Category: Environmental Engineering Objective Questions

Environmental Engineering Multiple Choice Questions on “Biological Characteristic of Water”.

1. Which type of bacteria has a rod shaped structure?
a) Bacilli
b) Cocci
c) Spirilla
d) Vibrio
Answer: a
Clarification: Bacilli (Singular-Bacillus) has a rod shaped structure. Cocci has a spherically shaped structure, Spirilla has a spiral shaped structure and Vibrio has a comma shaped structure.

2. ________ represents the bacterial density that is most likely to be present in water.
a) BOD
b) COD
c) MPN
d) Coliform index
Answer: c
Clarification: Most Probable Number is a number that indicates the bacterial density present in water.BOD and COD are the terms related to the oxygen required by microorganism to oxidize organic and inorganic matter.

3. Which of the following is a better test to identify Coliforms?
a) Coliform index
b) Multiple tube fermentation
c) MPN test
d) Membrane filter technique
Answer: d
Clarification: Membrane filter technique is a better and simpler technique to identify Coliforms. Various results are obtained in a shorter time than the multiple tube fermentation technique. MPN test and coliform index are not used now.

4. What is the temperature at which MPN test is performed?
a) 35^oC
b) 37 ^oC
c) 40^oC
d) 45 ^oC
Answer: b
Clarification: MPN test is performed at 37^oC where different samples of water are mixed with lactose broth and incubated in test tubes for 48 hours.

5. Which of the following statement is/are correct regarding coliform bacteria?
i. It is gram negative
ii. It is rod shaped bacteria
iii. It is a harmless aerobic microorganism
a) i, ii, iii
b) ii, iii
c) i, iii
d) i, ii
Answer: a
Clarification: Coliform bacteria is a gram negative, rod shaped and harmless aerobic microorganism which is found in the intestine of warm blooded animals including human beings.

6. Which of the following is the disease caused by bacterial infections?
a) Amoebic dysentery
b) Infectious hepatitis
c) Typhoid fever
d) Poliomyelitis
Answer: c
Clarification: Amoebic dysentery is caused by protozoan infection, Infectious hepatitis and Poliomyelitis are caused by a viral infection and Typhoid fever is caused by a bacterial infection.

7. The number of bacterial colonies by Agar plate count test should not exceed ____ per ml for potable water.
a) 1
b) 10
c) 100
d) 1000
Answer: c
Clarification: Agar plate count test is a test to count the number of bacterial colonies growing on a specified medium and the permissible limit for the number of bacterial colonies is 100 per ml.

8. If the acid and gas are formed in the multiple tube fermentation technique, the test is _____
a) Positive
b) Continued
c) Negative
d) Discarded
Answer: a
Clarification: The acid and gas formation in the Multiple tube fermentation technique indicates that the test is positive and there are coliform bacteria in the sample.

9. Which bacteria cause the reddish brown deposits in the tank?
a) Escherichia coli bacteria
b) Bacterium coli bacteria
c) Iron bacteria
d) Sulphur bacteria
Answer: c
Clarification: The growth of Iron bacteria causes the discoloration of tank due to reddish brown deposits and turbidity in water.

10. Which bacteria results in the corrosion of iron and steel pipes embedded in soil?
a) Escherichia coli bacteria
b) Bacterium coli bacteria
c) Iron bacteria
d) Sulphur bacteria
Answer: d
Clarification: Sulphur bacteria cause the corrosion of iron and steel pipes embedded in soil. They are both aerobic and anaerobic and are more destructive in marshy or clay soils where anaerobic conditions prevails.

11. Gelatin liquefying bacteria are helpful in the manufacturing of photographic films.
a) True
b) False
Answer: a
Clarification: These bacteria are capable of producing proteolytic ferments that digest and liquefy gelatin. So, their presence in water is helpful in photographic films and glue industries.

Environmental Engineering Multiple Choice Questions on “Various Other Filters”.

1. In which type of filter, water flows in upward direction?
a) Slow sand filter
b) Rapid sand filter
c) Pressure filter
d) Up flow filter
Answer: d
Clarification: Up flow filter is a rectangular or round shape filter in which water flows in upward direction.

2. The up flow filter is used in domestic water supply.
a) True
b) False
Answer: b
Clarification: The up-flow filter is not used in domestic water supply because sudden variation in pressure breaks the sand bridge and cause the bed to expand.

3. In which type of filter, the filtration is done in two opposite directions at the same time?
a) Dual media filter
b) Mixed media filter
c) Bi-flow filter
d) Rapid sand filter
Answer: c
Clarification: In Bi-flow filter, the filtration is done in the opposite direction at the same time. It is divided into single media and dual media bi-flow filter.

