SODIS SO LAR DIS INFECTION

1. SODISSOLAR DISINFECTION Team Aquafers Scott Weeks, Stephen Russo, James Berg & Jamison Hill

2. Procedure ©Fundacion SODIS Uniersidad Mayor de San Simon Casilla, 5783, Cochabamba, Bolivia sodis@supernet.com.bo, sodisla@fcyt.umss.edu.bo

3. Exposure Times

4. Turbidity • To be effective turbidity must be below 30 NTU • Turbidity test • In the shade place filled 2 Ltr bottle on SODIS logo. Look down through the top to the bottom • If you can read the letters, less then 30 NTU • If you can see the sun rays, less then 20 NTU

5. Bottle Type • 2 Ltr bottles usually made of PVC or PET • PET transmits UV rays more effectively • PVC bottles usually have a bluish gleam • If burnt PVC smoke smells pungent, PET smoke smells sweet • Glass bottles can also be used • Should not use containers greater then 10 cm (4 in) deep

6. SODIS Science • Thermal (Pasteurization) • UV Radiation Solar energy provides two mechanisms of treatment: Can work independently, but studies indicate synergistic effects when applied together

7. Thermal Effects Temperatures at which the most common waterborne pathogens are rapidly killed, resulting in 90 percent of the microbes becoming inactivated in one minute at the given temperature. Source: http://solarcooking.org/newsletters/scrnov02.htm#water

8. UV Radiation • Damages living cells (i.e. sunburns) • Causes fundamental changes in nucleic acids/DNA (by producing thymine-dimers) • Excessive radiation can also change enzymes and other fundamental structures

9. Types of UV Radiation • The inactivation rate of micro-organisms increases with decreasing wavelength: Visible light -> UV-A -> UV-B ->UV-C (260 nm) • The maximum DNA absorption corresponds to the wavelength of UV-C (but sunlight mostly provides UV-A radiation

10. Synergistic Effects 1997 EAWAG Study examined effects of radiation and temperature • Conclusions: • Between 12 and 40° C, inactivation of bacteria is mostly due to irradiation • Inactivation in dark control at is due to heat • Inactivation in transparent tubes at 50° C show a combined effect of thermal and radiation

11. Coliphage f2 Bacteria Results

12. Rotavirus Results

13. Limitations of SODIS • Weather Conditions need to be right • Only feasible for small volumes of water • Bottle restrictions • Not effective against all types of waterborne disease • Turbidity is a problem • Possibilities for misuse

14. 2 days exposure for 50-100% cover Doesn’t work when there is rain Central regions more favorable Climate

15. Can SODIS provide enough clean water for a household? • Would require 10 2-liter bottles of clean water per day • How would you prepare for rainy days if you don’t know when they are coming? • Is it wise to rely on the weather?

16. Water Depth in Bottle • Water depth should be as low as possible for maximum radiation and heating. • Should not exceed 10 cm • SODIS bags

17. Bottle Aging • Aging of PET bottles leads to a reduction of U.V transmittance -Scratches -Photochemical reactions

18. What is UV treatment effective against? • Bacteria: E. coli, Vibrio cholerae, Salmonella paratyphi, and others • Viruses: Bacteriophages, rotavirus

19. Not Effective Against: • Chemically contaminated waters • Spore and cyst forming organisms such as protozoa • Giardia and Cryptosporidium

20. Possibilities for Misuse • Bottles exposed to sun in morning, but in the shade after a couple of hours • Some users put the bottles on chairs, not considering that the back of the chair casts a shadow • Bottles placed with painted side up • Partially filled bottles • Recontamination!

21. Implementing SODIS in Uzbekistan JDA International, Inc.

22. BackgroundClimate and Topography • In April 2001, JDA (Joint Development Associates) started the SODIS pilot project in the Ferghana valley near the city of Kokand in Uzbekistan. • Uzbekistan lies on the 41st parallel in Central Asia. The country is characterized by deserts, semiarid steppes, vast plains. The climate in the valley can be described as arid. The winters are cold and summers are hot. Between April and September there is virtually no precipitation or cloud coverage (300 days sunshine/year) and abundant solar radiation (averaging 200 kW/m2 between May to September). • Uzbekistan seems to be a prime location to implement SODIS

23. BackgroundSocial History • Economical Status • Post-Soviet Union economic system • Collective farms were privatized • Government took care of people’s needs. Individual initiative • and responsibility were neither asked for nor encouraged. • Little experience in decentralized decision making • The water system • Aging and leaking • Depended on external Soviet bureaucracy for maintenance • Who built quite an advanced system for the time: deep wells, water towers, piping • Lack of training and funding for proper maintenance and operation by local Uzbek staff. Currently maintained on the village scale. • Has contamination issues (backflow, intermittency, and leakage). • Little capital available because of lack of usage fees. • Need for low-cost disinfection

24. BackgroundSocial History cont… • Cold water problem • Because of history of waterbourne diseases with water supply, most people boil water or drink tea. Cold water associated with disease. • In summertime, people sometimes drink contaminated water straight from the tap to cool off and get reinforcing the perception. • Thus SODIS was called “sun-boiled water”

25. What was done • Promoters • 10 local people were trained in the SODIS method. Encouraged to drink SODIS water. Employed by JDA to promote its use to others. Divided into 3 teams. 15 villages were targeted for the SODIS campaign • Approaches used: • Mystical approach: SODIS – a type of healing water! • rational approach: Emphasized strongly that drinking SODIS water prevents disease saves healthcare costs. Money! • The relational approach: emphasized good relationships with decision-makers and key people who they introduced the method to. • Marketing schemes • SODIS game, poster, brochures (highly efficient due to high literacy rates) • Never promoted as cold water but as “sun boiled water” to keep in line with cultural preferences.

26. Results • SODIS promotion project appears to be effective. Most people introduced will continue to use it Source: “Bottles in the Sun”, JDA report: 2001. http://www.sodis.ch/files/MaterialsJDA/Report_2001_e.pdf

27. Results 2003 I • Impact of SODIS on health

28. Results 2003 II Conclusion: Most villages saw a decrease 2/3 decrease in disease incidence after SODIS implementation.

29. Resources • http://www.sodis.ch • http://www.jdainternational.org/ • Weglin M. et al. Solar water disinfection: scope of the process and analysis of radiation experiments. J Water SRT-Aqua. Vol. 43 No. 3. 1994. • http://www.grilink.org/ibsrepor.htm • http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=348911 • http://www.wpi.edu/Pubs/ETD/Available/etd-0423103-124244/unrestricted/rojko.pdf • http://www.cdc.gov/safewater/manual/alt_water.htm • http://solarcooking.org/sunandwater.htm