Release of Microplastics from Urban Wastewater Treatment Plants to Aquatic Ecosystems in Acapulco, Mexico

Contamination of aquatic ecosystems by microplastics (MPs) is mainly due to the release of high levels of MP particles from treated effluents by wastewater treatment plants (WWTPs). Due to the lack of policies and regulations establishing criteria for the control and elimination of MPs from WWTP effluents, this research evaluates the presence of 38 and 150 mu m MPs in influents and effluents from three WWTPs in the port of Acapulco, Mexico. Optical microscopy and Fourier transform infrared spectroscopy revealed that the MPs were polyethylene, polypropylene, polyethylene terephthalate, and polyvinyl chloride. MP removal efficiencies of 82.5-98.7% (38 mu m) and 86.8-97.5% (150 mu m) were achieved. Moreover, the MP average daily emissions to the receiving bodies of the three WWTPs ranged from 9.5 x 106 to 4.70 x 108 particles, while the annual emissions ranged from 3.05 x 109 to 1.72 x 1011 particles. This work reveals the urgency of implementing regulatory policies to avoid the continuous emission of MPs into aquatic ecosystems from WWTPs in Acapulco, Mexico.