Quantifying and identifying microplastics in the effluent of advanced wastewater treatment systems using Raman microspectroscopy

Microplastics in wastewater treatment plant (WWTP) effluent have been identified and quantified, but few studies have examined the microplastics in advanced treatment systems. A new method for isolating, quantifying, and determining the polymer type of microplastics was developed that included chemical digestion coupled with Raman microspectroscopy to investigate microplastics in the effluent of reverse osmosis nanofiltration and activated carbon filtration systems. This method allows for the removal of organics and the quantification and identification of all microplastics present in the sample. A large number of microplastics, the majority of which were smaller than 10 μm, were identified in the effluent of the advanced filtration systems with polyethylene the most common polymer identified. This study not only reports a new method for microplastic identification and quantification but also shows the importance of measuring the smallest fraction of microplastics, those smaller than 20 μm, which have previously been understudied.