Life Cycle Inventory and Environmental Fate of Tire-Wear Particle and Textile Washing Microfiber in Japan


The consideration of the full life cycle impacts of plastics (and substitutes) is mandatory to achieve sustainable solutions to end plastic pollution. This requires considerations of fossil-based and biobased feedstocks for plastic production, plastic chemicals and additives, plastic degradation pathways and intermediates, environmental impacts, ecotoxicological and human health effects, socio-economic costs, etc. Life Cycle Assessment (LCA) is a tool to assess life cycle impacts. However, the current LCA methodological approaches have limitations in including the effects of microplastics in the LCA. This impact integration into LCA needs the development of life cycle inventory (LCI) and life cycle impact assessment methods. Tire-wear particles (TWP) and synthetic textile microfiber (TMF) is estimated to be 1.41 and 0.26 million tons/year. The present study estimated TWP and TMF emissions at the prefectural level and 10 km grid level in Japan for six vehicle classes, developed a fate model based on drainage and wastewater treatment systems (WWTPs) in Japan, and estimated the fate factors (FF) for several compartments. TWP emissions per unit distance of travel by different vehicle classes have been estimated for Japan. A WWTPs model was developed (ArcGIS) based on the features (treatment level and capacity, location) of the centralized 2114 units and decentralized treatment systems. The TWP and TMF fate in several compartments were estimated using the developed WWTPs model. Estimated TWP emissions for motorcycles and heavy vehicles were 111 to 1664 g/life-of-tire, respectively. The total TWP emission for Japan in the year 2019 was 33,796 T/year. The TWP and TMF emission LCIs were obtained for the prefectural and 10 km grid levels (data not given). Significant differences among the prefectures affect emissions per unit population (and unit GDP). The percentage of combined sewer coverage and WWTPs coverage are the governing parameters for Japan's TWP and TMF FFs to water, respectively. Even though the urbanized prefectures (i.e., Tokyo) emit more TWP, the FFs to water become lower (0.23). On the other hand, in prefectures like Hokkaido, where the road network is spread over a large area and has less combined sewer coverage, the FFs become higher (0.92). However, in the case of TMF, the FFs in water are correlated with the WWTPs coverage. Further, the FFs of land depend on the WWTPs' sludge management practices. Besides the fate studies, policy measures were recommended to minimize TWPs and TMFs releases to the environment.