Question

Problem 1. A lagoon with a volume of 1,200 m3 has been receiving a steady flow of a stream at a rate of 100 m3/day. A pollutant in the incoming stream has a concentration of 10 mg/Land the pollutant degrades at a rate of 0.20 day-1. Assuming completely mixed conditions,and that there is an outlet from the lagoon as well.What would be the concentration of pollutant in the effluent leaving the lagoon at steady state conditions?If the input waste concentration then suddenly increased to 100 mg/L, what would the concentration in the effluent be 7 days later.

Fig: 1