Occurrence of titanium dioxide nanoparticle in Taihu Lake (China) and its removal at a full-scale drinking water treatment plant

Abstract

\n The occurrence of titanium dioxide nanoparticle (TNP), an emerging contaminant, in Taihu Lake of China was investigated. Ti was present at a concentration of 224\u2009±\u200959 µg/L in the water source of east Taihu Lake. Approximately 0.19% of the Ti-containing matter was at the nano-scale. Scanning Electron Microscope analysis verified the existence of Ti-containing components, such as TiOX and FeTiOX. Furthermore, Ti K-edge X-ray absorption near-edge structure spectroscopy was used to detect the phase composition of nano-scaled Ti-containing matter. The spectra showed the three characteristic peaks of TiO2 in the samples, suggesting the occurrence of TNP in Taihu Lake. A least-squares linear combination fitting analysis indicated that the TNP concentration in the water source was 0.86 µg/L, with a crystal composition of 0.44\u2009±\u20090.1 µg/L amorphous, 0.14\u2009±\u20090.03 µg/L anatase and 0.28\u2009±\u20090.06 µg/L rutile. The removal performance of the TNP at a full-scale conventional drinking water treatment plant indicated that 58.8% of TNP was removed via coagulation/sediment, sand filtration and disinfection/clear water reservoir. The coagulation/sediment process accounted for approximately 76.6% of the total removed TNP. The finished water contained 0.33 µg/L TNP with a crystal composition of 0.24\u2009±\u20090.13 µg/L anatase and 0.09\u2009±\u20090.05 µg/L rutile. This study is the first that reported the presence and transport of TNP in a drinking water treatment system.