Environmental Engineering Interview Questions and Answers:

1. Define Environment.

Ans. The physical, chemical and biological presence of living and non-living things outside an individual species is called as its environment.

2. Define the term Environment with reference to ISO 14001.

Ans. According to ISO 14001, environment can be defined as, “surroundings in which an organization operates, including air, water, land, natural resources, flora, fauna, humans and inter relation”.

3. What are the two categories of environments?

Ans.

  • Biotic environment
  • Abiotic environment

4. Name the components of environment.

Ans. Air (Atmosphere), Land (Lithosphere) and Water (hydrosphere)

5. What are gases present in the air?

Ans. Nitrogen , oxygen, Argon , Carbon dioxide hydrogen, helium, ozone, radon, neon, krypton, xenon, Sulphur dioxide, ammonia, methane, hydrogen sulphide, etc

6. Name the various layers of atmosphere.

Ans.

  • Troposphere
  • Stratosphere (Ozonosphere)
  • Mesosphere
  • Heterosphere (Thermosphere)
  • Exosphere

7. Define the term Lithosphere

Ans. The solid component of Earth is called lithosphere.

8. Name different layers of Earth.

Ans. Crust , Mantle , Outer core and Inner core.

9. Define Hydrologic cycle.

Ans. HydrOlogic cycle is defined as the interchange of water between the atmosphere and the Earth’s surface.

10. Classify the zones available in the aquatic environment.

Ans. The aquatic environment can be divided into three zones as

  • Littoral zone
  • Limnetic zone
  • Profundal zone

11. Name some organisms generally found in fresh water environment.

Ans.

  • Benthos → Organisms living in the bottom sediments
  • Periphyton → Organisms living on stems and leaves
  • Plankton → Organisms flying freely with the water current
  • Nekton → Organisms swimming and navigating in water
  • Neuston → Organisms resting or swimming on the water surface.

12. Define the term “Sustainable Development”

Ans. Sustainable Development is defined as,” the development to meet the needs of the present without compromising the ability of future generations to meet their own needs”. Sustainable Development must balance the needs of society, the economy, and the environment.

13. What are the three important components of sustainable development?

Ans.

  • Economic development
  • Community development
  • Environmental protection

14. Define Sustainabilty

Ans. Sustainability can be defined as the ability of a society or ecosystem to continue functioning into the indefinite future without being forced into decline through complete loss of its strength or overloading of key resources on which that system depends.

15. What is the need of SDIs?

Ans. Sustainable Development Indicators (SDI) are various statistical values that collectively measure the capacity to meet present and future needs. SDI will provide information crucial to decisions of national policy and to the general public.

16. Differentiate between Resistance stability and Resilience stability.

Ans. Resistance stability is the ability of a system to remain stable in the face of stresses and resilience stability is the ability of the system to recover from the disturbance occurred due to the activities happened.

17. What are the main sources of pollution?

Ans. Natural sources and Anthropogenic sources.

18. Name the types of pollution.

Ans.

  • Air pollution
  • Water pollution
  • Land or Soil pollution
  • Radio active pollution
  • Noise pollution

19. Define the term Ecology.

Ans. Ecology is the branch of science that deals with the study of the pattern of relations between organisms and their environment. It is an interdisciplinary science. It is not only particular with organisms but with energy flows and material cycles on the land, in the water, in the air. It involves the basic knowledge of principles of physics, chemistry, microbiology, geography, mathematics, statistics, etc.

20. Define Ecosystem.

Ans. Ecosystem has been defined as a system of interaction of organisms with their surroundings. Numerous dynamic interactions are occurring within an ecosystem and these are complex. Always alterations to the biotic and abiotic components are happening within the ecosystems.

21. Enumerate some characteristics of an Ecosystem.

Ans.

  • Ecosystem is the major ecological unit.
  • It contains both biotic and abiotic components.
  • Through the biotic and abiotic components nutrient cycle and energy flow occur.
  • The boundary of the ecosystem is not rigidly defined and it is flexible.
  • The function of ecosystem is related to the cycling of materials and flow of energy.
  • The amount of energy needed to maintain an ecosystem depends on its structure.
  • Ecosystems pass from a less complex state to more complex state, which is called as succession.
  • Adaptation to local environmental condition is the important feature of the biotic components of an ecosystem, failing which they might perish

22. Classify the Ecosystem.

Ans. The ecosystem can be generally classified into three types.

  • Natural Ecosystem
  • Artificial Ecosystem
  • Incomplete Ecosystem

23. What are the functional components of eco system?

Ans. Biotic components and Abiotic components

24. Define heterotrophs.

Ans. Those organisms which depend on others (Producers-Autotrophs) for their energy requirements are known as Consumers or Heterotrophs.

