Microplastics from headwaters to tap water: occurrence and removal in a drinking water treatment plant in Barcelona Metropolitan area (Catalonia, NE Spain)

Nowadays, the presence of microplastics in drinking water is of concern worldwide due to potential impacts on human health. This paper has examined the presence of microplastics along the Llobregat river basin (Catalonia, Spain) and studied their behaviour and elimination along the drinking water treatment plant (DWTP). Due to different water composition, different sampling and sample preparation protocols were used to determine microplastics from river water and in the DWTP. Identification of microplastics of size range from 20 μm to 5 mm was performed by fourier-transform infrared spectroscopy (FTIR). Microplastics were detected in 5 out of 7 points along the Llobregat basin, with concentrations ranging between non-detected and 3.60 microplastics/L. In the intake of the DWTP, the mean concentration was 0.96 ± 0.46 microplastics/L (n=5), with a predominance of polyester (PES) and polypropylene (PP) and at the outlet the mean concentration was of 0.06 ± 0.04 microplastics/L with an overall removal efficiency of 93 ± 5%. Sand filtration was identified as the key stage in microplastic removal (78 ± 9%). Furthermore, the results showed that ultrafiltration/reverse osmosis (advanced treatment) is more effective for microplastic removal than ozonation/carbon filtration stage (upgraded conventional treatment). In addition, a preliminary migration test of the different materials used in the DWTP has been performed to identify potential sources of microplastics in each treatment step.

The authors are grateful to J. Martin, M. Minoves who provided advise and information where to sample in the DWTP and on the materials used in the treatment process, and arranged and adapted the pump to eliminate the plastic parts; M. Ganzer, S. Montes for assistance, help and for providing all the facilities to sample and extract microplastics in the DWTP; P. Hermo for assisting in the microplastic analysis with FTIR; F. Sanchez, X. Pardo, A. Vilaplana, C. Vega, I. García for their technical support and the members of Organic Chemistry Department for advise during the study. The authors thank the support of Industrial Doctorates Plan of the University and Research Secretary of the Economy and Knowledge Department of the Generalitat de Catalunya. SL acknowledges the Ministry of Science and Innovation of Spain under the project PID2019-105732GB-C21.

Peer reviewed