Unit - II Pollution and Its Types

 

1. Definition of Pollution and Pollutant

Pollution

Pollution is the undesirable change in the physical, chemical or biological characteristics of air, water or land that harms living organisms, property and the environment.

👉 Example:
Smoke from vehicles mixing with air and causing breathing problems.

Pollutant

A pollutant is any solid, liquid or gaseous substance present in the environment at a concentration that causes harm or discomfort.

👉 Examples:
Carbon monoxide, plastic waste, sewage, industrial chemicals, noise.

2. Air Pollution

Definition

Air pollution occurs when harmful gases, dust or smoke enter the atmosphere and reduce air quality.

Classification of Air Pollutants

1. Primary Pollutants

Emitted directly from sources.

  • Carbon monoxide (CO)

  • Sulphur dioxide (SO₂)

  • Nitrogen oxides (NOx)

👉 Example: Exhaust gases from vehicles.

2. Secondary Pollutants

Formed by chemical reactions in the atmosphere.

  • Ozone (O₃)

  • Photochemical smog

👉 Example: Smog formation in cities.

Sources of Air Pollution

SourceExamples
VehicularCars, buses, trucks
IndustrialPower plants, factories
DomesticCooking fuel, burning waste
NaturalVolcanoes, forest fires

3. Air Pollution Control Equipment

EquipmentFunction
Cyclone SeparatorRemoves large dust particles
Bag FilterRemoves fine dust using cloth bags
Electrostatic Precipitator (ESP)Removes smoke and fine particles
ScrubberRemoves gases using liquid spray

👉 Example:
ESP is used in thermal power plants.

4. Water Pollution

Definition

Water pollution occurs when harmful substances like sewage, chemicals or waste enter water bodies, making water unfit for use.

👉 Example: Industrial waste discharged into rivers.

Water Pollution Parameters

1. BOD (Biochemical Oxygen Demand)

  • Oxygen required by microorganisms to decompose organic matter

  • High BOD = High pollution

2. COD (Chemical Oxygen Demand)

  • Oxygen required to chemically oxidize waste

  • Indicates total pollution load

3. pH

  • Measures acidity or alkalinity

  • Normal range: 6.5 – 8.5

4. Total Suspended Solids (TSS)

  • Undissolved particles in water

5. Turbidity

  • Cloudiness of water

6. Total Solids

  • Sum of dissolved and suspended solids

5. Wastewater Treatment

Primary Treatment

  • Physical process

  • Removal of large solids by screening and sedimentation

👉 Example: Grit removal tanks

Secondary Treatment

  • Biological process

  • Uses microorganisms to remove organic matter

👉 Example: Activated sludge process

Tertiary Treatment

  • Advanced treatment

  • Removal of nutrients and pathogens

👉 Example: Chlorination, filtration

6. Solid Waste Generation

Definition

Solid waste refers to unwanted solid materials produced by human activities.

Sources of Municipal Solid Waste

SourceExamples
ResidentialKitchen waste
CommercialShops, markets
IndustrialPackaging waste
InstitutionalSchools, hospitals

Characteristics of Municipal Solid Waste

  • Physical: Size, weight, moisture

  • Chemical: Carbon, nitrogen content

  • Biological: Biodegradable or non-biodegradable

7. Collection and Disposal of Waste

Municipal Waste Disposal Methods

  • Open dumping

  • Sanitary landfills

  • Composting

  • Incineration

Hazardous Waste Disposal

  • Secure landfills

  • Chemical treatment

  • Incineration

👉 Example: Medical waste from hospitals

8. Noise Pollution

Definition

Noise pollution is unwanted or excessive sound that causes discomfort.

Sources of Noise Pollution

  • Traffic

  • Industries

  • Construction work

  • Loudspeakers

Effects of Noise Pollution

  • Hearing loss

  • Stress and anxiety

  • Sleep disturbance

  • High blood pressure

Measurement of Noise

  • Unit: Decibel (dB)

  • Measured using Sound Level Meter

9. Plastic Waste and Its Hazards

Plastic Waste

Plastic waste includes discarded plastic items like bags, bottles and packaging.

Hazards

  • Non-biodegradable

  • Blocks drainage causing floods

  • Harms animals and marine life

  • Releases toxic gases on burning

👉 Example: Cows eating plastic waste.

10. E-Waste and Its Hazards

E-Waste

Electronic waste includes discarded electronic items such as:

  • Computers

  • Mobile phones

  • TVs

Hazards of E-Waste

  • Contains toxic metals like lead and mercury

  • Causes soil and water pollution

  • Health issues like cancer and nerve damage



SHORT NOTES FOR EXAMS

1. Pollution

Pollution is the introduction of harmful substances into the environment which causes adverse effects on living organisms and natural resources.

