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EEES CLASS NOTES

Introduction to energy scenario

Energy is an important input for development. It aims at human welfare covering

household, agriculture, transport and industrial complexes like other natural resources.

Conventional sources of energy coal, petroleum, natural gas are the common sources.

These account for about 89.4% of the world‘s production of commercial energy, hydro

electric and nuclear power accounting for only 10.6%, oil – 39.5%, Natural gas – 19.6%,

Coal – 30.3%, Hydro-electric – 6.7%, Nuclear – 3.9%.

More than 80% of the total world consumption of energy is by developed world

which account for only 30% of the world production. On the other hand, 20% of the

energy is consumed by 70% of the world population in developing and social countries.

In India commercial energy constitutes 38.5% and 31.7% in industrial and

transport sectors respectively. Oil constitutes 71.2% in household sector, 61.8% in

agriculture and 47.6% electricity that are important.

Conventional and non-conventional resources of energy

i) Conventional energy sources: As most of the fuel wood is consumed for

domestic purposes, mainly in rural areas, very little of it is available to

industrial sector. Thermal coal, already in use in industries becomes a highly

priced source. It was then supplemented by mineral oil. Likewise the use of

hydroelectricity (water energy) becomes dearer, the areas where running water

and needed technology is not readily available.

After world war–II yet another source of energy, nuclear power was

developed. All these sources of energy are known as conventional sources of

energy, among which coal still occupies a central position.

ii) Non Conventional energy sources: Efforts were made to develop new sources

of energy. These are called non-conventional sources of energy and include

urban waste, agriculture waste, energy plantations, animal and human wastes,

solar energy, wind-energy, tidal energy, geothermal energy, ocean, biogas etc.

These are pollution-free, environmentally clean and socially relevant.

Renewable energy

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Renewable energy is energy which comes from natural resources such

as sunlight, wind, rain, tides, and geothermal heat, which are renewable (naturally

replenished). In 2008, about 19% of global final energy consumption came from

renewables, with 13% coming from traditional biomass, which is mainly used for heating,

and 3.2% from hydroelectricity. New renewables (small hydro, modern biomass, wind,

solar, geothermal, and bio-fuels) accounted for another 2.7% and are growing very

rapidly.The share of renewables in electricity generation is around 18%, with 15% of

global electricity coming from hydroelectricity and 3% from new renewables.

Resource energy or non-renewable energy is the energy taken from a source which is

depleted by extraction. It rely on consumable materials. Non-renewable energy sources

come from the earth and appear as either solids, liquids, and gases.

Energy sources that are almost always classified as non-renewable:

Fossil fuels

Coal

Petroleum

Natural gas

Fossil fuel

Fossil fuels are fuels formed by natural resources such as anaerobic

decomposition of buried dead organisms. The age of the organisms and their

resulting fossil fuels is typically millions of years and sometimes exceeds 650

million years. The fossil fuels, which contain high percentages of carbon,

include coal, petroleum, and natural gas. Fossil fuels range from volatile

materials with low carbon:hydrogen ratios like methane, to liquid petroleum to

nonvolatile materials composed of almost pure carbon, like anthracite coal.

Methane can be found in hydrocarbon fields, alone associated with oil, or in the

form of methane clathrates. It is generally accepted that they formed from the

fossilized remains of dead plants and animals by exposure to heat and pressure in

the Earth's crust over millions of years. This biogenic theory was first introduced

by Georg Agricolain 1556 and later by Mikhail Lomonosov in the 18th century.

Coal

Coal is a combustible black or brownish-black sedimentary rock normally

occurring in rock strata in layers or veins called coal beds or coal seams. The harder

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forms, such as anthracite coal, can be regarded as metamorphic rock because of later

exposure to elevated temperature and pressure. Coal is composed primarily

of carbon along with variable quantities of other elements, chiefly sulfur,

hydrogen, oxygen and nitrogen.

Coal begins as layers of plant matter accumulate at the bottom of a body of water.

For the process to continue the plant matter must be protected from biodegradation and

oxidization, usually by mud or acidic water. The wide shallow seas of the

Carboniferous period provided such conditions. This trapped atmospheric carbon in the

ground in immense peat bogs that eventually were covered over and deeply buried by

sediments under which they metamorphosed into coal. Over time, the chemical

and physical properties of the plant remains (believed to mainly have been fern-like

species antedating more modern plant and tree species) were changed by geological

action to create a solid material.

Petroleum

Petroleum {L. petroleum, from Greek: petra (rock)+ Latin: oleum (oil)} or crude

oil is a naturally occurring, flammable liquid consisting of a complex mixture

of hydrocarbons of various molecular weights and other liquid organic compounds, that

are found in geologic formations beneath the Earth's surface. Petroleum is recovered

mostly through oil drilling. It is refined and separated, most easily by boiling point, into a

large number of consumer products, from gasoline and kerosene to asphalt and chemical

reagents used to make plastics and pharmaceuticals.

The term petroleum was first used in the treatise De Natura Fossilium, published

in 1546 by the German mineralogist Georg Bauer, also known as Georgius Agricola. In

the 19th Century, the term petroleum was frequently used to refer to mineral oils

produced by distillation from mined organic solids such as cannel coal (and later oil

shale) and refined oils produced from them; in the United Kingdom storage (and later

transport) of these oils were regulated by a series of Petroleum Acts, from the Petroleum

Act 1862 c. 66 onward.

Natural gas

Natural gas is a gas consisting primarily of methane, typically with 0-20% higher

hydrocarbons (primarily ethane). It is found associated with other fossil fuels, in coal

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beds, as methane clathrates, and is an important fuel source and a major feedstock for

fertilizers.

Most natural gas is created by two mechanisms: biogenic and thermogenic.

Biogenic gas is created by methanogenic organisms in marshes, bogs, landfills, and

shallow sediments. Deeper in the earth, at greater temperature and pressure, thermogenic

gas is created from buried organic material.

Before natural gas can be used as a fuel, it must undergo processing to remove

almost all materials other than methane. The by-products of that processing include

ethane, propane, butanes, pentanes, and higher molecular weight hydrocarbons,

elemental sulfur, carbon dioxide, water vapour and sometimes helium and nitrogen.

Indian Scenario

India is one of the countries where the present level of energy consumption, by

world standards, is very low. The estimate of annual energy consumption in India is about

330 Million Tones Oil Equivalent (MTOE) for the year 2004. Accordingly, the per capita

consumption of energy is about 305 Kilogram Oil Equivalent (KGOE). As compared to

this, the energy consumption in some of the other countries is of the order of over 4050

for Japan, over 4275 for South Korea, about 1200 for China, about 7850 for USA, about

4670 for OECD countries and the world average is about 1690.

In so far as electricity consumption is concerned, India has reached a level of

about 600-kilowatt hour (kwh) per head per year. The comparable figures for Japan are

about 7,800, for South Korea about 7,000, for China about 1380, for USA about 13,000,

for OECD countries about 8050 and world average are about 2430. Thus, both in terms of

per capita energy consumption and in terms of per capita electricity consumption, India is

far behind many countries, and as a matter of fact, behind even the world average.

Therefore, to improve the standards of living of Indian people and to let them enjoy the

benefit of economic development, it is imperative that both energy consumption and

electricity consumption level is enhanced. India is targeting a growth rate of 9 – 10%,

having already reached a level of almost 8%. To sustain the double-digit growth rate for

next 10-15 years, it would be essential that the level of energy availability and

consumption, and electricity consumption in particular, is enhanced substantially.

In the profile of energy sources in India, coal has a dominant position. Coal

constitutes about 51% of India‘s primary energy resources followed by Oil (36%),

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Natural Gas (9%), Nuclear (2%) and Hydro (2%). To address the issue concerning energy

consumption, and more particularly, the need for enhancing the energy supply, India has

accorded appropriate priority to both - supply side management and demand side

management.

Non Conventional Energy Sources

Indian Government has accorded very high priority to develop and expand

installed capacity base through non-conventional sources of electricity generation. There

is a separate Ministry in the Government of India to exclusively focus on this important

area of power generation. National Electricity Policy notified in 2005 in pursuance of the

Electricity Act, 2003, prescribes that State Electricity Regulatory Commissions should

prescribe a proportion of power which should be produced and supplied to the grid

through the non-conventional sources. Some of the Regulatory Commissions have come

out with specific policy guidelines with a different approach on tariff for these plants in

order to encourage these technologies and plants. National Electricity Tariff Policy

mandates that State Commissions should fix such minimum percentage latest by April,

2006. India has very high potential for these capacities:

It may be seen from the above that India has achieved substantial success on wind turbine

based power generation. Ministry of Non-conventional Energy Sources (MNES) has set a

target of achieving at least 10,000 MW capacity through various non-conventional

sources, by the year 2012.

Conventional Sources of Electricity Generation

Fossil fuel based thermal power, hydro-electric, and nuclear constitute the

conventional sources of power. Non-conventional sources are less than 5% of total

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installed capacity in India. The present installed capacity (as in March 2006) is about

1,25,000 MW, consisting of coal based plants (56%), gas based plants (10%), hydro-

electric (26%), nuclear (3%) non-conventional (5%).

Indian Power Sector was opened up for private power generation in 1991. In

terms of ownership structure, the profile consists of Central Government owned

companies (32%), State Government owned companies/Electricity Boards (57%) and

Private Sector (11%). 100% FDI is permitted in all segments of electricity industry – viz.

Generation, Transmission, Distribution, Trading.

In the last three years far-reaching structural changes have been introduced in the

Indian Electricity Sector. Electricity Act 2003 is an historic legislative initiative with

powerful potential to transform the power sector industry and market structure.

Most important features of the Electricity Act 2003 are as follows:

1. The Act creates a liberal and transparent framework for power development

2. It facilitates investment by creating competitive environment and reforming

distribution segment of power industry.

3. Entry Barriers have been removed/reduced in following areas:

• Delicensed generation.

• Freedom to captive generation including group captive

• Recognizing trading as an independent activity

• Open access in transmission facilitating multi buyer and seller model.

4. Open access to consumers above 1 MW within five years commencing from 27th

January, 2004 (date of enforcement of amendment to Electricity Act) Regulators

have been mandated to ensure this.

5. Multiple licenses in distribution in the same area of supply so that competition

could yield better services to consumers.

6. Regulatory Commissions – to develop market and to fix tariff.

National Grid

The energy potential in the country is concentrated in certain pockets. Coal

reserves are located in a few states and similarly huge hydro-electric potential is located

in a few states. This poses a challenge to embark upon massive inter-regional

transmission capacity.

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Augmentation of National Grid

1. Intra-regional expansion of transmission capacity is linked to generation projects.

2. Inter-regional connectivity has been planned with hybrid systems, consisting of

HVDC, Ultra High Voltage AC (765 KV) & Extra High Voltage AC (400 KV)

lines.

3. Present Inter-regional transfer capacity is 9,500 MW, being enhanced to 17,000

MW by 2007.

4. 37,000 MW by 2012.

Table 1.1 : Projected Capacity Addition for 2007-12 (XI Plan)

May be revised to 67,000 MW, depending on the availability of Gas/LNG in

required quantities and right prices.

1. In addition, 5000 MW through Non-conventional Energy Sources.

2. Captive capacity not included.

Clean Development Mechanism

1. India is emerging as one of the largest potential source of Carbon Emission

Reduction (CER)

2. Designated National Authority is fully functional

3. Focus areas in Energy Sector:

R&M of old plants

Conversion of LT to HT lines

Supercritical Thermal Power Projects

Hydro projects

Distribution Sector Reform

The Government of India‘s Accelerated Power Development and Reform

Programme (APDRP) being implemented through the X Plan (2002-07) aims at

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comprehensive reform of electricity distribution in urban/industrial centres. Revamping,

augmenting and modernizing the distribution network and system for improved reliability

of power supply, reducing technical and commercial losses, and improving financial

health of distribution utilities are the main objectives of the scheme.

Utility and Waste management of thermal and Hydraulic energy

Thermal power plant is very much suitable for base load. They use coal,

petroleum and natural gas to produce the electricity. These sources are of mineral origin

and also called fossil fuels. They are exhaustible and polluting. Electricity, is the most

convenient and versatile form of energy. This is great demand in industry, agriculture,

transport and domestic sectors. Both big and small thermal power stations are scattered all

over the country. Electricity produced by them is fed into regional grids. It is proposed to

have a single national. The grids receive electricity produced from all the four major

sources - coal, oil, water and nuclear.

Hydro – Power

Fig. 1.1 (A) : Hydro Electric Power Station

Water-energy is most conventional renewable energy source and obtained from

water flow, water falling from a height. Hilly and highland areas are suitable for this

purpose, where there is continuous flow of water in large amounts falling from high

slopes.

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Fig. 1.1 (B) : Hydro Electric Power Station

It is clean, non-polluting source of energy. It can be transmitted to long distance

though wires and cables. Hydro-electric power generation is expected to upset the

ecological balance existing on earth. Hydro projects are responsible for catchments

degradation and soil erosion.

Solar Energy

Energy produced and radiate by sun is known as solar energy. This solar energy can be

converted directly or indirectly into other forms of energy such as heat and electricity.