25. Name the types of consumers.

Ans.

  • Herbivores (or) Primary Consumers
  • Carnivores (or) Secondary Consumers
  • Omnivores (or) Tertiary Consumers

26. Define Food chain and Food web.

Ans. A food chain is a picture or model that shows the flow of energy from Autotrophs to a series of organisms in an environment. The energy that it flows can be different for each food chain.

The relationships between the components of the food chain are very complex. The network like interaction of organisms is called as food web.

27. What are Decomposers?

Ans. The organisms which breakdown the complex compounds into simple products are called as decomposers or reducers.

28. What are the factors to be considered in abiotic eco system?

Ans. Climatic factors, Physical factors and Chemical factors.

29. Define biogeochemical cycle.

Ans. The characteristic pathway of macro and micronutrients circulation between the organisms and its environment in the biosphere is called as biogeochemical cycles.

30. Name the sedimentary cycles.

Ans. Phosphorous cycle and Sulphur cycle

31. What is Nitrogen fixation?

Ans. The process of converting the free nitrogen gas available in the atmosphere into compounds of nitrogen is called as nitrogen fixation.

32. Define the term Nitrification.

Ans. The process of converting ammonia into nitrites with the help of nitrosomonas bacteria, and nitrites into nitrates with the help of nitrobactor bacteria is called as nitrification.

33. What do you mean by Denitrification?

Ans. The process in which the nitrites and nitrates are converted back into free nitrogen is called as denitrification. This pfocess is accomplished with the help of soil bacteria called pseudomonas.

34. Define Biome.

Ans. Biome is defined as a major ecological community of organisms occupying in a larger area.

35. Define the term ‘anthroposystem’.

Ans. It is defined as the ecosystem developed by the humankind. It is also called as artificial eco system.

36. List the major biomes of the world.

Ans. Dessert, Trophical rain forest, Tundra etc.

37. What are the methods by which nitrogen fixation takes place in the nature?

Ans. Natural nitrogen fixation can be obtained from lightening of clouds and bacteria and fungi present in soil and water. Artificial fixation of nitrogen is obtained with the help of fertilizer industries, which convert the atmosphere nitrogen into ammonia.

38. List the four conceptual spheres in the Earth’s environment.

Ans. Crust, Mantle, Outer core and Inner core.

39. Define Ecological succession.

Ans. It is defined as the important consequences of biological regulations in the community. It is also called as ecological development.

40. Define the terms Climax and Sere.

Ans.

  • Climax : It is defined as the final steady state of the ecological developmental activity.
  • Sere : It is defined as the entire gradient of communities.

41. What are the two types of ecological succession?

Ans.

  • Allogenic succession
  • Autogenic succession

42. Define Primary and secondary succession

Ans.

  • Primary succession : It is the succession begins on a sterile area when the conditions of the existence are not at the first.
  • Secondary succession : It refers to the community developments on sites previously occupied by well developed communities.

43. What are the forces involved in succession?

Ans.

  • External Driving Forces
  • Internal forces of the organisms modifying the environment

44. List some examples for Autotrophic succession.

Ans.

  • An abandoned field or city lot.
  • A gravel or sand bar in a river or along a coast.
  • A new lava flow.
  • A receding glacier.
  • A new reservoir.

45. List the units used .for expressing the concentration of pollutants in water

Ans.

  • ppm
  • molarity
  • molality
  • normality

46. Define stoichiomehy.

Ans. Stoichiometry is the quantitative description of the proportions by moles of the substances in a chemical reaction.

47. Define mole.

Ans. Mole is defined as the amount of substance present in a material. The term mole can be applied to any particle. In general, it is the ratio between mass and molecular weight of a particle.

48. What is Avogadro’s number?

Ans. Avogadro’s number (or Avogadro’s constant) is the number of elementary particles in a mole of any substance. The number 6.022 x 1023 is known as Avogadro’s number.

49. Define equivalent weight.

Ans. Equivalent weight is defined as the weight of an element or compound which would combine or displace (by weight) 1.008 parts of hydrogen, 8 parts of oxygen or 35.5 parts of chlorine.

50. Define atomic weight.

Ans. Atomic weight is defined as the average relative weight of its atoms as compared with the weight of a carbon atom taken as 12.

51. Define molarity.

Ans. Molarity is defined as the number of moles of the solute present in 1000m1 of the solution.