2. Pollutant

A pollutant is any substance present in the environment at harmful concentration which causes pollution.
Examples: CO, plastic waste, sewage, noise.

3. Air Pollution

Air pollution is contamination of air by harmful gases, dust, smoke or fumes.

Sources: Vehicles, industries, burning of fuels, forest fires.

4. Air Pollution Control Equipment

Devices used to remove pollutants from air before releasing it into atmosphere.
Examples: Cyclone separator, Bag filter, Electrostatic precipitator.

5. Water Pollution

Water pollution occurs when harmful substances enter rivers, lakes or groundwater making it unfit for use.

6. BOD (Biochemical Oxygen Demand)

Amount of oxygen required by microorganisms to decompose organic matter in water.
High BOD indicates high pollution.

7. COD (Chemical Oxygen Demand)

Amount of oxygen required to chemically oxidize organic and inorganic matter in water.

8. Wastewater Treatment

Process of removing contaminants from wastewater before discharge.

Stages:
Primary → Secondary → Tertiary

9. Municipal Solid Waste

Solid waste generated from homes, markets, offices and institutions.

10. Noise Pollution

Unwanted or excessive sound that causes discomfort and health problems.

Unit: Decibel (dB)

11. Plastic Waste

Non-biodegradable waste made from synthetic polymers.

Hazards: Soil pollution, animal death, toxic gases on burning.

12. E-Waste

Discarded electronic devices like computers, mobiles, TVs.

Hazards: Toxic metals, health problems, groundwater pollution.

📊 B) DIAGRAMS WITH LABELS (EXAM DRAWING)

1. Sources of Air Pollution

   Factory Smoke     Vehicle Exhaust
        ↑                  ↑
     [INDUSTRY]         [VEHICLES]
             \           /
              \         /
               [ AIR POLLUTION ]
                    |
              Human Health

2. Electrostatic Precipitator (ESP)

   Dirty Gas Inlet
         ↓
  -----------------
  | Charging Zone |
  -----------------
         ↓
  -----------------
  | Collecting    |
  | Plates        |
  -----------------
         ↓
   Clean Gas Outlet

3. Wastewater Treatment Process

 Wastewater
     ↓
 Primary Treatment
 (Screening, Sedimentation)
     ↓
 Secondary Treatment
 (Biological Process)
     ↓
 Tertiary Treatment
 (Disinfection)
     ↓
 Treated Water

4. Municipal Solid Waste Disposal

 Households → Collection → Transport → Disposal
                                    ↓
                             Landfill / Compost

5. Noise Measurement

 Noise Source → Sound Level Meter → Reading (dB)

📝 C) MCQs (Multiple Choice Questions)

1. Pollution is defined as

A) Useful change in environment
B) Undesirable change in environment
C) Natural process
D) None

✅ Answer: B

2. Which is a primary air pollutant?

A) Ozone
B) Smog
C) Carbon Monoxide
D) Acid rain

✅ Answer: C

3. Unit of noise pollution is

A) Hertz
B) Decibel
C) ppm
D) Watt

✅ Answer: B

4. High BOD value indicates

A) Clean water
B) Less pollution
C) High pollution
D) No oxygen

✅ Answer: C

5. Which waste is non-biodegradable?

A) Food waste
B) Paper
C) Plastic
D) Leaves

✅ Answer: C

6. Which device removes fine dust particles?

A) Cyclone separator
B) ESP
C) Grinder
D) Filter paper

✅ Answer: B

7. E-waste contains

A) Oxygen
B) Nitrogen
C) Heavy metals
D) Water

✅ Answer: C

8. pH value of pure water is

A) 3
B) 5
C) 7
D) 9

✅ Answer: C

9. Municipal solid waste mainly comes from

A) Space
B) Households
C) Oceans
D) Mountains

✅ Answer: B

10. Noise above safe limit causes

A) Hearing loss
B) Vision loss
C) Digestion problem
D) Fever

✅ Answer: A

🎤 D) VIVA QUESTIONS & ANSWERS

Q1. What is pollution?

Pollution is the undesirable change in the environment that harms living organisms.

Q2. What is a pollutant?

A pollutant is a harmful substance present in environment at high concentration.

Q3. What is BOD?

BOD is the oxygen required by microorganisms to decompose organic matter.

Q4. What is COD?

COD is the oxygen required to chemically oxidize waste in water.

Q5. Name any two air pollution control devices.

Cyclone separator and Electrostatic precipitator.

Q6. What is municipal solid waste?

Waste generated from households, markets and institutions.

Q7. Unit of noise pollution?

Decibel (dB).

Q8. Give two hazards of plastic waste.

Soil pollution and animal death.

Q9. What is e-waste?

Discarded electronic devices like computers and mobiles.

Q10. Name stages of wastewater treatment.

Primary, Secondary and Tertiary.

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