Control of Air pollution Natural process of control

Control of Air pollution Natural process of control Anthropogenic Process Meteorological factors Control at source after the release of pollutant

Meteorological factors & removal of pollution �The study of the dynamics of atmosphere that ultimately govern the air quality at a given point is known as meteorology. �Ambient lapse rate �Adiabatic Lapse rate �Atmospheric Stability

Temperature Inversion �In unusual case temperature may increase with increasing altitude, which is known as temperature inversion. �Causes of temperature inversion are a. Radiation inversion b. Subsidence inversion c. Advective inversion Maximum mixing depth & ventilation coefficient

Stack & Plume �The dispersion of emitted gases from the source of their production is known as plume and the source is known as stack. �On the basis of ELR & ALR the nature of plume may be different. �Coning Plume �Fanning plume �Looping plume �Neutral plume �Lofting plume �Fumigating plume etc.

Control at sources �Control at sources can be of following types a. Source relocation b. Source shut down c. Fuel and energy substitution d. Process change e. Good operating condition f. Installation of air pollution device

Control after release of pollution �Contamination of Air are done in 2 ways 1) SPM & 2) Gas • Different process for controlling them

Control of gaseous pollution �It depend on the properties of specific gas to be controlled. � Common processes are – � Absorption in a liquid � Adsorption on a solid surface �Condensation to a liquid �Conversion to less polluting or non polluting gas.

Standard for air pollution control in India �The ambient air-quality standards have been prescribed for SO₂, SPM, CO, Nox. �These standards have been prescribed specially for I. Industrial and mixed used areas, II. Residential and rural areas III. Sensitive areas

Collection of SPM � 6 mechanisms are available for collecting polluting particles 1. Gravitational settling 2. Inertial impaction 3. Centrifugal impaction 4. Direct interception 5. Diffusion & 6. Electrostatic effects

Particulate collecting equipments 1. 2. 3. 4. 5. 6. Gravity settling chambers Cyclones Scrubbers or wet collectors Fabric filters / bag house Electrostatic precipitators Catalytic converter`

Values Area category cube Concentration micrograms per meter SPM SO₂ CO NOx 5000 120 Industrial & mixed used area 500 120 Residential and rural 200 80 2000 80 Sensitive 100 30 1000 30

Air Quality standard – EPA Sl no. Parameter 1. SPM 2. Carbon mono oxide 3. Standard concentration µg/ m Remarks ppm 75 260 - Annual geometric mean 24 h 10, 000 9 8 hours Sulfur dioxide 80 365 . 083 0. 14 Annual mean 24 h 4. Nitrogen dioxide 100 0. 05 Annual mean 5. Ozone 235 0. 12 1 h daily maximum 6. Lead 1. 5 - 3 months average