2. Introduction One of the most important basic necessities of human beings: potable water. Some are not able to have this service due to various variables: Limited access Puberty Natural disasters
3. Introduction Water that is not properly processed can have high concentrations of bacteria such as E.coli and coliforms. Escherichia Coli (E.coli),
4. Solar Disinfection (SODIS) A transparent PET bottle is cleaned with soap. Then, the bottle is filled with water and placed in full sunlight for at least 6 hours. The water has then been disinfected and can be drunk.
5. Colilert Colilert uses the patented Defined Substrate Technology® (DST®) to simultaneously detect total coliforms and E. coli. As coliforms grow in Colilert, they use β-galactosidase to metabolize ONPG and change it from colorless to yellow. E. coli use β-glucuronidase to metabolize MUG and create fluorescence. Since most non-coliforms do not have these enzymes, they are unable to grow and interfere.
6. Hypothesis UV rays are the cause for disinfection in the SODIS method, not the temperature. In order to see a decrease in the colonies of E.coli.
7. Methodology Phase I (Sample collection) Label 14 bottles with the numbers and a letter identifying each brook. (A) brook with less contamination; (B) brook with more contamination. Collect water samples from two different brooks, localization provided by the professor. In 14 PET bottles, fill ¼ of the bottle with the brook’s water to clean it. Then collect the sample by filling completely the bottle. Samples have to be put in ice at 4°C.
8. Methodology Phase II (Sample Incubation and Colilert) Four samples from each brook (1A-4A; 1B-4B), have to be covered in aluminum foil. Only sample 1A and 1B have to be kept in 4°C. The other three samples have to be exposed to UV rays. The other six samples will be exposed to UV rays without the aluminum foil. Every two hours, two samples( one with aluminum foil and one without it) will be removed. The environment temperature will be measured, also the waters temperature and written down. And put them in 4°C.
9. Methodology After the six hours, you have to let all the samples lower their temperatures to 37°C. Then put them in 100mL Erlenmeyer flask, add a Colilert package and transfer it to a quantitray and seal it. Incubate the samples in 35°C for 24 hours. After this period count the positive results.
10. Results Bothcontrolshadextremelyhighconcentrations of total coliforms and E. coli. Allthebottleswrapped in aluminumfoilshowed a significantamount of contamination and a posible repopulation of bacteria. Unwrappedbottlesthatwereleftforthelength of thewholeexperimentshowedsomedisinfection.
11. Possible Reasons for no Disinfection SODIS requires direct and constant UV rays in order to disinfect. Weather conditions on the day of the experiment only allowed for approximately two hours of direct sunlight.
