Abstract
Removal mechanisms of bacteria (Escherichia coli : E. coli, total coliform : T. coli, heterotrophic plate counts : HPC) in a contact purification process for river flow were examined with experimental apparatus which had activated carbon or string as packed medium. Bacteria was adsorbed to biofilm or sediment quite effectively (60-90%) within one hour treatment and the maximum removal rate of E. coli was 3.0 CFU · ml-1 · min-1 with string type medium. 99% of E. coli removed during for 2 month experiment were inactivated, but the concentration in the biofilm and sediment was so high that the sludge accumulated in the process must be handled carefully to avoid secondary contamination.
