Category: Environmental Engineering Objective Questions

Environmental Engineering Multiple Choice Questions on “Slow Sand Filter”.

1. The depth of an enclosed tank of a slow sand filter lies in the range of ______
a) 1-2m
b) 2.5-4m
c) 2-5m
d) 3-5m
Answer: b
Clarification: The depth of an enclosed tank of a slow sand filter lies in the range of 2.5-4m and its surface area lies between 50-1000m².

2. When the fineness of sand increases __________
a) The bacterial efficiency increases
b) The rate of filtration increases
c) The rate of filtration first decrease, then increase
d) The bacterial efficiency remains constant
Answer: a
Clarification: When the fineness of sand increases, the bacterial efficiency increases, but rate of filtration decreases. Fine sand is preferred when high bacteria and turbidity removal efficiency is desired.

3. The thickness of the base material on which filter media are supported is __________
a) 10-100cm
b) 20-80cm
c) 30-75cm
d) 10-30cm
Answer: c
Clarification: The base material consists of 30-75 cm thick gravel bed which is laid in layers of 15 cm with finer topmost layer and coarser bottom layer.

4. The minimum number of filter beds in the slow sand filter is __________
a) 1
b) 2
c) 3
d) 3
Answer: b
Clarification: The minimum number of filter beds provided in the slow sand filter is 2 where one unit is provided as stand by for an area of 20m².

5. The area of the filter is 1500. What is the number of beds to be provided?
a) 1
b) 2
c) 3
d) 6
Answer: b
Clarification: The area of filter is 1500 which lies between 1201-2000m². So, the number of beds to be provided is 6.

6. The slow sand filter is able to remove ______ % of bacteria in water.
a) 90
b) 95
c) 98-99
d) 100
Answer: c
Clarification: The slow sand filters are highly efficient in the removal of bacteria and can remove around 98-99% of bacteria present in water.

7. The slow sand filter is efficient in removing turbidity of water.
a) True
b) False
Answer: b
Clarification: The slow sand filter is not efficient in removing turbidity of water and is not capable of removing turbidity over 50ppm.

8. The maximum daily demand of a city is 24*10⁵ and the rate of filtration is 100 per litre per hour per m². What is the area of the filter?
a) 10
b) 100
c) 1000
d) 1500
Answer: c
Clarification: Maximum daily demand = 24*10⁵
Rate of filtration = 100
Area of filter=Maximum daily demand/Rate of filtration=24*10⁵/(100*24)
=1000m².

9. The slow sand filter is designed for _____________
a) Maximum daily demand
b) Maximum yearly demand
c) Average daily demand
d) Maximum weekly demand
Answer: a
Clarification: The slow sand filter is designed for maximum daily demand, which is 1.8 times the average daily demand.

10. What is the frequency of cleaning of a slow sand filter?
a) 1 week
b) 1-3 months
c) 2-3 days
d) 2-3 weeks
Answer: b
Clarification: The slow sand filter requires cleaning, depending upon the impurities present in water and normally it is done after 1-3 months.

11. What is the maximum filter head up to which slow sand filters are worked upon?
a) 25cm
b) 50cm
c) 75cm
d) 100cm
Answer: c
Clarification: Initially the filter head is only 10-15cm but it increases as suspended matter is arrested. When the filtration head reaches the maximum permissible value of 75cm, the filter requires cleaning.

Environmental Engineering Multiple Choice Questions on “Zeolite Process”.

1. In which process of water softening, ion exchange phenomenon takes place?
a) Lime soda process
b) Zeolite process
c) Boiling
d) Demineralization process
Answer: b
Clarification: In the zeolite process, calcium and magnesium are removed from hard water by ion exchange phenomenon.

2. In which process of water softening, the chemicals are added to remove hardness from water?
a) Lime soda process
b) Zeolite process
c) Boiling
d) Demineralization process
Answer: a
Clarification: In the Lime soda process, lime and soda are added to remove temporary and permanent hardness from water.

3. Zeolites are complex compound of ____________
a) Aluminium and lime
b) Silica and soda
c) Aluminium, silica and soda
d) Lime and soda
Answer: c
Clarification: Zeolites are complex compound of Aluminium, silica and soda. It has the property of removing calcium and magnesium from water and substituting sodium in their place.

