A University was opened on 21st March 2021. Due to the high number of students who reported at the main campus, there was waste water dischare into the universities River with dissolved oxygen concentration of 2.0 mg/l at a discharge rate of 1.10m3 /s from the stabilization ponds. After two days, there was another discharge downstream with dissolved concentration of 2.1 mg/l at a discharge rate of 1.20m3 /s. After 1 hour a different discharge of waste with dissolved oxygen concentration of 0.5 mg/l at a discharge rate of 1.10m3 /s was discharged in the River immediately after the second discharge point. The River that was receiving the waste had initial DO equal to 8.3mg/l, a constant flow of 8.70m3 /s, and the temperature of 20' C. The saturated value of dissolved oxygen DOs at 20 ‘C is normally 9.09 mg/l. Just below the point where a continuous first discharge of pollution mixes with a river, the BOD was 10.9 mg/l. Using a deoxygenation constant of 0.20/day, an average flow of the mixture of 0.30 m/s and the river depth of 3.0 m and assuming complete and instantaneous mixing, a. Estimate the initial dissolved oxygen deficit of the mixture of wastewater and river water just downstream from the third discharge point. b. Find the time and distance downstream at which the oxygen deficit was at a maximum. c. Find the minimum value of DO. d. Explain in details the effects of continuous waste water discharge into the universities River
A University was opened on 21st March 2021. Due to the high number of students who reported
at the main campus, there was waste water dischare into the universities River with dissolved oxygen
concentration of 2.0 mg/l at a discharge rate of 1.10m3
/s from the stabilization ponds. After two days,
there was another discharge downstream with dissolved concentration of 2.1 mg/l at a discharge rate of
1.20m3
/s. After 1 hour a different discharge of waste with dissolved oxygen concentration of 0.5 mg/l at a
discharge rate of 1.10m3
/s was discharged in the River immediately after the second discharge point. The
River that was receiving the waste had initial DO equal to 8.3mg/l, a constant flow of 8.70m3
/s, and the
temperature of 20' C. The saturated value of dissolved oxygen DOs at 20 ‘C is normally 9.09 mg/l. Just
below the point where a continuous first discharge of pollution mixes with a river, the BOD was 10.9
mg/l. Using a deoxygenation constant of 0.20/day, an average flow of the mixture of 0.30 m/s and the
river depth of 3.0 m and assuming complete and instantaneous mixing,
a. Estimate the initial dissolved oxygen deficit of the mixture of wastewater and river water just
downstream from the third discharge point.
b. Find the time and distance downstream at which the oxygen deficit was at a maximum.
c. Find the minimum value of DO.
d. Explain in details the effects of continuous waste water discharge into the universities River
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