Fig. 1.2 : Solar Pond Electric Power Plant

India receives 5000 Trillion KW/hr of sun shine in an year. India receives

abundant sunshine with about 1648-2108 KWhr/m2/yr with nearly 250-300 days of useful

sunshine in a year. The daily solar energy incidence is between 4 to 7 KWhr/m2.

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Energy radiated by the sun as electromagnetic waves (Wavelength 0.2 to 0.4 um).

Due to absorption and scattering in the atmosphere the maximum flux density is 1

KW/sq.m. 45% energy in the form of visible rays and 44% as infra-red radiation.

The enormous solar energy resource may be converted into other forms of energy

through thermal photovoltaic conversion routes. The solar thermal route uses radiation in

the form of heat in turn may be converted to mechanical electrical or chemical energy.

Application of solar energy

a) Solar Water heating.

b) Solar Heating of Building.

c) Solar – Distillation

d) Solar Furnaces

e) Solar Cooking

f) Solar Electric Power Generation (Photovoltaic System)

g) Solar Thermal Power Production.

h) Production of Power through Solar Ponds.

i) Solar Green Houses.

Environmental Implications

1. The sites to be selected as such that it should not reduce the forest cover.

2. Cadmium used in fabricating thin film solar cells, is both poisonous and a possible

carcinogen since only small quantities of cadmium are released from discarded

PV panels, the danger involved are not so serious.

3. Carbon dioxide produced while forming silicon from silica may increase the

atmospheric temperature causing green house effect.

4. Silicon dust is also an important occupational hazard.

Wind – Energy

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Fig. 1.3 (A) : Wind Power Direct Feed to Main Power line

Wind result from air in motion due to pressure gradient. Wind is basically caused

by the solar energy irradiating the earth. This is why wind utilization is considered a part

of solar technology.

Fig. 1.3 (B) : Wind Power Direct Feed to Main Power line

Energy of wind can be economically used for the generation of electrical energy.

Winds are caused from two main factors:

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1) Heating and cooling of the atmosphere which generates convection currents.

Heating is caused by the absorption of solar energy on the earth‘s surface and in

the atmosphere.

2) The rotation of the earth with respect to atmosphere and its motion around the

sun. Wind mill consists of wind turbine head, transmission and another supporting

structure. Wind energy conversion devices like wind turbines are used for

converting wind energy into mechanical energy.

Wind turbine consists basically of a few sails, vans and blades radiating from a

central axis when wind blows against the blades or vans they rotate about the axis. The

rotational motion is utilized to perform some useful work. By connecting the wind turbine

to an electric generator wind energy can be converted into electric energy.

Wind densities upto 10 KW/m3/day are available. More than 20,000 MW

electricity can be generated in India from wind.

Three factors which determine the output from a wind energy converter:

1. The wind speed.

2. The Cross-section of wind swept by rotor.

3. Conversion efficiency of the rotor transmission system and generator or pump.

A. Horizontal axis

B. Vertical axis

Biomass Based Energy

A) Petro-plants: There are attempts to identify potential plant species as sources of

liquid hydrocarbons, a substitute for liquid fuels. The hydrocarbons present in

such plants can be converted into petroleum hydrocarbons. The plants belong to

Euphorbiaceae, Apocynaceae, Sapotaceae and over 385 species have been

screened for hydrocarbon content. The Indian Institute of Petroleum, Dehradun

has done excellent work in this area, particularly on hydro-cracking of the crude

products. The products obtained from their latex processed biocrude were gases

naphtha, kerosene, gas oil, coke.

(B) Biomass Energy: A green plant converted into organic matter is biomass.

Biomass fermented is aerobically to produce biogases.

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Biogas is mixture of methane (CH4) (70%) and Carbon dioxide (CO2), Hydrogen

(H2), Nitrogen (N2). This is an environmentally clean technology.

At 40% methane content calorific value is 3214 Kcal/m3, at 50% is 4429 Kcal/m

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and at 55% is 4713 Kcal/m3. In biogas technology, the important factors are dung

excrement and availability, gas yield, calorific value and appliance efficiency.

In order to make best use of biogas technology, two things are relevant; restricted

use of water and better strains of methane generating bacteria. For normal microbial

activity 90% water content is needed, whereas in bovine-manure and human waste this

value is 80%.

Thus, we need additional water which may be critical to this technology in drier

areas of the country. There is need to be developed a dry process, that requires less of

water. Also there is need for methanogens, able to operate at temperatures lower than

20ºC, land area is also a factor. Biogas can also be generated from sludge obtained from

primary treatment of raw sewage and one such plant is in operation at Okhla, Delhi.

Besides gas, the rest matter from sewage is good manure. If biogas is used in boilers it

will reduce the air pollution.

Hydrogen Energy

An ecologically-friendly fuel which uses electrochemical cells or combusts in

internal engines to power vehicles and electric devices. It is also used in the propulsion of

spacecraft and can potentially be mass produced and commercialized for passenger

vehicles and aircraft.

In a flame of pure hydrogen gas, burning in air, the hydrogen (H2) reacts with

oxygen (O2) to form water (H2O) and heat. It does not produce other chemical by-

products, except for a small amount of nitrogen oxides. Hence a key feature of hydrogen

as a fuel is that it is relatively non-polluting (since water is not a pollutant). Pure

hydrogen does not occur naturally; it takes energy to manufacture it. Once manufactured

it is an energy carrier (i.e. a store for energy first generated by other means). The energy

is eventually delivered as heat when the hydrogen is burned. The heat in a hydrogen

flame is a radiant emission from the newly formed water molecules. The water molecules

are in an excited state on initial formation and then transition to a ground state, the

transition unleashing thermal radiation. When burning in air, the temperature is roughly

2000°C. Hydrogen fuel can provide motive power for cars, boats and aeroplanes, portable

fuel cell applications or stationary fuel cell applications, which can power an electric

motor.

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Fig. 1.4 : Hydrogen Energy

The current leading technology for producing hydrogen in large quantities is

steam reforming of methane gas (CH4). In addition, obtaining hydrogen from electrolysis

using renewable resources is being studied as a viable way to produce it domestically at a

low cost. This process involves the use of wind—or solar—generated electricity to power

an electrolyzer which would split water into hydrogen and oxygen. Other methods are

discussed in the Hydrogen Production article. Primarily because hydrogen fuel can be

environmentally friendly, there are advocates for its more widespread use. At present,

however, there is not a sufficient technical and economic infrastructure to support

widespread use. The proposed creation of such an infrastructure is referred to as the

hydrogen economy.

At the gas pressure at which hydrogen is typically stored, hydrogen requires four

times more storage volume than the volume of gasoline that produces the equivalent

energy, but the weight of this hydrogen is nearly one third that of the gasoline. With

regard to safety from unwanted explosions, hydrogen fuel in automotive vehicles is at

least as safe as gasoline. The advantages and disadvantages of hydrogen fuel compared to

its competitors are discussed at hydrogen economy.

Geothermal Energy

Geothermal energy is the heat energy deep within the earth. Huge amount of

(energy) heat are stored in the lower layer of the earth‘s crust. A temperature of 200ºC –

300ºC normally occur only at the depth of 10 km.

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US geological survey defines geothermal sources as ―all heat stored in the earth‘s

crust above 15ºC to a depth of 10 km.‖

Fig. 1.5 : Geothermal Reservoir

Sources:

1. Hydrothermal convenient systems

a) Vapour dominated or dry steam fields.

b) Liquid dominated system or wet steam field.

c) Hot water fields.

2. Geo-pressure resources.

3. Petro-thermal resources.

4. Magma resources.

5. Volcanoes.

Advantages of Geothermal Energy:

1. This energy is least polluting in comparison of other energy resources.

2. It is renewable source of energy.

3. It is cheaper source of energy.

Disadvantages:

1. Overall efficiency of power production is low.

2. Drilling operation is noisy.

3. Large areas are needed for exploitation of geothermal energy.

4. The steam and hot water coming out of earth may contain H2S, CO2, NH3, radon

etc. If these gases are vented into the air, may cause air pollution.

Hot molten rock called magma is present 25-40 km. depth in the core of the earth.

When the ground water finds its way into such a rock having molten in lava then it gets

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heated up by the heat of the rock and molten magma and comes to the surface of the earth

as steam and hot water 200ºC to 300ºC. This hot water or Steam is used to operate

turbines to generate electricity. A cold storage unit and 5 MW Power plant have been set

up a Manikaran (H.P.). At present nearly 350 geothermal springs have been located in the

country.

The International Geothermal Association (IGA) has reported that 10,715 MW of

geothermal power in 24 countries is online, which is expected to generate 67,246 GW of

electricity in 2010. This represents a 20% increase in online capacity since 2005.

Tidal Energy

The term tide is used for the periodic rise and fall of water of ocean and produced

by the attraction of moon and the sun. The tidal wave result by the gravitational pull on

ocean water by the moon and sun on ocean water and are effected by:

1. Spinning of earth around its axis.

2. Relative position of the earth, moon and sun.

About 70% of the tide producing force is due to the moon and 30% due to sun.

Thus the moon is the major factor in tide force.

Small tidal power plants have been constructed in China and North Asia. The

more important application of tidal power is an electricity generation.

Principle: The large scale up and down movement of sea water represents on unlimited

source of energy.

Advantage:

1. It is pollution free in nature.

2. These power plants do not demand large area of valuable land.

3. Peak power demand can be effectively met when it works in combination with

thermal or hydroelectric system.

Disadvantage:

1. This energy is variable in nature.

2. Sea water is corrosive and it was feared that the machinery may get corroded.

3. Construction in sea is difficult.

4. Cost is not favourable compared to other source of energy.

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A lot of energy is inherent in the twice a day rise and falls of the tides. Tidal

power is eternal and pollution free.

Fig. 1.6 : Tidal Power Generation

The incoming tide following through the turbines generated power. As the tide

shifts the blade may be reversed so that out flowing water continuously generates power.

A fluctuation of at least 6 meters in needed between the high tide and low tide.

Wave Energy:

Waves are formed by the wind action over the sea water surface, the incessant

motion of the sea surface in the form of wind waves. About 1.5% of the incoming

energy from sun is converted into wind energy. Part of this is transferred to sea surface

resulting in the generation of wave‘s breach.

Wave energy is concentrated through the interaction of the wind and the free

ocean surface.

A multipurpose wave regulator system in the form of a long barrier results in the

formation of a calm pool between the barrier and shore and this can be used as harbor.

Space of aquaculture space for coastal transport with light and faster crafts shore

protection against the erosion by sea. It is pollution free.

Nuclear Power Energy

This is of course a main source of energy. When the fossil fuel reserves are

depleting very fast. A small quantity of radioactive material can produce an enormous

amount of energy. For instance, one ton of Uranium235

would provide as much energy as

by 3 million tons of coal or 12 million barrels of oil. Besides electricity, atomic power is

also used as fuel for marine vessels, heat generation for generation for chemical and food

processing plants and for spacecrafts.

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For atomic energy, we need a nuclear reactor. The decay of fusion-able matter

produces enormous heat. This is used to make steam and channel through a turbine

connected to an electric generator. There are different types of nuclear reactor.

a) Light Water Reactor: Here we use ordinary water for cooling and moderation.

These are of two basic types (i) Boiling water reactor (ii) Pressurized Water

Reactor.

There are also high temperature gas cooled reactors (HIGCR) which are basically

of LWR types.

Fig. 1.7 : Nuclear Reactor Power Generator

b) Heavy Water Reactor: Here we use heavy water. The most popular one has been

Canadian Deuterium – Uranium (CANDU) reactor. Here the design is different

from that of LWR type. The fuel is arranged horizontally rather than vertically as

in LWR.

c) Liquid Metal Fast Breeder Reactor (LMFBR): Here we use liquid sodium as

coolant. Radioactive Pollutants released from nuclear power plants are chronically

hazardous. The dangerous radio waste cannot be buried in land without the risk of

polluting soil and underground water. Now the waste can be dumped into the river

without polluting aquatic life and human beings as well.

Electromagnetic Energy:

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It consists of visible light, Radio waves, heat, ultraviolet rays, X-rays.

Velocity of light C = ν λ

When λ = wave length

ν = number of peaks parting a fixed point in space

Unit time = wave frequency

Microwave 1 mm to 1 m. wave length, Radio wave length

1. Non-ionizing radiation, Microwave shorter than 10 cm are absorbed by the skin

that can be felt by heating of the surface.

2. 10 to 30 cm. can penetrate the epidermis and felt layer of the skin.

3. Longer than 30 cm. can penetrate deep tissues of dermis causing the skin hot.

Microwave Reflectors Disk, like reflections used to guide microwave beam.

Microwave oven, the cooking is done without converting heat by short electromagnetic

waves known as microwaves. That pan virtually under finished through many materials

such as glass, plastic papers and chin. When microwave comes in contact with food they

are absorbed their energy is converted into heat and they cook or heat the food from the

inside out.

Infrared energy waves have shorter wave length than microwaves. Recently the

hazardous level for microwave power density in United States installations, has been set

at 0.01 W/cm2 with a special limit of 0.01 W/cm

2 for eye exposure, around 10 cm

wavelength.

4. Russians have set lower exposure limits claiming that microwaves result in skin-

burns, fatigue, dizziness, headache, eye-injuries and cataracts, below heat injury

levels in man.