Molarity = Number of moles of solute / Volume of solution

52. Define molality.

Ans. Molality is defined as the number of moles of solute dissolved in 1000gm of the solvent. It is another common measurement of concentration.

Molality = Number of moles of solute / Weight of solvent

53. Define pH.

Ans. It is the logarthmic Scale used to specify whether a solution is acitic, basic or neutral.

54. What are colloids?

Ans. Colloids are the particles not removed by settling. Its approximate size is ranging from 1 milli micron to 1 micron.

55. Most of the colloids are in suspension. Why?

Ans. Since the colloidal particles are having negative surface charge they always repel each other. This causes most of the colloids are in suspension.

56. What is the significance of colloids in environmental science and engineering?

Ans. Colloidal conditioning is an internal conditioning method used for the prevention of scales in boilers. When chemicals like tannin or agar-agar gel is added, they get coated on the outer surface of crystalline precipitates and forms colloidal, non-sticky sludge and precipitates, which can be easily removed by mechanical method or blow down operation.

57. Define gas transfer

Ans. Gas transfer is defined as the process by which gas is transferred from one phase to another. It is normally in gaseous to liquid phase.

58. What are the different types of aerators used in waste water treatment?

Ans.

  • Fine bubble aerator
  • Medium bubble aerator
  • Course bubble aerator
  • Sparger turbine
  • Static tube mixer
  • Jet aerator
  • Low speed turbine aerator
  • High speed floating aerator
  • Rotor brush aerator

59. List the basic properties of acid and base.

Ans. A solution for which the hydrogen ions are greater than the hydroxil ions, it is called as acid whereas in base, the hydroxil ions are more than the hydrogen ions.

60. List the reactor types commonly used in the wastewater treatment processes.

Ans.

  • Batch reactor
  • Plug-flow reactor (or) Tubular flow reactor
  • Continuous flow stirred reactor (or) Complex mix reactor
  • Arbitary flow reactor
  • Packed bed reactor
  • Fluidized bed reactor (or) Expanded bed reactor.

61. Define microbiology.

Ans. Microbiology is the study of micro-organisms that are too small and not clearly visible to the naked eye.

62. What is the role of microorganisms in waste treatment?

Ans. Both aerobic and anaerobic micro-organisms are involved in the waste water treatment. Their purpose is to destroy the organic compounds present in the wastes into energy and gases. The energy derived from the respiration is used by the micro-organisms to synthesis new protoplasms.

63. What are the different types of bacteria based on the size?

Ans.

  • Spherical bacteria ( 0.5 to 1.0 µ diameter)
  • Cylindrical bacteria (0.5 to 1.0 µ width and 1.5 to 3.0 µ length)
  • Helical bacteria (0.5 to 5 µ width and 6 to 15 µ length)

64. What are the different types of bacteria based on the flagella distribution?

Ans.

  • Monotrichous bacteria — Only one flagella
  • Polar flagellum — Flagella is located at the end.
  • Amphitrichous bacteria — Single flagella at each pole
  • Lophotrichous bacteria — Group of flagella either at one end or both ends.

65. What are the principle nutrients required for algae?

Ans.

  • Nitrogen,
  • Phosphorus, and
  • Carbon dioxide.

66. List the different types of fresh water algae.

Ans.

  • Green algae (Chlorophyta)
  • Motile green algae (Volvocales Euglenophyta)
  • Yellow green (or) Golden brown algae (Chrysophyta)
  • Bluegreen algae (Cyanophyta)
  • Brown algae (Phoeophyta)
  • Red algae (Rhodophyta)

67. When does atmospheric inversion occur?

Ans. Atmospheric inversions occur when the temperature increases with altitude.

68. List some physical properties of water

Ans.

  • Colour
  • Temperature
  • Turbidity
  • Taste and Odour

69. What are the methods generally used in removal colour of water?

Ans.

  • Adsorption
  • Coagulation
  • Filteration

70. What are the different types of solids present in water?

Ans.

  • Suspended solids
  • Colloidal solids
  • Dissolved solids

71. Define Hardness of water:

Ans. Hardness of water is defined as the property of water which consumes more soap to produce foam or lather. It is due to the presence of certain salts of calcium, magnesium and other heavy metals dissolved in it.

72. Differentiate between temporary and permanent hardness.

Ans. Temporary hardness is caused due to the presence of dissolved bicarbonates of calcium, magnesium and other heavy metals and the carbonate of iron. It is mostly destroyed by boiling.

Permanent hardness is caused due to the presence of chlorides and sulphates of calcium, magnesium, iron and other heavy metals. This type of hardness is not destroyed by boiling.