4. Which material is provided for the down-flow bed in dual media bi-flow filter?
a) Coal sand
b) Garnet sand
c) Rice husk
d) Graphite
Answer: a
Clarification: In dual media bi-flow filter, coal sand is provided, If the sand is finer than that provided in rapid sand filter, excessive amount of sand will rise into coal bed and sand will become coarser.

5. The rate of filtration of a Micro-Strainer is __________ litres / hour.
a) 10,000-20,000
b) 20,000-30,000
c) 40,000-60,000
d) 50,000-80,000
Answer: d
Clarification: The rate of filtration of a Micro-Strainer is 50,000-80,000 litres per hour. It cannot remove color and other finely divided particles.

6. Which material is provided for the up flow bed in dual media bi-flow filter?
a) Anthracite
b) Sand
c) Rice husk
d) Graphite
Answer: b
Clarification: Sand is provided for the up-flow bed in dual media bi-flow filter. The quality of effluent obtained from up-flow bed in dual media bi-flow filter is inferior than that of the mixed media filter.

7. Which device is used for screening stored water which do not contain microscopic sized particles?
a) Tube settler
b) Clarifier
c) Flocculator
d) Micro-Strainers
Answer: d
Clarification: Micro-Strainers are stainless steel wire cloth that is used for screening stored water that do not contain algae, plankton and micro sized particles.

8. What is the diameter of drum of a Micro-Strainer?
a) 1m
b) 2m
c) 3m
d) 4m
Answer: c
Clarification: The diameter of a drum of Micro-Strainer is 3m and it is 3m wide and single unit of it can deal with about 50,000-80,000 litres/ hour.

9. What is the thickness of a layer of a diatomite filter?
a) 1mm
b) 2mm
c) 3mm
d) 4mm
Answer: c
Clarification: Diatomite filter consists of a layer of diatomaceous earth, having a thickness of 3mm supported on a filter element called the septum.

10. The diatomite is applied on the septum at the rate of ______
a) 100gm/m²
b) 200gm/m²
c) 300gm/m²
d) 400gm/m²
Answer: c
Clarification: The diatomite is applied on the septum at the rate of 300gm/m² to form a precoat of filter media.

11. Consider the following statements regarding diatomite filters.
i. They are not used for water having high turbidity.
ii. They are not suitable for municipal water supplies.
iii. They are not used for temporary and shifting camps.
Which of the above statement is/are false?
a) i, ii, iii
b) i only
c) ii only
d) iii only
Answer: d
Clarification: The diatomite filter is useful for temporary and shifting camps because they require less space, are lighter in weight and are more mobile.

Environmental Engineering Multiple Choice Questions on “Reciprocating Pump”.

1. The reciprocating pump has a ______ flow.
a) Pulsating
b) Uniform
c) Continuous
d) Constant
Answer: a
Clarification: The reciprocating pump has a continuous flow. It has a constant discharge even if head on the delivery side varies.

2. The speed at which the reciprocating pump runs (in m/min) is _____________
a) 28
b) 90
c) 100
d) 120
Answer: a
Clarification: The reciprocating pump runs at a low speed. Its speed is less than 30m/min. If they are connected to driving machines, speed reducing devices are necessary.

3. The maximum efficiency of a reciprocating pump is _____________
a) 50%
b) 60%
c) 85%
d) 100%
Answer: c
Clarification: The efficiency of the reciprocating pump lies between 40% and 85%. Long stroke engines have 85% efficiency while smaller pumps have 40%.

4.In which type of pump, the liquid is in contact with both sides of the plunger?
a) Single acting reciprocating pump
b) Double acting reciprocating pump
c) Single cylinder pump
d) Booster pump
Answer: b
Clarification: At the double acting reciprocating pump, the liquid is in contact with both sides of the plunger. It has two suction and deliver pipes having appropriate valves.

5. Based on the number of cylinders, the reciprocating pump is divided into ____ types.
a) 2
b) 3
c) 4
d) 5
Answer: d
Clarification: the reciprocating pump is divided into 5 types on the basis of number of cylinders. It includes single cylinder, double cylinder, triple cylinder, duplex double action and quintuplex pump.

6. Which type of reciprocating pump has a 1200 crank?
a) Single cylinder pump
b) Double cylinder pump
c) Triple cylinder pump
d) Duplex double action pump
Answer: c
Clarification: In a Triple cylinder reciprocating pump, each cylinder has its own suction and delivery pipes and has a 1200 crank.

7. Quintuplex pump has a crank of ____
a) 60^o
b) 72^o
c) 120^o
d) 1800^o
Answer: b
Clarification: Quintuplex pump has five single acting cylinders with separate suction and delivery having 72^o crank.

8. The number of valves required in rotary pump is _____________
a) 0
b) 1
c) 2
d) 3
Answer: a
Clarification: No valves are required in rotary pump and the flow is continuous. Gear, Lobe and Vane pumps are the examples of rotary pump.

