05 Civil Engineering Quiz | Waste Water MCQ #mcq.cetjob.com

05 Civil Engineering Quiz | Waste Water MCQ

1 >>In olden days the type of section adopted in trunk and out fall sewers was ?

• (A) circular shaped.
• (B) egg shaped
• (C) horse shoe shaped
• (D) parabolic shaped

2 >>An inverted siphon is designed generally for
 ?

• (A) three pipes
• (B) four pipes.
• (C) one pipe
• (D) two pipes

3 >>Aerobic bacterias
 ?

• (A) flourish in the presence of free oxygen
• (B) consume organic matter as their food
• (C) oxidise organic matter in sewage
• (D) all

4 >>The dimensions of a rectangular settling tank are : length 24 m, width 6 m and depth 3 m. If 2 hour detention period for tanks is recommended, the rate of flow of sewage per hour, is
 ?

• (A) 212 cu m
• (B) 208 cu m
• (C) 216 cu m
• (D) 204 cu m

5 >>The non-clog pump which permits solid matter to pass out with the liquid sewage, is
 ?

• (A) centrifugal pump
• (B) reciprocating pump
• (C) pneumatic ejector
• (D) none of these

6 >>For treating the sewage of a large city, you will recommend
 ?

• (A) sedimentation tanks with high rate trickling filters
• (B) a sedimentation tank and an activated sludge treatment plant
• (C) a plant consisting of Imhoff tanks with low rate trickling filters
• (D) none of these

7 >>The minimum recommended diameter of sewers, is
 ?

• (A) 20cm
• (B) 15cm
• (C) 5cm
• (D) 10cm

8 >>When drainage to sewage ratio is 20, the peak dry weather flow is
 ?

• (A) slightly less than 5% of the design discharge
• (B) 20% of the design discharge
• (C) slightly more than 5% of the design discharge
• (D) none of these

9 >>The screens are fixed
 ?

• (A) parallel to the direction of flow
• (B) perpendicular to the direction of flow
• (C) at an angle 30° to 60° to the direction of flow
• (D) none of these

10 >>The width of a rectangular sewer is twice its depth while discharging 1.5 m/sec. The width of the sewer is
 ?

• (A) 0.68 m
• (B) 0.88 m
• (C) 1.36 m
• (D) 1.76 m

11 >>A rainfall may be classified as acidic if its pH value is less or equal to
 ?

• (A) 6
• (B) 7
• (C) 5
• (D) 4

12 >>Self-cleansing velocity is
 ?

• (A) velocity of water at flushing
• (B) velocity at which no accumulation remains in the drains
• (C) velocity at dry weather flow
• (D) velocity of water in a pressure filter.

13 >>For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed
 ?

• (A) 5 PPm
• (B) 10 ppm.
• (C) 3 PPm
• (D) 4 PPm

14 >>If 2% solution of a sewage sample is incubated for 5 days at 20°C and depletion of oxygen was found to be 5 ppm, B.O.D. of the sewage is
 ?

• (A) 250 ppm
• (B) 225 ppm
• (C) 200 ppm
• (D) None of these.

15 >>In a fully mechanised composting plant, involves
 ?

• (A) mechanized receipt
• (B) mechanized segregation
• (C) mechanized pulverising of refuse
• (D) all of these.

16 >>Pick up the correct statement from the following :
 ?

• (A) In treated sewage, 4 PPm of D.O. is essential
• (B) Only very fresh sewage contains some dissolved oxygen
• (C) The solubility of oxygen in sewage is 95% that is in distilled water
• (D) All

17 >>If the over land flow from the critical point to the drain is 8 km and the difference in level is 12.4 m, the inlet time is
 ?

• (A) 3 hours
• (B) 4 hours
• (C) 5 hours
• (D) 2 hours

18 >>The rate of accumulation of sludge in septic tanks is recommended as
 ?

• (A) 25 litres/person/month.
• (B) 30 litres/person/month
• (C) 30 litres/person/year
• (D) 25 litres/person/year

19 >>If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is
 ?

• (A) 1 in 120
• (B) 1 in 60
• (C) 1 in 100
• (D) none of these

20 >>If D is the diameter of upper circular portion, the overall depth of a standard egg shaped section, is
 ?

• (A) D
• (B) 1.25 D
• (C) 1.75 D
• (D) 1.5 D

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