(Solved): Q3) A well-mixed sewage lagoon is receiving 250m3/d of untreated sewage. The lagoon has a surface ...

Q3) A well-mixed sewage lagoon is receiving $$250{\mathrm{m}}^3/\mathrm{d}$$ of untreated sewage. The lagoon has a surface area of $$7,500{\mathrm{m}}^2$$ and a depth of $$1\mathrm{m}$$. The pollutant concertation in the raw sewage discharging into the lagoon is 250 $$\mathrm{mg}\mathrm{L}$$. The organic matter in the sewage degrades biologically (decays) in the lagoon according to first order kinetics. The reaction rate (decay rate) is $$0.75{\mathrm{d}}^{?1}$$. Assuming no other water losses or gains and that the lagoon is completely mixed, find the steady state concentration of the pollutant in the lagoon effluent.