Category: Environmental Engineering Objective Questions

Environmental Engineering Multiple Choice Questions on “Filter Media”.

1. Which of the following is not commonly used as a filter material in the treatment of water?
a) Sand
b) Anthracite
c) Crushed rock
d) Garnet sand
Answer: c
Clarification: Sand, Anthracite and Garnet sand are used as a filter material but crushed rock is not used in the treatment of water.

2. Which of the following is correct regarding the cheapest filter material used in water treatment?
a) Sand>Anthracite>Garnet sand
b) SandGarnet sand
c) Sandd) Sand=Anthracite>Garnet sand
Answer: a
Clarification: Sand is the cheapest filter material followed by anthracite whereas Garnet sand is the costliest among them and is not used as a sole filter material but as a constituent in mixed media filter.

3. Consider the following statements regarding sand as filter material.
i. It should be free from clay or silt
ii. Organic matter should be present in the sand
iii. It should be nonuniform
Which of the above statement is/are correct?
a) i, ii
b) i only
c) ii, iii
d) i, ii, iii
Answer: b
Clarification: Sand used as a filter material should be free from clay, silt, organic matter or other impurity. It should be uniform and of proper size.

4. The uniformity characteristics of sand expressed in terms of __________
a) Effective size
b) Effective size and uniformity coefficient
c) Uniformity coefficient
d) Mean velocity
Answer: b
Clarification: The uniformity characteristics of sand are expressed in terms of effective size and uniformity coefficient. Effective size is called as effective diameter and uniformity coefficient is a measure of particle range.

5. ____ represents the size of sand particle such that 10% of particles are finer than this size.
a) D_0.1
b) D₁
c) D₁₀
d) D₁₀₀
Answer: c
Clarification: D₁₀ represents the size of sand particle such that 10% of particles are finer than this size. It is also called the effective size or effective diameter and is measured in mm.

6. What is CU in the expression C_U= D₆₀/D₁₀ where D₆₀ and D₁₀ are the sizes of particle such that 60% and 10% of the particles are finer than these sizes respectively?
a) Coefficient of compaction
b) Coefficient of consolidation
c) Uniformity coefficient
d) Effective size
Answer: c
Clarification: The uniformity coefficient is a measure of particle range and it is the ratio of D₆₀ and D₁₀ sizes. It is denoted by C_U.

7. The effective size of sand of the slow sand filter is __________
a) 0.1-0.2mm
b) 0.2-0.3mm
c) 0.4-0.7mm
d) 1-2mm
Answer: b
Clarification: The effective size of sand of the slow sand filter is 0.2-0.3mm and for rapid sand filter, the effective size is 0.4-0.7mm.

8. What is the value of specific gravity of sand filter?
a) 2
b) 2.6
c) 3.1
d) 3.5
Answer: b
Clarification: The specific gravity of sand filter lies in the range of 2.55-2.65. So, the value 2.6 lies in the range of specific gravity of sand filter.

9. The value of uniformity coefficient for uniformly graded sand is ______
a) 0
b) 1
c) 10
d) 100
Answer: b
Clarification: Uniformity coefficient C_U = D₆₀/D₁₀
For uniformly graded sand, C_U = 1
So, D₆₀ = D₁₀.

10. The value of specific gravity for Garnet sand is ____
a) 2.1
b) 3.6
c) 4.2
d) 5.1
Answer: c
Clarification: Garnet sand is a dense material with a specific gravity of 4.2 and is used as a constituent in mixed media filter. It is a costlier filter material.

11. Which of the following statement is correct?
a) Ignition loss of filter should not exceed 3%
b) Wearing loss of filter sand should not exceed 5%
c) The range of CU for the slow sand filter is 3-5
d) The range of CU for the rapid sand filter is 3-5
Answer: c
Clarification: The ignition loss of filter should not exceed 0.7%, wearing loss of filter sand should not exceed 3%, range of CU for the slow sand filter is 3-5 and for the rapid sand filter is between 1.3 and 1.7.

Environmental Engineering Multiple Choice Questions on “Lime Soda Process”.

1. The permanent hardness can be removed by adding lime and soda.
a) True
b) False
Answer: a
Clarification: The permanent hardness can be removed by adding Ca (OH)₂ as lime and sodium carbonate as soda in water and the process is called lime soda process.

