Microplastics in Wastewater Treatment Plants and Receiving Waters
Regulatory bodies have called for the ban of consumer use microplastics both internationally and within several states in the United States. Microplastics are particles of plastic smaller than 5 mm diameter and can be categorized as primary and secondary microplastics, with primary being intentionally produced and secondary being the decomposition or mechanical breakdown of larger macroplastics.
Microplastics enter wastewater treatment plants (WWTP) due to a variety of sources, but may not be effectively removed during treatment. Studies from Germany, the Netherlands and Sweden have shown close to 99% of microplastics remain in sewage sludge and the rest is emitted to surface waters via treated wastewater effluent. Sewage sludge that is converted to biosolids creates the potential to reintroduce microplastics back into the aquatic systems via runoff.
Despite regulatory and scientific scrutiny of microplastics, the distribution, occurrence, fate, and ecological impacts of microplastics are still poorly understood. The persistence of plastics in the environment coupled with the increases in production of plastics make them a potential threat to aquatic and terrestrial life in and around aquatic systems. Beyond the toxicity of microplastics, these particles can absorb other contaminants and become a source of contaminant exposure to wildlife. Further research on microplastics in WWTPs and receiving waters is needed to better understand the environmental risks of microplastics to better guide decision making for WWTP operators, lawmakers, and producers of microplastics. Waterborne scientists are currently positioning for involvement in this critical research and will remain on the pulse of this emerging topic in order to provide guidance to our clients.