4. The color of the artificial zeolite permutit is ____________
a) Grey
b) Yellow
c) Green
d) White
Answer: d
Clarification: The artificial zeolite permutit has a large and lustrous grain. They are white in color and has an appearance of coarse sand.

5. Natural zeolite is mainly processed from ____________
a) White sand
b) Green sand
c) Grey sand
d) Red sand
Answer: b
Clarification: The natural zeolite is mainly processed from Green sand, which is also called as Glauconite. It has lesser exchange value than artificial zeolite.

6. The color of the natural zeolite is ____________
a) Green
b) Grey
c) Black
d) Blue
Answer: a
Clarification: The color of the natural zeolite is green as it is processed from Glauconite which is green in color. It has an exchange value of 6500-9000gm of hardness per m³ of zeolite.

7. The chemical formula of Permutit is ____________
a) SiOAl₂O₃Na₂O
b) SiO₂Al₂O₃Na₂O
c) SiO₂Al₂O₃NaO
d) SiO₃Al₂O₃Na₂O
Answer: b
Clarification: The chemical formula of Permutit is SiO₂Al₂O₃Na₂O. The increase in the value of SiO₂ increases its resistance to aggressive attacks.

8. Permutit has an exchange value of ________ grams of hardness per m³ of zeolite.
a) 10,000
b) 20,000-30,000
c) 35,000-40,000
d) 40,000-50,000
Answer: c
Clarification: Permutit has an exchange value of 35,000-40,000 grams of hardness per m³ of zeolite. They absorb moisture from the atmosphere and should be kept in a dry place.

9. The thickness of the layers of filter sand of zeolite softener is ____________
a) 20cm
b) 30cm
c) 40cm
d) 100cm
Answer: d
Clarification: The thickness of the layers of filter sand of zeolite softener lies in the range of 75 to 150cm and their functioning is similar to the rapid sand filter.

10. Which of the following is a disadvantage of the zeolite process?
a) No sludge is formed
b) The process is almost automatic
c) Suspended impurities get deposited around the zeolite particles
d) Zero hardness can be occurred
Answer: c
Clarification: The zeolite process is unsuitable for highly turbid water where suspended impurities get deposited around the zeolite particles.

11. The zeolite process is unsuitable for water containing iron and manganese.
a) True
b) False
Answer: a
Clarification: Iron and manganese bearing water deposit hydroxides on the surface of zeolite or react with zeolite to substitute iron and manganese for sodium, which is an irreversible reaction. This makes the zeolite process unsuitable.

Environmental Engineering Multiple Choice Questions on “Dry Weather Flow”.

1. _________ is the flow through sewers available during non-rainfall period.
a) Gradually varied flow
b) Rapidly varied flow
c) Dry weather flow
d) Storm water flow
Answer: c
Clarification: Dry weather flow is the flow through sewers available during non-rainfall period. It consists of domestic sewage and waste water sewage.

2. _______ is the additional flow occurring during rainy season.
a) Gradually varied flow
b) Rapidly varied flow
c) Dry weather flow
d) Storm water flow
Answer: d
Clarification: The storm water flow is the additional flow occurring during the rainy season. It consists of runoff from roofs, streets or open spaces during rainfall.

3. Which flow is also called as sanitary sewage?
a) Dry weather flow
b) Storm weather flow
c) Uniform flow
d) Non uniform flow
Answer: a
Clarification: Dry weather flow is the quantity of wastewater that flows through a sewer in dry weather when no storm water is present in the sewer.

4. Which of the following factor does not effect the dry weather flow?
a) Rate of water supply
b) Temperature conditions
c) Population growth
d) Infiltration of ground water
Answer: b
Clarification: There are four factors that affect the dry weather flow, namely the rate of water supply, population growth, type of area served and infiltration of ground water.

5. The quantity of waste water is assumed to be ___________ % of the quantity of water supply.
a) 40
b) 50
c) 60
d) 80
Answer: d
Clarification: The quantity of waste water is assumed to be 80 % of the quantity of water supply when no extra water enters the sewer.