2. The time required for the mixing of lime and soda in lime soda process is _____________
a) 10min
b) 20min
c) 40min
d) 80 min
Answer: c
Clarification: The time required for the mixing of lime and soda in water in lime soda process is between 30-60min to allow completion of the chemical reaction. Precipitated chemicals are removed by sedimentation or filtration or both.

3. The temperature at which the softening of water takes place by lime soda process is ____________
a) 10^o-21^oC
b) 20^o-30^oC
c) 39^o-45^oC
d) 90^oC
Answer: a
Clarification: The lime soda process can be operated continuously or intermittently at either 10^o-21^oC or at 100^oC.

4. Which chemical is used for removing the permanent hardness of Calcium chloride?
a) Lime
b) Chlorine
c) Soda
d) Both lime and soda
Answer: b
Clarification: Only soda ash is used for removing the permanent hardness of Calcium chloride whereas for magnesium chloride both lime and soda are used for removing the permanent hardness.

5. Softening chemicals, lime and soda do not depend on ____________
a) Free carbon dioxide present
b) Non carbonate hardness
c) Total magnesium
d) Carbonate hardness
Answer: d
Clarification: Lime and soda depend on free carbon dioxide present, non carbonate hardness, total magnesium and does not depend on carbonate hardness.

6. The detention period of a lime soda treatment plant is ____________
a) 1hour
b) 3hours
c) 2-4hours
d) 4-7hours
Answer: c
Clarification: The detention period of a lime soda treatment plant is 2-4 hours to obtain greater clarification.

7. The minimum reaction time allowed in the recarbonation basin is ____________
a) 5minutes
b) 10minutes
c) 15minutes
d) 20minutes
Answer: d
Clarification: During lime soda treatment, the recarbonation of water is done in recarbonation basin where the minimum reaction time is 20minutes.

8. What is the pH at which recarbonation should be done?
a) 7
b) 4.5
c) 8.2
d) 9.5
Answer: d
Clarification: The carbonation of water containing excess lime will form a colloidal precipitate of calcium carbonate that is less soluble at pH 9.4-9.6, so the recarbonation should not be done below this range.

9. Which filter is normally used in the lime soda treatment plant?
a) Slow sand filter
b) Rapid sand filter
c) Dual media filter
d) Mixed media filter
Answer: b
Clarification: The recarbonated water in lime soda treatment plant is passed through the rapid filter to ensure complete clarification.

10. What is the detention time of a water softening accelerator?
a) 1-6minutes
b) 20minutes
c) 30 minutes
d) 1-2hours
Answer: d
Clarification: A water softening accelerator is a device that is used for mixing, flocculation and clarification of water and they have a short detention period in comparison to a sedimentation tank that is 1-2hours.

11. The sludge in water softening accelerator is deposited at ____________
a) Sedimentation tank
b) Reaction zone
c) Concentrator
d) Secondary mixing zone
Answer: c
Clarification: The sludge in water softening accelerator is deposited at a concentrator which can be discharged through a pipe continuously or can be discharged upon a schedule that can operate automatically.

Environmental Engineering Multiple Choice Questions on “Water Carriage System”.

1. Into how many types, the water carriage system is divided?
a) 2
b) 3
c) 4
d) 5
Answer: b
Clarification: The water carriage system is divided into a separate system, combined system and partially separate system.

2. The number of separate systems in a sewer area are?
a) 2
b) 3
c) 4
d) 6
Answer: a
Clarification: There are two separate systems of sewer, one for the conveyance of foul smell and other in the rain water.

3. The water carriage system is more suitable in rural conditions.
a) True
b) False
Answer: b
Clarification: The water carriage system is more suitable in urban conditions, whereas the conservancy system is more suitable in rural conditions.

4. Which of the following is an advantage of a separate water carriage system?
a) Get choked easily
b) Difficult to clean the sewer
c) Two sets of sewer are used
d) The more uniform character of sewage
Answer: d
Clarification: The sewage in the separate water carriage system will be of more uniform character and it will lend itself more easily to purification.

5. Which of the following is a disadvantage of a separate water carriage system?
a) Low installation charge
b) No loads on treatment units
c) Lesser air contact with small sized sewer
d) Provision of the automatic flushing tank is not required
Answer: c
Clarification: In a separate water carriage system, because of lesser air contact with small sized sewer, foul smell is formed due to the formation of sewage gas.

