Pollution

It is an undesirable change in the physical, chemical and biological characteristics of air, water, land and soil.

(i) Pollutants are agents that cause undesirable change in the environment.

(ii) The Government of India has passed the Environment Protection Act, 1986 to protect and improve the quality of our environment (air, water and soil).

Air Pollution

It is the presence of toxic chemicals or compounds (including those of biological origin) in the air, at levels that pose a health risk. Air pollutants cause injury to all living organisms. They deleteriously affect respiratory system of humans and animals.

Causes of Air Pollution

Smokestacks from thermal power plants, forest fires, volcanic eruptions, etc.
Garbage decomposition also releases unwanted gases in the air.
Excessive use of fossil fuels by automobiles and industries release particulate and air pollutants.
Use of leaded petrol.

Types of Air Pollutant

Air pollutants can be divided into following types: -

Suspended Particulates Matter (SMP): -Metallic particles, dust Particles, soot, aerosol and smoke
Gaseous Pollutants: - Carbon monoxide, nitrogen dioxide, hydrogen sulphide and Sulphur dioxide.

Harmful Effects of Air Pollution on Health

These effects depend on the concentration of pollutants, duration of exposure and the organism.

Carbon monoxide (CO) causes giddiness, headache, cardiovascular malfunction, asphyxia, etc.
Hydrogen supplied (H2S) causes nausea, eye and throat irritation.
Sulphur dioxide (S02) causes respiratory tract diseases like asthma, bronchitis, cancer, emphysema, etc.
Fine particulates released by industries cause breathing and respiratory problems, inflammation and damage to the lungs.
In plants reduced growth and yield and premature death occurs.

Control Methods of Air Pollution

Air pollutants must be separated/filtered out from the exhaust before releasing into the ionosphere. For this several methods are used for controlling air pollution in India. These include: -

(i)Electrostatic Precipitator (ESP) is an electrical device to re1nove particulate matter present in the exhaust of thermal power plant. About 99% of particulate matter can be removed by ESP.

It has electrode wires and a stage of collecting plates.
Electrode wires are provided with an electric current of several thousand volts, which produces a corona that releases electrons.
These electrons get attach to the dust particles and give them negative charge within a small fraction of a second.
Collecting plates are grounded which attract the charged dust particles.
The velocity of air between the plates must be low enough to allow the dust to fall.

Figure 16.1 Electrostatic precipitotor

(ii) Scrubber is used to remove harmful gases like Sulphur dioxide from industrial exhaust.

Figure 16.2 Scrubber

The exhaust is passed through a spray of water or lime.
Water dissolves the gases and lime reacts with sulphur dioxide to form a precipitate of calcium sulphate and sulphide.
Drawbacks Recently, the dangers of particulate matter (very small particles that cannot be removed by these precipitators) has been found.
According to Central Pollution Control Board (CPCB), particulate size 2.5 micrometers or less in diameter (PM 2.5) if inhaled can cause breathing and respiratory problems, irritation, damage to lungs and premature deaths.

(iii)Catalytic convertors are fitted into automobiles for reducing emission of poisonous gases like NO2 and CO.

They are made up expensive metals like platinum, palladium and rhodium as catalysts.
When exhaust passes through the catalytic convertor, nitric oxide splits into nitrogen and oxygen, carbon monoxide is oxidized into carbon dioxide and unburnt hydrocarbons get burnt completely into CO2 and H20.
However, only unleaded petrol should be used in motor vehicles fitted with catalytic convertor as leaded petrol inactivates the catalyst.

A case Study- Control of Air Pollution in Delhi: -

Delhi leads the country in high level of air pollution due to large numbers of vehicles. In 1990s, Delhi ranked fourth among the 41 most ITI polluted cities of the world.
As per directives of Supreme Court, all buses of Delhi were converted to run on Compressed Natural Gas (CNG) by the end of 2002.
Benefits of CNG over diesel/petrol, burns most efficiently and leaves no unburnt remains.
Cheaper than diesel/petrol. Cannot be siphoned off by thieves and adulterated like petrol or diesel.

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The problem with switching over to CNG is the difficulty of laying down pipelines to deliver CNG through distribution points and ensuring uninterrupted supply.
0ther ways to reduce vehicular pollution Phasing out of old vehicles. Use of unleaded petrol.
Use of low-Sulphur petrol and diesel. Application of stringent pollution level norms for vehicles.
Use of catalytic convertors in vehicles.

Auto Fuel Policy of Government of India

Euro II norm s stipulate that Sulphur be controlled at 350 parts per million (ppm) in diesel and 150 ppm in petrol. Aromatic hydrocarbons are to be contained at 42% of the concerned fuel.
According to it, all automobiles have to meet the Euro III emission specification in eleven Indian cities by 1 April 2005.
The same eleven cities have to meet the Euro IV norms by I April 2010.
The rest of the country will have Euro III emission norm compliant automobiles and fuels by 2010.
By all these efforts, a substantial fall in CO2 and S02 level has been found in Delhi between 1997 and 2005.

