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GAO-23-106261 1 (2022-11-21)

handle is hein.gao/gaonxp0001 and id is 1 raw text is: Science, Technology Assessment, G A O and Analytics SCIENCE & TECH SPOTLIGHT: BIORECYCLING OF PLASTICS What is it? Plastics, which are made primarily from fossil fuels, are widely used in products such as water bottles. Of the 353 million tons of plastic waste generated globally in 2019, nearly 70 percent was put in landfills or incinerated, according to the Organisation for Economic Co-operation and Development (OECD). According to the Environmental Protection Agency (EPA), the U.S. generated about 36 million tons of municipal plastic waste in 2018, with about 9 percent recycled. Biological recycling, or biorecycling, is an emerging technology that uses microbes, such as bacteria or fungi, to break down plastic into its basic components for reuse. In contrast, the most commonly used recycling technology-mechanical-grinds, washes, and re-granulates the plastic. As discussed in an earlier Sotight, chemical recycling, another emerging technology, uses heat, chemical reactions, or both to recycle plastic waste. Industry is considering advanced technologies such as biorecycling and chemical recycling as complements or alternatives to mechanical recycling. With mechanical recycling, repeated processing eventually results in lower quality plastic that is discarded in landfills. How does it work? The microbes' specialized proteins called enzymes degrade plastic into its most basic chemical components, or monomers. The monomers can then be recombined into plastics of the same type and quality. In a process called upcycling, the monomers are recombined into different materials or chemicals with more desirable qualities, such as plastics that are more biodegradable than originally made or high-value chemicals, such as vanillin found in vanilla flavorings (see fig. 1). Source: GAO analysis (data). kilroy79lstock.adobe.com (flower). GAO-23-106261 NOVEMBER 2022 Plastic waste in landfills and oceans can have adverse environmental and health effects. More than 350 million tons of such waste was generated globally in 2019, but little of it was recycled. Biorecycling uses microbes to convert plastic waste into new products of equal or better quality. This could benefit the environment and economy, but challenges remain, including higher costs. While some microbes have naturally evolved enzymes that can degrade certain plastics, the process in nature can take weeks or more. To make biorecycling viable at industrial scale, scientists can alter, or engineer, the natural enzyme to degrade plastics faster, reducing the time needed for complete degradation to hours. Research suggests that biorecycling of plastics could eventually help promote a circular economy in which plastic waste is continuously reincorporated into new products. A more circular economy can lead to social, economic, and environmental benefits, including reducing plastic pollution and dependence on fossil fuels, according to experts (see fig. 2). Fossil Fuels Ckcularconomy Source: GAO analysis (data). Tartifintararitstockadobe.com (images). GAO-23-1 06261 How mature is it? Of the three recycling technologies, biorecycling using engineered enzymes is the least mature. Interest in biorecycling grew after the 2016 discovery of a new species of bacteria capable of almost completely degrading polyethylene terephthalate (PET), a plastic commonly used in products such as water bottles and polyester clothes. Engineering these enzymes improves their degradation efficiency. Most biorecycling research has focused on PET and polyurethane, partly because breaking their chemical bonds is easier. More prevalent plastics, including polyethylene (PE) and polypropylene, which are used for trash bags and containers respectively, have stronger bonds and require more GAO-23-106261 Biorecycling of Plastics enayrne

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