73. Define covalent bond of water molecule.

Ans. Covalent bond of water molecule is defined as the bond which holds the hydrogen and oxygen atoms together. This bond is very strong.

74. State the reasons for the bent structure of water molecule.

Ans.

  • Presence of lone pair electrons on the oxygen
  • Tetrahedral arrangement around the oxygen.

75. What are lone pair electrons?

Ans. The electrons which are not involving in the covalent bonds are called as lone pair electrons.

76. What do your mean by hydrogen bonding of water molecule?

Ans. Hydrogen bonding of water molecule is defined as the bonding developed between the positive hydrogen end of one molecule and the negative lone pair of another water molecule. Four hydrogen bonds are formed around each and every water molecules.

77. Define buffering capacity.

Ans. Buffering capacity is the ability of water to maintain a stable pH value even if acids or bases are added.

78. Define permeability of soil.

Ans. It is defined as the ability of movement of waterthrdugh the pore spaces of soil particles.

79. Explain the hydraulic characteristics of the following types of rectors.

Ans.

  • Plug flow
  • Continuous flow stirred tank
  • Fluidized bed

80. Explain the basic classifications of microorganisms.

Ans.

  • Bacteria
  • Fungi
  • Algae
  • Protozoa
  • Rotifiers
  • Crustaceans
  • Viruses

81. What is meant by Air pollution?

Ans. Air pollution may be defined as the presence of impurities in excessive quantity and duration to cause adverse effects on plants, animals, human beings and materials.

82. What are the main sources of Air pollution?

Ans.

  • Natural Sources and
  • Man made or anthropogenic sources.

83. List the types of Air pollutants.

Ans.

  • Particulate Pollutants
  • Gaseous Pollutants

84. What is the size of particulate materials?

Ans. The size of particulate materials ranges from 100μm to 0.1μm.

85. What do you understand about Suspended particulate?

Ans. Suspended particulate matter is a complex mixture of small and large particles with size less than 100μ varying origin and chemical composition. The largest source of particulate matter is coal-fired power plants, but auto and diesel exhaust are also prime contributors, especially along busy transportation corridors.

86. Name some gaseous pollutants.

Ans. CO, chlorine, NH3, H2S, SO2, NO2, CO2

87. Which is the primary source of lead?

Ans. The primary source of lead in the atmosphere is the additive tetraethyl lead which is used as a catalyst to help gasoline burn in automobile engines.

88. Name some air pollutants emitted from Food and Agricultural Industries.

Ans. Vapours, odours, dust, chlorinated hydrocarbons, lead, arsenic, phosphate, smoke, fly ash and soot.

89. List the effects on Physical properties of Atmosphere due to Air pollution.

Ans. Decrease in the visibility, Reduction of Solar radiation, Effects on weather conditions and Effects on atmospheric constituents.

90. What are the ways to reduce pollution from automobiles?

Ans. There are four ways to reduce pollution from automobiles are:

  • Lower emissions from existing vehicles through tighter standards and emission testing
  • Engine with better design to minimize the pollutants during combustion (unburnt fuel, carbon, CO, hydrocarbons, etc.)
  • Reduce the number of vehicles on the road, and
  • Manufacture alternative vehicles which use fuels like natural gas, propane, electricity, fuel cells and hybrid technology

91. Define the term Biodiversity.

Ans. Biodiversity is defined as richness of species (micro-organisms, plants and animals) occurring in a given habitat. It is the sum of genes, species and ecosystems.

92. What are the types of Biodiversity?

Ans. The three types of biodiversity are

  • Genetic Level or Genetic diversity
  • Species Level or Species diversity
  • Ecosystem Level or Ecosystem diversity.

93. Define the term Genetic diversity.

Ans. Genetic diversity is the variation of genes within species. Genes are the basic units of all life on Earth. They are responsible for both the similarities and the differences between organisms. This type of diversity occurs at finer levels of organisms.

94. What do you mean by Species Diversity?

Ans. Species diversity is the number of different species of living things living in an area. Species is a group of plants or animals that are similar and able to breed and produce viable offspring under natural conditions.

95. What is Ecosystem Diversity?

Ans. Ecosystem diversity is the variety of ecosystems in a given place. An ecosystem is a community of organisms and their physical environment interacting together. An ecosystem can cover a large area, such as a whole forest, or a small area, such as a pond.

96. What are the main functions of Biodiversity?

Ans. There are two main functions of biodiversity.

  • It is the source of species on which the human compete depends for food, fiber, shelter, fuel and medicine.
  • It depends on the biosphere, which in turn leads to the stability in climate, water, soil, air, and the overall health of biosphere.