Radar Hazards

The radar hazards particularly in high-power installation, come mainly from the

acute heating effects these effects cause headache, fatigue, nervousness, and skin

diseases. In small power installations, radar hazards result in other severe diseases such as

disrupting artificial pacemakers for the heart (40,000 to 30,000,000 vibration / sec.)

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Effects of Radio Frequency Radiations

Recently an investigative agency of US congress reported that the current levels of

micro-wave and radio-frequency radiations in air pose severe hazards to human health.

Non-ionizing radiations of longer wave length cause a common thermal effect. These

radiations induce thermal agitation in molecules of the matter to produce heat.

A variety of non-thermal effects are potentially more dangerous as they pose acute

physiological effects. Non-thermal effects may be linked to the electric and magnetic

fields associated with the electromagnetic radiation. *

*[That the change in environmental magnetic field causes physiological effects is

corroborated by the discovery of I.O. Hays and N.O. Opdyke of the Lamont – Doherty

Geological Observatory, U.S.A. Who observed that reversal in the direction of magnetic

field of earth kills a large number of sea-animals.]

Waste Management of Different Power Plants

1. Thermal Plant: For every 1 MW of installed capacity about one acre of land is

needed for the disposal of ash generated. The material accumulating to a height of

8-10 meters converts fly ash into brick, cement. 85-90% of ash collecting in the

nearby ash pond. 10% is lost as fallout from the chimney.

2. Hydro Power Plant:

1. Big dam is dangerous to environments.

2. Catchments degradation.

3. Soil Erosion.

4. Deforestation.

3. Nuclear Power Plants: Radioactive waste generated by Nuclear Power Plants.

Low level radioactive liquid wastes

Radio active wastes in solution coming from power plants contaminate with

aquatic life. These radioactive elements are eventually conveyed to man from water

suppliers to food chain through soil, vegetation and live stock. Gaseous and particulate

radioactive waste. Radio – isotopes H3 – C14 , Kr85, I129. When these radio isotopes are

inhaled by man, they get concentrated in specific organs posing health effects. Fission

Fragments Radio nuclides Sr-90, I-131, Cs-137, Co-58. Induced radio nuclides P-32, Fe-

59, Zn-65 are released into the river, detaches, waste holding ponds, aquatic environment.

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Sr-90 concentrates in the aquatic food web. Become distributed to an altitude of about 10

km in the atmosphere and in the ocean to a depth of 13 km emanating radiation in the

environment. Heat relative Uranium produces enormous heat causing thermal pollution

and water bodies.

ECOSYSTEM

The Segments of Environment

Today the atmosphere is 78% nitrogen, 21% oxygen, and 0.93% argon. The

remaining 0.07% is made up of water vapor, carbon dioxide, ozone (a form of oxygen in

which three oxygen atoms bond chemically) and noble gases. The noble gases, including

argon and neon are noted for their lack of reactivity, meaning that they are extremely

resistant to chemical bonding with other elements.

Nitrogen also tends to be unreactive and the reason for its abundance in the

atmosphere lies in the fact that it never attempted to bond with other elements. Therefore,

nitrogen along with the noble gases, is simply "hanging in the air" (literally), left over

from the time when volcanoes hurled it into the atmosphere several billion years ago. By

contrast, oxygen (both in O2 and O3 or ozone molecules) and the other elements in air are

vital to life. Furthermore, oxygen is one of two elements, along with hydrogen, that goes

into the formation of water.

Overlap Between Subsystems

The present atmosphere would not exist without the biosphere. In order to put

oxygen into the air, there had to be plants, which take in carbon dioxide and release

oxygen in the process of photosynthesis. This resulted from an exceedingly complex

series of evolutionary developments from anaerobic or non-oxygen-breathing single-cell

life-forms to the appearance of algae. As plant life evolved, eventually it put more and

more oxygen into the atmosphere, until the air became breathable for animal life. Thus,

the atmosphere and biosphere have sustained one another.

Such overlap is typical and indeed inevitable where the open earth subsystems are

concerned and examples of this overlap are everywhere. For instance, plants (biosphere)

grow in the ground (geosphere), but to survive they absorb water (hydrosphere) and

carbon dioxide (atmosphere), nor are plants merely absorbing they also give back oxygen

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to the atmosphere, and by providing nutrition to animals, they contribute to the biosphere.

At the same time, the many components of the picture just described are involved in

complex biogeochemical cycles, which we look at later.

Water and the Hydrologic Cycle

As any backyard horticulturist knows, plants need good soil and water. In the

course of circulating throughout Earth, water makes its way through organisms in the

biosphere as well as reservoirs housed within the geosphere. It also circulates

continuously between the hydrosphere and the atmosphere. This movement known as the

hydrologic cycle, is driven by the twin processes of evaporation and transpiration.

The first of these processes, of course, is the means whereby liquid water is

converted into a gaseous state and transported to the atmosphere, while the second

process by which plants lose water through their stomata, small openings on the

undersides of leaves. Scientists usually speak of the two as a single phenomenon,

evapotranspiration. The atmosphere is just one of several "compartments" in which water

is stored within the larger environment. In fact, the atmosphere is the only major reservoir

of water on Earth that is not considered part of the hydrosphere.

Accounting for Earth's Water Supply

The water that most of us see or experience is only a very small portion of the

total. Actually, that statement should be qualified the oceans, parts of which most people

have seen, make up about 5.2% of Earth's total water supply. This may not sound like a

large portion, but in fact, the oceans are the second-largest water compartment on Earth.

If the oceans are such a small portion yet rank second in abundance, two things are true

there must be a lot of water on Earth, and most of it must be in one place.

In fact, the vast majority of water on Earth is stored in aquifers or underground

rock formations that hold 94.7% of the planet's water. Thus, deep groundwater and oceans

account for 99.9% of the total. Glaciers and other forms of permanent and semipermanent

ice take third place, with 0.065%. Another 0.03% appears in the form of shallow

groundwater, the source of most local water supplies. Next are the inland surface waters,

including such vast deposits as the Great Lakes and the Caspian Sea as well as the

Mississippi-Missouri, Amazon, and Nile river systems and many more, which

collectively make up just 0.003% of Earth's water.

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Atmospheric Moisture and Weather

That leaves only 0.002% which is the proportion taken up by moisture in the

atmosphere: clouds, mist and fog, as well as rain, sleet, snow, and hail. While it may seem

astounding that atmospheric moisture is such a small portion of the total, this fact says

more about the vast amounts of water on Earth than it does about the small amount in the

atmosphere. That "small" amount, after all, weighs 1.433 × 1013

tons (1.3 × 1013

tonnes)

or 28,659,540,000,000,000 pounds (12,999,967,344,000,002 kg).

This moisture in the atmosphere is the source of all weather, which clearly has an

effect on Earth's life-forms. (Weather is the condition of the atmosphere at a given time

and in a given place, whereas climate is the pattern of weather in a particular area over an

extended period of time.) On the one hand, rain is necessary to provide water to plants

and desert conditions can sustain only very specific life-forms; on the other hand,

storms, icy precipitation, and flooding can be deadly.

Our biosphere is the global sum of all ecosystems. It can also be called the zone

of life on Earth, a closed (apart from solar and cosmic radiation) and self-regulating

system. From the broadest biophysiological point of view, the biosphere is the

global ecological system integrating all living beings and their relationships, including

their interaction with the elements of the lithosphere, hydrosphere and atmosphere. The

biosphere is postulated to have evolved, beginning through a process

of biogenesis or biopoesis, at least some 3.5 billion years ago.

Atmosphere

Sources and sinks of most gaseous components are situated at the land or sea

surface, often by mediation of the biosphere and biological activity. This is true for the

case of carbon dioxide, oxygen and water, as well as for most anthropogenic gases and

greenhouse gases such as methane (CH4). However, water stands out as the only one

whose phase transition occurs in the temperature range of the (lower) atmosphere itself,

resulting in a sink by condensation within the air column and a residence time which is

short relative to the mixing and transport rates within the atmosphere.

The vertical distribution of mass in the atmosphere is basically controlled by

gravity and described by pz = po

exp (-z/H) where po

and pz are the pressures at

groundlevel and at altitude z, respectively; H is the scale height, about 8.4 km in the

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lower troposphere. The vertical temperature distribution shown in Fig. 2.1 controls the

vertical motions and also the partitioning of the atmosphere into discrete spheres.

In the lower atmosphere, the troposphere, a noticeable convection driven by the

heating of the Earth's surface by absorption of solar radiation results in mixing of the air

column. The thermally driven convection is dampened at a height of about 8 to 15 km,

where the temperature lapse rate is reduced, a region called the tropopause. At a height of

about 15 to 25 km, the atmosphere is further heated by absorption of UV radiation. The

resulting rise in temperature with height imparts stability to this part of the atmosphere,

the stratosphere, against vertical motions.

Fig. 2.1 : Structure of Atmosphere

The vertical distribution of the water vapour content in the atmosphere is also

primarily controlled by temperature. However, since both sources and sinks of water

reside in the troposphere and its lower boundary, and as the residence time of water is

short compared to the air mixing rates, there is a large variability in the amount of water

in the lower atmosphere in both space and time.

Horizontal motion in the atmosphere results primarily from the revolution of the

earth and proceeds along bands of latitude. However it is modified by the differential

pressure fields which respond to the unequal heating of the surface and the resultant

convective motions.

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Characteristic residence times in the atmosphere are given. These are turbulent

systems where molecular diffusion is not the dominant process, except in the upper

atmosphere, the exosphere, where the atmosphere is rarefied and at the lower boundary

near the ground surface where the turbulent motion is suppressed. This has far reaching

consequences regarding the source term of the gases above the sea.

Lithosphere

The word lithosphere is derived from the word sphere, combined with the Greek

word lithos, meaning rock. The lithosphere is the solid outer section of Earth, which

includes Earth's crust (the "skin" of rock on the outer layer of planet Earth), as well as the

underlying cool, dense, and rigid upper part of the upper mantle. The lithosphere extends

from the surface of Earth to a depth of about 44–62 mi (70–100 km). This relatively cool

and rigid section of Earth is believed to "float" on top of the warmer, non-rigid, and

partially melted material directly below.

Fig. 2.2 : Composition of Lithosphere

Earth is made up of several layers. The outermost layer is called Earth's crust. The

thickness of the crust varies. Under the oceans, the crust is only about 3–5 mi (5–10 km)

thick. Under the continents, however, the crust thickens to about 22 mi (35 km) and

reaches depths of up to 37 mi (60 km) under some mountain ranges. Beneath the crust is a

layer of rock material that is also solid, rigid and relatively cool, but is assumed to be

made up of denser material. This layer is called the upper part of the upper mantle, and

varies in depth from about 31–62 mi (50–100 km) below Earth's surface. The

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combination of the crust and this upper part of the upper mantle, which are both

comprised of relatively cool and rigid rock material is called the lithosphere.

Below the lithosphere, the temperature is believed to reach 1,832°F (1,000°C),

which is warm enough to allow rock material to flow if pressurized. Seismic evidence

suggests that there is also some molten material at this depth (perhaps about 10%). This

zone which lies directly below the lithosphere is called the asthenosphere, from the Greek

word asthenes, meaning weak. The lithosphere, including both the solid portion of the

upper mantle and Earth's crust, is carried "piggyback" on top of the weaker, less rigid

asthenosphere, which seems to be in continual motion. This motion creates stress in the

rigid rock layers above it, forcing the slabs or plates of the lithosphere to jostle against

each other, much like ice cubes floating in a bowl of swirling water. This motion of the

lithospheric plates is known as plate tectonics, and is responsible for many of the

movements seen on Earth's surface today including earthquakes, certain types of volcanic

activity, and continental drift.

Hydrosphere

A hydrosphere in physical geography describes the combined mass

of water found on, under, and over the surface of a planet.

The total mass of the Earth's hydrosphere is about 1.4 × 1018

tonnes, which is

about 0.023% of the Earth's total mass. About 20 × 1012

tonnes of this is in the Earth's

atmosphere (the volume of one tonne of water is approximately 1 cubic metre).

Approximately 75% of the Earth's surface, an area of some 361 million square kilometres

(139.5 million square miles), is covered by ocean. The average salinity of the Earth's

oceans is about 35 grams of salt per kilogram of sea water (3.5%)

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Fig. 2.3 : Hydrosphere

A thick hydrosphere is thought to exist around the Jovian moon Europa. The outer

layer of this hydrosphere is almost entirely ice, but current models predict that there is an

ocean up to 100 km in depth underneath the ice. This ocean remains in a liquid form

because of tidal flexing of the moon in its orbit around Jupiter. The volume of Europa's

hydrosphere is 3 × 1018

m3, 2.3 times that of Earth.

It has been suggested that the Jovian moon Ganymede and the Saturnine

moon Enceladus may also possess sub-surface oceans. The ice covering is expected to be

thicker on Jupiter's Ganymede than on Europa.

Hydrological cycle

Insulation, or energy (in the form of heat and light) from the sun, provides the

energy necessary to cause evaporation from all wet surfaces including oceans, rivers,

lakes, soil and the leaves of plants. Water vapor is further released as transpiration from

vegetation and from humans and other animals.

Aquifer draw-down or over-drafting and the pumping of fossil water increases the

total amount of water in the hydrosphere that is subject to

transpiration and evaporation thereby causing accretion in water vapour and cloud

cover which are the primary absorbers of infrared radiation in the Earth's atmosphere.

