A water treatment plant treats a continuous flow rate of 50,000 m^3/day and plans to build a 10,000 m^3 tank to house an additional treatment process. The reaction occurring in the tank will remove nitrate according to first order decay with a rate of 0.25 per hour (12 hrs/day). The influent concentration of nitrate is 50 g/m^3.
a) What will be the residence time of the tank?
b) What will be the steady-state effluent concentration of an ideal CSTR?
c) What will be the steady-state effluent concentration of two equally-sized (5,000 m^3 each), ideal CSTR's in series?
d) What will be the steady-state effluent concentration for an ideal PFR? Assume dimensions of length = 500m, cross sectional area of flow = 20 m^3