waste water engineering MCQs – Page 10

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

waste water engineering Mcqs

181. The following is the physical characteristic of sewage___________________?
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A. Turbidity

B. All the above

C. Colour

D. Odour

182. Self-cleansing velocity is__________________?
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A. Velocity at dry weather flow

B. Velocity of water at flushing

C. Velocity of water in a pressure filter

D. Velocity at which no accumulation remains in the drains

183. For design of sewers, percentage of sewage discharge is assumed_____________________?
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A. 75 to 80%

B. 70 to 75%

C. 65 to 70%

D. 85%

184. Imhoff cone is used to determine_____________________?
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A. None of these

B. Suspended solids

C. Settleable solids

D. Dissolved solids

185. Pick up the correct statement from the following ?
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A. Sewers are designed for minimum permissible velocity at minimum flow

B. Maximum daily flow = average daily flow

C. All the above

D. Maximum daily flow = 2 times the average daily flow

186. The width of a rectangular sewer is twice its depth while discharging 1.5 m/sec. The width of the sewer is______________?
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A. 1.36 m

B. 1.76 m

C. 0.68 m

D. 0.88 m

187. The spacing of man holes along a straight portion of a sewer is 300 m, the diameter of the sewer may be__________________?
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A. > 1.5 m

B. 0.9 cm

C. 1.5 m

D. 1.2 m

188. In Chezys formula V = C rs for calculating the velocity of flow in circular sewer of diameter running full, the value of hydraulic mean radius is_______________?
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A. D /2

B. D/3

C. D/4

D. D

189. The grit chambers of sewage treatment plants, are generally cleaned after__________________?
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A. 12 days

B. 14 days

C. 7 days

D. 2 days

190. The settlement velocity of a solid (diameter 0.5 mm, specific gravity 1.75) in water having temperature 10C, is______________________?
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A. 413.5 cm/sec

B. 500 cm/sec

C. 313.5 cm/sec

D. 213.5 cm/sec

191. hydraulically equivalent, the relationship which holds good, is _______________?
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A. D3/2 = 4 b3/2

B. D8/3 = 4 b8/3

C. D3/8 = 4 b3/8

D. D2/3 = 4 b2/3

192. Aerobic activity is maximum_______________?
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A. None of these

B. In sewer treatment plants

C. At sewer pipes

D. In freshly produced sewage

193. If the grit in grit chambers is 4.5 million litres per day, its cleaning is done____________________?
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A. Mechanically

B. Manually

C. Hydraulically

D. Electrically

194. The temperature affects the________________?
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A. Solubility of gases in sewage

B. Viscosity of sewage

C. Biological activity of bacteria in sewage

D. All the above

195. The detention time (t) of a settling tank, may be defined as the time required for_________________?
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A. A particle to travel from top surface to bottom sludge zone

B. A particle to travel along its length

C. None of these

D. The flow of sewage to fill the tank

196. Cement concrete sewers are only suitable if non-scouring velocity is between_________________?
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A. 2.5 to 3.0 m/sec

B. 4.5 to 5.5 m/sec

C. 3.0 to 4.0 m/sec

D. 3.5 to 4.5 m/sec

197. If 2% solution of a sewage sample is incubated for 5 days at 20C and depletion of oxygen was found to be 5 ppm, B.O.D. of the sewage is____________________?
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A. None of these

B. 225 ppm

C. 250 ppm

D. 200 ppm

198. To maintain aerobic biological activity, the moisture content of the compost mass should be about_________________?
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A. 50%

B. 60%

C. 55 %

D. 45%

199. A cylindrical ejector having its height 2 m fills after every 10 minutes with a peak sewage discharge of 0.0157 cumec. The diameter of the ejector chamber, is_____________________?
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A. 2.30 m

B. 2.40 m

C. 2.45 m

D. 2.50 m

200. The sewer which transports the sewage to the point of treatment, is called________________?
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A. Main sewer

B. House sewer

C. Out-fall sewer

D. Branch sewer

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