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Global discharge of microplastics from mechanical recycling of plastic waste
Summary
Researchers found that the mechanical recycling process for plastics actually generates significant amounts of new microplastics, with global emissions from recycling projected to grow from 0.017 million tonnes in 2000 to 0.749 million tonnes by 2060. While recycling accounted for about 3.1% of total microplastic emissions in 2017, this share could grow as recycling increases. The study highlights an important paradox: efforts to reduce plastic waste through recycling can themselves contribute to microplastic pollution unless wastewater treatment at recycling facilities is improved.
The increasing production of plastic products and generation of plastic waste have had increasingly negative environmental impacts. Although recycling could reduce plastic pollution, microplastics can be generated during the process of crushing plastic products during mechanical recycling. We conducted crushing tests with 13 different plastics and documented the size distribution of particles generated. We then estimated the discharge of microplastics associated with recycling and their removal in wastewater treatment plants. We estimated that the global discharge of microplastics would increase from 0.017 Mt in 2000 to 0.749 Mt in 2060. Although mechanical recycling was estimated to account for 3.1% of the total emissions of microplastics for 2017, discharges of microplastics from plastic recycling may increase, even if plastic pollution from well-known sources decreases. Non-OECD (Organization for Economic Cooperation and Development) Asia could be a major discharging region and would play a vital role in reducing discharges of microplastics. Reduction of the discharge of microplastics will require less use of plastic products and upgrading wastewater treatment in many countries.
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