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GAO-21-105317 1 (2021-09-14)

handle is hein.gao/gaomdz0001 and id is 1 raw text is: Science, Technology Assessment, and Analytics SCIENCE & TECH SPOTLIGHT: ADVANCED PLASTIC RECYCLING What is it? Plastics are found in many everyday items-including food packaging, water bottles, bags, and appliances. They are largely made from fossil fuel-based chemicals combined with various additives-such as stabilizers or flame retardants-to achieve a desired result (e.g., strength, rigidity, color, heat resistance). The majority of plastic waste in the U.S. ends up in landfills, with a relatively small portion incinerated and an even smaller portion recycled. The accumulating plastic waste in landfills generally does not biodegrade or break down. 15.8% (5.62 million tons) Incineration 8.7% (3.09 million tons) Recycling Source: GAO analysis of 2018 U.S. Environmental Protection Agency (EPA) data. I GAO-21-105317 Fir. Mth ds ofjIplsi wat i a in th U.S. Plastic recycling technologies reprocess or remanufacture plastic waste for reuse. Currently, the dominant technology for plastic recycling is mechanical recycling, which uses physical processes-such as sorting, grinding, washing, separating, drying, and re-granulating-to recover plastics that can be substituted for virgin, or new, plastics. However, mechanical recycling technology is expensive, labor intensive, and generally results in lower quality plastics than virgin plastics. Consequently, industry is considering advanced recycling technologies- namely, chemical recycling-as an alternative or complement to mechanical recycling. Chemical recycling technologies use heat, chemical reactions, or both, to recycle used plastic into virgin-equivalent plastic, fuel, or other chemicals. In addition, recent advances in sorting technology-one of the physical processes common to both chemical and mechanical recycling technologies-may also increase the efficiency of chemical recycling and lead to increased plastic recycling. For example, artificial intelligence technologies have the potential to increase automated sorting efficiency. Similarly, another advanced technology efficiently sorts materials by identifying their molecular vibrations. How does it work? Chemical recycling can promote a closed-loop system, known as a circular economy, wherein plastics are reused rather than discarded in landfills or incinerated. There are three general categories of chemical recycling technologies: conversion, decomposition, and purification. Fossil fuels Raw materials Product (virgin plastics) manufacturing Consumers Plastic waste Virgin-equivalent Chemical plastics recycling Source: GAO illustration based on review of literature. IGAO-21-105317 Conversion focuses on converting polymers-long-chain hydrocarbon molecules built from smaller repeating units called monomers-in mixed or sorted plastics into smaller molecules. This can occur through a variety of techniques, including pyrolysis and gasification. * Pyrolysis, sometimes called plastics to fuel, turns plastic waste into a synthetic crude oil that can be refined into diesel fuel, gasoline, heating oil, or waxes. This process involves heating the plastic waste to high temperatures (300-900*C) in the absence of oxygen. Different forms of pyrolysis use different temperatures, pressures, and processing times. a Gasification also heats plastic waste to high temperatures (500- 1300*C) in a low-oxygen environment to convert plastic waste to synthesis gas, or syngas. Syngas-a fuel mixture containing mainly hydrogen and carbon monoxide-can be combusted for electric power generation or converted into other fuels or chemicals, such as ethanol and methanol. Decomposition breaks down polymers in sorted plastics into monomers to produce new plastics. This decomposition can be done with heat or chemicals. Chemical decomposition uses solvents to break the polymers into monomers. Some decomposition technologies use enzymes to break down polymers at temperatures as low as room temperature, resulting in less energy consumption. GAO-21-105317 Advanced Plastic Recycling

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