title: Identification of microplastic in effluents of waste water treatment plants using focal plane array-based micro-Fourier-transform infrared imaging.
abstract: The global presence of microplastic (MP) in aquatic ecosystems has been shown by various studies. However, neither MP concentrations nor their sources or sinks are completely known. Waste water treatment plants (WWTPs) are considered as significant point sources discharging MP to the environment. This study investigated MP in the effluents of 12 WWTPs in Lower Saxony, Germany. Samples were purified by a plastic-preserving enzymatic-oxidative procedure and subsequent density separation using a zinc chloride solution. For analysis, attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FT-IR) and focal plane array (FPA)-based transmission micro-FT-IR imaging were applied. This allowed the identification of polymers of all MP down to a size of 20 μm. In all effluents MP was found with quantities ranging from 0 to 5 × 101m-3MP > 500 μm and 1 × 101to 9 × 103m-3MP < 500 μm. By far, polyethylene was the most frequent polymer type in both size classes. Quantities of synthetic fibres ranged from 9 × 101to 1 × 103m-3and were predominantly made of polyester. Considering the annual effluxes of tested WWTPs, total discharges of 9 × 107to 4 × 109MP particles and fibres per WWTP could be expected. Interestingly, one tertiary WWTP had an additionally installed post-filtration that reduced the total MP discharge by 97%. Furthermore, the sewage sludge of six WWTPs was examined and the existence of MP, predominantly polyethylene, revealed. Our findings suggest that WWTPs could be a sink but also a source of MP and thus can be considered to play an important role for environmental MP pollution.
authors.affiliation: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Biologische Anstalt Helgoland, P.O. Box 180, 27483 Helgoland, Germany; Copernicus Institute of Sustainable Development, Environmental Science Group, Utrecht University, P.O. Box 80115, 3508 TC Utrecht, The Netherlands. Electronic address: s.m.mintenig@uu.nl.
authors.forename: S M
authors.initials: SM
authors.lastname: Mintenig
authors.affiliation: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Biologische Anstalt Helgoland, P.O. Box 180, 27483 Helgoland, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Int-Veen
authors.affiliation: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Biologische Anstalt Helgoland, P.O. Box 180, 27483 Helgoland, Germany; Animal Ecology I, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: M G J
authors.initials: MGJ
authors.lastname: Löder
authors.affiliation: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Biologische Anstalt Helgoland, P.O. Box 180, 27483 Helgoland, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Primpke
authors.affiliation: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Biologische Anstalt Helgoland, P.O. Box 180, 27483 Helgoland, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Gerdts
mesh_terms: D004784:Environmental Monitoring; D012722:Sewage; D017550:Spectroscopy, Fourier Transform Infrared; D014865:Waste Disposal, Fluid; D062065:Wastewater; D014867:Water; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D012722:Sewage; D062065:Wastewater; D014867:Water; D014874:Water Pollutants, Chemical
keywords: Enzymatic purification; FT-IR spectroscopy; Microplastic identification; Pollution; Synthetic fibres; Treated waste water