Solar Water Disinfection
The lower the degree of transparency of the plastic bottle surface, the lower the level of disinfection.
What is Solar Water Disinfection (SODIS)?
Solar Water Disinfection is a method of killing unwanted microorganisms in water by exposing water in sunlight. Usually, clear plastic bottles are filled with water and then left in the sun, exposed to UV ray for hours on end.
This method is accredited by the World Health Organization because it is a cheap and efficient way to produce water safe for drinking and is currently widely used in many third world countries.
Experiments have shown that exposing polluted water to sunlight deactivates disease causing microorganisms due to the UV rays which proves to be deadly for harmful microorganisms.
What types of bottles are suitable for SODIS?
PET, which stands for Polyethylene terephthalate bottles are used in SODIS. PET bottles are used in SODIS because they are light and hard to break. In addition, PET bottles are also easily obtained in many countries. However, certain glass bottles and specifically engineered plastic bags can also be used.
However, over time, these PET bottles may become scratched from overuse. This would cause the plastic to lose its transparency and potentially hindering the potential effects from SODIS.
Students must take personal safety steps by wearing gloves, mask and goggles before starting the experiment. Disinfectants should be available for standby in case of bacterial contamination. Teachers should be over watching students at all times during the experiment in case of any accidents. Students with respiratory problems should refrain from doing this experiment.