(SEM V) THEORY EXAMINATION 2022-23 AIR AND NOISE POLLUTION CONTROL

Course: B.Tech (Civil Engineering)                             Semester: V

Subject Code: KCE057                                              Title: Air and Noise Pollution Control

Maximum Marks: 100                                             Duration: 3 Hours

Type: Theory Paper

Paper Structure:

Section A: Short Questions – 20 marks

Section B: Descriptive Questions – 30 marks

Section C: Analytical / Application-based – 50 marks

 SECTION A — Short Answer Questions (2 × 10 = 20 Marks)

All questions are compulsory.

Define Planetary Boundary Layer.

The lowest part of the atmosphere directly influenced by surface friction and characterized by turbulent air movement.

Classification of Air Pollutants.

Based on origin:

Primary pollutants – emitted directly (CO, SO₂, NOx, etc.)

Secondary pollutants – formed by chemical reactions (ozone, PAN).

Based on physical state: Gaseous, particulate, biological, etc.

Features of Wind Rose.

A diagram showing frequency and direction of winds at a location, useful in studying pollutant dispersion.

Define Lapse Rate.

The rate of temperature decrease with increase in altitude; affects vertical mixing of air pollutants.

State Ambient Air Quality.

The physical and chemical characteristics of outdoor air maintained within permissible limits prescribed by CPCB or WHO.

Emission Standards.

Regulatory limits that specify maximum permissible emission levels from industrial, vehicular, and power sources.

Types of Condensation Equipment.

Spray towers, surface condensers, contact condensers, and venturi scrubbers used to remove vapors or gaseous pollutants.

Define Adsorption.

The process by which gas or vapor molecules adhere to the surface of a solid (e.g., activated carbon).

Noise Pollution.

Unwanted or excessive sound that causes discomfort or health issues to humans and animals.

Noise Indices.

Quantitative measures such as Leq (Equivalent noise level), L10, L90, and CNEL (Community Noise Equivalent Level).

SECTION B — Descriptive Questions (10 × 3 = 30 Marks)

Attempt any three out of five.

Sources and Classification of Air Pollutants:

Natural sources: Volcanic eruptions, forest fires, dust storms.

Anthropogenic sources: Industry, vehicles, thermal plants.

Classification: Primary, secondary, gaseous, particulate.

Plume Behavior (with sketches):

Types:

Coning – neutral stability.                           Looping – unstable atmosphere.

Fanning – stable atmosphere.                    Fumigation – downward dispersion.

Lofting – upward dispersion.

Selection of Equipment for Particulate Control:

Depends on particle size, concentration, gas temperature, flow rate, and efficiency required.

Euro I–III Specifications:

European emission standards regulating permissible levels of pollutants (CO, NOx, HC, PM) for vehicles.

Noise Pollution Control and Prevention:

At source: Maintenance of equipment, silencers, enclosures.

Along path: Green belts, sound barriers.

At receiver: Ear protection, zoning regulations.

SECTION C — Analytical / Application-Based Questions (5 × 10 = 50 Marks)

Attempt one part from each question (Q3–Q7).

Q3. Effects of Air Pollution

(a) On Humans, Animals, and Vegetation:

Respiratory diseases, eye irritation, and reduced lung function. Acid rain damages crops and forests.

Animal health impacts via contaminated feed and water.

(b) On Property and Aesthetics:

Corrosion of metals, deterioration of buildings and monuments (e.g., Taj Mahal).

Reduction in visibility due to smog and haze.

Q4. Atmospheric Factors

(a) Environmental Lapse Rates:

Dry Adiabatic (9.8°C/km), Moist Adiabatic (4–6°C/km), and Environmental Lapse Rate — determines air stability.

(b) Dispersion Factors:

Wind speed, turbulence, temperature inversion, and terrain influence pollutant dispersion.

Q5. Air Pollution Control Devices

(a) Cyclone Separator:

Uses centrifugal force to separate particulates from gas.

Advantages: Low cost, handles high temperature. Disadvantages: Ineffective for very fine particles.

(b) Electrostatic Precipitator (ESP):

Uses electrostatic forces to capture dust. Advantages: High efficiency (up to 99%), low pressure drop.

Disadvantages: High cost, limited for sticky particles.

Q6. Absorption and Pollution Boards

(a) Absorption Units:

Packed towers, plate columns, spray chambers — used for gaseous pollutant removal.

(b) Central vs State Pollution Control Boards:

CPCB: Formulates national standards, coordinates state boards.

SPCB: Enforces state-level monitoring, licensing, and control actions.

Q7. Noise Pollution

(a) Sources of Noise and Control at Source:

Sources: Transport, industry, construction.

Control: Mufflers, isolation mounts, equipment design.

(b) Noise Levels in Modern Society:

Traffic (~85–100 dB), factories (~90–120 dB), household appliances (~60–80 dB).

Continuous exposure leads to hearing loss and stress.

 Key Topics Covered

Air pollutant sources, effects, and control                          Atmospheric dispersion and plume behavior

Pollution control equipment (Cyclone, ESP, Absorber)      Noise sources, measurement, and control methods                                                                       CPCB & SPCB functions and air quality standards