A lagoon with volume 1200 m3 has been receiving a steady flow of a conservative waste at a rate of 120 m3/day for a long enough time to assume that steady-state conditions apply. The waste entering the lagoon has a concentration of 100 mg/L. Assuming completely mixed conditions:
(a) What would be the concentration of pollutant leaving the lagoon?
(b) If the input waste concentration suddenly increased to 1000 mg/L, what would the concentration in the effluent be 7 days later?
(c) On a spreadsheet plot the concentration of waste (C) as a function of time in days considering that t = 0 corresponds to the time when the input concentration increases to 1500 mg/L.