Microplastic (MP), an emerging pollutant, has been identified as a critical target in tackling plastic pollution. Although a plethora of studies have explored MP generation from various sources, limited attention has been paid to plastic processing. This study investigated MP (10 μm-5 mm) generation in virgin and waste plastic extrusion processing. MPs at a density of 2.13 × 105-9.79 × 107 (approximately 0.01-10.85 g) were generated when processing 1 t of plastic. Feedstock sources, polymer types, and pelletizing techniques were found to influence the process. With a moderate weight (270.58-527.34 t) but enormous amount (1.34 × 1016-2.63 × 1016) of MPs generated globally in 2022, plastic processing is an underestimated but vital source of MPs, emphasizing the need for MP inspection and appropriate removal technologies in the industry, especially for virgin plastic processing and water ring pelletizing. Further simulation indicated that up to 84.35% of MPs could be removed using commonly available materials in the investigated plastic processing facility, with a higher removal efficiency for larger-sized particles. In this regard, plastic recycling was superior to virgin plastic processing with fewer and larger-sized MPs generated, which could facilitate MP removal and should be fostered.
Keywords: cooling water; influencing factor; microplastic; plastic processing; waste plastic recycling.