A lagoon with volume 1500 m3 has been receiving a steady flow of a non-conservative waste stream (at a rate of 120 m3/day, concentration of 140 mg/L, a decay rate of 0.3/day, without any generation) for a long enough time to assume that steady-state condition apply. Assuming completely mixed conditions: A: What is the concentration of the pollutant in the effluent leaving the lagoon? B: If the input waste concentration suddenly decreased to 60 mg/L, determine the concentration in the effluent 5 days later? C: Draw a rough graph of concentration vs. time from 2 days before to 5 days after this sudden change and beyond.