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Waste Water Engineering MCQ

Solids in wastewater treatment are removed in ________.

Pre-treatment

Primary treatment

Secondary treatment

Tertiary treatment

Sludge digestion

Answer

Correct Answer: Pre-treatment

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All of the following are examples of point sources of pollution except ________.

Oil spills , irrigation , fertilizers , pesticides

Pesticides , oil spills , irrigation , leaky underground storage tanks

Drainage from industrial plants , oil spills , runoff from street gutters , chemical spills

Pesticides , herbicides , animal waste , irrigation

Answer

Correct Answer: Pesticides , herbicides , animal waste , irrigation

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________ is are formed during primary wastewater treatment

Gray water

Sludge

Bacteria

Inorganic nutrients

Toxins

Answer

Correct Answer: Sludge

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What do aerobic bacteria require for growth?

Free (elementary) oxygen

Nutrients

High temperatures

Dark conditions

Answer

Correct Answer: Free (elementary) oxygen

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What is the purpose of an Aeration Tank?

To inject air into water

To absorb pollutants

To collect water

To process sewage

Answer

Correct Answer: To inject air into water

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What does the process of aeration involve?

Boiling the liquid

Bringing about intimate contact between air and a liquid

Cooling the liquid

Mixing the liquid with oil

Answer

Correct Answer: Bringing about intimate contact between air and a liquid

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What is the Activated Sludge Process used for?

Disposing of pollution in wastewaters

Treating industrial waste

Producing electrical power

Removing heavy metals from water

Answer

Correct Answer: Disposing of pollution in wastewaters

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What does "activated sludge" refer to?

A brownish flocculent culture of organisms

An oxygen-emitting device

A process used in wastewater treatment

A type of bacteria

Answer

Correct Answer: A brownish flocculent culture of organisms

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When considering using graywater, you might use the water for ________.

Washing clothes.

Flushing toilets.

Washing hands.

Taking baths

Answer

Correct Answer: Flushing toilets.

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

None of these

A plant consisting of Imhoff tanks with low rate trickling filters

Sedimentation tanks with high rate trickling filters

A sedimentation tank and an activated sludge treatment plant

Answer

Correct Answer: A sedimentation tank and an activated sludge treatment plant

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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 is false but R is true.

Both A and R are true and R is the correct explanation of A

A is true but R is false

Both A and R are true but R is not a correct explanation of A

Answer

Correct Answer: Both A and R are true and R is the correct explanation of A

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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

250 ppm

225 ppm

200 ppm

None of these

Answer

Correct Answer: 250 ppm

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The screens are fixed

At an angle 30° to 60° to the direction of flow

Parallel to the direction of flow

Perpendicular to the direction of flow

None of these

Answer

Correct Answer: At an angle 30° to 60° to the direction of flow

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In SI units the power of sound is represented in

Joules

Watts.

Kgs

Neutons

Answer

Correct Answer: Watts.

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The asbestos cement pipes are generally laid

Vertically

At an angle of 30°

At an angle of 60°

Horizontally

Answer

Correct Answer: Vertically

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

1.5 D

1.25 D

1.75 D

Answer

Correct Answer: 1.5 D

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

None of these.

1 in 120

1 in 60

1 in 100

Answer

Correct Answer: 1 in 120

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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

3 hours

5 hours

2 hours

4 hours

Answer

Correct Answer: 4 hours

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What the house drainage minimum gradient is

1 in 80

1 in 60

1 in 400

1 in 10

Answer

Correct Answer: 1 in 60

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House connections to the laterals is generally made by

P.C.C.

Cast iron

Glazed stonewares

R.C.C.

Answer

Correct Answer: Glazed stonewares

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For house drainage minimum gradient is

1 in 60

1 in 400

1 in 10

1 in 80

Answer

Correct Answer: 1 in 60

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

Horse shoe shaped

Egg shaped

Parabolic shaped

Circular shaped

Answer

Correct Answer: Horse shoe shaped

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A rain sanitary sewer is constructed to carry

Storm sewage

All these

Ground water

Sanitary sewage

surface water

Answer

Correct Answer: Sanitary sewage

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

Carbonaceous demand

First stage demand

Initial demand

All of these.

Answer

Correct Answer: All of these.

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The coagulant widely used for sewage treatment, is

Chlorinated copperas

Alum

Ferric sulphate

Ferric chloride

Answer

Correct Answer: Ferric chloride

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Clogging of sewers, is caused due to

Silting

Greasy and oily matters

Low discharge

Domestic wastes thrown in manholes

All these

Answer

Correct Answer: All these

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

1.5 D

1.75 D

1.25 D

Answer

Correct Answer: 1.5 D

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

A breaker

A test tube

A jar

An Imhoff cone

Answer

Correct Answer: An Imhoff cone

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Pick up the correct statement from the following:

The solubility of oxygen in sewage is 95% that is in distilled water

In treated sewage, 4 PPm of D.O. is essential

Only very fresh sewage contains some dissolved oxygen

All these

Answer

Correct Answer: All these

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