6. The sewer should be designed for a minimum of ______ litres of waste water per capita per day.
a) 50
b) 100
c) 150
d) 1000
Answer: c
Clarification: Sewer is an underground carriage system that takes impure water from houses and commercial buildings through pipes to treatment units and they should be designed for a minimum of 150 litres of waste water per capita per day.

7. The size of the town is 15,000. What is the density of population per hectare?
a) 50
b) 75
c) 100
d) 200
Answer: d
Clarification: When the size of the town is between 5000 and 20,000, the density of population per hectare is between 150 and 200.

8. The design period of main and branch sewer is ___________
a) 5years
b) 10years
c) 30years
d) 40years
Answer: c
Clarification: The main and branch sewer is designed for the population that may occur at the end of one generation of 30 years.This period of 30 years is called a design period.

9. ___________ is the process in which ground water unfiltrate into the sewers.
a) Exfiltration
b) Infiltration
c) Filtration
d) Osmosis
Answer: b
Clarification: Infiltration is the process in which ground water unfiltrate into the sewers. It increases the load on the treatment work.

10. ________ is the process which indicates the flow of waste water from the sewer into the ground.
a) Exfiltration
b) Infiltration
c) Filtration
d) Osmosis
Answer: a
Clarification: Exfiltration is the reverse process of Infiltration where flow through sewer decreases and pollution of the ground water increases.

11. Infiltration of water does not depend on ___________
a) Size of sewer
b) Sewer material
c) Quality of water
d) Type of soil
Answer: c
Clarification: The infiltration of water depends on depth of sewer below ground water, size and length of sewer, sewer material, type of joints, nature and type of soil through which sewer is laid.

12. The rate of infiltration lies in the range of ______ m³/hectare/day.
a) 0.20-0.28
b) 0.42-0.63
c) 0.60-0.80
d) 0.70-0.90
Answer: a
Clarification: The rate of infiltration is expressed as litres per hectare of area per day. The rate of infiltration lies in the range of 0.2-0.28m³/hectare/day.

13. The relation between the maximum and average rate of flow is defined by ___________
a) QMAX = (1 + 14/(4 + P^0.5)) * Q_AVG
b) QMAX = (1 + 1/(4 + P^0.5)) * Q_AVG
c) QMAX = (1 + 4 + P^0.5) * Q_AVG
d) QMAX = (1 + P^0.5) * Q_AVG
Answer: a
Clarification: According to Harmon’s formula, the maximum and the average rate of flow is defined by QMAX = (1 + 14/(4 + P^0.5)) * Q_AVG where P is the population in thousands.

Environmental Engineering Multiple Choice Questions on “Diffused Air System”.

1. Which of the following is called as air diffusion method?
a) Activated sludge aeration
b) Diffused air aeration
c) Mechanical aeration
d) Combined aeration
Answer: b
Clarification: Diffused air aeration method is also called as air diffusion method where diffused air aerators are used for diffusing the air in the aeration tank.

2. The maximum quantity of air required in diffused aerator is ______ m³ per million litres of sewage.
a) 4000
b) 5000
c) 6000
d) 8000
Answer: d
Clarification: The minimum and maximum quantity of air required in diffused aerator is 6000 and 8000 m³ respectively per million litres of sewage.

3. The effective area of the diffuser plate used in the aeration tank is ___________
a) 400cm²
b) 780cm²
c) 1160cm²
d) 800cm²
Answer: b
Clarification: Diffuser plates are provided at the bottom of the aeration tank. It is square in shape with the dimension of 30cm x 30cm.

4. The maximum depth of aeration tank used in activated sludge process is ___________
a) 1m
b) 2m
c) 4.5m
d) 5.5m
Answer: c
Clarification: The depth of aeration tank lies between 3 to 4.5m and is 4-6m wide.

5. Which device is used in the aeration tank for cleaning purposes?
a) Diffuser plate
b) Paddles
c) Tube diffuser
d) Header pipe
Answer: c
Clarification: Tube diffuser is suspended in the aeration tank and can be used for cleaning without emptying the tank.

