Water And Wastewater Engineering Set 4

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This set of Water and Wastewater Engineering Multiple Choice Questions & Answers (MCQs) focuses on Water And Wastewater Engineering Set 4

Q1 | In the activated sludge process
  • Aeration is continued till stability
  • Aeration is done with an admixture of previously aerated sludge
  • Sludge is activated by constant stirring
  • Water is removed by centrifugal action
Q2 | For detecting the nitrates in sewage, the colour may be developed by adding
  • Potassium permanganate (B) (C) (D)
  • Sulphuric acid and napthamine
  • Phenol-di-sulphuric acid and potassium hydroxide
  • None of these
Q3 | The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock's law, is
  • Vs = 418 (Gs- Gw)d [(3T + 70)/100]
  • Vs = 418 (Gs - Gw)d² [(3T + 70)/100]
  • Vs = 218 (Gs - Gw)d² [(3T + 70)/100]
  • Vs = 218 (Gs - Gw)d [(3T + 70)/100]
Q4 | Inter-distance between ventilation columns in a sewer line is kept
  • 25 to 50 m
  • 50 m to 100 m
  • 100 m to 150 m
  • 150 m to 300 m
Q5 | Stone ware pipes are
  • Highly resistant to sulphide corrosion (B) (C) (D)
  • Highly impervious
  • Hydraulically efficient because of their smooth interior surface
  • Especially suited to pressure pipes
Q6 | The intensity of rain is expressed in
  • cm/minute (B) (C) (D)
  • cm/hour
  • cm/day
  • None of these
Q7 | The ratio of the diameter of a circular section and the side of a square section hydraulicallyequivalent, is
  • 1.095
  • 1.085
  • 1.075
  • 1.065
Q8 | Which one of the following part of human body withstands minimum radiation?
  • Thyroid
  • Kidneys
  • Eyes
  • Ovaries/testis
Q9 | Drop manholes are the manholes
  • Without entry ladders
  • Without manhole covers
  • With depths more than 3.5 m
  • Having drains at different levels
Q10 | The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope
  • 1 in 5
  • 1 in 10
  • 1 in 15
  • 1 in 20
Q11 | Primary treatment of sewage consists of removal of
  • Large suspended organic solids
  • Oil and grease
  • Sand and girt
  • Floating materials
Q12 | Cement concrete sewers are only suitable if non-scouring velocity is between
  • ) 2.5 to 3.0 m/sec (B) (C) (D)
  • 3.0 to 4.0 m/sec
  • 3.5 to 4.5 m/sec
  • 4.5 to 5.5 m/sec
Q13 | The most widely used pump for lifting sewage is
  • Centrifugal pump
  • Reciprocating pump
  • Pneumatic ejector
  • Air pressure pump
Q14 | Setting out the alignments of sewers may start from
  • City
  • Out-fall
  • Tail end
  • Any point
Q15 | The detention time of a circular tank of diameter d and water depth H, for receiving the sewageQ per hour, is
  • d² (0.011d + 0.785H)/Q
  • d (0.022d + 0.085H)/Q
  • d (0.785d + 0.011H)/Q
  • d (0.285d + 0.011H)/Q
Q16 | Lead acetate test in sewer manhole is done to test the presence of
  • Methane gas (B) (C) (D)
  • Hydrogen sulphide
  • Carbondioxide gas
  • Diesel vapours
Q17 | Anti syphonage pipe is fitted
  • At the end of septic tanks (B) (C) (D)
  • On manholes
  • With a W.C. trap
  • At the beginning of sewer line
Q18 | In a grit chamber of a sewage treatment plant,
  • Flow velocity 0.15 m to 0.3 m/sec is kept
  • Depth of 0.9 m to 1.20 m is kept
  • One minute of detention period is kept
  • All the above
Q19 | The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is
  • 1.5 (B) (C) (D)
  • 2
  • 3
  • 4
Q20 | pH value of sludge during alkaline regression stage, is
  • More than 7
  • Less than 7
  • Less than 6
  • More than 6
Q21 | The arrangement made for passing the sewer line below an obstruction below the hydraulicgradient lines called
  • Inverted syphon
  • Depressed sewer
  • Sag pipe
  • all of these
Q22 | Pick up the incorrect size of stone ware sewers
  • 52.5 cm (B) (C) (D)
  • 67.5 cm
  • 82.5 cm
  • None of these
Q23 | Chlorination of water is done for the removal of
  • Bacterias
  • Suspended solids
  • Sediments
  • Hardness
Q24 | Sludge banks are formed if sewage is disposed of in
  • Rivers
  • Seas
  • Lakes
  • None of these
Q25 | The clarigesters are
  • Circular septic tanks
  • Rectangular septic tanks
  • Circular Imhoff double tanks with bottom hoppers
  • Circular Imhoff double storey tanks without bottom hoppers