Two rivers meet at a confluence. River A is has a flow of 20m³/s, a DO level of 12mg/l and a five-day BOD of1mg/l. River B is polluted and has a flow of 30m³/s, a DO level of 4mg/l and a five-day BOD of 34mg/1. The rivervelocity downstream of the confluence is 0.5m/s. The saturated DO level in the river is 12.0 mg/l, the BODreaction rate constant is 0.25 day and the re-aeration constant of the river is 0.45 day¹.a) Calculate the minimum DO in the river and how far downstream of the confluence that this occurs.b) Describe 3 assumptions of this calculation that may differ in reality compared to our simplifiedmodelling.c) In up to 8 sentences, define 4 different types of water pollutants and describe their common sources,and consequencesd) Describe the role of water temperature in aggravating pollutant impact, and suggest how this could becontrolled from an industrial point of view

Given Data: River A QA=20m3/sDOA=12mg/lB0D=1mg/lRiver BQB=30m3/sDOB=4mg/lBOD= 34mg/lsat. DO level =…

Answered: Two rivers meet at a confluence. River…

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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A stream with a flow of 1.7 m°/s and BOD 3.4 mg/l is saturated with DO (9.27 mg/l at 20°C). It receives a treated effluent discharge from a cocoa processing factory of BOD 6780 kg/day and DO of 5.0 mg/I. The BOD of the stream immediately after mixing is 7.6 mg/l. The DO at a point 36 km downstream is 7.20 mg/l. The average velocity of the stream flow is 0.2 m/s. Determine the flow and the BOD in mg/l of the treated effluent discharged from the cocoa
4. The stream shown below has a flow of 28,000 m/d, and a cross-sectional area of 35 m2. The stream is saturated with dissolved oxygen (C* = 10 mg/L) and its BOD, concentration is 0.5 mg/L. At point (A)7 km upstream from the stream's confluence with another much larger river, a food processing industry is continuously discharging 1,500 m/day of wastewater with an average organic composition of CH,0 (which is 90% degradable). The wastewater has a dissolved oxygen concentration of 2 mg/L. A stream sample taken just before the confluence of stream and river has a BOD, 20°C of 3.0 mg/L ( k = 0.24/day for BOD assimilation in the lab). a) Calculate the concentration of the wastewater (in units of mg CH,0/L) before it is mixed in the river. Relevant constants are given below. b) Determine whether the D.O. level in the stream remains above 5 mg/L between point A and confluence of the stream with the larger river. You may assume the following: i) plug flow ii) instantaneous mixing of stream and…
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4.6 Poorly treated municipal wastewater is discharged to a stream. The river flow rate upstream of the discharge point is Qu = 8.7 m³/s. The discharge occurs at a flow of Q₁ = 0.9 m³/s and has a BOD concentration of 50.0 mg/L. Assume the upstream BOD concentration is negligible. (a) What is the BOD concentration just downstream of the discharge point? (b) If the stream has a cross-sectional area of 10 m², what is the BOD concentration 50 km downstream? (BOD is removed with a first-order decay rate constant equal to 0.20/day.)
An oxidation pond having a surface area of 90 000 m2 is loaded with a waste flow of 500 m3/d containing 200 kg of BOD5. The pond has a depth of 1.2 m. Determine BOD5 loading rate (kg(Ha.d) Determine hydraulic retention time (d)
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