Category: Environmental Engineering Objective Questions

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

1. Which of the following represents the physical characteristics of water?
a) Chloride content
b) BOD
c) Turbidity
d) COD
Answer: c
Clarification: Turbidity represents the physical characteristic of water, whereas BOD, COD and chloride content represents the chemical characteristic of water.

2. Which of the following is measured in mg/L?
a) Unit weight
b) Coefficient of cohesion
c) Discharge
d) Turbidity
Answer: d
Clarification: The turbidity of waste water is measured in mg/L. The other units of turbidity are ppm, NTU and JTU.

3. Which of the following instrument is used to measure turbidity?
a) Olfactometer
b) Turbidity meter
c) Colorimeter
d) Spectrophotometer
Answer: b
Clarification: Turbidity can be measured by Jackson’s turbidity meter, Baylis turbidity meter, turbidity rod and Nephelometer.

4. When the sewage becomes stronger, the turbidity of wastewater?
a) Increases
b) Decreases
c) Becomes constant
d) Slightly decrease
Answer: a
Clarification: When the sewage becomes stronger, the milkiness in water increases and thus, the turbidity increases.

5. Which color indicates the fresh sewage?
a) Pink
b) Red
c) Black
d) Grey
Answer: d
Clarification: If the color of sewage is grey, yellow and light brown, then it means that the sewage is fresh.

6. The color of the septic sewage is __________
a) Pink
b) Red
c) Black
d) Grey
Answer: c
Clarification: The color of septic sewage is black or dark brown. It contains either little or no oxygen.

7. The odor in wastewater is measured by __________
a) Osmoscope
b) Chromatography
c) Olfactometer
d) Turbidity meter
Answer: a
Clarification: The odor in waste water is measured by Osmoscope which consist of two 10mm diameter glass tubes which is 300mm long and 8mm wide.

8. In India, the average temperature of sewage is __________
a) 10^oC
b) 20^oC
c) 40^oC
d) 80^oC
Answer: b
Clarification: The average temperature of sewage is 20^oC. The temperature of sewage is higher than that of the water supply.

9. Identify the incorrect statement from the following?
a) High odor intensity indicates odorless water
b) Fresh sewage is odorless
c) Turbidity can be measured by turbidity rod
d) NTU is a unit of turbidity
Answer: a
Clarification: If the odor intensity of water is 6, it indicates extremely strong odor and when it is 0, it indicates the odorless water.

10. _______ indicates the freshness of sewage.
a) Turbidity
b) Color
c) Temperature
d) COD
Answer: b
Clarification: The color indicates the freshness of sewage. It can be detected easily by the naked eye.

11. ______ represents the number of dilutions required to reduce odor.
a) Dispersion
b) Threshold odor number
c) BOD
d) COD
Answer: b
Clarification: The threshold odor number is equal to the volume of samples of water required to add to 100 units of odorless fresh water at which the mixture gives the first detectable odor.

12. The odor quality of Amines is __________
a) Rotten egg
b) Fishy
c) Fecal matter
d) Decayed cabbage
Answer: b
Clarification: The odor quality of Amines is fishy and its chemical formula is CH₃NH₂.

13. The odor quality of compound is ammoniacal. Identify the type of compound from the following options.
a) Acetic acid
b) Benzene
c) Ammonia
d) Methane
Answer: c
Clarification: Ammonia has an ammoniacal type of odor quality and its chemical formula is NH₃.

14. The wastewater from the kitchen is an example of __________
a) Black water
b) Yellow water
c) Green water
d) Grey water
Answer: d
Clarification: The wastewater from the kitchen is an example of grey water. It also includes water from the bathroom without urine and feces.

15. The type of wastewater from the flushing operation of toilet is __________
a) Green water
b) Red water
c) Black water
d) Brown water
Answer: c
Clarification: The type of wastewater from the flushing operation of toilet is black in color and if it does not include urine, then it is brown in color.

Environmental Engineering Multiple Choice Questions on “Types of Sewage Filter”.

1. The intermittent sand filters have better BOD removal efficiency than trickling filters.
a) True
b) False
Answer: b
Clarification: The trickling filters have the best BOD removal efficiency in comparison to the types of filters used in aerobic treatment with a maximum value of 95%.

2. The filter material used in contact bed is ___________
a) Sand
b) Stone ballast
c) Gravel
d) Fine sand
Answer: b
Clarification: The filter material used in the contact bed is broken stones called as stone ballast.

