Concentrations and size distribution of TiO2 and Ag engineered particles in five wastewater treatment plants in the United States

Md. Mahmudun Nabi; Jingjing Wang; Madeleine Meyer; Marie Noele Croteau; Niveen Ismail; Mohammed Baalousha

doi:10.1016/j.scitotenv.2020.142017

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Concentrations and size distribution of TiO2 and Ag engineered particles in five wastewater treatment plants in the United States

Md. Mahmudun Nabi·Jingjing Wang·Madeleine Meyer·Marie Noele Croteau·Niveen Ismail·Mohammed Baalousha

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Abstract

The growing use of engineered particles ( e.g. , nanosized and pigment sized particles, 1 to 100 nm and 100 to 300 nm, respectively) in a variety of consumer products increases the likelihood of their release into the environment. Wastewater treatment plants (WWTPs) are an important pathways of introduction of engineered particles to the aquatic systems. This study reports the concentrations, removal efficiencies, and particle size distributions of Ag and TiO 2 engineered particles in five WWTPs in three states in the United States. The concentration of Ag engineered particles was quantified as the total Ag concentration, whereas the concentration of TiO 2 engineered particles was quantified using mass-balance calculations and shifts in the elemental ratio of Ti/Nb above their natural background elemental ratio. Ratios of Ti/Nb in all WWTP influents, activated sludges, and effluents were 2–12 times higher ( e.g. , 519 to 3243) than the natural background Ti/Nb ratio ( e.g. , 267 ± 9), indicating that 49–92% of Ti originates from anthropogenic sources. The concentration of TiO 2 engineered particles (in μg TiO 2 L −1 ) in the influent, activated sludge, and effluent varied within the ranges of 70–670, 3570–6700, and 7–30, respectively. The concentration of Ag engineered particles (in μg Ag L −1 ) in the influent, activated sludge, and effluent varied within the ranges of 0.11–0.33, 1.45–1.65, and 0.01–0.04, respectively. The overall removal efficiency ( e.g. , effluent/influent concentrations) of TiO 2 engineered particles ( e.g. , 90 to 96%) was higher than that for Ag engineered particles ( e.g. , 82 to 95%). Particles entering WWTPs are in the nanosized range for Ag ( e.g. , >99%) and a mixture of nanosized ( e.g. , 15 to 90%) and pigment sized particles ( e.g. , 10 to 85%) for TiO 2 . Nearly all Ag (>99%) and 55 to 100% of TiO 2 particles discharged to surface water with WWTP effluent are within the nanosize range. This study provides evidence that TiO 2 and Ag engineered nanomaterials enter aquatic systems with WWTP effluents, and that their concentrations are expected to increase with the increased applications of TiO 2 and Ag engineered nanomaterials in consumer products.

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Science of the Total Environment Article

Source-reported bounding extent: 32.75306566002286° to 42.40317854182803° latitude; -122.23251342773438° to -72.49500274658203° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Md. Mahmudun Nabi, Jingjing Wang, Madeleine Meyer, Marie Noele Croteau, Niveen Ismail, Mohammed Baalousha. 2020. Concentrations and size distribution of TiO2 and Ag engineered particles in five wastewater treatment plants in the United States. https://doi.org/10.1016/j.scitotenv.2020.142017

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