Practical considerations for sampling, processing, analysis and reporting microplastic occurrence in increasingly complex media: microplastics in the water treatment process

, Cross Richard, Horton Alice, Jurgens Monika, Johnson Andrew, Ball Hollie, Read Dan, Svendsen Claus.

Microplastics may be considered as plastic anywhere between 1nm and 5mm, presenting an analytical challenge for their detection and quantification. No single method can enumerate all polymers, across this full size range. Clarity on the operational limits that define m̈icroplasticsïs an essential part of any investigation to allow for comparison between studies. At each stage, from sampling through to analysis, consideration should be made as to how these steps influence quantification of microplastics. Sampling strategies often require filtration, introducing a minimum size for microplastics that must be reported. Similarly, imaging approaches such as Raman or infra-red techniques can resolve microplastics to different sizes. The choice of analytical method must be balanced by the study requirements. Practical considerations of cost and time balanced against gains in precision are not trivial when large sample numbers are required. We present our experiences in sampling, method development, and analysis as part of a campaign monitoring 8 water treatment works and 8 wastewater treatment works over 7 months. This campaign (UK Water Industry Research Ltd, “Sink to River-River to Tap”) enumerated the number and polymer identity of microplastics in raw water, potable water, influent, effluent and treatment residues. This presentation focuses on practical recommendations, in particular the use of blanks, spike-recoveries and replication, in the context of controlling sources of contamination and the p̈atchinessïnherent in inhomogeneous samples. Efforts are underway to harmonise methods and analytical approaches quantifying microplastics in the environment. In the meantime, there is much value in increasing the longevity of the data generated in this highly productive field of research. By necessity, data comes from a plethora of different sampling, processing and analytical strategies. Sharing experiences from the lab and improving transparency in reporting goes some way to allowing data generated today to retain its value as the field develops.

View online