What to do with plastic waste? A lot, actually

23 April 2020

Plastic pollution has reached pandemic levels worldwide, with the colossal amounts of plastic waste posing grave risks to the health of ecosystems both on land and in the oceans. It’s also a threat to human health with microplastics having permeated our food and water, and even our table salt.

There is little that can be done about the vast amounts of plastic already in the oceans, but we can still do a whole lot to ensure we won’t be adding much more plastic waste to that already out there.

Encouragingly, several promising initiatives are under way.

One involves the use of chemical recycling. This advanced recycling process, explains Alvin Orbaek White, a lecturer in the College of Engineering at Swansea University, “breaks the plastic down to the molecular level, making available ‘platform molecules’ that can then be used to make other materials. It’s early days for this idea but, in principle, it could open up a whole range of opportunities.”

Meanwhile, China, the world’s leading plastic polluter, is working on ways to reuse plastic waste as a fuel in its massive cement industry as part of a Norwegian project called Ocean Plastic Turned into an Opportunity in Circular Economy (OPTOCE).

“Globally, 5 to 13 million tonnes of plastics end up in the oceans every year. Plastic debris is then transported by marine currents, sometimes over very long distances. It can be washed up on land, degrade into microplastics or form dense areas of marine litter trapped in ocean gyres,” OPTOCE explains on its website.

“UNEP estimates that damage to marine environments is at least USD 8 billion per year globally,” the initiative adds.

Yet much of that plastic waste can be used as fuel in the manufacturing of cement, which involves heating limestone in large furnaces at temperatures of 1,450 degrees Celsius until it liquifies. The fuel widely used is coal, of which cement factories burn half a billion tons every year around the planet. Some of this vast quantity of coal could be replaced by non-recyclable plastics.

The potential for plastic waste as an alternative fuel in the cement industry is “enormous,” according to Kåre Helge Karstensen, a senior research scientist who heads the OPTOCE project. “However, even if the cement factories of Asia can burn as much as 160 million tons of plastic refuse each year, they will still only be replacing between 10 and 15 percent of their industrial coal consumption,” he stresses.

At five pilot projects in Asia OPTOCE is using refuse from landfills as industrial fuel. “It is crucial that both the industry itself and [local] authorities recognize the opportunities made available by the use of plastic refuse,” Karstensen says.

“We now have cement factories in China, India, Thailand, Vietnam and Myanmar taking part in the project,” he adds. “All of them are testing the use of plastic as a fuel. All that remains is to document the environmental and commercial benefits.”

Potentially, those benefits could be considerable since these and other countries around Asia are the world’s worst plastic polluters.

At the same time, scientists are also creating new types of more ecofriendly polymers. A team of chemists at Cornell University in the United States, for one, has developed a new polymer that degrades rapidly when exposed to ultraviolet radiation from the sun.

The new polymer could be used in fishing gear such as ropes and nets, which routinely end up in the oceans. They then stay there for decades while taking a toll on coral reefs and a myriad of marine creatures.

“We have created a new plastic that has the mechanical properties required by commercial fishing gear. If it eventually gets lost in the aquatic environment, this material can degrade on a realistic time scale,” says lead researcher Bryce Lipinski, whose team has spent 15 years developing the new polymer called isotactic polypropylene oxide.

Objects made from the new plastic could degrade fast in nature, leaving no trace behind, the researchers say. “This material could reduce persistent plastic accumulation in the environment,” Lipinski notes.

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