1 (a)
Explain the need for good sanitation. Hence, describe types of sewerage system and their suitability.

6 M

1 (b)
Explain factors affecting DWF and teh effects of flow variations on the design of sewerage system.

7 M

1 (c)
A certain district of a city has a projected population of 50000 residing over a area of 40Ha. Find the design of discharge for the sewer line, for the following data:

i) Rate of water supply = 200 lped ii) Average impermeability factor for the area = 0.3 iii) Time of concentration = 50 minutes. The sewer line is to be designed for a flow equivalent to the WWF plus twice the DWF. Take sewage generated as equal to 75% of water supplied. Use the formula: \[ R_i = \dfrac {25.4a} {t+b} . \] Comment on the result.

i) Rate of water supply = 200 lped ii) Average impermeability factor for the area = 0.3 iii) Time of concentration = 50 minutes. The sewer line is to be designed for a flow equivalent to the WWF plus twice the DWF. Take sewage generated as equal to 75% of water supplied. Use the formula: \[ R_i = \dfrac {25.4a} {t+b} . \] Comment on the result.

7 M

2 (a)
Explain the effect of flow variation on velocity of flow in sewers.

6 M

2 (b)
Explain i) Self cleansing velocity ii) Non-scouring velocity.

5 M

2 (c)
A 600mm diameter sewer is required to flow at 0.4 depth on a grade ensuring a degree of self cleansing equivalent to that obtained at full depth at a velocity of 850mm/s. Find the required grade, associated velocities and rates of discharge at full depth and 0.4 depth. Take n=0.015 for all depth of flow \[ \left \{ Given : \ \dfrac {a} {A} = 0.374 : \ \ \dfrac {r} {R} = 0.857 \right \} .\]

9 M

3 (a)
Explain the need for providing sewer appurtenances in sewerage system. Hence name common sewer appurtenances.

4 M

3 (b)
What are inlets? Draw the locations and section of inlet and explain.

6 M

3 (c)
What is Manholes? Explain the need of manhole. Draw neat sketch of deep manhole.

10 M

4 (a)
Differentiate between fresh sewage, scale sewage and septic sewage.

3 M

4 (b)
What is first stage BOD? Derive the equation for 1

^{st}stage BOD, with a neat sketch.
5 M

4 (c)
Explain COD and its relation with BOD.

4 M

4 (d)
What is Treatability Index? What is the use of treatability index?

8 M

5 (a)
Explain various factors that affect self purification process of stream.

7 M

5 (b)
Explain waste water disposal into sea.

5 M

5 (c)
100m

^{3}/s of a city sewage is discharged in a river is fully saturated with oxygen and flows at a minimum rate of 1250 m^{3}/s, with a minimum velocity of 0.15 m/s. If the 5-day BOD of the sewage is 260 mg/lt, find where the critical DO will occur in the river. Take K_{D}=0.11 d^{-}, f=4.0. Also ultimate BOD is 125% of 5-d BOD of the mixture of sewage and river water. DO saturated for river water = 9.17 mg/lt.
8 M

6 (a)
Explain the importance of providing rocks and screens in a waste - water treatment plant. Draw a neat sketch of a bar - screen and explain the loss of head through the screen.

10 M

6 (b)
Write a note on grit-chambers.

5 M

6 (c)
What are skimming tanks? Explain with a neat sketch.

5 M

7 (a)
Explain the biological treatment techniques for treating waste-water.

6 M

7 (b)
What are HRTF's? Explain importance of recirculation and its effect on the efficiency of HRTF's.

6 M

7 (c)
The MLSS concentration in an aeration tank is 2000mg/lt and the sludge volume after 30 minutes of settling in a 1000ml cylinder is 176ml. Calculate:

i) SVI ii) SDI iii) Required return sludge ratio and iv) SS concentration in the recirculated sludge.

i) SVI ii) SDI iii) Required return sludge ratio and iv) SS concentration in the recirculated sludge.

8 M

8 (a)
What are stabilization ponds? Explain the algae - bacteria symbiosis in an oxidation pond with a neat sketch.

6 M

8 (b)
Explain the stages i anaerobic sludge digestion.

6 M

8 (c)
Draw a neat sketch of septic tank with soak pit. Write the design criteria required for septic tank.

8 M

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