6. _______ provides only one sewer to carry both foul sewage and rainwater.
a) Separate water carriage system
b) Combined water carriage system
c) Partially combined water carriage system
d) Conservancy system
Answer: b
Clarification: In combined water carriage system, the sewage and the rain water are carried to the treatment units through only one sewer, before its final disposal.

7. Which of the following is correct regarding combined water carriage system?
a) The sewers are of small size
b) The strength of sewer is reduced by dilution
c) Low cost of construction
d) More chances of choking are there
Answer: b
Clarification: In the combined water carriage system, the sewers are of large size, the strength of sewer is reduced by dilution, there is the high cost of construction and rare chances of choking.

8. Which of the following is an advantage of the combined water carriage system?
a) There is more air in large sewer
b) There is the inclusion of storm water
c) There is difficulties in ventilation of large sewer
d) Overflowing of sewer
Answer: a
Clarification: In combined water carriage system, due to more air in large sewer, the sewer gas formed gets diluted and the chances of foul smell reduces.

9. Which of the following is incorrect regarding partially combined water carriage system?
a) The sewers are of reasonable size
b) There is choking of sewer
c) The storm water increases load on treatment units
d) The storm water increases the cost of pumping
Answer: b
Clarification: The storm water permitted in the sewer eliminates its chances of choking. The sewers are completely cleaned during rainy season.

10. The choice of combined water carriage system does not depend on ____________
a) Space consideration
b) Even rainfall pattern
c) Steep topography
d) Pumping requirements
Answer: c
Clarification: The choice of a combined water carriage system depends on space consideration, even rainfall pattern, conversion of existing storm water drains and pumping requirements.

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

1. Which of the following is an end product formed from both the aerobic and anaerobic decomposition of organic matter?
a) NO₃
b) CH₄
c) H₂S
d) CO₂
Answer: d
Clarification: Carbon dioxide is formed due to the oxidation and reduction of organic matter by aerobic and anaerobic bacteria respectively.

2. The aerobic decomposition of carbonaceous organic matter gives __________
a) Nitrites and water
b) Carbon dioxide and water
c) Sulfates and water
d) Nitrogen and Ammonia
Answer: b
Clarification: Carbonaceous organic matter (oxidation by aerobic bacteria) —–> CO₂ + H₂O + Energy.

3. BOD of wastewater having aerobic oxidation is more than that, having anaerobic oxidation.
a) True
b) False
Answer: b
Clarification: The BOD of wastewater where oxidation of organic matter takes place is very less in comparison to that formed by anaerobic oxidation, where BOD of 5000ppm can be formed.

4. The aerobic decomposition of nitrogenous organic matter gives __________
a) Nitrites and water
b) Carbon dioxide and water
c) Nitrates and ammonia
d) Nitrogen and ammonia
Answer: c
Clarification: Nitrogenous organic matter (oxidation by aerobic bacteria) —–> NO^–₃ + NH₃ + Energy.

5. Methane is formed due to the reduction of __________
a) Nitrates
b) Sulfates
c) Carbon dioxide
d) Organic acids
Answer: d
Clarification: Organic acids (oxidation by anaerobic bacteria) —–> CH₄ + CO₂ + Energy.

6. Which of the following is formed due to the anaerobic decomposition of carbonaceous organic matter?
a) Nitrites
b) Carbon dioxide
c) Water
d) Nitrogen
Answer: b
Clarification: Carbonaceous organic matter (reduction by anaerobic bacteria) —–> CO₂ + Energy.

7. Which of the following is formed due to the reduction of sulfurous organic matter?
a) Hydrogen sulfide
b) Hydrochloric acid
c) Sulfuric acid
d) Sulfur dioxide
Answer: a
Clarification: Sulfurous organic matter (reduction by anaerobic bacteria) —–> H₂S + Energy.

8. Partially oxidized sewage contains __________
a) Nitrites and Nitrates
b) Nitrates and sulfur
c) Sulfates and nitrates
d) Nitrites and sulfur
Answer: d
Clarification: Partially oxidized sewage contains nitrites and sulfur whereas fully oxidized sewage contains nitrates and sulfates.

9. The aerobic decomposition of sulfurous organic matter gives __________
a) Nitrites and water
b) Carbon dioxide and water
c) Sulfates and water
d) Nitrogen and Ammonia
Answer: c
Clarification: Sulfurous organic matter (oxidation by aerobic bacteria) —–> SO^–₄ + Energy.