3. Which of the following is called as contact bed?
a) Primary clarifier
b) Secondary clarifier
c) Contact filter
d) High rate digester
Answer: c
Clarification: Contact filters are water tight tanks that are used for the aerobic treatment of sewage. They are also called as contact bed.

4. How many types of trickling filters are used in sewage treatment?
a) 6
b) 5
c) 3
d) 2
Answer: d
Clarification: The trickling filters are divided into conventional and high rate trickling filters.

5. The depth of the filter media of intermittent filter is ___________
a) 45cm
b) 60cm
c) 20cm
d) 25cm
Answer: b
Clarification: The minimum depth of filter media of intermittent filter is 60cm. These filters give highly nitrified effluent.

6. Which of the following filter is used in the anaerobic treatment of sewage?
a) Intermittent sand
b) Trickling filter
c) Contact filter
d) Biological filter
Answer: d
Clarification: Biological filter is used in anaerobic treatment, whereas intermittent sand filter, trickling filter and contact filter are used in the aerobic treatment of sewage.

7. The maximum size of filter media of a percolating filter is ___________
a) 10mm
b) 25mm
c) 60mm
d) 75mm
Answer: d
Clarification: The minimum and maximum size of filter media of a percolating filter is 25mm and 75mm respectively.

8. The recirculation ratio for the low rate trickling filter is ___________
a) 1
b) 2
c) 3
d) 0
Answer: d
Clarification: The recirculation system is not provided in the low rate trickling filter. So, when the recirculation is 0, the type of filter used is a low rate trickling filter.

Environmental Engineering Question Bank on “Dispersion of Air Pollutants, Contol of Gaseous Pollutants”.

1. When environmental Lapse Rate (ELR) is less is than Adiabatic Lapse Rate (ALR), then which of the following occurs?
a) Sub adiabatic lapse rate
b) Super adiabatic lapse rate
c) Neutral lapse rate
d) Adiabatic lapse rate
Answer: a
Clarification: When the temperature increases with an increase in altitude, Sub adiabatic lapse rate occur and there will be stable environment.

2. _______ occurs when atmospheric temperature increases with height.
a) Negative lapse rate
b) Super adiabatic lapse rate
c) Neutral lapse rate
d) Positive lapse rate
Answer: d
Clarification: Under negative lapse rate, the colder air is below the warmer air. It can be occurred near the earth’s surface.

3. When environmental Lapse Rate (ELR) is equal to the Adiabatic Lapse Rate (ALR), then which of the following occurs?
a) Sub adiabatic lapse rate
b) Super adiabatic lapse rate
c) Neutral lapse rate
d) Adiabatic lapse rate
Answer: c
Clarification: When the temperature is constant with height, then neutral lapse rate occurs.

4. The wet adiabatic rate is greater than the dry adiabatic rate.
a) True
b) False
Answer: b
Clarification: The value of wet adiabatic rate is 60C per 1000m whereas of dry adiabatic rate is 9.80C per 1000m.

5. When Environmental Lapse Rate (ELR) is greater than Adiabatic Lapse Rate (ALR), then which of the following occurs?
a) Sub adiabatic lapse rate
b) Super adiabatic lapse rate
c) Neutral lapse rate
d) Adiabatic lapse rate
Answer: b
Clarification: In Super adiabatic lapse rate, the environment is unstable due to the quick dispersion of pollutants.

6. Which of the following is the absorption unit?
a) Cyclone collector
b) Plate tower
c) Gravitation settling chamber
d) Dynamic precipitator
Answer: b
Clarification: Cyclone collector, Gravitation settling chamber and Dynamic precipitator are used to remove particulate matter, whereas Plate tower is used to remove gaseous matter and is an absorption unit.

7. Which of the following catalyst is used for removing hydrocarbon from gaseous pollutant in combustion unit?
a) Platinum
b) Activated alumina
c) Vanadium
d) Potassium permanganate
Answer: b
Clarification: Activated alumina is used as a catalyst for removing gaseous pollutant called hydrocarbons from the air. The concentration of hydrocarbon emitted from automobiles is 300-1000 mg/l.

8. Which of the following is not a part of adsorption unit?
a) Packed towers
b) Multiple fixed bed
c) Fluidized bed
d) Moving bed
Answer: a
Clarification: Packed tower is a part of the absorption unit, whereas multiple fixed bed, fluidized bed and moving bed are the examples of absorbers.

9. Which of the following is a bulk phenomena?
a) Physical adsorption
b) Chemical adsorption
c) Absorption
d) Sorption
Answer: c
Clarification: Adsorption is a bulk phenomena, whereas absorption is a surface phenomena.

