Air, Water and Sludge Pollution- Control and Treatment

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Air, Water and Sludge Pollution-

Control and Treatment

Presented By:

Sumana mitra

Vaishali Bhati

Vibhuti SharmaNitul Chaudhary

Pankaj dusad

Vikash Kumar



Air Pollution

� Contamination of the air by noxiousgases, minute particles of solid andliquid matter, in concentrations thatendanger health.

� Among the major sources of pollutionare power and heat generation, theburning of solid wastes, industrialprocesses, and, especially,transportation. The six major types of

pollutants are carbon monoxide,hydrocarbons, nitrogen oxides,particulates, sulphur dioxide, andphotochemical oxidants.



www.envis.nic.com



Examples of Air Pollution

� Tobacco SmokeTobacco smoke is one of the major forms of pollution in buildings. It is not only thesmoker who is infected, but everyone who inhales the polluted air. There is a verystrong connection between smoking and lung cancer. Bronchitis is common amongsmokers and unborn babies of mothers who smoke also suffer from the harmfuleffects of smoking.

� Exhaust Gases of VehiclesPollution from exhaust gases of vehicles is responsible for 60% of all air pollutionand in cities up to 80%. There is a large variety of harmful chemicals present inthese gases, with lead being one of the most dangerous.

� Combustion of CoalThe combustion of coal without special precautions can have seriousconsequences. If winds do not blow away the poisonous gases, they can have fatal

effects and may lead to death.� Acid rainAcid rain is the term for pollution caused when sulphur and nitrogen dioxidescombine with atmospheric moisture to produce highly acidic rain, snow, hail, orfog. The acid eats into the stone, brick and metal articles and pollutes watersources.



Control Measures

Although individual people can help to

combat air pollution in their own immediate

environment, efficient control can be best

achieved by legislation. Some commonly

enforced control measures include

� the establishment of more smokeless zones;

� control over the kinds of fuel used in cars,

airplanes, power stations, etc.



Methods of Air Pollution Control

Methods of air pollution control can be divided intotwo categories:

� the control of particulate emissions and

� the control of gaseous emissions.The term particulate refers to tiny particles of mattersuch as smoke, soot, and dust that are released duringindustrial, agricultural, or other activities. Gaseous

emissions are industrial products such as sulphurdioxide, carbon monoxide, and oxides of nitrogen alsoreleased during various manufacturing operations.



Particulate Emissions ControlThere are many kinds of equipment which can be used to reduce particulateemissions. Physical separation of the particulate from the air using settlingchambers, cyclone collectors, wet scrubbers, and filtration devices, are allprocesses that are typically employed.

1. Settling chambers use gravity separation to reduce particulate emissions.

2. cyclone collector is a cylindrical device with a conical bottom which is used tocreate a tornado-like air stream. A centrifugal force is thus imparted to the

particles, causing them to cling to the wall and roll downward, while the cleanerair stream exits through the top of the device.

3. Wet scrubbers control particulate emissions by wetting the particles in order toenhance their removal from the air stream. The particulate matter becomesentrained in the water droplets, and it is then separated from the gas stream.

4. One of the oldest and most efficient methods of particulate control, however, isfiltration. The most commonly-used filtration device is known as a baghouse andconsists of fabric bags through which the air stream is directed. Particles aretrapped in the fiber mesh on the fabric bags, as well as the filter cake which issubsequently formed.

� Centrifugal forces (the forces that move things away from the center of rotation)send solid particles in the gas outward against the walls of the container. Theycollect there briefly, then fall to the bottom of the container. Gases from which theparticles have been removed then escape from the top of the container.



Gaseous Emissions Control

Many different methods are available for removing unwanted gases, mostof which are acidic.

� Absorption-Scrubbers are smokestack devices that contain a moistchemical such as lime, magnesium oxide, or sodium hydroxide. Whengases escape from a factory and pass through a scrubber, they react with

the moist chemical and are neutralized. From time to time, the scrubbersare removed from the smokestack, cleaned, and replaced.

� Adsorption- Activated charcoal is charcoal that has been ground into avery fine powder. In this form, charcoal has the ability to adsorb, or adhereto, other chemicals. When unwanted gases flow over activated charcoalon the inside of a smokestack, they are adsorbed on the charcoal. As withscrubbers, the charcoal is removed from time to time, and a new lining of

charcoal is installed in the smokestack.



Air (Prevention and Control of

Pollution) Act, 1981

State govt has Power to declare air

pollution control areas. Government has Power to giveinstructions for ensuring standards foremission from automobiles.

Government impose Restrictions onuse of certain industrial plants whichcauses more pollution.



