Reducing or eliminating the amount of plastic waste generated is critically important, especially when the current loading may persist for years to even decades,” they say.

 COVID’s toll on the oceans 

Meanwhile, researchers from China’s School of Atmospheric Sciences at Nanjing University and the Scripps Institute of Oceanography at the University of California-San Diego say the COVID-19 pandemic is making an already bad situation in the oceans even worse.

Also writing in the Proceedings of the National Academy of Sciences of the United States of America, the scientists say that of the 8 million tons of plastic waste generated until recently in the fight against the virus, about 25,000 tons of medical waste, mostly from hospitals, has entered the world’s oceans. And more is expected to come, not only damaging marine species but potentially spreading contaminants including the COVID-19 virus.

The hospital trash, they say, dwarfs the amount of waste from discarded personal-protective equipment (PPEs) and plastic packaging produced by a surge of online shopping in the wake of the pandemic. For a little perspective, the authors cite another study estimating that 1.56 million face masks made it to the oceans in 2020.

Plastics that wash into the oceans are endangering wildlife. IMAGE: Shutterstock

Five of the top six rivers associated with medical-waste discharge are in Asia (Shatt al Arab, Indus, Yangtze,Ganges Brahmaputra and Amur). The other, the Danube, is in Europe.

The authors call for increased public awareness of plastics’ environmental impacts; better collection, treatment and recycling of plastic waste; and improved waste-management practices at pandemic epicenters, particularly in developing countries.

 Microbots to the rescue? 

A solution to microplastics in water might come in an equally small package: microbots.

The bacterium-size bots when added to water with a little hydrogen peroxide attach to microscopic bits of plastic and begin to break them down. The research was recently published in ACS Applied Materials & Interfaces.

“They can sweep a much larger area than you would be able to touch with stationary technology,” says study co-author Martin Pumera, a researcher at the University of Chemistry and Technology, Prague.

Pumera envisions setting the microbots loose in the oceans to collect microplastics, but Win Cowger, an expert in plastic pollution at the University of California, Riverside, who was not involved with the study, tells Scientific American that closed systems such as those for drinking-water or wastewater treatment would probably be better potential targets.