waste water engineering MCQs – Page 15

Practise focused waste water engineering questions with marked answers for exam preparation and subject revision.

waste water engineering Mcqs
281. The width of a settling tank with 2 hour detention period for treating sewage 378 cu m per hour, is __________________?
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A. 6.5 m

B. 7 m

C. 5 m

D. 5.5 m

282. If the depth of flow in a circular sewer is 1/4th of its diameter D, the wetted perimeter is______________?
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A. /2

B. D

C. /3

D. /4

283. Imhoff cone is used to measure________________?
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A. Total organic solids

B. Settleable solids

C. Total solids

D. Total in organic solids

284. In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for a discharge Q, is____________________?
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A. Q/(B D)

B. Q/(B L)

C. Q/(L D)

D. Q/L

285. The grit and silt of the grit chambers, may not be used for_________________?
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A. Raising low lying areas by dumping

B. Concreting

C. Both A. and B.

D. Neither A. nor B

286. For the COD test of sewage, organic matter is oxidised by K2Cr2O7 in the presence of________________?
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A. HCl

B. H2SO4

C. HNO3

D. None of these

287. The sewer that unloads the sewage at the point of treatment is called_________________?
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A. Outfall sewer

B. Main sewer

C. Branch sewer

D. House sewer

288. If the flame of a miners safety lamp in a manhole extinguishes within 5 minutes, the sewer certainly contains_______________?
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A. Hydrogen sulphide

B. Carbon dioxide

C. Oxygen

D. Methane

289. Pick up the correct statement from the following?
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A. All the above

B. Inlets are provided on the road surface at the lowest point for draining rain water

C. Inlets having horizontal openings, are called horizontal inlets

D. Inlets are generally provided at an interval of 30 m to 60 m along straight roads

290. Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for__________________?
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A. Unexpected increase in the population

B. Unexpected large scale infiltration of stream water

C. All of the above

D. Under estimates of maximum and average flows

291. The layers of vegetable wastes and night soil alternatively piled above the ground to form a mound, is called_______________?
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A. A heap

B. Windrow

C. Plateau

D. None of these
292. Sewer ventilating columns are generally placed at_______________?
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A. All the above

B. Every change in the size of sewers

C. Upper ends of branch sewers

D. Distances 150 m to 300 m

293. For a grit chamber, if the recommended velocity of flow is 0.2 m/sec and detention period is 2 minutes, the length of the tank, is__________________?
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A. 30 m

B. 20 m

C. 24 m

D. 16 m

294. Pick up the correct statement from the following?
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A. The circular section of sewers provides maximum hydraulic mean depth

B. The circular sewers work efficiently if the sections run at least half full

C. The circular sewers are provided for separate sewerage system

D. All the above
295. Pick up the correct statement from the following?
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A. pH value indicates acidity and alkalinity of sewage

B. In acidic sewage, the pH value is less than 7

C. In alkaline sewage, the pH value is more than 7

D. All the above
296. The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known_________________?
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A. Chemical Oxygen Demand (C.O.D.)

B. Dissolved Oxygen (D.O.)

C. None of these

D. Bio-Chemical Oxygen Demand (B.O.D.)

297. In sewers the effect of scouring is more on__________________?
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A. Horizontal side

B. Bottom side

C. All sides

D. Top side

298. Pick up the correct statement from the following?
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A. Aerobic bacteria flourish in the presence of oxygen

B. Anaerobic bacteria flourish in the absence of oxygen

C. Facultative bacteria flourish with or without oxygen

D. . All the above
299. Pick up the correct statement from the following ?
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A. All the above

B. The black colour indicates septic sewage

C. The sewage omits offensive odours after four hours

D. Turbidity is more in strong sewage

300. Dilution method of disposing of sewage, is not preferred to_______________?
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A. When diluting water has high dissolved oxygen content

B. When diluting water is used for water supply near the point of sewage disposed

C. When the diluting water is having flow currents

D. When sewage is fresh