The effectiveness of household cleaning agents for killing bacteria
Our hypothesis that Dettol was the most effective disinfectant, was proven to be false. Clorox was the most effective disinfectant, followed by Dettol, and then the dish-washing soap.
There is rising concern that frequent use of antibiotics is causing bacteria to mutate and become more resistant. The same concern is being raised regarding overuse of antibacterial soaps and similar cleaning agents.
Try to repeat the science fair project using other cleaning detergents like antibacterial soap, Listerine or Bleach.
How effective are alternative household cleaners? - http://www.uwex.edu/news/2001/3/how-effective-are-alternative-household-cleaners
Bacteria and household cleaners - http://www.articlegarden.com/article.php?id=24882&act=print
The bacteria should be destroyed before being disposed of. Pour some bleach into the petri dish to kill all the bacteria before disposing of the dishes in the trash.