### Water And Wastewater Engineering Set 4

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