Elective - III - Water & Waste Water Treatment w18
Elective - III - Water & Waste Water Treatment w18
Elective - III - Water & Waste Water Treatment w18
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Elective - III : Water & Waste Water Treatment
P. Pages : 2 NIR/KW/18/3628
Time : Three Hours *1388* Max. Marks : 80
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Notes : 1. All questions carry marks as indicated.
2. Solve Question 1 OR Questions No. 2.
3. Solve Question 3 OR Questions No. 4.
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4. Solve Question 5 OR Questions No. 6.
5. Solve Question 7 OR Questions No. 8.
6. Solve Question 9 OR Questions No. 10.
7. Solve Question 11 OR Questions No. 12.
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8. Due credit will be given to neatness and adequate dimensions.
9. Assume suitable data whenever necessary.
10. Diagrams and chemical equations should be given whenever necessary.
11. Illustrate your answers whenever necessary with the help of neat sketches.
12. Use of non programmable calculator is permitted.
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1. a) Explain the factors to be considered while selecting the site for water treatment plant. 6
b) Draw the flow diagram of conventional water treatment plant and explain the function of 7
each unit in brief.
OR
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2. a) Write short note on gas transfer in aeration process. 6
b) Design the cascade type aerator for the design flow of 15 MLD. 7
6. a) State the difference between slow sand and rapid sand filter. 6
b) Result of chlorine demand test on raw water as given below. 7
Sample No. Chlorine dose (mg/lit) Residual Chlorine after 10min contact (mg/lit)
1 0.2 0.19
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2 0.4 0.36
3 0.6 0.5
4 0.8 0.48
5 1.0 0.2
6 1.2 0.4
7 1.4 0.6
8 1.6 0.8
sketch chlorine demand curve. What is break point dose and what is the chlorine demand
at dose of 1.2 mg/lit?
NIR/KW/18/3628 1 P.T.O
7. a) For the sample of sewage 5 day BOD at 20ºC is 300 mg/lit and it is 70% of ultimate BOD. 7
What will be its 3 days BOD at 30ºC?
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8. a) A town discharges 100 cumec of sewage into a stream having flow rate of 1500 cumec 9
during lean days with a velocity of 0.12 m/sec. the 5 day BOD of sewage at a given
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temperature is 350 mg/lit. Find the amount of critical D. O. deficit and when and where it
will occur in the down stream portion of river. Assume deoxygenation constant 'K' as
0.1/day and coefficient of self purification as 3.5 saturation D. O. at given temperature is
9.2 mg/lit Assume D.O. in sewage is zero.
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b) What are the different methods to determine the BOD rate constants (K) and ultimate BOD. 5
Explain any one in detail.
9. a) Draw the conventional flow diagram of waste water treatment plant and explain the function 6
of each unit in brief.
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b) Design the grit chamber for design flow of 15MLD. Average temperature of sewage is 20ºC. 7
Specific gravity of grit particle is 2.65 and diameter of grit, particle to be removed is 0.2mm.
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OR
10. a) Explain the various types of screens used in waste water treatment plant. 6
b) Design bar screen channel for the peak flow of 40 MLD. Also calculate the length of 7
tu
channel.
Data given
i) Size of bar = 15mm x 50mm
ii) Clear spacing between bar = 30mm
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i) Conventional type
ii) Tappered type
iii) Step aeration
OR
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NIR/KW/18/3628 2