Top 250+ Solved Water and Wastewater Engineering MCQ Questions Answer

From 91 to 105 of 273

Q. In sewers the effect of scouring is more on

a. Top side

b. Bottom side

c. Horizontal side

d. All sides

  • b. Bottom side

Q. The sewer which resists sulphide corrosion, is

a. Brick sewer

b. Cast iron sewer

c. R.C.C. sewer

d. Lead sewer

  • d. Lead sewer

Q. The formula which accepts the value of rugosity coefficient n = 0.012 to be used in Manning'sformula, is given by

a. Bazin

b. Crimp and Bruges

c. William-Hazen

d. Kutter

  • b. Crimp and Bruges

Q. The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known

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

b. Dissolved Oxygen (D.O.)

c. Chemical Oxygen Demand (C.O.D.)

d. None of these

  • b. Dissolved Oxygen (D.O.)

Q. Water content of sewage is about

a. 90 %

b. 95 %

c. 99 %

d. 9.9 %

  • d. 9.9 %

Q. Skimming tanks are

a. Used to remove the grease and oil

b. Those from which sludge is skimmed out

c. Tanks provided with self-cleansing screens

d. Improved version of grit chambers

  • a. Used to remove the grease and oil

Q. The most efficient cross-section of sewers in a combined sewerage system is

a. ) Parabolic

b. Circular

c. Rectangular

d. New egged

  • b. Circular

Q. The detention period for plain sedimentation water tanks, is usually

a. 4 to 8 hours

b. 8 to 16 hours

c. 16 to 24 hours

d. 24 to 36 hours

  • a. 4 to 8 hours

Q. The factor responsible for purification of sewage in river is

a. Hydrology

b. Dissolved oxygen in water

c. Temperature

d. All the above

  • d. All the above

Q. Hume steel pipes are

a. Steel pipes

b. Steel shell coated from inside with cement mortar

c. Steel shell coated from outside with cement mortar

d. Both (B) and (C)

  • d. Both (B) and (C)

Q. The pH value of sewage is determined with the help of

a. Imhoff Cone

b. Turbid meter

c. Potentiometer

d. None of these

  • c. Potentiometer

Q. The normal value of over flow rates for plain primary sedimentation tanks, ranges between

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

b. 40,000 to 50,000 litres/sqm/day

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

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

  • b. 40,000 to 50,000 litres/sqm/day

Q. Which one of the following statements regarding septic tanks is wrong?

a. A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided

b. The outlet invert level is kept 5 to 7.5 cm below the inlet invert level

c. The minimum width of septic level is 90 cm

d. The depth of tank is kept equal to its width

  • d. The depth of tank is kept equal to its width
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