Water And Wastewater Engineering Set 4 MCQs

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