1. Design a chlorine contact basin (serpentine) to disinfect 1 MGD flow and meet 4- log virus removal with a free chlorine residual of 0.1 mg/L (pH=7, Temp = 25C). Use a length:width ratio of approximately 20:1 and a depth of 4 to 6 feet.
2. Alter the design to achieve 3-log removal of Giardia cysts using free chlorine (still must treat 1 MGD, pH=7, T=25C). How would the design change if you used chlorine dioxide?
3. Design the disinfection system for an existing pipeline and storage tank as follows: the chlorine is added to the filter effluent in a 12-inch pipe that is 400 ft long and empties into a 2 MG storage tank. Flow rate is 2 MGD and you must achieve 4-log virus removal. Assume pH = 7, Temp = 20C and the tank is square with dimensions, L:W:H= 134:134:15ft You will select the chlorine residual and any internal modifications to the tank.