waste water engineering Mcqs
201. The pH value of sewage is determined with the help of_________________?
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A. Imhoff Cone

B. Potentiometer

C. None of these

D. Turbid meter

202. For trunk sewers more than 1.25 m in diameter, the ratio of the maximum daily sewage flow to the average daily sewage flow is assumed________________?
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A. 2

B. 2.5

C. 1.5

D. 3

203. The pH value of fresh sewage is usually ______________________?
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A. Equal to zero

B. Equal to 7

C. More than 7

D. Less than 7

204. Which one of the following part of human body withstands minimum radiation ?
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A. Kidneys

B. Thyroid

C. Ovaries/testis

D. Eyes

205. The asbestos cement pipes are generally laid___________________?
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A. At an angle of 30

B. At an angle of 60

C. Vertically

D. Horizontally

206. A sewer pipe contains 1 mm sand particles of specific gravity 2.65 and 5 mm organic particles of specific gravity 1.2, the minimum velocity required for removing the sewerage, is_____________________?
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A. 0.30 m/sec

B. 0.40 m/sec

C. 0.35 m/sec

D. 0.45 m/sec
207. The first stage of neutral process of sludge digestion, is__________________?
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A. Acid fermentation

B. None of these

C. Acid regressio

D. Alkaline fermentation

208. In sewage having fully oxidised organic matter, the nitrogen exists in the form of________________?
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A. Aluminoid nitrogen

B. Nitrates

C. Free ammonia

D. Nitrites

209. The rate of accumulation of sludge per person per year, is_______________________?
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A. 15 litres

B. 20 litres

C. 10 litres

D. 25 litres

210. weight of water, the hydraulic mean depth of the sewer and the bed slope w is the unit of the sewer, then the tractive force exerted by flowing water, is________________________?
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A. w r S S

B. w r1/2

C. w r S

D. w r2/3

211. The digested sludge from septic tanks, is removed after a maximum period of__________________?
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A. 3 years

B. 4 years

C. 5 years

D. 3.5 years

212. For non-scouring velocity 5 m/sec, the type of sewers generally preferred to, is____________________?
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A. Cast iron sewers

B. Glazed bricks sewers

C. Stone ware sewers

D. Cement concrete sewers

213. The design period in years for pumping plants, is___________________?
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A. 5 to 10

B. 3 to 5

C. 2 to 3

D. 1

214. Boussinesqs equation for ascertaining unit pressure at a depth on sewers due to traffic loads, is__________________?
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A. pt = 2 3p/3Z5

B. pt = 3H3p/2Z5

C. pt = 3H3p/2 Z5

D. pt = 2H3p/3 Z5

215. If the length of overland flow from the critical point to the mouth of drain is 13.58 km and difference in level between the critical point and drain mouth is 10 m, the inlet time is___________________?
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A. 2 hours

B. 4 hours

C. 6 hours

D. 8 hours
216. The angle subtended by the surface of sewer water with partial flow, at sewer centre is 120, the depth of sewerage is________________________?
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A. 25 cm

B. 40 cm

C. 20 cm

D. 50 cm
217. As compared to fresh river water, sea water contains oxygen_________________?
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A. 10% less

B. 20% more

C. 20% less

D. 10% more

218. You are asked to design sewer pipes of diameters 0.4 m to 0.9 m at maximum flow, you will assume the sewer flow running at___________________?
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A. Three fourth full

B. Full depth

C. Half full

D. Two third full

219. Kjeldahl nitrogen is a mixture of___________________?
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A. All the above

B. Ammonia and nitrogen

C. Nitrogen and organic nitrogen

D. Organic nitrogen and ammonia

220. Assertion A. : Discharging the effluents from the oxidation ponds just up stream of lakes or reservoirs is undesirable. Reason (R) : The discharged algae get settled in the reservoirs and cause anaerobic decomposition and other water qualities_________________?
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A. Both A and R are true and R is the correct explanation of A

B. Both A and R are true but R is not a correct explanation of A

C. A is true but R is false

D. A is false but R is true

221. are available in size Stoneware sewers________________?
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A. All the above

B. 10 cm

C. 20 cm

D. 15 cm

222. The sewage treatment in septic tanks is due to__________________?
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A. Aerobic decomposition

B. None of these

C. Parasitic decomposition

D. Anaerobic decomposition
223. The water carried sewerage system removes__________________?
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A. Domestic sewage

B. Storm sewage

C. Industrial sewage

D. All the above
224. Sludge banks are formed if sewage is disposed of in____________________ ?
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A. Seas

B. Lakes

C. Rivers

D. None of these

225. The intensity of rain is expressed in________________?
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A. cm/minute

