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Waste Water Engineering MCQ Questions & Answers

Waste Water Engineering MCQs : This section focuses on the "Waste Water Engineering". These Multiple Choice Questions (MCQs) should be practiced to improve the Waste Water Engineering skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

In primary sedimentation, the 0.2 mm inorganic solids get separated if specific gravity is

A. 2.25
B. 2.5
C. 2.55
D. 2.65

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Question 2

Assertion (A) : Discharging the effluents from the oxidation ponds just up stream of lakes or reservoirs is undesirable. Reason (R) : The discharged algae get settled in the reservoirs and cause anaerobic decomposition and other water qualities.

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true.

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Question 3

In a fully mechanised composting plant, involves

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

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Question 4

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. 200 ppm
B. 225 ppm
C. 250 ppm
D. None of these.

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Question 5

Self-cleansing velocity is

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

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Question 6

Removal of oil and grease from sewage, is known

A. screening
B. skimming
C. filtration
D. none of these.

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Question 7

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. 204 cu m
B. 208 cu m
C. 212 cu m
D. 216 cu m

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Question 8

The ratio of minimum hourly flow to the average flow of sewage is

A. 01-Apr
B. 01-Mar
C. 01-Feb
D. 03-Apr

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Question 9

Pick up the in-correct statement from the following :

A. Manholes are provided in sewer pipes at suitable intervals
B. Catch basins are generally provided in sewers for carrying drainage discharge
C. Inlets are generally provided in all sewers
D. None of these.

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Question 10

If the side of a square sewer is 1000 mm, the diameter of a hydraulically equivalent circular section, is

A. 1045 mm
B. 1065 mm
C. 1075 mm
D. 1095 mm.

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Question 11

Dilution method of disposing off sewage, is not preferred to

A. when sewage is fresh
B. when diluting water has high dissolved oxygen content
C. when diluting water is used for water supply near the point of sewage disposed
D. when the diluting water is having flow currents

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Question 12

The asbestos cement pipes are generally laid

A. horizontally
B. vertically
C. at an angle of 30°
D. at an angle of 60°.

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Question 13

Disposal to sewage in large cities, is done in

A. irrigation
B. dilution
C. oxidation
D. putrifaction.

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Question 14

Chlorination of water is done for the removal of

A. bacterias
B. suspended solids
C. sediments
D. hardness.

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Question 15

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. 2 hours
B. 3 hours
C. 4 hours
D. 5 hours.

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Question 16

The minimum recommended diameter of sewers, is

A. 5 cm
B. 10 cm
C. 15 cm
D. 20 cm.

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Question 17

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.

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Question 18

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

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

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Question 19

For evaporation and measurement of settlable solids, the apparatus used, is

A. a jar
B. a breaker
C. a test tube
D. an Imhoff cone.

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Question 20

The gas which may cause explosion in sewers, is

A. carbondioxide
B. methane
C. ammonia
D. carbon monoxide.

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Question 21

House connections to the laterals is generally made by

A. R.C.C.
B. P.C.C.
C. Cast iron
D. Glazed stonewares.

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Question 22

The screens are fixed

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

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Question 23

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. 1.5 D
D. 1.75 D

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Question 24

The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is

A. 1.5
B. 2
C. 3
D. 4

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Question 25

A rain sanitary sewer is constructed to carry

A. sanitary sewage
B. storm sewage
C. surface water
D. ground water

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Question 26

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.

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Question 27

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 the above.

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Question 28

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

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

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Question 29

In R.C. sewer pipes, the percentage longitudinal reinforcement to the cross-sectional area of concrete is kept

A. 10
B. 5
C. 2
D. 0.25

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Question 30

Flocculated particles do not change their

A. size
B. shape
C. weight
D. none of these.

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Question 31

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

A. 6
B. 7
C. 5
D. 6.5

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Question 32

The rate of accumulation of sludge in septic tanks is recommended as

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

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Question 33

Bio-chemical oxygen demand (BOD) for the first 20 days in generally referred to

A. initial demand
B. first stage demand
C. carbonaceous demand
D. all of these.

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Question 34

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

A. 1 in 60
B. 1 in 100
C. 1 in 120
D. none of these.

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Question 35

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 the above.

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Question 36

For house drainage minimum gradient is

A. 1 in 60
B. 1 in 80
C. 1 in 10
D. 1 in 400

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Question 37

The coagulant widely used for sewage treatment, is

A. alum
B. ferric chloride
C. ferric sulphate
D. chlorinated copperas.

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Question 38

For non-scouring velocity 5 m/sec, the type of sewers generally preferred to, is

A. cast iron sewers
B. cement concrete sewers
C. glazed bricks sewers
D. stone ware sewers.

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Question 39

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

A. 3 PPm
B. 4 PPm
C. 5 PPm
D. 10 ppm.

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Question 40

An inverted siphon is designed generally for

A. one pipe
B. two pipes
C. three pipes
D. four pipes.

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Question 41

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

A. parabolic shaped
B. horse shoe shaped
C. egg shaped
D. circular shaped.

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Question 42

For the COD test of sewage, organic matter is oxidised by K2Cr207 in the presence of

A. H2SO4
C. HCl
D. none of these.

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Question 43

In SI units the power of sound is represented in

A. kgs
B. joules
C. neutons
D. watts.

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Question 44

A sewer pipe contains 1 mm sand particles of specific gravity 2.65 and 5 mm organic particles of specific gravity 1.2, the minimum velocity required for removing the sewerage, is

A. 0.30 m/sec
B. 0.35 m/sec
C. 0.40 m/sec
D. 0.45 m/sec

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Question 45

In sewers the effect of scouring is more on

A. top side
B. bottom side
C. horizontal side
D. all sides.

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