Adding water to the system has a forcing effect on the whole earth system, an accurate

estimate of which hydro-geological fact is yet to be quantified.

ECO-SYSTEM

An ecosystem consists of the biological community that occurs in some locale and

the physical and chemical factors that make up its non-living or abiotic environment.

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There are many examples of ecosystems -- a pond, a forest, an estuary, a grassland. The

boundaries are not fixed in any objective way, although sometimes they seem obvious, as

with the shoreline of a small pond. Usually the boundaries of an ecosystem are chosen for

practical reasons having to do with the goals of the particular study.

The study of ecosystems mainly consists of the study of certain processes that link

the living, or biotic, components to the non-living, or abiotic, components. Energy

transformations and biogeochemical cycling are the main processes that comprise the

field of ecosystem ecology. As we learned earlier, ecology generally is defined as the

interactions of organisms with one another and with the environment in which they occur.

We can study ecology at the level of the individual, the population, the community, and

the ecosystem.

Studies of individuals are concerned mostly about physiology, reproduction,

development or behavior, and studies of populations usually focus on the habitat and

resource needs of individual species, their group behaviors, population growth and what

limits their abundance or causes extinction. Studies of communities examine how

populations of many species interact with one another, such as predators and their prey, or

competitors that share common needs or resources.

Components of an Ecosystem

You are already familiar with the parts of an ecosystem. You have learned about

climate and soils from past lectures. From this course and from general knowledge, you

have a basic understanding of the diversity of plants and animals, and how plants and

animals and microbes obtain water, nutrients, and food. We can clarify the parts of an

ecosystem by listing them under the headings "abiotic" and "biotic".

ABIOTIC COMPONENTS BIOTIC COMPONENTS

Sunlight Primary producers

Temperature Herbivores

Precipitation Carnivores

Water or moisture Omnivores

Soil or water chemistry (e.g., P, NH4+) etc. Detritivores etc.

All of these vary over space/time

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By and large, this set of environmental factors is important almost everywhere, in

all ecosystems.

Usually, biological communities include the "functional groupings" shown above.

A functional group is a biological category composed of organisms that perform mostly

the same kind of function in the system; for example, all the photosynthetic plants or

primary producers form a functional group. Membership in the functional group does not

depend very much on who the actual players (species) happen to be, only on what

function they perform in the ecosystem.

Processes of Ecosystems

This figure with the plants, zebra, lion, and so forth illustrates the two main ideas

about how ecosystems function: ecosystems have energy flows and ecosystems cycle

materials. These two processes are linked, but they are not quite the same (see Figure 2.5)

Fig. 2.4 : Energy flows and material cycles.

Energy enters the biological system as light energy, or photons, is transformed

into chemical energy in organic molecules by cellular processes including photosynthesis

and respiration, and ultimately is converted to heat energy. This energy is dissipated,

meaning it is lost to the system as heat; once it is lost it cannot be recycled. Without the

continued input of solar energy, biological systems would quickly shut down. Thus the

earth is an open system with respect to energy.

During decomposition these materials are not destroyed or lost, so the earth is a

closed system with respect to elements (with the exception of a meteorite entering the

system now and then). The elements are cycled endlessly between their biotic and abiotic

states within ecosystems. Those elements whose supply tends to limit biological activity

are called nutrients.

The Transformation of Energy

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The transformations of energy in an ecosystem begin first with the input of energy

from the sun. Energy from the sun is captured by the process of photosynthesis. Carbon

dioxide is combined with hydrogen (derived from the splitting of water molecules) to

produce carbohydrates (CHO). Energy is stored in the high energy bonds of adenosine

triphosphate, or ATP.

The prophet Isaah said "all flesh is grass", earning him the title of first ecologist,

because virtually all energy available to organisms originates in plants. Because it is the

first step in the production of energy for living things, it is called primary production.

Herbivores obtain their energy by consuming plants or plant products, carnivores eat

herbivores, and detritivores consume the droppings and carcasses of us all.

Fig. 2.5 : Food Chain

A simple food chain, in which energy from the sun, captured by plant

photosynthesis, flows from trophic level to trophic level via the food chain. A trophic

level is composed of organisms that make a living in the same way, that is they are all

primary producers (plants), primary consumers (herbivores) or secondary consumers

(carnivores). Dead tissue and waste products are produced at all levels. Scavengers,

detritivores, and decomposers collectively account for the use of all such "waste" --

consumers of carcasses and fallen leaves may be other animals, such as crows and

beetles, but ultimately it is the microbes that finish the job of decomposition. Not

surprisingly, the amount of primary production varies a great deal from place to place,

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due to differences in the amount of solar radiation and the availability of nutrients and

water.

Usually when we think of food chains we visualize green plants, herbivores, and

so on. These are referred to as grazer food chains, because living plants are directly

consumed. In many circumstances the principal energy input is not green plants but dead

organic matter. These are called detritus food chains. Examples include the forest floor

or a woodland stream in a forested area, a salt marsh, and most obviously, the ocean floor

in very deep areas where all sunlight is extinguished 1000's of meters above. In

subsequent lectures we shall return to these important issues concerning energy flow.

Finally, although we have been talking about food chains, in reality the

organization of biological systems is much more complicated than can be represented by

a simple "chain". There are many food links and chains in an ecosystem, and we refer to

all of these linkages as a food web. Food webs can be very complicated, where it appears

that "everything is connected to everything else", and it is important to understand what

are the most important linkages in any particular food web.

Controls on Ecosystem Function

Now that we have learned something about how ecosystems are put together and

how materials and energy flow through ecosystems, we can better address the question of

"what controls ecosystem function"? There are two dominant theories of the control of

ecosystems. The first, called bottom-up control, states that it is the nutrient supply to the

primary producers that ultimately controls how ecosystems function. If the nutrient

supply is increased, the resulting increase in production of autotrophs is propagated

through the food web and all of the other trophic levels will respond to the increased

availability of food (energy and materials will cycle faster).

The second theory, called top-down control, states that predation and grazing by

higher trophic levels on lower trophic levels ultimately controls ecosystem function. For

example, if you have an increase in predators, that increase will result in fewer grazers,

and that decrease in grazers will result in turn in more primary producers because fewer

of them are being eaten by the grazers. Thus the control of population numbers and

overall productivity "cascades" from the top levels of the food chain down to the bottom

trophic levels.

So, which theory is correct? Well, as is often the case when there is a clear

dichotomy to choose from, the answer lies somewhere in the middle. There is evidence

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from many ecosystem studies that both controls are operating to some degree, but that

neither control is complete. For example, the "top-down" effect is often very strong at

trophic levels near to the top predators, but the control weakens as you move further

down the food chain. Similarly, the "bottom-up" effect of adding nutrients usually

stimulates primary production, but the stimulation of secondary production further up the

food chain is less strong or is absent.

Thus we find that both of these controls are operating in any system at any time

and we must understand the relative importance of each control in order to help us to

predict how an ecosystem will behave or change under different circumstances, such as in

the face of a changing climate.

Summary

Ecosystems are made up of abiotic (non-living, environmental) and biotic

components, and these basic components are important to nearly all types of

ecosystems. Ecosystem Ecology looks at energy transformations and

biogeochemical cycling within ecosystems.

Energy is continually input into an ecosystem in the form of light energy, and

some energy is lost with each transfer to a higher trophic level. Nutrients, on the

other hand, are recycled within an ecosystem, and their supply normally limits

biological activity. So, "energy flows, elements cycle".

Energy is moved through an ecosystem via a food web, which is made up of

interlocking food chains. Energy is first captured by photosynthesis (primary

production). The amount of primary production determines the amount of energy

available to higher trophic levels.

The study of how chemical elements cycle through an ecosystem is termed

biogeochemistry. A biogeochemical cycle can be expressed as a set of stores

(pools) and transfers, and can be studied using the concepts of "stoichiometry",

"mass balance", and "residence time".

Ecosystem function is controlled mainly by two processes, "top-down" and

"bottom-up" controls.

A biome is a major vegetation type extending over a large area. Biome

distributions are determined largely by temperature and precipitation patterns on

the Earth's surface.

Biogeochemical Cycles

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Water is not the only substance that circulates through the various earth systems.

So, too, do six other substances or, rather, chemical elements. These elements are

composed of a single type of atom, meaning that they cannot be broken down chemically

to make a simpler substance, as is the case with such compounds as water. The six

elements that cycle throughout Earth's systems are hydrogen, oxygen, carbon,

nitrogen, phosphorus, and sulfur. The two following lists provide rankings for their

abundance. The first shows their ranking and share in the entire known mass of the

planet, including the crust, living matter, the oceans and atmosphere. The second list

shows their relative abundance and ranking in the human body.

Abundance of Selected Elements on Earth (Ranking and Percentage):

1. Oxygen (49.2%)

9. Hydrogen (0.87%)

12. Phosphorus (0.11%)

14. Carbon (0.08%)

15. Sulfur (0.06%)

16. Nitrogen (0.03%)

Abundance of Selected Elements in the Human Body (Ranking and Percentage):

1. Oxygen (65%)

2. Carbon (18%)

3. Hydrogen (10%)

4. Nitrogen (3%)

6. Phosphorus (1%)

9. Sulfur (0.26%)

Note that the ranking of all these elements (with the exception of oxygen) is relatively

low in the total known elemental mass of Earth, whereas their relative abundance is

much, much higher within the human body. This is significant, given the fact that these

elements are all essential to the lives of organisms. All six of these elements take part in

biogeochemical cycles, a term used to refer to the changes that a particular element

undergoes as it passes back and forth through the various earth systems and particularly

between living and nonliving matter.

Nitrogen Cycle

The nitrogen cycle is the process by which nitrogen is converted between its

various chemical forms. This transformation can be carried out via both biological and

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non-biological processes. Important processes in the nitrogen cycle include fixation,

mineralization, nitrification, and denitrification. The majority of Earth's atmosphere

(approximately 78%) is nitrogen, making it the largest pool of nitrogen. However,

atmospheric nitrogen has limited availability for biological use, leading to a scarcity of

usable nitrogen in many types of ecosystems. The nitrogen cycle is of particular interest

to ecologists because nitrogen availability can affect the rate of key ecosystem processes,

including primary production and decomposition. Human activities such as fossil fuel

combustion, use of artificial nitrogen fertilizers, and release of nitrogen in waste water

have dramatically altered the global nitrogen cycle.

Fig. 2.6 : Nitrogen Cycle

The processes of the nitrogen cycle

Nitrogen is present in the environment in a wide variety of chemical forms

including organic nitrogen, ammonium (NH4+), nitrite (NO2

-), nitrate (NO3

-), and nitrogen

gas (N2). The organic nitrogen may be in the form of any living organism, or humus, and

in the intermediate products of organic matter decomposition or humus built up. The

processes of the nitrogen cycle transform nitrogen from one chemical form to another.

Many of the processes are carried out by microbes either to produce energy or to

accumulate nitrogen in the form needed for growth. The diagram above shows how these

processes fit together to form the nitrogen cycle.

Nitrogen fixation

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Atmospheric nitrogen must be processed, or "fixed" to be used by plants. Some

fixation occurs in lightning strikes, but most fixation is done by free-living or symbiotic

bacteria. These bacteria have the nitrogenase enzyme that combines gaseous nitrogen

with hydrogen to produce ammonia, which is then further converted by the bacteria to

make their own organic compounds. Most biological nitrogen fixation occurs by the

activity of Mo-nitrogenase, found in a wide variety of bacteria and some Archaea. Mo-

nitrogenase is a complex two component enzyme that contains multiple metal-containing

prosthetic groups. Some nitrogen fixing bacteria, such as Rhizobium, live in the root

nodules of legumes (such as peas or beans). Here they form a mutualistic relationship

with the plant, producing ammonia in exchange for carbohydrates. Nutrient-poor soils can

be planted with legumes to enrich them with nitrogen. A few other plants can form such

symbioses. Today, about 30% of the total fixed nitrogen is manufactured in ammonia

chemical plants.

Conversion of N2

The conversion of nitrogen (N2) from the atmosphere into a form readily available to

plants and hence to animals and humans is an important step in the nitrogen cycle, which

distributes the supply of this essential nutrient. There are four ways to convert N2

(atmospheric nitrogen gas) into more chemically reactive forms:

1. Biological fixation: some symbiotic bacteria (most often associated with

leguminous plants) and some free-living bacteria are able to fix nitrogen as

organic nitrogen. An example of mutualistic nitrogen fixing bacteria are the

Rhizobium bacteria, which live in legume root nodules. These species are

diazotrophs. An example of the free-living bacteria is Azotobacter.

2. Industrial N-fixation: Under great pressure, at a temperature of 600 C, and with

the use of an iron catalyst, atmospheric nitrogen and hydrogen (usually derived

from natural gas or petroleum) can be combined to form ammonia (NH3). In the

Haber-Bosch process, N2 is converted together with hydrogen gas (H2) into

ammonia (NH3), which is used to make fertilizer and explosives.

3. Combustion of fossil fuels: Automobile engines and thermal power plants, which

release various nitrogen oxides (NOx).

4. Other processes: In addition, the formation of NO from N2 and O2 due to photons

and especially lightning, can fix nitrogen.

