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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