Waterless urinals and hygiene
The materials required for this science fair project:
- 10 petri dishes prepared with agar
- 10 disinfected swabs
- 1 bottle of sterilized water
- latex gloves
- 1 marker pen
1. For this science fair project, the independent variable is the sample collected from the waterless urinal and the water-based urinal. The dependent variable is the amount of bacteria growth in the Petri dishes. This is determined by measuring the approximate diameter of the growth of the bacteria colony with a ruler. The constants (control variables) are room temperature, the amount of sunlight and the petri dish preparation.
2. The 10 petri dishes are filled with agar and stored in a refrigerator. The petri dishes are taken out of the refrigerator and brought to room temperature before the start of the experiment.
3. The petri dishes are labeled A1, A2, A3, A4, A5, B1, B2, B3, B4 and B5. The petri dishes labeled A1 to A5 will be used for the waterless urinals and the Petri dishes labeled B1 to B5 will be used for the water-based urinals.
4. 5 toilets that have waterless urinals and another 5 toilets that have water based urinal are located. Once the locations of the toilets are identified, samples of bacteria are collected from each toilet.
5. The 5 waterless urinals are tested first. A sterilized swab is moistened using some sterilized water. The swab is dabbed onto the walls inside the urinal and then dabbed on the surface of the agar inside Petri dish labeled A1. Similarly, petri dishes A2 to A5 are used to collect bacteria samples from the other 4 waterless urinals. The 5 petri dishes are sealed with their cover and they are set aside in a cool shaded place to allow the bacteria to grow.
6. The 5 water-based urinals are next tested. Bacteria samples are collected in the same way described in procedure 5 (from the same spot within the urinal) and the swabs are rubbed onto the surface of the agar in petri dishes labeled B1 to B5.
7. The approximate diameter of the bacteria colony growth is measured everyday for 5 days and recorded in the table below.
The agar in the Petri dishes should be properly disposed of and the Petri dishes decontaminated after the experiment. This can be done by washing the Petri dishes with bleach.