10. The energy released during the aerobic oxidation of organic matter is _____ kilo calories.
a) 26
b) 254
c) 360
d) 484
Answer: d
Clarification: Large amount of energy is released during the oxidation of organic matter with a magnitude between 484 and 674 kilo calories.

11. The decomposition of nitrogenous organic matter in the absence of oxygen gives __________
a) Nitrites and water
b) Carbon dioxide and water
c) Nitrates and ammonia
d) Nitrogen, ammonia and organic acids
Answer: d
Clarification: Nitrogenous organic matter (reduction by anaerobic bacteria) —–> N₂ + NH₃ + organic acids + Energy.

12. Which of the following is formed from the anaerobic oxidation of organic matter?
a) NO₃
b) SO₄
c) H₂S
d) NH₂
Answer: c
Clarification: H₂S is formed from the anaerobic oxidation of sulfurous organic matter.

13. The number of stages required for the completion of aerobic oxidation is __________
a) 1
b) 2
c) 3
d) 4
Answer: a
Clarification: Aerobic oxidation gets completed only in single step, whereas anaerobic oxidation gets completed in two steps.

14. Which of the following is formed from oxidation of organic matter in the presence of oxygen?
a) NO₃
b) SO₄
c) H₂S
d) NH₂
Answer: a
Clarification: NO₃ is formed due to the aerobic decomposition of nitrogenous organic matter.

15. The energy released during the anaerobic oxidation of organic matter is _____ kilo calories.
a) 26
b) 254
c) 360
d) 484
Answer: a
Clarification: Small amount of energy is released during the anaerobic oxidation in comparison to aerobic oxidation of organic matter with a magnitude of 26 kilo calories.

Environmental Engineering Quiz on “High Rate Trickling Filter and Secondary Clarifier”.

1. The maximum removal of suspended and dissolved impurities from the sewage is?
a) 65
b) 70
c) 92
d) 99
Answer: c
Clarification: The maximum and minimum removal of suspended and dissolved impurities from the sewage is 92% and 65% respectively.

2. The color of the secondary sludge produced from the high rate trickling filter is ___________
a) Gray
b) Black
c) Brown
d) Green
Answer: c
Clarification: The color of the secondary sludge produced from the high rate trickling filter is brown and the secondary sludge obtained is partially oxidized.

3. _______ is the ratio of volume of recirculated sewage to the raw sewage.
a) Recirculation factor
b) Recirculation ratio
c) Food to mass ratio
d) BOD
Answer: b
Clarification: Recirculation ratio is the ratio of volume of recirculated sewage to the raw sewage. It is denoted by R/I where, ‘R’ is the recirculated sewage and I is the volume of raw sewage.

4. The range of organic loading in kg/hectare metre/ day in a high rate trickling filter is ___________
a) 6000-18000
b) 10000-20000
c) 5000-10000
d) 900-2200
Answer: a
Clarification: The range of organic loading in high rate trickling filter lies between 6000 to 18000 kg of 5 days BOD per hectare metre of filter media per day.

5. The expression of the recirculation factor F is given by ___________
a) F = 1 / (1+0.1 (R/I))²
b) F = (1+ R) / (1+0.1 (R/I))²
c) F = (1+ I/R) / (1+0.1(R/I))²
d) F = (1+ R/I) / (1+0.1(R/I))²
Answer: d
Clarification: The expression of the recirculation factor F is given by
F = (1+ R/I) / (1+0.1 (R/I))² where, R/I represents the recirculation ratio.

6. The size of filter media in a high rate trickling filter is ___________
a) 10-20mm
b) 34-68mm
c) 25-60mm
d) 20-50mm
Answer: c
Clarification: The size of filter media in a high rate trickling filter is 25-60mm and it can be a rock, slag or any synthetic material.

7. Recirculation increases the efficiency of high rate trickling filters.
a) True
b) False
Answer: a
Clarification: Recirculation reduces the loading in high rate trickling filter and thus, increase the efficiency infiltration process.

8. The surface loading rate of a secondary clarifier is ______ litres/m²/day.
a) 1000
b) 10000
c) 20000
d) 40000
Answer: d
Clarification: The range of surface loading rate of a secondary clarifier lies between 40,000 litres/m²/day to 70,000 litres/m²/day.