Assimilation

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Plants get nitrogen from the soil, by absorption of their roots in the form of either

nitrate ions or ammonium ions. All nitrogen obtained by animals can be traced back to the

eating of plants at some stage of the food chain.

Plants can absorb nitrate or ammonium ions from the soil via their root hairs. If

nitrate is absorbed, it is first reduced to nitrite ions and then ammonium ions for

incorporation into amino acids, nucleic acids, and chlorophyll. In plants that have a

mutualistic relationship with rhizobia, some nitrogen is assimilated in the form of

ammonium ions directly from the nodules. Animals, fungi, and other heterotrophic

organisms obtain nitrogen as amino acids, nucleotides and other small organic molecules.

Ammonification

When a plant or animal dies, or an animal expels waste, the initial form of

nitrogen is organic. Bacteria, or fungi in some cases, convert the organic nitrogen within

the remains back into ammonium (NH4+), a process called ammonification or

mineralization. Enzymes Involved:

GS: Gln Synthetase (Cytosolic & PLastid)

GOGAT: Glu 2-oxoglutarate aminotransferase (Ferredoxin & NADH dependent)

GDH: Glu Dehydrogenase:

Minor Role in ammonium assimilation.

Important in amino acid catabolism.

Nitrification

The conversion of ammonium to nitrate is performed primarily by soil-living

bacteria and other nitrifying bacteria. The primary stage of nitrification, the oxidation of

ammonium (NH4+) is performed by bacteria such as the Nitrosomonas species, which

converts ammonia to nitrites (NO2-). Other bacterial species, such as the Nitrobacter, are

responsible for the oxidation of the nitrites into nitrates (NO3-). It is important for the

nitrites to be converted to nitrates because accumulated nitrites are toxic to plant life.

Due to their very high solubility, nitrates can enter groundwater. Elevated nitrate in

groundwater is a concern for drinking water use because nitrate can interfere with blood-

oxygen levels in infants and cause methemoglobinemia or blue-baby syndrome. Where

groundwater recharges stream flow, nitrate-enriched groundwater can contribute to

eutrophication, a process leading to high algal, especially blue-green algal populations

and the death of aquatic life due to excessive demand for oxygen. While not directly toxic

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to fish life like ammonia, nitrate can have indirect effects on fish if it contributes to this

eutrophication. Nitrogen has contributed to severe eutrophication problems in some water

bodies. As of 2006, the application of nitrogen fertilizer is being increasingly controlled

in Britain and the United States. This is occurring along the same lines as control of

phosphorus fertilizer, restriction of which is normally considered essential to the recovery

of eutrophied waterbodies.

Denitrification

Denitrification is the reduction of nitrates back into the largely inert nitrogen gas

(N2), completing the nitrogen cycle. This process is performed by bacterial species such

as Pseudomonas and Clostridium in anaerobic conditions. They use the nitrate as an

electron acceptor in the place of oxygen during respiration. These facultatively anaerobic

bacteria can also live in aerobic conditions.

Anaerobic ammonium oxidation

In this biological process, nitrite and ammonium are converted directly into

elemental nitrogen (N2) gas. This process makes up a major proportion of elemental

nitrogen conversion in the oceans.

Human influences on the nitrogen cycle

As a result of extensive cultivation of legumes (particularly soy, alfalfa, and

clover), growing use of the Haber-Bosch process in the creation of chemical fertilizers

and pollution emitted by vehicles and industrial plants, human beings have more than

doubled the annual transfer of nitrogen into biologically-available forms. In addition,

humans have significantly contributed to the transfer of nitrogen trace gases from Earth to

the atmosphere, and from the land to aquatic systems. Human alterations to the global

nitrogen cycle are most intense in developed countries and in Asia, where vehicle

emissions and industrial agriculture are highest.

N2O (nitrous oxide) has risen in the atmosphere as a result of agricultural

fertilization, biomass burning, cattle and feedlots and other industrial sources. N2O has

deleterious effects in the stratosphere, where it breaks down and acts as a catalyst in the

destruction of atmospheric ozone.

N2O in the atmosphere is a greenhouse gas, currently the third largest contributor

to global warming, after carbon dioxide and methane. While not as abundant in the

atmosphere as carbon dioxide, for an equivalent mass, nitrous oxide is nearly 300 times

more potent in its ability to warm the planet.

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NH3 (ammonia) in the atmosphere has tripled as the result of human activities. It

is a reactant in the atmosphere, where it acts as an aerosol, decreasing air quality and

clinging on to water droplets, eventually resulting in nitric acid (HNO3) acid rain.

Atmospheric NH3 and HNO3 damage respiratory systems.

Water Cycle

The water cycle, also known as the hydrologic cycle or H2O cycle, describes the

continuous movement of water on, above and below the surface of the Earth. Water can

change states among liquid, vapour and ice at various places in the water cycle. Although

the balance of water on Earth remains fairly constant over time, individual water

molecules can come and go, in and out of the atmosphere. The water moves from one

reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by

the physical processes of evaporation, condensation, precipitation, infiltration, runoff and

subsurface flow. In so doing, the water goes through different phases: liquid, solid and

gas.

The hydrologic cycle involves the exchange of heat energy, which leads to

temperature changes. For instance, in the process of evaporation, water takes up energy

from the surroundings and cools the environment. Conversely, in the process of

condensation, water releases energy to its surroundings, warming the environment.

The water cycle figures significantly in the maintenance of life and ecosystems on

Earth. Even as water in each reservoir plays an important role, the water cycle brings

added significance to the presence of water on our planet. By transferring water from one

reservoir to another, the water cycle purifies water, replenishes the land with freshwater,

and transports minerals to different parts of the globe. It is also involved in reshaping the

geological features of the Earth, through such processes as erosion and sedimentation. In

addition, as the water cycle also involves heat exchange, it exerts an influence on climate

as well.

Description

The sun, which drives the water cycle, heats water in oceans and seas. Water

evaporates as water vapor into the air. Ice and snow can sublimate directly into water

vapor. Evapotranspiration is water transpired from plants and evaporated from the soil.

Rising air currents take the vapor up into the atmosphere where cooler temperatures cause

it to condense into clouds. Air currents move water vapor around the globe, cloud

particles collide, grow, and fall out of the sky as precipitation. Some precipitation falls as

39

snow or hail, and can accumulate as ice caps and glaciers, which can store frozen water

for thousands of years. Snowpacks can thaw and melt, and the melted water flows over

land as snowmelt. Most water falls back into the oceans or onto land as rain, where the

water flows over the ground as surface runoff. A portion of runoff enters rivers in valleys

in the landscape, with streamflow moving water towards the oceans. Runoff and

groundwater are stored as freshwater in lakes. Not all runoff flows into rivers, much of it

soaks into the ground as infiltration. Some water infiltrates deep into the ground and

replenishes aquifers, which store freshwater for long periods of time. Some infiltration

stays close to the land surface and can seep back into surface-water bodies (and the

ocean) as groundwater discharge. Some groundwater finds openings in the land surface

and comes out as freshwater springs. Over time, the water returns to the ocean, where our

water cycle started.

Fig. 2.7 : Water Cycle

Precipitation

Condensed water vapor that falls to the Earth's surface . Most precipitation occurs

as rain, but also includes snow, hail, fog drip, graupel, and sleet. Approximately 505,000

km3 (121,000 cu mi) of water falls as precipitation each year, 398,000 km

3 (95,000 cu mi)

of it over the oceans.

Canopy interception

40

The precipitation that is intercepted by plant foliage and eventually evaporates

back to the atmosphere rather than falling to the ground.

Snowmelt

The runoff produced by melting snow.

Runoff

The variety of ways by which water moves across the land. This includes both

surface runoff and channel runoff. As it flows, the water may seep into the ground,

evaporate into the air, become stored in lakes or reservoirs, or be extracted for agricultural

or other human uses.

Infiltration

The flow of water from the ground surface into the ground. Once infiltrated, the

water becomes soil moisture or groundwater.

Subsurface Flow

The flow of water underground, in the vadose zone and aquifers. Subsurface water

may return to the surface (e.g. as a spring or by being pumped) or eventually seep into the

oceans. Water returns to the land surface at lower elevation than where it infiltrated,

under the force of gravity or gravity induced pressures. Groundwater tends to move

slowly, and is replenished slowly, so it can remain in aquifers for thousands of years.

Evaporation

The transformation of water from liquid to gas phases as it moves from the ground

or bodies of water into the overlying atmosphere. The source of energy for evaporation is

primarily solar radiation. Evaporation often implicitly includes transpiration from

plants, though together they are specifically referred to as evapotranspiration. Total

annual evapotranspiration amounts to approximately 505,000 km3 (121,000 cu mi) of

water, 434,000 km3 (104,000 cu mi) of which evaporates from the oceans.

Sublimation

The state change directly from solid water (snow or ice) to water vapor.

Advection

The movement of water - in solid, liquid, or vapor states - through the atmosphere.

Without advection, water that evaporated over the oceans could not precipitate over land.

Condensation

41

The transformation of water vapor to liquid water droplets in the air, creating

clouds and fog.

Transpiration

The release of water vapor from plants and soil into the air. Water vapor is a gas

that cannot be seen.

Carbon Cycle

The carbon cycle is the biogeochemical cycle by which carbon is exchanged

among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.

It is one of the most important cycles of the earth and allows for carbon to be recycled

and reused throughout the biosphere and all of its organisms.

The carbon cycle was initially discovered by Joseph Priestley and Antoine Lavoisier, and

popularized by Humphry Davy. It is now usually thought of as including the following

major reservoirs of carbon interconnected by pathways of exchange:

The atmosphere.

The terrestrial biosphere, which is usually defined to include fresh water systems

and non-living organic material, such as soil carbon.

The oceans, including dissolved inorganic carbon and living and non-living

marine biota.

The sediments including fossil fuels.

The Earth's interior, carbon from the Earth's mantle and crust is released to the

atmosphere and hydrosphere by volcanoes and geothermal systems.

The annual movements of carbon the carbon exchanges between reservoirs, occur

because of various chemical, physical, geological and biological processes. The ocean

contains the largest active pool of carbon near the surface of the Earth, but the deep ocean

part of this pool does not rapidly exchange with the atmosphere in the absence of an

external influence, such as a black smoker or an uncontrolled deep-water oil well leak.

The global carbon budget is the balance of the exchanges (incomes and losses) of

carbon between the carbon reservoirs or between one specific loop (e.g., atmosphere ↔

biosphere) of the carbon cycle. An examination of the carbon budget of a pool or

reservoir can provide information about whether the pool or reservoir is functioning as a

source or sink for carbon dioxide.

42

Fig. 2.8 : Carbon Cycle

Carbon exists in the Earth's atmosphere primarily as the gas carbon dioxide (CO2).

Although it is a small percentage of the atmosphere (approximately 0.04% on a molar

basis), it plays a vital role in supporting life. Other gases containing carbon in the

atmosphere are methane and chlorofluorocarbons (the latter is entirely anthropogenic).

Trees and other green plants such as grass convert carbon dioxide into carbohydrates

during photosynthesis, releasing oxygen in the process. This process is most prolific in

relatively new forests where tree growth is still rapid. The effect is strongest in deciduous

forests during spring leafing out.

The carbon cycle is the biogeochemical cycle by which carbon is exchanged

among the biosphere, pedosphere, geosphere, hydrosphere and atmosphere of the Earth. It

is one of the most important cycles of the earth and allows for carbon to be recycled and

reused throughout the biosphere and all of its organisms.

Genetic and Plant Biodiversity

Meaning: The sum total of various types of microbes, plants and animals present

in a system is referred to as Bio-diversity.

OR

Complex beyond understanding and valuable beyond measure biological diversity

is the total variety of life on our planet.

The biosphere comprises of a complex collection of innumerable organisms,

which constitutes the vital life support for the survival of human race. As per in the

43

convention on Biological Diversity held at Rio-De-Janeiro (Brazil) in 1992, the

Biological Diversity is defined as ―The variability among living organisms from all

sources including, interalia, terrestrial, marine and other aquatic ecosystems and the

ecological complexes of which they are part. This includes diversity within species,

between species and of eco-systems.

Nature has developed complex spectrum of life forms over 600 million years. It is

understood that anywhere between 10 to 80 million species exist on earth.

I. Diversity of Biotic Communities and Ecosystem: Different types of ponds,

lakes, rivers, wetlands, meadows, grass-lands, forests etc., represent diverse

ecosystems with their own characteristic biotic community. Ex: A pond may

possess different sets of flora and fauna as compared to another ecosystem such as

river.

II. Diversity of Species Composition within a Community: The Biotic

components of an ecosystem composed of a number of species consisting of

plants, microbes, and animals which interact with each other on one hand and

interact with the abiotic factors of the environment on the other. The richness of

species in an ecosystem is called ―species diversity‖.

III. Diversity of Genetic Organization within a Species: Within a species, we can

find several varieties or strains or races which slightly differ from each other in

one or more characteristics namely size, shape, quality of their respective product,

resistance against pests, insects, diseases etc., and resilience to survive under

adverse environmental conditions. These differences are due to slight variation in

their genetic organization. Such diversity in the genetic make-up of a species is

called ―genetic diversity‖. A species having large numbers of varieties, strains or

races is considered as rich and more diverse in its genetic organization.

IV. Diversity within a Landscape: This type of diversity refers to size and

distribution of several ecosystems and their interactions across a given land

surface.