Water Pollution

Water pollution is the introductionof chemical, physical, or biologicalmaterial into fresh or ocean waters,that degrades the quality of the

water and affect the organismsliving in it. This process ranges fromsimple addition of dissolved orsuspended solids to discharge of the most dangerous and persistent

toxic pollutants (such as pesticides,heavy metals, and non-degradable,bio-accumulative, chemicalcompounds).



Examples of Water Pollution

� Industrial effluentWater is discharged from after having been used inproduction processes. This waste water may contain acids,alkalis, salts, poisons, oils and in some cases harmful

bacteria.� Mining and Agricultural WastesMines, especially gold and coal mines, are responsible forlarge quantities of acid water.

Agricultural pesticides, fertilizers and herbicides may wash

into rivers and stagnant water bodies.� Sewage Disposal and Domestic WastesSewage as well as domestic and farm wastes often polluterivers and dams.



Control Measures

The following measures can be used to stop water pollution.

1. Use non-toxic soaps, detergents and cleaning products at home. Refrain from theuse of chemical fertilizers and pesticides on lawns and gardens. Always disposeof paints, motor oil, gasoline and other harmful chemicals in accordance withyour local laws and safety regulations.

2. Protect groundwater, which is critical for drinking water, irrigation systems andnatural ecosystems. If you are using chemicals that may be harmful to theenvironment, store them correctly. Improperly stored chemicals can slowly seepinto the groundwater system, so keep them in tightly sealed containers, insidestructures with cement floors, to avoid groundwater contamination.

3. Prevent polluted runoff and soil erosion. Polluted runoff is caused when rainwashes toxic pollutants into surface waters from sources that include city streets,

farms, or logging and mining sites. Plant bushes and trees along roads andnatural water sources. The roots of trees and bushes can slow the speed of runoff and erosion, protecting surface water.



Physical

� Screening

� Filtration

� Sedimentation

One form of water pollution consists of suspendedsolids such as fine dirt and dead organisms. Thesematerials can be removed from water by simplyallowing the water to sit quietly for a period of time,thereby allowing the pollutants to settle out, or by

passing the water through a filter. (The solid pollutantsare then trapped in the filter)



Chemical

� Chemical precipitation

� Adsorption

� Disinfection reaction

Chemical reactions can be used to remove pollutantsfrom water. For example, the addition of alum(potassium aluminum sulphate) and lime (calciumhydroxide) to water results in the formation of a thick,sticky precipitate. When the precipitate begins to settle

out, it traps and carries with it solid particles, deadbacteria, and other components of polluted water.



Biological

Biological agents can also be used to remove

pollutants from water. Aerobic bacteria (those

that need oxygen to survive) and anaerobic

bacteria (those that do not require oxygen)

attack certain chemicals in polluted water and

convert them to a harmless form.



WATER (PREVENTION AND CONTROLOF POLLUTION) ACT, 1974

Power to obtain information and takesamples of industrial waste water.

Government has the power to enter and

inspect any industrial area to measure waterpollution level.



Sludge pollution

Sludge refers to theresidual, semi-solidmaterial left fromindustrial wastewater, or

sewage treatmentprocesses. It can alsorefer to the settledsuspension obtained from

conventional drinkingwater treatment, andnumerous other industrialprocesses.



Treatment of sludge

The sludge is transformed into biosolids using anumber of complex treatments such as digestion,thickening, dewatering, drying, and lime/alkaline

stabilizationThe common methods of treatment are :

> Anaerobic digestion

> Aerobic digestion

> Composting



Anaerobic digestion

Anaerobic digestion is a bacterial process that is

carried out in the absence of oxygen. The process

can either be thermophilic digestion in which sludge

is fermented in tanks at a temperature of 55°C or mesophilic at a temperature of around 36°C.

Though allowing shorter retention time, thus smaller

tanks, thermophilic digestion is more expensive in

terms of energy consumption for heating the sludge.



Aerobic digestion

Aerobic digestion is a bacterial process occurring in the

presence of oxygen. Under aerobic conditions, bacteria

rapidly consume organic matter and convert it into

carbon dioxide Once there is a lack of organic matter,bacteria die and are used as food by other bacteria. This

stage of the process is known as endogenous

respiration. Solids reduction occurs in this phase.

Because the aerobic digestion occurs much faster than

anaerobic digestion, the capital costs of aerobic

digestion are lower.



Composting

� Composting is an aerobic bacterial decomposition processto stabilize organic wastes and produce humus (compost).

� Composting can be carried out in a specially builtcomposter, such as an inclined rotating cylinder, fed on one

end with the raw materials, and the aerated productcollected at the other end. As the materials are slowlytumbled over a period of about one week, they are mixedand aerated. Because bacterial decomposition producesheat, temperatures in the insulated composter can easilyreach 55 degree Celsius. The immature compost is thenwindrowed for at least 12 weeks to allow the compostingprocess to complete, with occasional turning of thewindrow.

Air, Water and Sludge Pollution- Control and Treatment

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