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Presented by John M. Schineller Paul D. Schreiber High School

A practical demonstration of water disinfection using TiO 2 films and sunlight Water Research, Volume 40, Issue 17, October 2006. Silvia Gelover, Luis A. Gomez, Karina Reyes, Ma. Teresa Leal. Presented by John M. Schineller Paul D. Schreiber High School. Introduction. Need for clean water

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Presented by John M. Schineller Paul D. Schreiber High School

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  1. A practical demonstration of water disinfection using TiO2films and sunlightWater Research, Volume 40, Issue 17, October 2006 Silvia Gelover, Luis A. Gomez, Karina Reyes, Ma. Teresa Leal Presented by John M. Schineller Paul D. Schreiber High School

  2. Introduction • Need for clean water • Existing water treatment options • Solar water disinfection (SODIS) • UV- A radiation • Titanium Dioxide TiO2 • Coliforms • Total • Fecal

  3. Review of Literature Reduction in per capita water supply (WHO/UNICEF 2000) Temperature and UV radiation can inactivate pathogens ( EAWAG and SANDEC, 2002) Titanium Dioxide can promote cellular destruction (Yu et al. (2002); Sunada et al. (2003) and Huang et al. (2000))

  4. Review of Literature -continued TiO2 control microorganisms (Lonnen et al. 2005) Homemade Solar Boxes ( Martin et al. 2000)

  5. Problem Statement • This research used water polluted with coliforms and exposed it to sunlight in plastic bottles with and without titanium dioxide.

  6. Hypothesis • Not explicit • TiO2 and SODIS will have a complementary affect greater than SODIS • Both total coliforms and fecal coliforms will decrease

  7. Methodology • Solar boxes were used at angles for maximum UV exposure • Exposure times of 0, 15, 30, 45, and 60 min • 87.5mg TiO2 per liter • Control of bottle without TiO2 • Aliquots tested with chromogenic substrate method (yellow color) • 21 trials • 7 additional 7 day cycles

  8. Results - continued Fig. 2 – Decrease of total coliforms during the treatment of SODIS plus TiO2 disinfection (average radiation 1037Wm2).

  9. Results - continued Fig. 3 – Fecal coliforms decrease during treatment SODIS and SODIS with TiO2 disinfection (average radiation 1037Wm2).

  10. Results - continued Fig. 4 – Total coliform daily regrowth.

  11. Discussion • Increased exposure times showed a decrease in both total and fecal coliforms • TiO2 and SODIS results were greater • Total coliform daily regrowth was minimal

  12. Conclusion • TiO2 and SODIS will have a complementary affect greater than SODIS - supported • Both total coliforms and fecal coliforms will decrease - supported • Time was reduced – 15 minutes for fecal coliforms and 30 minutes for total coliforms; half the time required for SODIS alone

  13. Acknowledgements • All figures and graphs are from the original paper or used with permission of the authors. • Thanks to current and past students and teachers from the Schreiber Science Research Program

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