9. Consider the following statement regarding Reciprocating pump.
i. High initial cost
ii. Requires a small space
iii. Less power required
Which of the following is/are incorrect statements?
a) Only 1
b) Only 2
c) Only 3
d) 2, 3
Answer: d
Clarification: The reciprocating pump has high initial and maintenance cost, more power required and required large space.

Environmental Engineering Multiple Choice Questions on “Types of Sewers”.

1. Which type of sewer serves as an outlet for large territory?
a) Lateral sewer
b) Main sewer
c) Branch sewer
d) Separate sewer
Answer: b
Clarification: Main sewer acts as an outlet for the large territory as it receives sewage from many tributary branches.

2. Which sewer collects sewage directly from the house?
a) Main sewer
b) Outfall sewer
c) Lateral sewer
d) Intercepting sewer
Answer: c
Clarification: The first stage of collection of sewage starts from the house which is done by Lateral sewer.

3. _______ sewer collects sewage from collecting system to a disposal plant?
a) House sewer
b) Outfall sewer
c) Lateral sewer
d) Separate sewer
Answer: b
Clarification: The Outfall sewer is a sewer that carries the sewage from collecting systems and transfers it to a point of final discharge i.e a disposal plant.

4. Which sewer carries both sewage and storm water?
a) Outfall sewer
b) Separate sewer
c) Main sewer
d) Combined sewer
Answer: d
Clarification: Combined sewer carries both the sewage and the rain water from the roofs of the house and from the street.

5. Which sewer is also called as submain sewer?
a) Branch sewer
b) Separate sewer
c) Main sewer
d) Lateral sewer
Answer: a
Clarification: Submain sewer receives sewage from small area which finally get discharged into the main sewer. It is also called as branch sewer.

6. Which sewer is used to carry the excess flow of existing sewer?
a) Branch sewer
b) Relief sewer
c) Main sewer
d) Lateral sewer
Answer: a
Clarification: The Relief sewer is used to carry the excess flow of the existing sewer. It is also called as overflow sewer.

7. Asbestos cement sewers are made from __________
a) Cement, silica
b) Asbestos fibre, copper
c) Asbestos fibre, cement, silica
d) Asbestos fibre, magnesium
Answer: c
Clarification: Asbestos cement sewers are made from the composition of asbestos fibre, cement, silica asbestos fibre acts as a reinforcing material.

8. Which of the following is a disadvantage of asbestos cement sewer?
a) They are light weight
b) They can be easily jointed
c) They are brittle
d) Inside surface is smooth
Answer: c
Clarification: Asbestos cement sewer is weak against the impact force and requires care in handling.

9. Asbestos cement sewer offers resistant to sulfide corrosion.
a) True
b) False
Answer: b
Clarification: Asbestos cement sewer is used as verticals only because they are prone to sulfide corrosion.

Global Education & Learning Series – Environmental Engineering .

Environmental Engineering Multiple Choice Questions on “Racks and Screen”.

1. The minimum spacing between the bars on fine screen is ____________
a) 0.3mm
b) 0.9mm
c) 1.5mm
d) 0.5mm
Answer: c
Clarification: The range of space between the bars in fine screen is 1.5-3mm having minimum spacing as 1.5mm.

2. The spacing between the bars in racks is ____________
a) 30mm
b) 50mm
c) 70mm
d) 90mm
Answer: b
Clarification: The spacing between the bars in racks is 50mm. It is commonly called as coarse screen.

3. Screens are inclined to the direction of flow to ____________
a) Increase the flow velocity
b) Increase the opening area
c) Decrease the flow velocity
d) Increase the head loss
Answer: c
Clarification: Screens are inclined to the direction of flow to decrease the flow velocity in order to increase the efficiency of the screen.

4. The maximum spacing between the bars in medium screen is ____________
a) 40mm
b) 50mm
c) 70mm
d) 90mm
Answer: a
Clarification: The range of space between the bars in fine screen is 7-40mm having maximum spacing as 40mm.

5. __________ is used to cut the sewage into smaller parts.
a) Flocculator
b) Tube settlers
c) Shredders
d) Aerators
Answer: c
Clarification: Shredder is a device which is used to cut large size sewage particles into a smaller size. It is composed of screens and cutting teeth.

6. What is the maximum capacity of medium screen in collecting solids?
a) 30L
b) 40L
c) 50L
d) 90L
Answer: d
Clarification: Medium screen can collect up to the maximum capacity of 90L of solids per 106 L of effluent.

7. The head loss through the screen is given by HL = k* (Vt2 – Va2), where Vt and Va are velocities through and above the screen respectively. What is the value of constant k?
a) 1
b) 0.0050
c) 0.0729
d) 0.0236
Answer: c
Clarification: The expression for the head loss through the screen is given by
HL = 0.0729* (V_t² – Va²), where Vt and Va are the velocities through and above the screen respectively.