Note: -

The entire nation is next targeted to be covered under BS IV (Bharat norms under European Regulation) by 1 April 2017.
The BS IV norms were introduced in 13 cities.
apart from the NCR from April 2010 onwards.
BS IV norms stipulates the permissible limit of Sulphur to be only 50 ppm compared with 350 ppm under BS 111. Also, the limit of hydrocarbons, N02 and particulate matter emissions have been lowered further.

Noise Pollution: -

It is undesirable high level of sound. In India, the Air (Prevention and Control of Pollution) Act came into force in 1881 but was amended in l 987 to include noise as an air pollutant.

Noise Measurement

Sound is expressed in decibels (dB). A sound of over 115 dB is very harmful for ears. Prolonged exposure to noise level above 80 dB leads to permanent hearing loss.

Causes: -

(i) Use of loudspeakers and music systems.

(ii) Jet planes and rockets during take-off (150 dB).

(iii) Industrial, factory noises, etc.

Harmful Effects: -

These include sleeplessness, stress, increased heartbeat, breathing problems, damage to ear drums and impaired hearing ability.

Control Methods: -

Noise pollution can be controlled by adopting following measures: -

(i) By using sound absorbent materials during constructions or by muffing noise in industrial units.

(ii) Delimitation of horn free zones around hospitals and schools.

(iii) Strict laws for permissible sound levels of crackers and loudspeakers sound be followed.

(iv)Loudspeakers should be played up to a fixed time only.

Water Pollution

It is any undesirable change in the physical, chemical or biological properties of water that may affect the human beings and aquatic species. The Government of India has passed the Water (Prevention and Control of Pollution) Act. 1974 to safeguard our water resources.

Sources of Water Pollution

(i) Domestic sewage includes everything that comes from residential area to common public sewage. A mere 0.1% impurities make domestic sewage unfit for human use.

It mainly contains biodegradable organic wastes, which are readily decomposed with the help of decomposers.
Other components of domestic sewage are suspended solids, e.g. sand, slot and clay.
Colloidal materials, e.g., faecal matter. bacteria, cloth and paper fibers.
Dissolved materials, e.g., nutrients (nittrate, ammonia, phosphate, sodium and calcium)
During sewage treatment, it is easy to remove solid, but very difficult to remove dissolved salts such as nitrates, phosphates and toxic metal ions from wastewater.

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(ii) Industrial wastes arc released by petroleum, paper manufacturing, metal extraction and processing units. It contains heavy metals like mercury and many organic compounds.

(iii) Heated (Thermal) wastewater flowing out of electricity genera ting units, e.g., thermal power plants.

Harmful Effects of Water Pollution

(i) Death of biodiversity Thermal wastewater, eliminates or reduces the number of organisms sensitive to high temperature and may enhance the growth of' plants and fish in extremely cold area s, but only after causing damage to the indigenous flora and fauna.

(ii) Biological magnification can be defined as an increase in concentration of toxicant is at successive trophic levels in aquatic food chain. Mercury and DDT arc well-known cause of biological magnification

Toxic material cannot be metabolized or excreted. Therefore, they get accumulated in an organism and pass on to higher trophic levels.
DDT accumulates in birds and disturbs calcium metabolism, which results in thinning of eggshell and their premature breaking. this results in decline of bird population.

(iii) Eutrophication can be defined as the natural ageing of a lake by nutrient enrichment of its water.

Process of Eutrophication

Water in young lake is cold and clear to support little life.
Gradually with time, it gets enriched with nutrients such as nitrogen and phosphorus by streams draining in it.
Due to this, aqua tic life (plants and animals) flourish in lake.
Organic deposit at the bottom of the lake and with time, water becomes warmer. This warm water support even more growth of plants. Eventually, floating plants develop in the lake, finally converting it into land. Natural
Eutrophication generally takes 1000 of years or more. Bur, human activities have accelerated this natural process and as a result many lakes are already extinct. It is caused due to dumping of nutrient rich and thermal waste into lakes. This is known as Accelerated or cultural eutrophication.

(iv) Biochemical Oxygen Demand (BOD) is the amount of oxygen required for microbial breakdown of biodegradable organic matter. It is higher in polluted water and lesser in clean water.

(v) Algal bloom is excessive growth of planktonic (free-floating) algae in aquatic bodies.

In domestic sewage, nutrients like nitrogen and phosphorus Favours the growth of algal bloom.
It causes fish mortality and deterioration of water quality. Example, Excessive growth of water hyacinth (Eichhornia crassipes). It is the most problematic aquatic weed, also called Terror of Bengal.
It grows abundantly in eutrophic water bodies and imbalances water ecosystem.

A Case Study- Integrated Wastewater Managemet: -

(i) Wastewater including sewage can be treated in an integrated manner by utilizing a mix of artificial and natural processes.

One such example is town of Arcata situated along. Northern coast of California. An integrated wastewater treatment process was developed with the treatment process was developed with the help of biologists from Humboldt State University in this town. The cleaning occurs in two steps: -
(a) The heavy conventional sedimentation, filtration and chlorine treatment is carried out the treated water still contains loss of heavy metals and other toxic pollution.
(b) In second step, algae, fungi and through which this water flows. These life forms neutralize, absorbed and assimilate the pollutants and purify the water naturally, the marshes also constitute a sanctuary, with a high level of biodiversity.
A citizen's group called Friends of the Arcata Marsh (FOAM) are responsible for the upkeep and safeguarding of this project.