10. Which of the following is not an adsorbent?
a) Molecular sieves
b) Activated carbon
c) Activated alumina
d) Water
Answer: d
Clarification: Water is an absorbent whereas molecular sieves, activated carbon and activated alumina are adsorbents.

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Environmental Engineering Multiple Choice Questions on “Theory and classification of Filtration”.

1. Which of the following statement is wrong regarding filtration?
a) It removes fine particle
b) It removes suspended solids not removed by sedimentation
c) It does not remove turbidity
d) It removes color
Answer: c
Clarification: Filtration is a primary turbidity removal process. It also removes color, suspended solids and fine particles.

2. In which action of filtration, particles coarser than the void size is arrested?
a) Mechanical Straining
b) Sedimentation
c) Biological mechanism
d) Electrolytic action
Answer: a
Clarification: In Mechanical Straining, particles coarser than the void size is arrested. The water passing the voids will be free from such particles.

3. In which action of filtration, colloidal particles are removed?
a) Mechanical Straining
b) Sedimentation
c) Biological mechanism
d) Electrolytic action
Answer: b
Clarification: In the sedimentation action of filtration, colloidal particles arrested in the voids attract other finer particle, settle down in the voids and get removed.

4. Which is the first zone of purification in a sand bed?
a) Autotrophic zone
b) Heterotrophic zone
c) Schmutzdecke zone
d) Electrolytic zone
Answer: c
Clarification: Schmutzdecke zone is the first zone of purification in a sand bed. It comes under the biological action of filtration. Schmutzdecke is known as the surface coating.

5. Schmutzdecke acts as an extremely fine meshed straining mat.
a) True
b) False
Answer: a
Clarification: Schmutzdecke is a film of algae, bacteria and protozoa formed on the uppermost layer of sand which helps in the breakdown of organic impurities into harmless compounds acting as a fine mesh straining mat.

6. In which action of filtration, removal of particulate matter takes place?
a) Mechanical Straining
b) Sedimentation
c) Biological mechanism
d) Electrolytic action
Answer: d
Clarification: Filter removes the particulate matter by electrostatic exchange where the charge of the filter medium neutralizes the charge of the floc and permitting it to be removed.

7. In which type of filter, rate of filtration is low?
a) Slow sand filter
b) Rapid sand filter
c) Gravity filter
d) Pressure filter
Answer: a
Clarification: In Slow sand filter, rate of filtration is low and due to this they requires large land and are expensive to install.

8. What is the color of the surface coating formed during the filtration process?
a) White
b) Brown
c) Green
d) Reddish brown
Answer: d
Clarification: The surface coating is formed by the reddish brown deposit of partially decomposed organic matter together with Iron, Alumina, Manganese and Silica.

9. In the ________ zone of purification in filter media, bacteria oxidizes the organic matter completely.
a) Autotrophic
b) Heterotrophic
c) Schmutzdecke
d) Electrolytic
Answer: b
Clarification: In Heterotrophic zone, bacteria multiplies in large number, breaks down not only the organic matter but also destroys each other to maintain a balance of life in the filter.

10. The filtration rate of a slow sand filter is _____ litres of water per square metre.
a) 20
b) 30
c) 50
d) 100
Answer: d
Clarification: The surface area of the slow sand filter lies between 50m² to 1000m² and its filtration rate lies between 100 to 200 litres of water per m².

11. Identify the correct statement from the following options.
a) Rapid sand filter has a high initial cost
b) Coagulation is essential in slow sand filter
c) Slow sand filter requires skilled supervision
d) Period of cleaning of Rapid sand filter is 1-2 days
Answer: d
Clarification: Rapid sand filter is cheap and economical and its period of cleaning is 1-2 days. Neither the coagulation nor the skilled supervision is required in the slow sand filter.

Environmental Engineering Questions for Freshers on “Types of Hardness and Method of their Removal”.

1. The Total hardness of soft water as CaCO₃ equivalent is __________
a) 50ppm
b) 100ppm
c) 150ppm
d) 200ppm
Answer: a
Clarification: The Total hardness of soft water as CaCO₃ equivalent is 50ppm while of hard water, it is 150-300ppm.

2. The total hardness of water is 100ppm as CaCO₃ equivalent. What is the type of water?
a) Soft
b) Moderately hard
c) Hard
d) Very hard
Answer: b
Clarification: When the total hardness of water is between 50 and 150ppm as CaCO₃ equivalent, then the water is moderately hard.

