(b) A wastewater treatment plant discharges effluent into a river at a rate of 4.5 m /s. The effluent has an ammoniacal

[answerhappygod]

B A Wastewater Treatment Plant Discharges Effluent Into A River At A Rate Of 4 5 M S The Effluent Has An Ammoniacal 1 (52.95 KiB) Viewed 27 times

(b) A wastewater treatment plant discharges effluent into a river at a rate of 4.5 m /s. The effluent has an ammoniacal nitrogen concentration of 40 mg/l. The river has a flow rate of 120 m²/s and a background ammoniacal nitrogen concentration of 2 mg/l. Mixing in the river has been shown to be predominantly due to advection. Assuming a 1D system: () Calculate the steady-state concentration of ammoniacal nitrogen in the river at the point of discharge. [3 marks] () Calculate the concentration of ammoniacal nitrogen at a location 10.5 km downstream of the discharge where a water abstraction point is proposed. The cross-sectional area of the river at the location is 1,750 m2. The conversion rate of ammoniacal nitrogen to nitrate can be assumed to be first order with a conversion rate of k = 0.46 d.[3 marks)