Importance of Biodiversity

Bio-sphere is life support system for human-race. Plants and animals have been

exploited by human since time immemorial for need of food, clothing, shelter etc. So far

about 1.5 million species of plants (10% of existing plants) have been recorded similarly

many living organisms are yet to be recognized.

44

A huge wealth of biological resources is yet to be tapped by the mankind. The

price we might have been paying for this neglect may be illustrated by the fact that if

“penicillium” or “cinchona” would have been extinct before their curative properties

were discovered, what would have been the plight of mankind.

Work to be done:

1. The ―Ecosystem services‖ provided to us by nature is ―gratis‖ also consists supply

of fresh water, generating soils, supply of plant pollinators, and maintaining a

huge ―genetic library‖.

2. In many cultures, maintenance of mountains and other diverse landforms are of

religious significance.

3. A diversity of biological communities such as parks, gardens, natural animal

habitats, forests, mountains, sea-shores, etc. are useful for educational, picnicking

and other recreational activities.

4. The vast insect fauna contains large number of species which is potentially

superior crop pollinators, weed-control agents and are parasites of insect pests.

5. In a simple ecosystem, loss of even one or a few species could be disastrous

because of the lack of alternatives.

There are several examples of genetic modifications:

a) A wild variety of rice grown in U.P. saves millions of hectares of paddy crop from

‗grassy stand‘ virus.

b) The kans grass known as “saccharum spontaneum‖ from Indonesia provided

genes for resistance to red rot diseases of sugar cane.

c) The genes from a wild melon grown in U.P. helped in imparting resistance to

powdery mildew in musk melons grown in California.

d) Maintaining the Bio-Diversity helps in preservations of socio-economic, aesthetic

cultural and religious values of ecosystems.

El-Nino Phenomenon

Under normal circumstances the water of the eastern pacific off Ecuador, Peru and

Northern Chile are surprisingly cold, as much as 10ºC cooler than the waters of the

western pacific. This part of the eastern pacific is teeming with fish, since here cold

waters, rich in nutrients, well up from the deep ocean.

But once every five to ten years from December to March, the waters of the

Eastern Pacific warm up a little (28ºC i.e., 4ºC higher than normal) which disrupts the

45

upwelling of the rich, cold water. This in turn disrupts the anchovy fishery, Key to

Peruvian economy.

This phenomenon is called El-Nino (Spanish term for ―The Christ Child) since it

starts in December. El-Nino is not a regular event as it takes place once every five years

on the average. But when it occurs, the local environment suffers from enormous

disruption. The anchovy fish die for shortage of food, followed by birds that normally

feed off the anchovy.

Since the 1950‘s with off-shore fishing, the Peruvian fishery became the world‘s

largest, by weight. The anchovies are also dried and ground up into fish meal for animal

feed, especially for poultry forms. A major El-Nino can wreck the Peruvian economy and

send world fish meal prices soaring.

El-Nino struck Chile and Peru in mid-1970s and 1982. El-Nino affected climate

over half the globe.

In the late 1960‘s it was found that El-Nino events coincided with the southern

oscillation, an irregular but recurrent relationship between atmosphere pressures and sea-

surface temperatures over the south-eastern pacific and the Indian oceans, particularly

between Darwin, Australia and the Pacific island of Tahiti. These two events, El-Nino and

the southern oscillation, are called ENSO by climatologists. They usually last for 12

months from December to December. They bring with them impacts for Peruvian

anchovies. The most notorious ENSO event was in 1982 making full impact all around

the globe. There were droughts in north-eastern Brazil (14 million people affected) India

(food production dropped by 4%), north china (grain, yield reduced by 10%), Indonesia

(350 starvation deaths) and eastern Australia as well as major floods in Ecuador, Bolivia

and Peru.

The science of El-Nino / ENSO process is not yet fully understood. Its relationship

with greenhouse effect remains to be established. In order to forecast ENSO event it is

necessary to monitor regularly sea-surface temperatures of Peru and atmospheric pressure

differences between Tahiti and Darwin. A team of scientists have been conducting

research on El-Nino under the sponsorship of the permanent south-pacific commission,

which supports oceanographic research and governs maritime policy in Chile, Colombia,

Ecuador and Peru. The commission co-ordinates the work of 17 scientific organizations.

They have fitted in the seas all along the equator more than 200 buoys which are

equipped with wind sensors, satellite transmitters and thermostats. The experts keep track

46

of ocean temperature, salinity levels, and wind patterns and thus are in a position to

forecast the approach of El-Nino several months before it hits South America.

AIR POLLUTION & SOUND POLLUTION

„Air Pollution is the excessive concentration of foreign matter in the air which

adversely affects the well being of individual or causes damage to property‟

American Medical Association

Older people are highly vulnerable to diseases induced by air pollution. Those

with heart or lung disorders are under additional risk. Children and infants are also at

serious risk. Studies have estimated that the number of people killed annually in the US

alone could be over 50,000.

Because people are exposed to so many potentially dangerous pollutants, it is

often hard to know exactly which pollutants are responsible for causing sickness. Also,

because a mixture of different pollutants can intensify sickness, it is often difficult to

isolate those pollutants that are at fault.

Many diseases could be caused by air pollution without their becoming apparent

for a long time. Diseases such as bronchitis, lung cancer, and heart disease may all

eventually appear in people exposed to air pollution.

Air pollutants such as ozone, nitrogen oxides, and sulfur dioxide also have

harmful effects on natural ecosystems. They can kill plants and trees by destroying their

leaves, and can kill animals, especially fish in highly polluted rivers.

Defining ―air pollution‖ is not simple. One could claim that air pollution started

when humans began burning fuels. In other words, all man-made (anthropogenic)

emissions into the air can be called air pollution, because they alter the chemical

composition of the natural atmosphere. The increase in the global concentrations of

greenhouse gases CO2, CH4 and N2O, can be called air pollution using this approach,

even though the concentrations have not found to be toxic for humans and the ecosystem.

One can refine this approach and only consider anthropogenic emissions of harmful

chemicals as air pollution.

Air pollution is the presence of substances in air in sufficient concentration and

for sufficient time, so as to be, or threaten to be injurious to human, plant or animal life,

or to property, or which reasonably interferes with the comfortable enjoyment of life and

property.

47

Air pollutants arise from both man-made and natural processes. Pollutants are also

defined as primary pollutants resulting from combustion of fuels and industrial operations

and secondary pollutants, those which are produced due to reaction of primary pollutants

in the atmosphere. The ambient air quality may be defined by the concentration of a set of

pollutants which may be present in the ambient air we breathe in. These pollutants may be

called criteria pollutants. Emission standards express the allowable concentrations of a

contaminant at the point of discharge before any mixing with the surrounding air.

There are many health effects of air pollution including irritation of the eyes, nose,

mouth, and throat, chest pain, labored breathing, and increased susceptibility to lung

infection. At its least severe levels, air pollution is a nuisance to healthy individuals and a

burden to those with respiratory diseases.

Millions of tons of harmful gases and pollutants are released into the air each year.

Once inhaled, polluted air weakens the lungs natural defenses against harmful

contaminants. In fact, lung tissue has no reliable defense against air pollution, and

therefore, is gradually destroyed by invasive pollutants

Pollutants

1. Primary Pollutants

2. Secondary Pollutants

S.No. Primary Pollutants Secondary Pollutants

1. Carbon monoxide (CO) Ozone (O3)

2. Nitrogen Oxide (NOx) Peroxyactyl nitrate (PAN)

3. Sulphur Oxide (SOx) Aldehydes

4. Hydrocarbon (HC) Ketones

5. Particulates Sulphur trioxide

Primary air pollutants are emitted directly into the air from sources. They can have

effects both directly and as precursors of secondary air pollutants (chemicals formed

through reactions in the atmosphere).

1. Primary Pollutants:

I . CO (Carbon monoxide)

II. NOx (Nitrogen Oxide)

48

III. SOx (Sulphur Oxide)

IV. HC (Hydrocarbon)

V. Particulates

I . CO (Carbon monoxide)

It is odourless, colourless and tasteless gas. It is insoluble of water. It is

96.5% as heavy as air. It is produced by incomplete combustion of fuel. It

burns in air or oxygen with blue flame.

2C+ O2 2 CO

Dissociations of CO2 at high temperature

CO2 CO + O

Sources

1. Natural Sources – volcano, electric discharge during storms, marsh gas .

2. Transportation – motor vehicle, aircraft, rail.

3. Industrial activities – petroleum, paper and steel industries

4. Miscellaneous – forest fire, agricultural waste

Harmful effects

CO can cause oxygen deprivation (hypoxia), displacing oxygen in bonding with

hemoglobin, causing cardiovascular and coronary problems, increasing risk of stroke, and

impairing learning ability, dexterity and sleep. CO is mostly hazardous in relatively

confined areas such as tunnels under bridges and overpasses, and in dense urban settings.

In unconfined areas or away from population centres, it will stabilize into CO2 before

damage to human health is likely.

It circulate directly into blood through lungs. Carbon monoxide binds to

hemoglobin (Hb) in red blood cells, reducing their ability to transport and release oxygen

throughout the body because of Carboxy hemoglobin (CO Hb). The affinity of Carboxy

hemoglobin is 210 times greater to that of oxygen. Low exposures can aggravate cardiac

ailments, while high exposures cause central nervous system impairment or death. It also

plays a role in the generation of ground-level ozone.

Hb + CO CO Hb

Controls

49

1. Development of exhaust systems.

2. Modifications of internal combustions systems

3. Development of substitute fuel for gasoline

Sulfur dioxide

Sulfur dioxide is a colourless gas with a pungent odour. It is a liquid when under

pressure. Sulfur dioxide dissolves in water very easily. It cannot catch fire.

Sources

1. Volcanic eruptions.

2. Burning of fossil fuels.

3. Copper smelting.

4. Manufacture of sulfuric acid.

5. Manufacture of paper.

6. Food preservatives industries.

7. Manufacture of fertilizers.

Once released into the environment, sulfur dioxide moves to the air. In the air,

sulfur dioxide can be converted to sulfuric acid, sulfur trioxide, and sulfates. Sulfur

dioxide dissolves in water. Once dissolved in water, sulfur dioxide can form sulfurous

acid.

Harmful effects

1. Body absorb sulfur oxide through lungs. It can easily and rapidly enter

bloodstream through your lungs and it breaks down to sulfate.

2. Exposure to 100 ppm is considered immediately dangerous to life and health,

copper mine developed burning of the nose and throat, breathing difficulties.

3. Lung function changes have been observed in some workers exposed to 0.4–3.0

ppm.

4. Studies in animals support the human data regarding respiratory effects of sulfur

dioxide.

5. Children may be exposed to more sulfur dioxide than adults because they breathe

more air for their body. Long-term exposed studies reduced breathing ability.

6. It also causes to damage crops.

50

7. SO2 dissolves in cloud droplets and oxidizes to form sulfuric acid (H2SO4) which

can fall to Earth as acid rain or snow or form sulfate aerosol particles in the

atmosphere.

Controls

1. Development of substitute fuel for gasoline.

2. Use of low sulphur fuel.

3. Removal of SOx from fuel gases.

Nitrogen Oxides

Nitric oxide (NO) which is colourless, odourless gas and Nitrogen dioxide (NO2) which

is radish brown, pungent are main primary pollutants.

Sources

Coal Burning.

Motor vehicle exhausts.

Fixation of lighting.

Bio mass burning.

Emission from acid manufacturing.

Harmful effects

1. Respiratory disease like bronchitis.

2. Formation of smog in acid humid condition.

3. Acid rain when NO2 combines with water.

Control

There are only two way to reduce NOx emissions:

Modifying combustion processes to prevent NOx formation.

Treating combustion gases after flame to convert NOx to N2.

Combustion Modification

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This is the most widely used approach to NOx control. Combustion modification

involves mixing part of the combustion air with the fuel and burning as much of the fuel

that the air will allow. Then, some of the heat from the flames is transferred to whatever

is being heated. Next, the remaining air is added and combustion is finished. This is

known as two-stage combustion or reburning .

One of the major advantages to this technique is that it is cheap. The

disadvantages are that it requires a larger firebox without a higher combustion rate. Also,

it is difficult to get complete burning of the fuel in the second stage. Therefore, the

amount of unburned fuel and/or carbon monoxide in the exhaust gas increases.

