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> 2. Consider a 6 MGD water treatment system with conventional filtration (e.g., coagulation/flocculation and sedimentation followed by filtration) serving a population of >10,000 with 15°C source water containing 3 oocysts/L Cryptosporidium. A. What is the additional Cryptosporidium logio reduction requirement for disinfection of the filtered water? B. If chlorine dioxide is applied to a contact chamber with a contact time of 360 min, what residual chlorine concentration is needed at the effluent of the contact tank in order to comply with the logio reduction requirement? C. Suppose the chlorine dioxide decays at a first order rate of -0.1 per hour in the disinfection contact chamber. Assuming plug flow conditions, what concentration would have to be added to the water at the influent of the contact chamber? D. Given the concentration calculated in part C, what is the approximate dosing rate of chlorine dioxide? Express your answer in kg/day.