A well-mixed sewage lagoon (shallow pond) is receiving 400 m/day of untreated sewage. The pollutant concentration in the untreated sewage discharging into the lagoon is 180 mg/L. The lagoon has a volume of 100.000 m2. The organic matter in the sewage decays in the lagoon according to first-order kinetic with a decay coefficient of 0.7/day. Assuming the pollutant is completely mixed in the lagoon and assuming no evaporation or other water losses or gains, answer the following: a. Sketch the problem and label all variables and quantities. b. Beginning with the Law of Conservation of mass and the terms included in the general material or mass balance equation, perform mass "mass rate" balance around the lagoon and state which terms maybe neglected or ignored and why. c. Find the steady-state concentration of the pollutant in the lagoon effluent (flowing out) in mg/L