Post-Flame Treatment

Many of these processes require the addition of a reducing agent to the

combustion gas stream to take oxygen away from NO. In automobile engines, a platinum-

rhodium catalyst is used. The reaction is:

2NO + 2CO + p-r catalyst-----------> N2 + 2CO2

On the other hand, for power plants and other large furnaces, there are many

choices of reducing agents. However, the most popular is ammonia. The desired

conversion reaction is:

6NO + 4NH3 -------------> 5N2 + 6H2O

However, there is always some oxygen present. This oxygen causes reactions like

the following:

4NO + 4NH3 +O2 ---------> 4N2 + 6H2O

If the above reaction occurs, the NO2 is reduced by the following reaction:

2NO2 + 4NH3 +O2 ---------> 3N2 + 6H2O

All of these reactions are expensive to carry out. They can occur either over a

zeolite catalyst or in a gas stream in a part of a furnace where the temperature is between

1600 and 1800 degrees Fahrenheit. If the temperature is greater than 1800 degrees, the

NO content increases rather than decreases, which exactly what we don't want. The

dominant reaction is:

NH3+O2 ---------> NO + 3/2H2O

52

Particulate Matter Pollution

The term Particulate Matter (PM) includes both solid particles and liquid droplets

found in air. Many man-made and natural sources emit PM directly or emit other

pollutants that react in the atmosphere to form PM. These solid and liquid particles come

in a wide range of sizes. Particles less than 10 micrometers in diameter tend to pose the

greatest health concern because they can be inhaled into and accumulate in the respiratory

system. There different type of particulate matters like

1. Dust.

2. Fumes.

3. Mist.

4. Smoke.

5. Aerosol.

6. Fog.

7. Coarse particles.

Sources

1. Volcanic eruptions.

2. Motor vehicles.

3. Power plants.

4. Wood burning.

5. Crushing or grinding operations.

6. Dust from paved (Cemented) or unpaved roads.

7. Harvesting and trashing of crops.

8. Constructions works.

Harmful effects

1. It has found that numerous health effects arise from both fine and coarse particles

when they accumulate in the respiratory system.

2. When exposed to even small levels of PM, people with existing heart or lung

diseases-such as asthma.

3. Exposure to fine particles is associated with several serious health effects, and it

will cause death.

53

4. Chronic obstructive pulmonary disease, congestive heart disease are at increased

risk of premature death.

5. Children and people with existing lung disease may not be able to breathe as

vigorously as they normally would, and they may experience symptoms such as

coughing and shortness of breath when exposed to levels of PM.

Controls

1. Gravity Setting Chamber : This is the simplest of all separation equipment. It

has big box, with the inlet and outlet streams way up at the top, and as the fluid

flows through, the particles fall out. If the box is long enough, then all the

particles should fall out. This brings us back to the settling velocity; if the flow

rate through is too fast for the size of the box you are using, then not all the

particles, if any, are going to settle.

Fig. 3.1 : Gravity setting chamber

2. Mechanical Collectors – It is also known as cyclone collector. Mechanical

collectors use the inertia of the particles for collection. The particulate-laden gas

stream is forced to spin in a cyclonic manner. The mass of the particles causes

them to move toward the outside of the vortex. Most of the large-diameter

particles enter a hopper below the cyclonic tubes while the gas stream turns and

exits the tube.

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Fig. 3.2 : Top Inlet cyclone

3. Wet Scrubbers –

There are a number of major categories of particulate wet scrubbers such as Ventures

Impingement and Sieve Plates.

Spray Towers.

Mechanically Aided.

Condensation Growth.

Packed Beds.

Ejector.

Mobile Bed.

Caternary Grid.

Froth Tower.

Oriented Fiber Pad.

Wetted Mist Eliminators.

Spray Tower Scrubbers

A typical spray tower scrubber is shown in figure 3.3. This is the simplest type of

particulate wet scrubber in commercial service. Sets of spray nozzles located near the top

of the scrubber vessel generate water droplets that impact with particles in the gas stream

as the gas stream moves upwards.

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Fig. 3.3 : Spray Tower Scrubbers

4. Electrostatic Precipitator

An electrostatic precipitator is a large, industrial emission-control unit. It is

designed to trap and remove dust particles from the exhaust gas stream of an industrial

process. Precipitators are used in Electric, Cement , Chemicals, Metals, Paper industries .

Fig. 3.4 : Electrostatic Precipitator

Hydrocarbon

Hydrocarbons are natural chemical compounds made up of carbon and hydrogen.

Hydrocarbon are mainly two types - saturated and unsaturated.

56

Saturated hydrocarbons: They have no double, triple, or aromatic bonds between

carbons.

Unsaturated hydrocarbons: They have at least one aromatic ring of carbons, they have

at least one double or triple bond between carbons, polycyclic aromatic hydrocarbons

(PAH).

Sources

1. Natural sources like CH4.

2. Coal.

3. Wood.

4. Petroleum Products.

Harmful Effects

1. Irritation on mucus secretions

2. They undergo chemical reactions in the presence of sunlight and nitrogen oxides.

They form photochemical oxidants leading to photochemical smog.

3. This causes irritation in the eyes and lungs leading to respiratory diseases.

Table – 1

Pollutants Sources Environmental Effects

Carbon

Monoxide

(CO)

Natural Sources –

volcano, electric

discharge during

storms, marsh gas .

Transportation –

motor vehicle,

aircraft, rail.

Industrial activities –

petroleum, paper and

steel industries.

Forest fire,

agricultural waste.

It binds with Hb in red blood cells, reducing

their ability to transport and release oxygen

throughout the body because of Carboxy

hemoglobin (CO Hb). The affinity of Carboxy

hemoglobin is 210 times greater to that of

oxygen. Low exposures can aggravate cardiac

ailments, while high exposures cause central

nervous system impairment or death.

Nitrogen

Oxides

(NOx)

Combustion of oil,

coal, gas.

Combustion of

Decreased visibility due to yellowish

colour of NO2.

NO2 contributes to heart and lung

57

automobiles.

Bacterial action in

soil.

Forest fires.

Lightning volcanic

action.

problems.

NO2 can suppress plant growth.

Decreased resistance to infection.

May encourage the spread of cancer.

Sulfur oxide

(SOx)

Volcanic eruptions.

Burning of fossil

fuels.

Copper smelting.

Manufacture of

sulfuric acid.

Manufacture of

paper.

Food preservatives

industries.

Manufacture of

fertilizers.

Nose and throat, breathing difficulties.

Lung function changes have been

observed.

Studies in animals support the human data

regarding respiratory effects of sulfur

dioxide.

Long-term exposed studies reduced

breathing ability.

It also causes to damage crops.

SO2 dissolves in cloud droplets and

oxidizes to form sulfuric acid (H2SO4),

which can fall to Earth as acid rain or

snow or form sulfate aerosol particles in

the atmosphere.

Hydrocarbon

(HC)

Natural sources like.

CH4 .

Coal.

Wood.

Petroleum Products.

Irritation on mucus secretions.

They undergo chemical reactions in the

presence of sunlight and nitrogen oxides.

They form photochemical oxidants

leading to photochemical smog.

This causes irritation in the eyes and lungs

leading to respiratory diseases.

Particulate

Matters (PM)

Volcanic eruptions.

Motor vehicles.

Power plants.

Wood burning.

Crushing or grinding

Accumulate in the respiratory system.

Heart or lung diseases-such as asthma.

Exposure to fine particles is associated

with several serious health effects, and it

will cause death.

58

operations.

Dust from paved

(Cemented) or

unpaved roads.

Harvesting and

trashing of crops

Constructions works.

Children and people with existing lung

disease may not be able to breathe as

vigorously as they normally would, and

they may experience symptoms such as

coughing and shortness of breath.

Volatile

Organic

Compounds

(VOCs)

Evaporation of

solvents.

Evaporation of fuels.

Incomplete

combustion of fossil

fuels.

Naturally occurring

compounds like

terpenes from trees.

Eye irritation.

Respiratory irritation.

Some are carcinogenic.

Decreased visibility due to blue-brown

haze.

Ozone (O3) Formed from

photolysis of NO2 .

Sometimes results

from stratospheric

ozone intrusions.

Bronchial constriction.

Coughing, wheezing.

Respiratory irritation.

Eye irritation.

Decreased crop yields.

Retards plant growth.

Damages plastics.

Breaks down rubber.

Harsh odour.

Peroxyacetyl

Nitrates (PAN)

Formed by the

reaction of NO2 with

VOCs (can be formed

naturally in some

environments).

Eye irritation.

High toxicity to plants.

Respiratory irritation.

Damaging to proteins.

59

Causes of Air Pollution

Carbon dioxide is one the main pollutants that causes air pollution. This is because

although living beings do exhale carbon dioxide, this gas is harmful when emitted from

other sources, which are caused due to human activity. An additional release of carbon

dioxide happens due to various such activities. Carbon dioxide gas is used in various

industries such as the oil industry and the chemical industry. The manufacturing process

of most products would require the use of this gas. There are various human activities that

add to the increased proportions of carbon dioxide in the atmosphere. The combustion of

fossil fuels and the harmful effects of deforestation have all contributed towards the same.

Show that amongst the various gasses emitted during a volcanic eruption, carbon dioxide

remains to be at least 40% of the emission. Scientists have now therefore identified

carbon dioxide as one of those elements that have contributed to global warming.

Causes of air pollution are not limited to this. The combustion of fuels in

automobiles, jet planes etc all cause the release of several primary pollutants into the air.

The burning of fossil fuels in big cities which is seen at most factories, offices and even a

large number of homes, it is no wonder that air pollution is increasing at an alarming rate.

The release of other harmful gases all adds to the state that we see today. Although

carbon dioxide plays an important role in various other processes like photosynthesis,

breathing an excess of the same also causes harmful effects towards one‘s health.

The various causes of air pollution that releases harmful gases into the atmosphere

are caused due to the increasing number of power plants and manufacturing units or

industries that mostly have activities related to the burning of fuels. Besides, as

mentioned earlier, most automobiles, marine vessels, activities that involve the burning of

wood, fumes that are released from aerosol sprays, military activities that involve the use

of nuclear weapons, all are the numerous causes of air pollution.

Carbon monoxide is another such gas which although was present in the

atmosphere earlier, is now considered to be a major pollutant. An excess of the same has

a harmful effect on our system. There are many reasons why carbon monoxide can be

released into the atmosphere as a result of human activities. This is also produced due to

any fuel burning appliance and appliances such as gas water heaters, fireplaces,

woodstoves, gas stoves, gas dryers, yard equipments as well as automobiles, which add to

the increased proportion of this gas into the atmosphere.

60

Sulfur dioxide is yet another harmful pollutant that causes air pollution. Sulfur

dioxide is emitted largely to the excessive burning of fossil fuels, petroleum refineries,

chemical and coal burning power plants etc. Nitrogen dioxide when combined with sulfur

dioxide can even cause a harmful reaction in the atmosphere that can cause acid rain.

Nitrogen dioxide is one more gas that is emitted into the atmosphere as a result of

various human activities. An excess of nitrogen dioxide mainly happens due to most

power plants seen in major cities, the burning of fuels due to various motor vehicles and

other such sources, whether industrial or commercial that cause the increase in the levels

of nitrogen dioxide. These and a number of other hazardous air pollutants are emitted

with the various numbers of activities that we carry out during the day which are the main

causes of air pollution.

Fig. 3.5 : Air pollution

Secondary Air Pollutants

These types of pollutants are formed in the atmosphere by chemical reaction

between primary pollutants and atmospheric constituents. Oxidation reactions, hydrolysis

reaction and photochemical reactions are takes place during interaction. There are

following type of secondary pollutants

1. Ozone.

2. Peroxyactyl nitrate (PAN).

3. Aldehydes.

4. Ketones.

5. Sulphur trioxide.

61

Ozone Layer

Fig. 3.6 : Ozone Layer

The ozone layer is a deep layer in the stratosphere, encircling the Earth that has

large amounts of ozone in it. The layer shields the entire Earth from much of the harmful

ultraviolet radiation that comes from the sun.

"The ozone layer" refers to the ozone within stratosphere, where over 90% of the

earth's ozone resides. Ozone is an irritating, corrosive, colorless gas with a smell

something like burning electrical wiring.

Ozone is a special form of oxygen, made up of three oxygen atoms rather than the

usual two oxygen atoms. It usually forms when some type of radiation or electrical

discharge separates the two atoms in an oxygen molecule (O2), which can then

individually recombine with other oxygen molecules to form ozone (O3).

O2 + O O3

Sources

1. Lighting.

2. Forest Fire.

3. Vehicles exhaust.

Harmful effects

1. Increased concentration of ozone effect RNA & DNA.

2. Lung Cancer.

3. Loss of immune system.

62

4. It retarded the growth of vegetation.

5. It also effect the food production.

Ozone Depletion

Arctic Ozone

The maximum depletion is generally less severe than that observed in the

Antarctic, with no large and recurrent ozone hole taking place in the Arctic.

Since the 1980's, scientists at ESRL have been participants in field, theoretical and

laboratory research to demonstrate some of the key processes that contribute to the

observed difference between the depletion of ozone in the Arctic and Antarctic.

Ozone-Depleting Substances

Certain industrial processes and consumer products result in the atmospheric

emission of ozone-depleting gases. These gases contain chlorine and bromine atoms,

which are known to be harmful to the ozone layer. Important examples are the CFCs and

hydro- chloro-fluoro-carbons (HCFCs), human-produced gases once used in almost all

refrigeration and air conditioning systems. These gases eventually reach the stratosphere,

where they are broken apart to release ozone-depleting chlorine atoms.

Photochemical Smog

Photochemical smog is produced when sunlight is mixed with various pollutants

like nitrogen dioxide or hydrocarbons. The photochemical smog is often colorless and

invisible. However, it can cause various problems like eye irritation, respiratory problems

and so on. Smog is caused when smoke released from vehicles and factories gets mixed

with fog. This smog (smoke + fog) becomes heavy and remains on the surface of the land

rather than moving up, which causes a number of accidents and respiratory problems.

This harmful smog may contain any of the following:

NOx.

Various harmful organic compounds.

Aldehydes.

Peroxyacyl Nitrate (PAN).

