A review on microplastic fibers and beads in wastewater: The current knowledge on their occurrence, analysis, treatment, and insights on human exposure impact

Abstract

The persistent presence of microplastic (MP) pollution in conventional wastewater treatment plants (WWTPs) is observed worldwide as they are currently not designed to remove MPs effectively. This pollution eventually re-enters and circulate in the environment, elevating the risks posed to ecosystems and organisms through biotoxicity and ecological destabilization. The most common MP shape in wastewater are microfibers (MFs) yet focused comprehensive studies on MFs is limited. Although not as abundant as MFs, microbeads (MBs) are also an important shape in WWTPs as they were among the first shapes to be targeted for production regulation, highlighting their significant impacts. Targeting these specific shapes are crucial as they represent the foundational components of wastewater MP pollution, and the current lack of these studies hinders our ability to address MP persistence and mitigation and management strategies properly. Therefore, this review aims to present the most up-to-date information on the distribution of MFs and MBs across WWTPs. Specifically, the source, detection, and analysis of MFs and MBs in wastewater, physicochemical characterization and interactions of common MF/MB polymers, and the current efforts to mitigate the production and release of these shaped MPs are summarized. This is the first literature review to focus on MFs and MBs in the aspects of their source, human toxicity, detection, and analysis in wastewater.