97. What are values of Biodiversity?

Ans. Direct values and Indirect values.

98. How Biodiversity can be expressed?

Ans. Biodiversity can be expressed in numbers. The following indices are used to express the biodiversity.

  • Species Richness (S)
  • Simpson’s Index (D)
  • Shannon — Wiener Index (H)
  • Evenness (E).

99. Define Species Richness.

Ans. It is the total number of species found in an environment.

100. What do you mean by the terms Simpson’s Index and Shannon — Wiener Index?

Ans.

  • Simpson’s Index is the probability that randomly selected individuals belongs to two different species.
  • Shannon — Wiener Index is measuring the order or disorder of species in a particular system.

101. Write short notes on Evenness.

Ans. Evenness is a measure of how similar the abundances of different species are in a community. It is ranged from 0 to 1. When the value of E is close to 0, it indicates that most of the individuals belong to one or a few species. When the value of E is close to 1, it indicates that each species consists of the same number of individuals.

102. What are Biomedical Wastes?

Ans. Biomedical wastes are defined as any solid fluid or liquid waste including its containers and any intermediate product which arc generated during diagnosis, treatment or immunization of human being/animals or in production and testing of biological.

103. Name some Biomedical wastes.

Ans. Needles, Scalpel blades, Syringes, Contaminated gloves, Petrie dishes used for microbiological cultures, Human anatomical waste, Blood soaked items such as gauze pads and other absorbents.

104. List the different locations of waste generation.

Ans.

  • Operation theaters/wards/labour room/OPD
  • Injection rooms
  • Intensive Care Units
  • Dressing rooms
  • Dialysis room
  • Laboratory

105. What are the types of treatments given for the processing of biomedical wastes?

Ans. Incineration, Autoclaving, Micro waving, Hydroclaving, Chemical Disinfection and Shredding.

106. Define the Incineration process used for processing Biomedical wastes.

Ans. Incineration is a controlled combustion process where waste is completely oxidized and harmful microorganisms present in it are destroyed/denatured under high temperature.

107. Explain micro waving process.

Ans. Micro waving is an inter-molecular heating process with electromagnetic radiation between 300 to 300,000 MHz. The heating occurs inside the waste material in the presence of steam.

108. What is mean by Shredding process?

Ans. Shredding is a process by which waste are reshaped or cut into smaller pieces so as to make the wastes unrecognizable. It helps in prevention of reuse of biomedical waste.

109. Define the terms Climate and Climate Change.

Ans. Climate is the long-term average of a region’s weather events grouped together. Climate change is the representation of change in these long-term weather patterns.

110. Name some green house gases present in the atmosphere.

Ans. Carbon dioxide (CO2); methane (CH4); nitrous oxide (N2O); chlorofluorocarbons (CFC); water vapour (H2O) and tropospheric ozone (03) are some of the green house gases present in the atmosphere.

111. What are the sources of CFC?

Ans. Air conditioners, Refrigerators, Fire extinguishers.

112. Define green house effect.

Ans. The greenhouse effect is a naturally occurring process that makes the earth warmer by trapping more energy in the atmosphere. The green house gases absorb and hold heat from the sun, preventing it from escaping back into the space; much like a green house absorbs and holds the sun’s heat.

113. Define Global warning.

Ans. Global warming is defined as the increase in the temperature of the earth, which causes more changes in climate.

114. What are the effects of Global warning?

Ans.

  • More heat waves
  • Expansion of desert area
  • Natural fires in forest lands
  • More evaporation of water from oceans and water bodies
  • Melting of ice caps in Arctic and Antarctica regions
  • More cloud formation in the atmosphere.
  • Shorter and wanner winters and longer and shorter summer.
  • Changes in pattern of rainfall
  • Rise in sea level
  • Flooding and submergence of low lying coastal areas
  • Disruption in farming
  • More drought
  • More impacts on plants, animals and humans

115. What is meant by Hazardous waste?

Ans. Wastes that create danger to the living community, immediately or over time, are called as hazardous wastes.

116. What are the characteristics of hazardous wastes?

Ans. Toxicity, Reactivity, Ignitability, Radioactivity and Corrosivity

117. What are the classifications of hazardous wastes?

Ans.

  • Radioactive substances
  • Chemicals
  • Biological wastes
  • Flammable wastes and
  • Explosives

118. What is meant by radioactive substances?

Ans. The substances that are emitting ionizing radiation are being defined as radioactive substances.

119. Define Half life of a radio active substance.

Ans. The half-life of a radioactive substance is defined as the time taken for decaying of half of the material present.

