Control of Air pollution Natural process of control Meteorological factors Anthropogenic Process 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 Radiation inversion Subsidence inversion 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 - Source relocation Source shut down Fuel and energy substitution Process change Good operating condition 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 Industrial and mixed used areas, Residential and rural areas Sensitive areas

Collection of SPM 6 mechanisms are available for collecting polluting particles Gravitational settling Inertial impaction Centrifugal impaction Direct interception Diffusion & Electrostatic effects

Particulate collecting equipments Gravity settling chambers Cyclones Scrubbers or wet collectors Fabric filters / bag house Electrostatic precipitators Catalytic converter`

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

Air Quality standard – EPA Sl no. Parameter Standard concentration µg/ m ppm Remarks 1. SPM 75 260 - Annual geometric mean 24 h 2. Carbon mono oxide 10,000 9 8 hours 3. Sulfur dioxide 80 365 .083 0.14 Annual mean 4. Nitrogen dioxide 100 0.05 5. Ozone 235 0.12 1 h daily maximum 6. Lead 1.5 3 months average