(ii) Ecosan' toilets have been developed in areas of Kerala and Sri Lanka for ecological sanitation. The advantages of ecological sanitation are:

A practical, hygienic and efficient method of disposal.
Cost effective approach.
Human excreta can be recycled into natural fertiliser to red uce need of chemical fertiliser.

Solid Wastes

Solid wastes refer to everything that goes out in trash. The various types are: -

Municipal solid wastes contain wastes from homes, offices, schools, hospitals, etc, that are collected and disposed by the municipality, which generally consists of paper, leather, textile, rubber and glass, metals and plastic, elc
Industrial wastes contain wastes like scraps, fly ash, etc. generated by industries.
Hospital wastes contain disinfectants and other harmful chemicals generated by hospitals.
Electronic wastes (e-wests) are the damaged electronic goods and irreparable computers.
All wastes can be categorized into Three types:

Biodegradable
Recyclable
Non-biodegradable

Methods of Solid Waste Disposal

There are various methods of solid waste disposal. Some of them are: -

Open burning involves burning of municipal waste in open dumps, but the unburnt piled waste serves as breeding ground for rats and flies.
Sanitary landfills are areas where wastes are dumped in a depression or trench a ft er compaction and covered with dirt. The problem is seepage of chemicals from these landfills can pollute underground water resources.
Rag-pickers and kabadiwalas collect and separate out wastes int o reusable or recyclable categories.
Natural breakdown involves dumping biodegradable materials into deep pits for natural degradation.
Incineration is a method of hospital waste disposal. It involves burning of waste materials to ash.

e-Wastes

e-wastes are buried in landfills or incinerated.
About half of thee-wastes generated in the developed world are exported to developing countries, mainly to China, India and Pakistan, where metals like copper, iron, silicon, nickel and gold are recovered during recycling process.
Developed countries have specifically built facilities for recycling of e-wastes.
Recycling is the only solution available for treating e-waste, but caution should be taken to carry out this process in environment friendly ways.

A Case Study - Remedy for Plastic Waste

A plastic sack manufacturer, Ahmad Khan from Bengaluru realized that plastic waste was a real problem.
His company developed a fine powder, called polyblend of recycled modified plastic.
This mixture is mixed with the bitumen and used to lay roads.

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It enhanced the bitumen's water repellant properties and helped to increase road life by a factor of three.
Using this technique, by the year 2002, more than 40 kms of road in Bengaluru has already been laid.

Soil Pollution

It is any undesirable change in soil profile affecting its productivity. Green revolution led to manifold increase in crop production by the use of inorganic fertilizers and pesticides. Pesticides, herbicides, fungicides, etc., are being increasingly used afterwards which resulted in soil pollution.

Causes of Soil Pollution

(i) Chemical seepage from industries.

(ii) Excessive use of inorganic fertilizers, pesticides, etc.

Harmful Effects of Soil Pollution

(i) Non-target organisms are killed in the soil, due to pesticides.

(ii) Soil becomes unfertile.

(iii) Pesticides can result in biomagnification, as well as eutrophication.

Control Methods

(i) Strict ways should be adopted by the industries and other sources for waste disposal.

(ii) Use of organic farming It is a cyclic, zero-waste method, where waste products from one process are cycled in as nutrients for other processes, allowing maximum utilization of resources and increasing the efficiency of production.

A Case Study- Organic Farming

Ramesh Chandra Dagar, a farmer in Sonipat (Haryana) included beekeeping, dairy management, water harvesting, composting and agriculture in a chain of processes.
This chain supports each other and allow an extremely economical and sustainable venture.
Chemical fertilizers are not required as cattle excreta is used as manure.
Crop waste is used for making compost, which is u sed as natural fertilizer or to generate natural gas, which is u sed for satisfying energy needs of farm.
To spread information and help the practice of integrated organic farming. Dagar has created the Haryana Kisan Welfare club, with current membership of 5000 farmers.

Radioactive Wastes

The waste produced from nuclear fission of heavy atoms such as uranium, thorium, etc., for the production of power is radioactive waste. Radiation that is given off by nuclear waste is extremely damaging to biological organisms.

Nuclear energy was initially considered as a non-polluting way for generating electricity initially.
Later, two serious inherent problems were realized. The first is accidental leakages as occurred in the Three Mile Island and Chernobyl, which proved that radioactive wastes are most potent pollutants. The second is safe disposal of radioactive wastes.

Harmful Effects

(i) Radiations cause mutation at a very high rate.

(ii) At high doses, nuclear radiations are lethal.

(iii) At low doses, these cause disorders and diseases like cancer.

Disposal method of Radioactive wastes

It involves pretreatment and storage in shielded containers and then burying at about 500 m deep below the earth's surface. However, this method of disposal is getting opposition from public.

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