3. The permanent hardness in water is due to the presence of __________
a) Sulfates, Chlorides
b) Sulfates, chlorides, nitrates
c) Carbonates and bicarbonates
d) Sulfates and carbonates
Answer: b
Clarification: The permanent hardness is due to the presence of sulfates, chlorides and nitrates of calcium and magnesium in water.

4. The temporary hardness in water is due to the presence of __________
a) Sulfates, Chlorides
b) Sulfates, Chlorides, nitrates
c) Carbonates and bicarbonates
d) Sulfates and carbonates
Answer: c
Clarification: The temporary hardness is due to the presence of carbonates and bicarbonates of calcium and magnesium in water.

5. Which of the following causes the temporary hardness?
a) CaSO₄
b) MgSO₄
c) MgCl₂
d) Ca (HCO₃) ₂
Answer: d
Clarification: As the temporary hardness is caused due to the presence of carbonate and bicarbonates, therefore Ca (HCO₃) ₂ cause temporary hardness.

6. The permanent hardness is also known as __________
a) Pseudo hardness
b) Non carbonate hardness
c) Carbonate hardness
d) Brinell hardness
Answer: b
Clarification: The permanent hardness is also known as non carbonate hardness whereas temporary hardness is also known as carbonate hardness.

7. Which of the following is not used for removing the permanent hardness?
a) Lime soda process
b) Zeolite process
c) Demineralization
d) Adding lime
Answer: d
Clarification: Adding lime is a method that is used to remove temporary hardness and it cannot remove the permanent hardness.

8. Which of the following statement is wrong regarding hard water?
a) It causes more consumption of soap in laundry work
b) It causes difficulties in the manufacturing process
c) It increases the taste of food
d) It causes the formation of scales on the boilers
Answer: c
Clarification: Hard water makes the food tasteless, tough and rubbery. So, the process of softening is done to improve the cooking of food.

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Environmental Engineering Multiple Choice Questions on “Conservancy System”.

1. Which system of collection of sewage is a dry system?
a) Conservancy system
b) Biological digestion
c) Incernation
d) Water carriage system
Answer: a
Clarification: The conservancy system is a dry and old system where sewage is deposited in the pit and then removed periodically after 24 hours.

2. After how many years, night soil gives good quality manure?
a) 1
b) 5
c) 10
d) 14
Answer: a
Clarification: Night soil is buried into the ground or trenches to give good quality manure in 1 or 2 years.

3. Hog feeding is a type of ______
a) Campaign
b) Food
c) Garbage disposal method
d) Disease
Answer: c
Clarification: Hog feeding is a type of garbage disposal method where hog eats the garbage. However, this method is opposed by health official as the place where hogs are kept smelling very bad.

4. Conservancy system is a highly unhygienic system, causing insanitary conditions.
a) True
b) False
Answer: a
Clarification: In conservancy system, the excreta starts decomposing within the few hours of its production, produce bad smell and give rise to fly nuisance.

5. Which of the following is not correct regarding conservancy system?
a) High maintenance cost
b) Highly unhygienic system
c) Independent of labour
d) Chances of epidemic
Answer: c
Clarification: This system is highly dependent on labour. Absence of Labour even for a day will cause a foul smell in the whole area.

6. Which system of collection of sewage is called a dry system?
a) Conservancy system
b) Biological digestion
c) Incernation
d) Water carriage system
Answer: a
Clarification: The conservancy system is an old method of collection of sewage where instead of water; humans are responsible for its collection, conveyance and disposal.

7. ________ is a method where water is used as a medium for the flow of sewage from its production of the treatment unit.
a) Conservancy system
b) Biological digestion
c) Incernation
d) Water carriage system
Answer: d
Clarification: In water carriage system, the collection, conveyance and disposal of various types of wastes are carried out with the help of water.

8. Normally, the amount of water required for flushing operation is _____ litres.
a) 10-20
b) 5-10
c) 15-20
d) 20-30
Answer: b
Clarification: In water carriage system, water closets are used where human excreta is removed by the flushing 5-10 litres of water by each person.

9. The water carriage system is a hygienic system without any bad smell.
a) True
b) False
Answer: a
Clarification: Water carriage system is very hygienic as the night soil and other waste water is conveyed through close conduits which are not directly exposed to the atmosphere.

10. Which of the following is correct regarding water carriage system?
a) Chances of the epidemic is there
b) Foul smell is produced
c) Does not cause pollution
d) Highly dependent on labours
Answer: c
Clarification: The liquid waste in the water carriage system is directly conveyed through the sewer, so there is no chance of the waste being soaked into the ground or contaminating the soil.