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The demand for single-use plastic significantly increased when the COVID-19 pandemic began, especially with the steady need for personal protective equipment (PPE) such as surgical face masks, gloves, face shields, and gowns to prevent virus transmission.

An estimated 3.4 billion single-use face masks or face shields are discarded every day due to the pandemic. Food packaging and plastic bag waste in households also multiplied with the increase in online shopping and delivery services.

Improper waste management will only aggravate existing global pollution and endanger the lives of both people and animals. It’s necessary to come up with an effective strategy that will minimize the environmental impact of the continuous COVID-19 waste stream—and some scientists think turning trash into fuel could be an option.

Numerous studies propose that COVID-19 waste could be converted to fuel

Several studies over the past two years have proposed pyrolysis—an effective method that will not only mitigate plastic pollution but also convert waste into usable fuel. A 2020 study published in Biofuels proposed that discarded PPE kits be converted into liquid fuel through the process, which is the thermal decomposition of a solid material. Pyrolysis heats the material to a temperature high enough to deconstruct polymers.

“Typically, when we talk about pyrolysis as a technology, we heat a solid up without oxygen and then collect the vapors as an oil,” says George Huber, director of the Center for Chemical Upcycling of Waste Plastics who was not involved in the study. “Pyrolysis of plastics is a technology that is being used to produce oils from plastics. These oils can then be used to make new plastics or fuels.”

According to a 2021 study published in Chemosphere, pyrolysis is an environmentally friendly, efficient, and cost-effective COVID-19 waste management technique. “Considering the advantageous nature of pyrolysis techniques and its capacity in effective dealing of municipal wastes, the same can be enforced for the treatment of COVID-19 waste. The technology utilizes high-temperature combustion, which can be applied for complete degradation of the infectious agents that are carried along with the COVID-19 waste,” the researchers said.

Face masks and surgical gloves can be easily converted into fuel because they are made of polypropylene and polyvinyl chloride, which are thermoplastic polymers with high oil content. The oil obtained through pyrolysis is comparable with commercial fuel because its properties are similar to that of fossil fuels.

A 2022 study published in Bioresource Technology converted surgical masks into liquid oil and found that its higher heating value is 43.5 megajoules per kilogram, which is only slightly lower than that of diesel fuel and gasoline at 45.8 and 46.3 MJ/kg respectively.

Pyrolysis-based waste processing systems would produce fewer carbon dioxide emissions

In a life-cycle assessment (LCA) conducted by the authors of the Bioresource Technology study, the researchers found that processing waste through pyrolysis produces fewer carbon dioxide and phosphorus emissions than most conventional waste management approaches.

A different 2022 study published in Renewable and Sustainable Energy Reviews also proposed an optimal pyrolysis-based PPE waste processing system that could reduce the use of fossil fuels by 31.5 percent and produce 35.04 percent fewer greenhouse gas emissions compared to the incineration process. Compared to their proposed system, the landfilling process poses 143 and 46 percent higher environmental impacts on marine ecotoxicity and human toxicity.

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Source: Popular Science

Date: 30 March

Posted in News on Mar 30, 2022

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