120. What are the steps to be followed in the Management of hazardous wastes?

Ans.

  • Storage
  • Collection and Transportation
  • Treatment, and
  • Disposal

121. What are the effects of radioactive pollutants?

Ans.

  • The duration of exposure to the radiation
  • The strength of the radiation
  • The half life period of the radioactive pollutant
  • The rate of diffusion of the pollutant
  • The environmental conditions.

122. What are the types of solid wastes?

Ans.

  • Municipal Wastes
  • Industrial Wastes
  • Hazardous Wastes

123. What are the main components of Municipal solid waste?

Ans.

  • Garbage (or) Food wastes
  • Rubbish
  • Ashes and Residues
  • Special Wastes
  • Construction and Demolition Wastes
  • Treatment Plant Wastes

124. What do you mean by Onsite Handling?

Ans. The activities involved in handling of solid wastes, at the point of generation, until they are placed in the containers used for their storage before collection are called as on-site handling.

125. Name the containers used in Hauled Container Systems.

Ans. Tilt frame container, Hoist truck and Trash trailer.

126. What are the purposes of processing techniques used in solid wastes management systems?

Ans.

  • To improve the efficiency of solid waste management systems,
  • To recover the usable materials for reuse, and
  • To recover conversion products and energy.

127. Name the techniques involved in processing of SWMS.

Ans. The processing of solid wastes includes the following five techniques.

  • Compaction ( Mechanical volume reduction)
  • Incineration ( Chemical volume reduction)
  • Shredding ( Mechanical size reduction)
  • Component separation
  • Drying and Dewatering ( Moisture content reduction).

128. What are the types of system used in the collection of wastewater?

Ans.

  • Separate System,
  • Combined System and
  • Partially Separate System

129. Enumerate the steps involved in Municipal sewage treatment.

Ans.

  • Preliminary treatment
  • Secondary treatment
  • Tertiary treatment
  • Disinfection
  • Sludge Digestion

130. Define screening and skimming.

Ans. The process of removing the large matters from sewage by allowing it to pass through screens is called as screening.

The process of removal of floating matters such as oils, grease, etc. by skimming tanks is called as skimming.

131. Name any three disinfection methods.

Ans. Chlorination , Ozonation , UV treatment

132. Define Ozone depletion potential of a compound.

Ans. The ozone depletion potential (ODP) of a compound is defined as the measure of its ability to destroy the stratospheric ozone:

In other words it is defined as the ratio of the total amount of ozone destroyed by a particular agent to the amount of ozone destroyed by the same mass of CFC-11

133. What do you understand about the term Dobson Unit?

Ans. Dobson Unit (DU) is the scale for measuring the total amount of ozone occupying a column overhead.

One Dobson unit ( I DU) is defined as 0.01 mm at 0°C and 1 atmospheric pressure.

If the ozone layer thickness is compressed to 0°C and 1 atmosphere pressure, is about 5 mm thick, then the average thickness of the ozone layer would be about 500 DU.

In absolute terms, 1 DU is about 2.7 x 1016 molecules/cm2.

134. What are the deceases caused due to ozone layer depletion?

Ans. Reddening of skin in sun shine (Sun burn), Skin Cancer, Reduction in body’s immunity to disease and Eye disorders like Cataracts and Blindness.

135. Write short notes on chemical precipitation.

Ans. Very fine suspended matters are removed by adding chemical coagulants in the sedimentation tank. These tanks are called as chemical precipitation tanks and that process is known as chemical precipitation.

136. Define engineering interventions?

Ans. Engineering interventions arc defined as the involvement of technologies used to protect the environment from the generation of wastes from different sources including its minimization. The results of engineering intervention should be well protected environment.

137. Write the three “R”s of waste minimization.

Ans. The three “R”s involved in waste minimization are

  • Reduce
  • Reuse
  • Recycle

138. What are the waste minimization techniques?

Ans.

  • Waste reduction at source
  • Recycling of wastes
  • Product modifications

139. How the waste reduction can be achieved?

Ans. The waste reduction can be achieved by

  • good house keeping
  • modification in processes

140. What are the benefits of waste minimization?

Ans.

  • Saves the waste disposal cost
  • Avoids possible fines
  • Avoids the cleaning cost
  • Produces of environmental friendly products
  • Protects the environment

141. Define good house keeping.

Ans. Good house keeping means changing the existing practices and introducing new ways of operating and maintaining equipments.

