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Issue 5, 2011
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Occurrence and removal of titanium at full scale wastewater treatment plants: implications for TiO2 nanomaterials

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Abstract

Titanium dioxide nanoparticles increasingly will be used in commercial products and have a high likelihood of entering municipal sewage that flows to centralized wastewater treatment plants (WWTPs). Treated water (effluent) from WWTPs flows into rivers and lakes where nanoparticles may pose an ecological risk. To provide exposure data for risk assessment, titanium concentrations in raw sewage and treated effluent were determined for 10 representative WWTPs that use a range of unit processes. Raw sewage titanium concentrations ranged from 181 to 1233 µg L−1 (median of 26 samples was 321 µg L−1). The WWTPs removed more than 96% of the influent titanium, and all WWTPs had effluent titanium concentrations of less than 25 µg L−1. To characterize the morphology and presence of titanium oxide nanoparticles in the effluent, colloidal materials were isolated via rota-evaporation, dialysis and lyophilization. High resolution transmission electron microscopy and energy dispersive X-ray analysis indicated the presence of spherical titanium oxide nanoparticles (crystalline and amorphous) on the order of 4 to 30 nm in diameter in WWTP effluents. This research provides clear evidence that some nanoscale particles will pass through WWTPs and enter aquatic systems and offers a methodological framework for collecting and analyzing titanium-based nanomaterials in complex wastewater matrices.

Graphical abstract: Occurrence and removal of titanium at full scale wastewater treatment plants: implications for TiO2 nanomaterials

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Publication details

The article was received on 10 Jan 2011, accepted on 22 Mar 2011 and first published on 14 Apr 2011


Article type: Paper
DOI: 10.1039/C1EM10017C
Citation: J. Environ. Monit., 2011,13, 1195-1203
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    Occurrence and removal of titanium at full scale wastewater treatment plants: implications for TiO2 nanomaterials

    P. Westerhoff, G. Song, K. Hristovski and M. A. Kiser, J. Environ. Monit., 2011, 13, 1195
    DOI: 10.1039/C1EM10017C

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