B. None of these

C. cm/hour

D. cm/day

226. The drop man holes are generally provided in sewers for____________________?
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A. Hilly town ships

B. Industrial areas

C. Large town ships

D. Cities in plains

227. If is the rugosity coefficient, is the bed slope of sewer, the velocity of flow in m/sec may be obtained by the formula V = (1/n) r2/3 s1/2 evolved by_________________?
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A. Bazin

B. Kutter

C. Manning

D. Chezy

228. For providing an Indian type W.C., the R.C.C. slabs in the toilet portion__________________?
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A. Should be sunk by 50 cm

B. Should be sunk by 20 cm

C. Should be kept 20 cm above the adjacent portion

D. Need not be sunk

229. The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope_________________?
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A. 1 in 15

B. 1 in 20

C. 1 in 5

D. 1 in 10
230. Assertion A.: A free board of 0.3 m is provided above the top sewage line in septic tanks. Reason (R): It helps to accommodate the scum in the septic tank_________________?
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A. Both A and R is true and R is the correct explanation of A

B. Both A and R is true but R is not a correct explanation of A

C. A is true but R is false

D. A is false but R is true

231. The quantity of liquid waste which flows in sewers during the period of rainfall, is known__________________?
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A. Sanitary sewage

B. None of these

C. Industrial waste

D. Storm sewage
232. When drainage to sewage ratio is 20, the peak dry weather flow is_______________?
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A. 20% of the design discharge

B. Slightly less than 5% of the design discharge

C. None of these

D. Slightly more than 5% of the design discharge

233. If is the diameter of upper circular portion, the area of cross-section of a standard egg shaped sewer, is____________________?
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A. D

B. D

C. D

D. D
234. If a paper moistened with lead acetate for five minutes when placed in manhole turns black. The sewer certainly contains__________________?
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A. Methane

B. Carbon dioxide

C. Hydrogen sulphide

D. Oxygen

235. In SI units the power of sound is represented in __________________?
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A. Watts

B. Newtons

C. Kgs

D. Joules

236. Water content of sewage is about___________________?
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A. 90%

B. 99%

C. 95%

D. 9.9 %
237. Drop manholes are the manholes___________________?
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A. With depths more than 3.5 m

B. Without entry ladders

C. Having drains at different levels

D. Without manhole covers

238. Pick up the incorrect size of stone ware sewers_________________?
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A. 82.5 cm

B. None of these

C. 52.5 cm

D. 67.5 cm

239. Primary treatment of sewage consists of removal of__________________?
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A. Large suspended organic solids

B. Sand and girt

C. Floating materials

D. Oil and grease

240. The minimum recommended diameter of sewers, is_________________?
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A. 10 cm

B. 15 cm

C. 5 cm

D. 20 cm

241. The effluent of a septic tank is_________________?
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A. None of these

B. Foul and contains dissolved and suspended solids

C. Fit for discharge into any open drain

D. As good as that from a complete treatment

242. For a peak discharge of 0.0157 cumec, with a velocity of 0.9 m/sec, the diameter of the sewer main, is________________?
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A. 15 cm

B. 18 cm

C. 12 cm

D. 10 cm

243. The settlement of a particle in sedimentation tank, is affected by_____________________?
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A. All the above

B. Velocity of flow

C. Size and shape of solid

D. Viscosity of water

244. In areas where light rains are uniformly distributed throughout the year, the type of sewerage system to be adopted is_______________?
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A. None of these

B. Combined system

C. Separate system

D. Partially combined system

245. In case of sewer lines_________________?
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A. Obstruction test is carried out with the help of smooth ball of diameter 13 mm

B. Water test is carried out to check water tightness of the joints

C. Test for straightness is carried out with the help of a lamp and mirror

D. All the above
246. If the discharge of a sewer running half is 628 1.p.s., i = 0.001, and n = 0.010, the diameter of the sewer, is__________________?
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A. 1.69 m

B. 1.39 m

C. 1.59 m

D. 1.49 m

247. Fresh sewage is generally_____________________?
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A. Acidic

B. Alkaline

C. A source of objectionable odour

D. Highly decomposed

248. The ratio of maximum sewage flow to average sewage flow for trunk mains having diameters more than 1.25 m, is____________________?
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A. 4

B. 3

C. 1.5

D. 2

249. For estimating the peak run off the rational formula Q = 0.0278 KpA was evolved by______________?
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A. Frubling

B. Kinchling

C. All the above

D. Lloyd Davis

250. In septic tanks, decomposition of organic bacteria, is done by_____________________?
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A. Anaerobic bacteria

B. Aerobic bacteria

C. Both types of bacterias

D. None of these