waste water engineering Mcqs
301. The discharge per unit plan area of a sedimentation tank, is generally called________________?
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A. All the above

B. Over flow rate

C. Over flow velocity

D. Surface loading

302. Pick up the incorrect statement from the following?
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A. The treated sewage effluents, are generally used for irrigating the crops

B. The mixture of water and waste products, is called sewage

C. The process of collecting, treating and disposing off the sewage, is called sewerage

D. The old convergence system was definitely better than water carried sewerage system
303. The reduced levels of the string at the consecutive sight rails A and B are 203.575 m, 203.475 m respectively. If the difference of their R.D.s is 10 m, the gradient of the sewer line is_________________?
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A. 1 in 503 upward

B. 1 in 500 upward

C. 1 in 100 upward

D. 1 in 100 downward
304. To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning velocity recommended for Indian conditions, is_________________?
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A. 0.50 m/sec

B. 0.75 m/sec

C. 0.70 m/sec

D. 0.60 m/sec

305. The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m per sec. The detention period recommended for the tank, is____________________?
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A. 1 hour

B. 1 hour and 30 minutes

C. 2 hours

D. 30 minutes

306. The gas which may cause explosion in sewers, is_________________?
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A. Methane

B. Ammonia

C. Carbondioxide

D. Carbon monoxide

307. The sewage treatment units in which anaerobic decomposition of organic matter is used, are called________________?
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A. Imhoff tanks

B. Sludge sedimentation tanks

C. None of these

D. Trickling filters
308. If the diameter of a sewer is 150 mm, the gradient required for generating self cleansing velocity, is________________?
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A. 1 in 100

B. 1 in 60

C. None of these

D. 1 in 120

309. If q is the average sewage flow from a city of population P, the maximum sewage flow______________?
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A. Q = [(18 + P)/(4 + )] q

B. Q = [(18 + )/(4 + )] q

C. Q = [(5 + )/((15 + )] q

D. Q = [(4 + )/(18 + )] q

310. Pick up the incorrect statement from the following?
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A. Sludge digestion is carried out in sludge tank

B. The gases produced in sludge digestion process, contain 75% carbon dioxide

C. The gases produced in sludge digestion process, contain 75% methane

D. The process of decomposing the organic matter under controlled anaerobic conditions, is called sludge digestion

311. Pick up the correct statement from the following?
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A. Indore method of composting involves decomposition under aerobic conditions

B. Bangalore method of composting involves decomposing under anaerobic conditions

C. all of these

D. Fully stabilised refuse by the Bangalore method of compositing is a powdery mass called humus

312. Pick up the incorrect statement from the following for allowing workers to enter sewers_______________?
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A. The men entering the manhole should be advised to smoke in the sewer

B. Proper tests for the presence of poisonous gases must be carried out

C. Warning signals should be erected

D. The particular manhole and one manhole on upstream and one manhole on downstream should remain open for 30 minutes

313. The normal values of over flow rates for sedimentation tanks using coagulant, ranges between__________________?
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A. 40,000 to 50,000 litres/sqm/day

B. 80,000 to 100,000 litres/sqm/day

C. 50,000 to 60,000 litres/sqm/day

D. 25,000 to 35,000 litres/sqm/day

314. At the junction of sewers___________________?
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A. Top of smaller sewer is kept lower

B. Top of larger sewer is kept lower

C. Tops of both the sewers are at the same level

D. None of these
315. Pick up the correct statement from the following?
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A. The boning rod is used for checking the levels of the sewer inverts

B. A manhole is classified as shallow manhole if its depth is less than 0.9 m

C. All the above

D. Manhole covers are made circular for the convenience of the cleaning staff

316. In sewers the velocity of flow should not be_________________?
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A. Less than 10 m/sec

B. More than 20 m/sec

C. Less than the self-cleansing velocity

D. More than the self-cleansing velocity