Aquatic toxicity evaluation of TiO2 nanoparticle produced from sludge of TiCl4 flocculation of wastewater and seawater
Flocculation using titanium tetrachloride (TiCl4) as a coagulant is an efficient and economical application because the flocculated sludge can be recycled to produce a valuable byproduct, namely titanium dioxide (TiO2) nanoparticles. However, toxicity of TiCl4 has not yet been assessed while it is used in water treatment. The aquatic toxicity of TiCl4 flocculation process was investigated to assess the environmental safety of the coagulant. D. magna and V. fischeri bioassays were carried out to evaluate the supernatant toxicity after TiCl4 flocculation. Artificial wastewater, biologically treated sewage effluent, and seawater were used to study the toxicity of TiCl4 flocculation. Results showed that supernatant toxicity was very low when TiCl4 flocculation was conducted (no observed effect concentration = 100 mg/L and lowest observed effect concentration = 150 mg/L exposed to D. magna and V. fischeri, respectively). Similarly, TiO2 nanoparticles recovered from wastewater and seawater flocculated sludge were also found to have low toxicity. The regenerated TiO2 nanoparticles indicated low toxicity values when compared to the commercial-TiO2 nanoparticle, P-25.
KeywordsAquatic toxicity D. magna V. fischeri Flocculation TiO2 nanoparticle Environment Health and safety EHS
This research was supported by UTS, ARC, Center for Seawater Desalination Plant (SeaHERO), Korea Research Foundation (KRF-2007-412-J02002), and NRL (NOM Ecology lab: ROA-2007-000-20055-0) grants.
- ASTM International (2002) Standard test method for assessing the microbial detoxification of chemically contaminated water and soil using a toxicity test with a luminescent marine bacterium. Document number: ASTM D5660-96. ASTM International, West ConshohockenGoogle Scholar
- DeWolfe J, Dempsey B, Taylor M, Potter JW (2003) Guidance manual for coagulant changeover. American Water Works Association Press, DenverGoogle Scholar
- Lewis RJ (1996) Sax’s dangerous properties of industrial materials, 9th edn. Van Nostrand Reinhold, New YorkGoogle Scholar
- Schaefer M, Scott-Fordsmand J (2006) Nanoparticles: does size matters? In: 16th annual meeting of SETAC Europe, The Hague, Netherlands, 7 to 11 May 2006, p. 222, Meeting, Lille (France), 22 May 2005/26 May 2005Google Scholar
- Suryanarayana C (1995) Nanocrystalline materials. Int Mater Rev 40:41–64Google Scholar
- Upton WV, Buswell AM (1937) Titanium salts in water purification. Ind Eng Chem (August):870–871. doi: 10.1021/ie50332a006
- USEPA (1993) Methods for measuring the acute toxicity of effluents and receiving waters to freshwater and marine organisms. Cinciniti, EPA/600/4-90/027FGoogle Scholar