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(08 Marks)

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Environmental Engineering - ll

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i) So$arate system of sewerage ii) Combined system of sewerage.

c. Explain:the rational method of estimation of storm water. (04 Marks)

2a.:,,,.

Explain thpl;@prns: i) Self cleaning velocity and non scouring velocity;" t't,i'., i:\ T--ct1--^]:^.^ ^.^l ^,-Cl+-^+:^- (12 Marks),r', .: ,, llii) InfiltratiItration and exfiltrati10n

b. Design u ,"*"i io.r".r" a population of 36,000 the rate of water supply being 135 litres per

capita per day of w, icfr 80% finds its way into sewer. fhe'.sewer are laid at a slope of I in625 and sewer should designed to carry three times dfy weather flow when running full.

Note: l. Answer FIVEfull questions, selectingat least TWO questions from each part.

2. Assume uny missing data d necessary.

PART _ AExplain the necessity and importance of sewerage system.

EXplain what do you man by sewerage system and discuss relative merits

N:0.012.3 a. List the desirable character$$,f sewer material,I. s.l the sewer material commonly used.

, :.,,r,. (06 Marks)

b. Briefly explain how the sewers are.,tffted for.'treakage after laying. (04 Marks)

c. What are sewer appurtenances? LiStthemand explain with a neat sketch any one of them.

",ri , (10 Marks)

4 a. Explain BOD and discuss the advantqageS and limitation of BOD. (06 Marks)

b. Explain the concept of Aerobig,and Anaerobis- activity with respect to sewage ,..u,,ffit1".u,,..

c. The 5 day BOD at 30oC of.h sewage sample is 120 mg4. Calculate 5 days BOS at 20oC.

Assume deoxygenation,,C'onstant at 20o C, K : 0. l l day . (08 Marks)

'""' """'5 a. Explain with a rteatifigure the oxygen sag curve indicating fu.ialient features related to self

purification o-f stieams. " (10 Marks)

b. List the conditions favourable for on land disposal of sewage. '.' ', (05 Marks)

c. A partially treated sewage from a town 1.7 million litres per day having'BoD of 120 mgd is

to bE diicharged into a stream. The stream has a BOD of l0 mg/|. what sh$uld be minimum

flqnv of the stream. ':1';:' ' (05 Marks)

6 a.:,;.''l'Write the flow diagram employed for a conventional waste water treatment plant, Indicate

,...,....',,,,. the importance of each unit indicated in the flow diagram. (10 Plarks)

,, -,;.',,b. Design a rectangular sedimentation-tank for a population of 90 thousand with rate of water

.., supply 140 litres per capacity per day, 80% of which reaches the treatment plant. Assumepeak factor as 1.2 and horizontal velocity of flow 0.3 m/minute. Check for over flow rate.

(10 Marks)

7 a. With a neat sketch, explain the working of a conventional trickling filter. (10 Marks)

b. Discuss the effect of recirculation in filters with figure. (04 Marks)

c. Define and explain the significance of sludge volume index and food to micro organismratio. (06 Marks)

8 Write short notes on any four of the following:Oxidation pond b. Sludge digestiona.

d. Time of concentration e. Traps in house plumbingc. Sewage sickness

(20 Marks)

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