142. What are the advantages of good house keeping?

Ans. The advantages of good house keeping are

  • Less expense
  • Shorter pay back period

143. What are the options can be used in modification process?

Ans. The modification processes have four options.

  • Changing raw material
  • Better process control
  • Modifications in equipment
  • Change in technology

144. How the recycling of wastes can be achieved?

Ans. The recycling of wastes can be achieved in the following two ways.

  • On-site recovery of materials and energy
  • Reuse of materials and energy

145. What are the stages involved in the sources of wastes in construction industries?

Ans.

  • Planning and designing
  • Estimating and purchasing
  • Manufacturing of materials
  • Operational wastes
  • Transportation of materials

146. What are the causes of wastes during pre-construction stage?

Ans.

  • Improper coordination of materials
  • Disposal of excess materials
  • Improper planning
  • Rapid and frequent design modifications
  • Insufficient knowledge about materials
  • Damage of materials during loading and unloading.

147. What are the causes of wastes during construction stage?

Ans.

  • Improper packaging of materials
  • Low quality materials
  • Lack of skilled materials
  • Improper supervision
  • Poor workmanship
  • Improper storage of materials
  • Inefficient transferring from store to worksitc
  • Improper loading and unloading.

148. Define e-waste management.

Ans. c-waste management is defined as the management of electronic and IT industrial wastes.

149. Write some types of e-wastes.

Ans.

  • Out dated PC
  • Printed Circuit Boards (PCBs)
  • Mobile phones
  • Stereos
  • Microwave ovens
  • Damaged and outdated printers
  • Storage devices

150. What is the difference between the normal osmosis process and reverse osmosis process?

Ans. In the normal osmosis process, more dilution of concentrated solution occurs by the movement of molecules from the less concentrated side. But incase of reverse osmosis process, due to the application of high external pressure, the molecules of solution move from the more concentrated side to the less concentrated side through the semi-permeable membrane.

151. What are the factors affecting the efficiency of R.O. units?

Ans.

  • Total Dissolved Solids (TDS)
  • Hardness of water
  • pH
  • Temperature
  • Operating pressure

152. What are the commercially used types of membranes?

Ans.

  • Cellulose Acetate
  • Cellulose Tri-Acetate
  • Thin Film Composite

153. What are the merits of R.O. process?

Ans. The R.O. units remove high percentage of dissolved organics, which are less selectively removed by other demineralization techniques.

154. What is the main demerit of R.O. process in water treatment?

Ans. Its high cost and general lack of operating experience are the main demerits of this R.O. process in water treatment.

155. Write down the main limitation of trickling filters?

Ans. The main limitation of the trickling filters is that an excess amount of nutrients produce an excessive amount of slime on the bed. This excess slime reduces the aeration process. That makes the need for renewal of the porous bed frequently.

156. Define the term clean technology.

Ans. Clean technology is defined as the technology which improves the environmental performance relative to the other technologies.

157. What are the characteristics of clean technologies?

Ans.

  • Minimised effluent and other waste production
  • High quality products
  • Maximum use of raw materials, energy and any other input

158. What are the benefits of Clean Technology?

Ans.

  • Protecting the environment
  • Less polluting technology
  • Sustainable use of resources
  • Recycle of more products and wastes
  • Preservation of diversity in nature and culture

159. What are the different Clean Technologies used?

Ans.

  • Biomass Technology
  • Fuel Cell Technology
  • Land Fill Gas (LFG)
  • Solar Technology
  • Wave / Ocean Technology
  • Wind Technology

160. Define biomass gasification.

Ans. Biomass gasification is a method used for obtaining renewable enrgy from biomass.

161. What are the benefits of biomass technology?

Ans.

  • Reduced green house gas emissions
  • Reduced dependence on foreign oil / fuel
  • Improved rural economy

162. How does the fuel cells work?

Ans. The fuel cells generate electricity due to the electro chemical reaction held between hydrogen and oxygen in the air. This process has no emissions and the only by products are water and heat.

163. Define Land.filling gas?

Ans. Land filling gas is defined as the gas emitted from decomposition of organic wastes in a land filling site.

164. What are the benefits of land filling gas?

Ans.

  • Reduced demand for non-renewable sources like coal, oil, etc.
  • Reduced emission of air pollutants
  • Reduced unpleasant odours
  • No release of green house gas into the atmosphere

165. What is the role of ISO in environmental protection?

Ans. The main involvement of ISO is to develop the standards in the following ares.

  • Environmental Management System (EMS)
  • Environmental Auditing
  • Environmental Labelling
  • Environmental Performance Evaluation
  • Life cycle assessment
  • Terms and definitions

166. What is the main objective of ISO 14000 series.

Ans. The main purpose of ISO 14000 series is to promote effective and efficient environmental management in organizations.

