The flow of microplastics from wastewater to the urban aquatic environment: Occurrence, fate, and an outlook on management strategies in Asia

Plastic pollution has grown into an epidemic. Among them, plastics smaller than 5mm, defined as microplastics (MPs), have caused severe environmental pollution and emerged as the second major global environmental and ecological issue in the 21st century. As the major receptacles for land-based MPs, the aquatic systems in the urbanized region are considered to be one of the most widely polluted environments, where waterborne MPs can be transported and distributed through water flow; coherent strategies are required to segregate and control MPs pollution. This chapter reviews and describes MPs pollution in urbanized aquatic environments, where wastewater treatment plants and estuarine fronts (for coastal cities) can act as control points for the retention of MPs during transportation. Furthermore, waterborne MPs also undergo complex processes, including sedimentation, fragmentation, aging, and aggregation, further increasing the challenge of MPs pollution assessment and control. This chapter highlights that the Asiatic region displays greater MPs pollution in the aquatic environment. Hence, taking Asia as an example, we further explored the causes of increased MPs pollution and provided an outlook on plausible management strategies for pollution control.