9. The detention period of a secondary clarifier is ___________
a) 30 minutes
b) 1 hour
c) 2 hours
d) 4 hours
Answer: c
Clarification: The detention period of a secondary clarifier is between 1.5 hours to 2 hours.

10. Which of the following is the cause of rising sludge?
a) Sedimentation
b) Denitrification
c) Chlorination
d) Flocculation
Answer: b
Clarification: When nitrogen is formed in the sludge, the rise of the sludge mass takes place. These phenomena is called as rising sludge.

11. The minimum weir loading rate of primary clarifier is ____m³/m/day.
a) 125000
b) 50000
c) 10000
d) 20000
Answer: a
Clarification: The minimum and maximum weir loading rate of primary clarifier is 125000 and 500000 m³/m/day respectively.

12. Hopper bottom vertical flow type tank is _____ in shape.
a) Circular
b) Triangular
c) Rectangular
d) Elliptical
Answer: a
Clarification: Hopper bottom vertical flow type tank is circular in shape and it consists of conical hoppers.

Global Education & Learning Series – Environmental Engineering .

To practice all areas of Environmental Engineering for Quizzes, .

Environmental Science Multiple Choice Questions on “Air Pollution – Effects – 1”.

1. What is the primary standard level for carbon monoxide for assuring air quality?
a) 10ppm
b) 90ppm
c) 1ppm
d) 9ppm
Answer: d
Clarification: The primary standard level for carbon monoxide is 9ppm.

2. The pulmonary section of the respiratory tract consists of ___________
a) Nose and mouth as well as down till epiglottis and larynx
b) Bronchi down till the end of bronchiole
c) Respiratory bronchiole, alveoli and alveoli ducts
d) Alveoli ducts and alveoli
Answer: c
Clarification: Respiratory bronchiole, alveoli and alveoli ducts are categorised under the pulmonary section of the respiratory tract.

3. What is the primary function(s) of the alveoli?
a) Transfer of oxygen to the blood
b) Removal of carbon dioxide from the blood
c) Transfer of toxic substances to the blood
d) All of the mentioned
Answer: d
Clarification: The thin walls of the alveoli contain capillaries which aid in transfer of oxygen and toxic substances into the blood and removal of carbon dioxide.

4. The velocity of air reduces to zero by the time it reaches the bronchi.
a) True
b) False
Answer: b
Clarification: The velocity of air reduces to zero only when it reaches the alveoli and not the bronchi.

5. Particles of what size are filtered by the nasal passage?
a) >10micrometre
b) >500 micrometre
c) >1 mm
d) >5 micrometre
Answer: a
Clarification: The moist nasal passage can capture dust particles above 10 micrometre.

6. What is the effect of ozone on human respiratory system?
a) It has higher affinity to bind with haemoglobin and does not allow binding of oxygen
b) It causes the disfigurement of the alveoli reducing the surface area for gaseous transfer
c) It damages lung tissues and aggravates asthma
d) All of the mentioned
Answer: c
Clarification: Ozone scars lung tissues when exposed for a long time and it intensifies asthma by increasing the individual’s sensitivity towards allergens.

7. Which of the following pollutants is the major contributor to photochemical smog?
a) Peroxynitrates
b) Hydroperoxides
c) Nitrogen dioxide
d) Ozone
Answer: d
Clarification: Ozone is the major constituent of photo-chemical smog.

8. What are the effects of sulphur dioxide on the human body?
a) It causes the malfunction of liver and kidney
b) It breaks down body’s immunity towards particulate matter and bacteria
c) It causes blood cells to dilate thereby affecting blood flow through the circulatory system
d) All of the mentioned
Answer: b
Clarification: Sulphur dioxide interrupts our immunity towards particulate matter and allows bacteria to enter through our respiratory system.

9. How does increase in temperature affect air pollution?
a) Higher temperatures reduce air pollution
b) Higher temperatures increase air pollution
c) Temperature does not affect the air pollution levels
d) Humidity factor is also necessary to predict variance of air pollution with temperature
Answer: b
Clarification: Generally, air pollution increases with increase in temperature because it leads to increase in ground level ozone, nitrogen dioxide concentrations increase since higher temperature favours the oxidation of nitrogen monoxide.

10. Ocean is a source for carbon monoxide.
a) True
b) False
Answer: a
Clarification: It was earlier assumed oceans served as a sink, but marine organisms contribute enough carbon monoxide to highly saturate the ocean surface.

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