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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