Find the contact time for inactivating Gardia cysts.
How much contact time would be required for inactivating Gardia cysts using the following chemicals at the concentrations and temperatures stated:
a) Chlorine dioxide, 23C, 1.0 mg/L
b) Chlorine, 12C, 1.6 mg/L
c) Ozone, 10C, 5 mg/L
d) Chloramines, 20C, 250 mg/L