The Sterilization of Water Through Ultraviolet Radiation

Without water, every living thing would perish, yet, for some people, the issue is not access to water, but the quality of the water. Many microorganisms, such as Escherichia coli, live within water, so it becomes necessary to sterilize water before it can be utilized. The purpose of this experiment was to discover if a variation of ultraviolet light radiation could be an effective way of purifying water. The experiment was conducted through the use of a UVC light filter. Through this filter, E. coli infected water was run. Using a spectrometer, the water was tested to observe the changes, if any, to the amount of bacteria found in the water. The spectrometer measures the amount of light that passes through a test tube. The bacteria were grown in separate Petri dishes to ensure that one batch of infected water would not infect another. It was found that the exposure to the UVC light did have a significant effect on the amount of E. coli found in a batch of water. Using the data collected from the trials, a matched-pairs t-test was conducted, resulting in a p-value of 0.006894. The E. coli numbers shrank because the ultraviolet light disrupted the bacterium’s ability to reproduce by damaging its nucleic acid, thus decreasing the amount of bacteria present.

Research Conducted By:

Alexandra Nash
Cousino High School

Cheyenne Taylor
Cousino High School