6. With how much pressure the air is filled in the aeration tank?
a) 70-90kN/m²
b) 34-56kN/m²
c) 10-20kN/m²
d) 35-70kN/m²
Answer: d
Clarification: The air is compressed in the diffused air aerator with the pressure of 35-70kN/m² resulting in the formation of the bubbles, improving the efficiency of aeration.

7. The effective area of tube diffuser used in the aeration tank is ___________
a) 400cm²
b) 780cm²
c) 1160cm²
d) 800cm²
Answer: c
Clarification: Tube diffuser is 60cm long tube having an internal diameter of 7.5cm and an effective area of 1160cm².

8. With which device, the air is introduced in the aeration tank?
a) Diffuser plate
b) Paddles
c) Cone with spiral vanes
d) Header pipe
Answer: a
Clarification: The air is introduced in the diffuser air aerators with the help of diffuser plates. It rotates and results in the formation of small bubbles causing aeration of sewage.

Environmental Science Multiple Choice Questions on “Air Pollution – Effects – 2”.

1. How does carbon monoxide affect the human body?
a) It does not allow binding of oxygen with haemoglobin
b) It reduces the surface area of the alveoli and disrupts gaseous transfers
c) It causes the liver to malfunction, increasing bile secretion
d) It reduces the body’s tendency to absorb water thereby making us feel dehydrated
Answer: a
Clarification: Carbon monoxide has higher affinity to bind with haemoglobin and does not allow binding of oxygen.

2. What is the Haldane equation used for?
a) To measure the amount of oxygen converted to ozone for a given wavelength of UV light
b) To measure the ratio of affinity of carbon monoxide and oxygen to bind to a haemoglobin molecule
c) To measure the percentage of carbon monoxide that is oxidised to carbon dioxide in various levels of oxygen
d) To calculate the percentage of oxygen addition and carbon dioxide removal during respiratory action
Answer: b
Clarification: Haldane equation is used to measure the ratio of affinity of carbon monoxide and oxygen to bind to a haemoglobin molecule.

3. How does nitrogen affect the human body?
a) Increases vulnerability to pathogens
b) Destroys the macrophages
c) Injures the defence mechanism of the lungs
d) All of the mentioned
Answer: d
Clarification: Nitrogen dioxide destroys macrophages and injures lung’s defence mechanism thereby making us more vulnerable to air-borne pathogens.

4. Which of the following is the current major contributor to lead air pollution?
a) Motor vehicles
b) Metal processing centres
c) Waste incinerators
d) Lead acid battery manufacturing units
Answer: b
Clarification: Metal processing, namely lead smelting is the major cause for presence of lead in air.

5. How does lead affect the human body?
a) Increases blood pressure
b) Damages the cerebellum, liver and kidney
c) Leads to reproductive disorders and osteoporosis
d) All of the mentioned
Answer: d
Clarification: Lead has extreme effects on the human body like increase in blood pressure and damages the organs and reproductive system.

6. Which of the following belongs to class of extremely toxic dioxin compound(s)?
a) Polychlorinated dibenzo-p-dioxins
b) Polychlorinated dibenzofurans
c) Polychlorinated biphenyls
d) All of the mentioned
Answer: d
Clarification: PCDDs, PCDFs and PCBs are all persistent organic pollutants with extremely high toxicity released as industrial by-products.

7. Which of the following compounds was earlier produced for the utility of transformers?
a) PDD
b) PCDF
c) PCB
d) TCDD
Answer: c
Clarification: Polychlorinated biphenyls were used for transformer purposes, but now it is prohibited due to its adverse environmental impact.

8. Crocidolite, actionide and amosite belong to which of the following category of pollutants?
a) Particulate matter
b) Asbestos
c) Dioxins
d) Cigarette smoke
Answer: b
Clarification: Crocidolite, actionide and amosite are amphiboles which is a type of asbestos.

9. Which of the following plants is extremely sensitive towards sulphur dioxide?
a) Onion
b) Potato
c) Corn
d) Tomato
Answer: d
Clarification: Tomato is sensitive towards sulphur dioxide whereas onion, potato and corn are relatively tolerant.

10. TCDD is a human carcinogen.
a) True
b) False
Answer: a
Clarification: TCDD – 2,3,7,8-tetrachlorodibenzo-p-dioxin, is extremely dangerous and regarded as a human carcinogen.

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