Dr. Rajarshi MitraAssistant Professor and Head

Department of Environmental Science

Vivekananda College, Thakurpukur, Kolkata – 700 063

rajarshimitra@yahoo.com

POLLUTION CONTROLStrategies and Practices

Control Strategies

Control at Source

Recycle and Reuse

End of Pipe

Treatment

Raw materials /

Fuel alteration

Process alternatives

Byproduct Recovery

Primary, Secondary and

Tertiary treatment

Control at Source

Alternative Fuel / Raw materials

Process alteration

Pollution means the wastage. A fuel with high ash content

or sulphur concentration is expected to cause higher level of air pollution than a cleaner option.

Liquid or gaseous fuels with less non-combustible impurities are always cleaner than the solid fuels.

Similarly a raw material having high amount of impurity leads to higher pollution problem. Impure raw materials in turn also put economic burdens to the company.

Process modification leads to efficiency enhancement by:

Making the existing process more efficient, i.e. reduced wastage. For example if a car engine drive it 12kms in litre of petrol it is using more resource and causing more pollution than a car with 15 kms mileage.

Switching over to a new technology which reduce pollution.

Recycling and Reuse

Recycling and Reuse technology is defined as the process of using the same resource again and again after value addition to it following a single use.

In industrial set up and with chemical waste materials it may not be possible to recycle or reuse any material in most of the cases, but in that case a few other strategies may be adopted. 1. Byproduct recovery 2. Value addition of waste material to make

wealth from the waste.

End of Pipe system

This is the treatment strategy, where the treatment of the exhaust or effluent is done once the pollutants have been generated. Although this strategy is being used in most of the cases due to its easy implementation procedure, but is considered less effective in view of development, because:

It treats the waste material and thus incur additional money flow.

No value addition and byproduct recovery having potential economic benefit is possible in this system.

It releases the final or treated effluent to the environment directly.

End of pipe treatment for Wastewater

Tertiary Treatment:This is the last phase of water treatment, where the treated effluent are kept or treated again mostly on the basis of retention time and natural degradation process in Effluent pit or Oxidation pond.

A comprehensive Effluent Treatment Plant

Activated Sludge Process

Trickling Filter

End of Pipe treatment for Air pollution control:

Major pollutants to control:

Particulate mattersFlue gasesAcid Vapours

Cyclone Precipitator.Electrostatic Precipitator.Fabric filter/ Bag filter / Baghouse.Scrubber – Wet, Dry and Venturi.

Cyclone or cyclone precipitator

Electrostatic Precipitator (ESP)

Fabric Filter / Bag House

Scrubbers

Solid Waste disposal

Segregation At source Reuse of inert materials like glass, metal goods. Reuse of inert materials like construction debris etc. in

road construction, earth work. Recycling of Metals, glass, plastics. Organic composting or vermi-composting of market

biodegradable waste. Immobilization of toxic waste through solidification and

vitrification. Dumping on ground. Sanitary Landfill technology.8

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