A 4MGD groundwater treatment plant receives its source water at temperature and pH of 20oC and 6.5 respectively, a 82mg/L CO2 concentration and a 6.2mg/L Fe2+concentration. An induced draft aerator with 90% efficiency for CO2removal and the capability to achieve equilibrium concentration of dissolved oxygen in water will be used as the initial unit process in the treatment plant.

a. Using Henry's Law, determine the equilibrium concentration of oxygen in mg/L Henry's constant at 20°C is 41,619 atm, and the partial pressure of oxygen is 0.21 atm.
b. Considering equilibrium concentration of dissolved oxygen from (a), will the aerator provide adequate oxygen to oxidize Fe2+ to meet EPA's secondary MCL?
c. For a 20 minute contact time criteria for iron removal, will alkaline chemical addition to adjust pH be necessary?
d. esign a contact tank to achieve optimum Fe2+ oxidation, along with a baffle wall. Show all calculations and clearly provide all assumptions you make for the design criteria.
e. Present your contact tank design through a schematic diagram showing the longitudinal section of the tank with dimensions. Also, present a preliminary layout of the baffle wall with estimated number of orifices. The design drawing does not have to be to scale.