167. Mention some of the Environmental Quality Objectives.

Ans.

  • Reduced climate impact
  • A non-toxic environment
  • Cleaner air
  • A perfect ozone layer
  • Good quality ground water
  • Sustainable forests

168. Define Environmental Impact Assessment?

Ans. Environmental Impact Assessment (EIA) is a study of the probable alterations in the biophysical and socio-economic characteristics of the environment that may occur due to a proposed action.

169. What is the need of EIA?

Ans. All the developmental activities are proposed to facilitate the public. For that the resources are used more and that may alter and affect the environmental parameters. Hence this EIA is carried out in order to ensure the depletion of resources and the alterations and effects on the quality of environmental parameters.

170. What are the goals of EIA?

Ans. The goals of EIA are:

  • Conservation of resources
  • Minimization of wastes
  • Recovery of by-products
  • Utilization of efficient equipments.

171. List the key elements of EIA.

Ans.

  • Organising the job
  • Assessment performance
  • Preparation of Environment Impact Statement
  • Reviewing of Environment Impact Statement
  • Approval of Plan with or without modifications

172. What is the beneficiary pays principle?

Ans. According to this principle, ‘the people who get benefited due to an activity, which increases the pollution, should pay for that’.

173. What do you know about risk management?

Ans. Risk management is the process of resolving various policies regarding acceptable risk. It consists of risk assessment and risk control.

174. Define risk assessment.

Ans. Risk assessment is defined as the process of identifying, quantifying and evaluating the risk. It contains risk determination and risk evaluation.

175. What are the activities covered in risk assessment?

Ans.

  • Risk identification
  • Risk estimation
  • Risk acceptance
  • Risk aversion.

176. State the Precautionary Principle.

Ans. According to that statement, ‘When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context the proponent of an activity, rather than the public, should bear the burden of proof’.

177. What are the components of Precautionary Principle?

Ans. The principle of precautionary action has four parts

  • People have a duty to take anticipatory action to prevent harm.
  • The burden of proof of harmlessness of a new technology, process, activity or chemical lies with the proponents, not with the general public.
  • Before using a new technology, process, chemical or starting a new activity, people have an obligation to examine ‘a full range of alternatives’ including the alternative of doing nothing.
  • Decisions applying the precautionary principle must be ‘open, informed and democratic’ and ‘must include affected parties’.

178. Define the Polluter-Pays Principle.

Ans. The Polluter-Pays Principle states, ‘The polluter is responsible for the environmental and economic effects of his polluting activities’.

179. What are the limitations of Polluter Pays Principle?

Ans.

  • The polluter pay taxes would be used to enrich government funds, not to compensate those who were harmed by the pollution.
  • The pollution control boards are in no position to assess the actual costs imposed by pollution. Pollution taxes enacted through the political process are likely to reflect political priorities rather than environmental ones.

180. List the major environmental conventions of 20th century.

Ans.

  • World summit on sustainable development
  • The Earth Summit
  • World conference on women

181. What are the common objectives of Environmental Legislation?

Ans. All the Acts were enacted to achieve the following:

  • To control further damage to the environment and ecosystem
  • To conserve the environment.
  • To restore the environment in areas damaged including such measures as reclamation of degraded land.
  • To create authorities to administer the policy and contents of the legislation
  • To provide penalties and prosecution for violation of laws.

182. List the major environmental protocols of 20th century.

Ans.

  • Kyoto protocol
  • Montreal protocol

183. What are Non-Governmental Organisations (NGOs)?

Ans. NGOs are voluntary organisations that are creating environmental awareness through academic, scientific and real life practical activities. It includes academic and industrial experts as well as common layman.

184. What are the functions of Central Pollution Control Board?

Ans.

  • To advise the Central Government on matters relating to pollution
  • To coordinate the activities of the State Boards
  • To provide Technical assistance to the State Boards, carry out and sponsor investigations and research relating to control of pollution
  • To plan and organize training of personnel
  • To collect, compile and publish technical and statistical data, prepare manuals and code of conduct
  • To formulate the standards of environmental parameters
  • To plan nation wide programme for pollution control

185. What are the functions of the State Pollution Control Boards?

Ans.

  • To advise the State Government on matter relating to pollution and on siting of industries
  • To plan programme for pollution control
  • To collect and distribute information
  • To carry out inspection
  • To formulate the effluent and emission standards for industries
  • To issue consent to industries and other activities for compliance of prescribed emission and effluent standards.

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