O3 .

63

Fig. 3.7 (A) : Photochemical Smog

Smog is often used as a generic term for any kind of air pollution that reduces

visibility, especially in urban areas. However, it is mainly two types:

1. Industrial smog.

2. Photochemical smog.

Events like the London smog of 1952 are often referred to as industrial smog because

SO2 emissions from burning coal play a key role. Typically, industrial smog also called

gray or black smog develops under cold and humid conditions. Cold temperatures are

often associated with inversions that trap the pollution near the surface allows for rapid

oxidation of SO2 to form sulfuric acid and sulfate particles.

64

Fig. 3.7 (B) : Photochemical Smog

London smog occurred in the industrial towns of Liege, Belgium, in 1930, killing

more than 60 people and Donora, Pennsylvania, in 1948, killing 20. Today coal

combustion is a major contributor to urban air pollution in China, especially from

emissions of SO2 and aerosols.

Air pollution regulations in developed countries have reduced industrial smog

events, but photochemical smog remains a persistent problem, largely driven by vehicle

emissions.

Photochemical smog forms when NOx and VOCs react in the presence of solar

radiation to form ozone. The solar radiation also promotes formation of secondary aerosol

particles from oxidation of NOx, VOCs, and SO2. Photochemical smog typically develops

in summer (when solar radiation is strongest) in stagnant conditions promoted by

temperature inversions and weak winds.

Nevertheless, people have started taking some measure to reduce the harmful

effects of photochemical smog. Tight control on emissions throughout the world is one

such excellent example of this. Many countries have banned the usage of a few harmful

65

chemicals that create photochemical smog. Most governments have started taking such

measures and have started monitoring air quality to gauge the increase level.

Acid Rain

Rain is acidified by oxides of sulfur and nitrogen. Acid rain is formed when

pollutants called oxides of sulfur and nitrogen, contained in car exhaust, power plant,

smoke, and factory smoke, react with the moisture in the atmosphere.

Acid rain is formed when sulfur dioxide and nitrogen oxides reach the air and are

transformed into sulfate or nitrate particles. When combined with water vapour, they are

converted into sulfuric or nitric acids. Acid rain can adversely affect aquatic life, erode

stone buildings and marble statues, and seriously threaten trees and crops.

Power plants that burn coal to generate electricity are a chief cause of acid rain.

Coal burning releases sulfur dioxide into the air. Sulfur dioxide then combines with free

oxygen and water vapour to form small quantities of sulfuric acid in our rain.

Nitrogen oxide emissions from cars also contribute to acid rain. Nitrogen oxide

controls are also required for new municipal waste incinerators and power plants.

NOx + O2 HNO3

SOx + O2 H2SO4

Harmful Effects of Acid Rain

1. It has been found that acidification causes adverse effects on aquatic animals.

2. Ancient monuments, structure, building, bridges, roads are weakens due to attack

of acid.

3. Corrosive effect on steel or iron windows and doors.

4. Hair, skin and lungs are affected by acid rain.

5. Acidification damage to crops and forest.

6. Acid rain causes a cascade of effects that harm or kill individual fish, reduce fish

population numbers, completely eliminate fish species from a water body, and

decrease biodiversity.

66

Fig. 3.8 – Acid Rain

Controls

1. By using catalytic converter to emit less pollutant in the environment.

2. By using bio fuels instead of gasoline or diesel.

3. Developing more efficient vehicles to reduce the harmful gases.

4. It is also observed that neutralize the acid with lime but this is expensive.

Global Warming

The heat balance of the earth is defined as the ratio of energy received by the earth

from the sun to the energy the earth loses by reflection and by radiation is form of heat.

This ratio is essentially unit. That is, the earth loses as much heat energy as it receives. As

a result, a near steady state of the average of global temperature has been maintained.

Although there have been imbalances in local regions, the average temperature of

the earth has remained more or less constant over a span of millions of years.

The atmosphere plays a significant role in maintaining the heat balance of the

earth. It is through the atmosphere that the earth radiates back the heat energy or reflects

back solar radiations. On an average 33% of the solar radiations received from the sun are

reflected back, primarily by clouds and partially by snow and ice sheets on the earth‘s

surface. The reflecting capacity of the earth is called albedo. The remaining 67% of the

solar energy is absorbed of this one-fourth is absorbed by the atmosphere, three-fourth by

the earth‘s surface. Ultimately both the atmosphere and the earth‘s surface radiate back

67

the absorbed energy as heat. The amount of heat energy radiated into the outer space

almost equals 67%. The heat gain and loss factors are thus balanced over the global scale.

It is feared that human activities are likely to disturb the delicate heat balance of

the earth. Industrial operations have induced large amounts of greenhouse gases, like

carbon dioxide, ozone, nitrous oxide, methane and water vapours into the atmosphere.

These gases tend to increase the average global temperature. The industrial operations

have also injected particulate load into the atmosphere. The particulates tend to counter

the warming effect of green house gases.

The current global trends in deforestation along with increased combustion of

fossil fuels have a cumulative effect on the net increase in carbon dioxide content. From

previous 283 ppm to present 356 ppm (0.03%) and it will be 600 ppm in future. However,

the rate of increase of CO2 is only about 50% of the expected magnitude. The removal

mechanisms, i.e., due to sinks of carbon dioxide photosynthesis & ocean are shown in fig.

3.9

Fig. 3.9 : Global Warming

The major sink is the ocean which contains the bulk of dissolved carbon dioxides

as bicarbonate.

It has been estimated that this combined effect will bring about a 3ºC rise in

surface temperature for a doubling of the carbon dioxide concentration, which may occur

around 2050 A.D.

It may be noted that a slight increase in surface temperature, say 1ºC, can

adversely affect the world food production. Thus the wheat growing zones in the northern

latitude will be shifted from the North Asia and Canada to the poles, i.e., from fertile to

poor soils. The biological productivity of the ocean would also decrease due to warming

of the surface layer, which in turn reduces the transport of nutrients from deeper layers to

the surface by vertical circulation.

68

Another effect is the rise in sea levels. Since oceans act as reservoirs of heat, it

could result in rise of sea levels by as much as 2 meters due to expansion of sea water at

increased temperatures, partial melting of glaciers, ice-gap of Greenland and also polar

ice caps. This rise of sea levels would threaten coastal countries some 60 odd island

nations who face deep inroads by the sea, like the Maldives, Bangladesh may be totally

submerged. In India coastal cities such as Chennai, Goa may meet similar fates.

On the other side without carbon dioxide the earth would be as cold as the moon.

By trapping the heat radiating from the earth‘s surface, carbon dioxide regulates global

temperature to life-sustaining 15ºC. But if its quantity increases too much, the earth may

share the fate of its neighboring planet Venus with surface temperature of 450ºC.

Although scientist agree on the theory of green house warming, debate continues

as to whether the increase in these greenhouse gases have actually begun to warm the

global climate. They hope to settle the question with measurements of the speed of sound

by sending pulses of underwater sound around the world through all five of its ocean

basins.

The potential of a greenhouse gas to cause greenhouse warming is expressed by

―Global warming potential‖ (GWP), originally defined by the United Nations

Intergovernmental panel on climate change, which is a function of both the infra-red

sorption characteristics and the lifetime of the gas. The greenhouse gases can be arranged

in GWP sequence as follows:-

10000x 150x 25x

CFC > N2O > CH4 > CO2

In other words, CFC is 38 million times stronger, N2O 3800 times and CH4 25

times stronger than CO2 in terms of GWP.

69

Ozone Hole

The major culprit in ozone depletion consists of CFC compounds, commonly

known as ―Freons‖. The extreme chemical stability and non-toxicity of CFC‘s enable

them to persist for years in the atmosphere and to enter, the stratosphere. In the

stratosphere CFC‘s are subjected to photochemical dissociation by intense UV radiation.

Fig. 3.10 : Ozone Layer Depletion

The net result is regeneration of Cl. radical which sustains the chain reaction.

It is known that one Cl. atom / radical can destroy one lakh O3 molecules. CFC‘s

have lifetimes of the order of 100 years.

The Antarctic Ozone Hole appears during Antarctic‘s late winter and early spring

of severely depleted ozone (upto 50%) over the polar region. The reasons why this occurs

are related to the normal effect of NO2 in limiting Cl –atom -catalyzed destruction of

ozone by combining with ClO

ClO + NO2 -------------- ClONO2

But these NOx gases in Antarctica are removed along with water by freezing in

polar stratospheric clouds at temperatures below –70ºC as HNO3.3H2O. Furthermore

Chlorine species can be liberated from ClO.NO2 and other chlorine compounds such as

HCl by reactions in the cloud, followed by photo-dissociation to yield ozone destroying

Cl

ClO.NO2 + H2O ----------- HOCl + HNO3

ClO. NO2 + HCl ------------- Cl2 + HNO3

HOCl + hv -------------- HO. + Cl

Cl2 + hv ------------------ Cl + Cl

70

The destruction of O3 by Cl involves an intermediate ClO., which should be

observed if Cl is the cause of O3 depletion. Satellite measurements have confirmed the

presence of ClO. (radical) in both the Arctic Antarctic atmospheres during periods of

severe O3 depletion.

CFC Substitutes

The frequency used CFCs are CFC-11 (CFCl3) and CFC-12 (CF2Cl2). As a

Safeguard against ozone depletion, the recommended CFC substitutes are hydrohalo-

alkanes, compounds containing at least one H atom–HCFCs (Hydro chloro flouoro

carbons) or HFCs (hydrofluorocarbons).

Typical such compounds are HCFC-22 (CHClF2), HCFC-142 (CH3CClF2), HFC –

134a (CH2FCF3) and HFC – 152a (CH3CHF2). Each of such molecules has an H-C bond,

susceptible to attack by HO.. In the troposphere thereby eliminating the compound with

its potential to produce O3 – depleting Cl atom before it reaches the stratosphere. All

these substitutes have low O3 depletion. Potential, short tropospheric so lifetime so that

the compound is destroyed before migrating to the stratosphere.

Human Activity and Meteorology

Our activities have some impact on the climate, although we may not be aware of

it. Meteorology, the science of atmosphere phenomenon, involves the study of physical

parameters such as temperature, wind, moisture and movement of air masses in the

atmosphere. It is, however, affected by the chemical properties of the atmosphere and the

chemical reactions going on it.

The pattern of air circulation governs the dispersal of air pollutants. In this context

temperature inversion has an important role. It happens when a warm air mass is above a

cold air mass, resulting in air stagnation and trapping of air pollutants in localized areas.

Thus occurs when warm air blows over a mountain range and flows over cool air on the

other side of the range. Such a phenomenon is observed in Denver, Colorado, USA, on

the east of the Rocky Mountains.

Human activities are partly responsible for changing the meteorology of the earth.

1. Deforestation and depletion of forest cover.

2. Shifting of surface water and ground water in massive amounts.

3. Release of heat from energy –producing sources.

71

4. Emission of particles and trace gases into the atmosphere.

5. Release of carbon-dioxide into the atmosphere by combustion of fossil fuels.

6. Effect of transportation system on land surface and effect of their emissions upon

the lower and upper atmosphere.

An approximate calculation shows that if the particle loading in the atmosphere

increases by 50%, the average temperature of the earth will decrease by 0.5 to 1ºC. The

same order of temperature drop will result from particle – induced cloud formation. This

partly counterbalances temperature increase due to the greenhouse effect.

Green House effect

When sunlight reaches Earth's surface some is absorbed and warms the earth and

most of the rest is radiated back to the atmosphere at a longer wavelength than the sun

light. Some of these longer wavelengths are absorbed by greenhouse gases in the

atmosphere before they are lost to space. The absorption of this longwave radiant energy

warms the atmosphere. These greenhouse gases act like a mirror and reflect back to the

Earth.Some of the heat energy which would otherwise be lost to space. The reflecting

back of heat energy by the atmosphere is called the "greenhouse effect".

The major natural greenhouse gases are water vapor, which causes about 36-70% of the

greenhouse effect on Earth (not including clouds), carbon dioxide CO2, which causes 9-

26%, methane, which causes 4-9%, and ozone, which causes 3-7%. It is not possible to

state that a certain gas causes a certain percentage of the greenhouse effect, because the

influences of the various gases are not additive. Other greenhouse gases include, but are

not limited to, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, perfluorocarbons

and chlorofluorocarbons.

72

Fig. 3.11 : Green House Effect

Causes of green house effects

1. Choloroflouro carbon.

2. Carbon dioxide.

3. Methane.

4. Ozone.

5. Nitrogen oxide.

Harmful effects

1. Global temperatures are rising. Observations suggest that the average land surface

temperature has risen 0.45-0.6°C in the last century.

2. Rising global temperatures are expected to raise sea level, change precipitation

and local climate conditions. This could affect forests, crop fields, and water

supplies. It could also harm human's health, birds, fish and ecosystems. Deserts

may expand and some national parks may be affected.

3. Human's health depend largely on local climate. Extreme temperatures can cause

the loss of life. Several diseases only appear in warm areas.

4. People with heart problems are vulnerable in this case.

73

5. Air and water pollution, caused by warm temperatures can harm human health as

well. Higher air temperatures also increase the concentration of ozone at ground

level and this is a harmful pollutant at this level.

6. it can cause problems for people with asthma and other lung diseases. As well as

chest pains, nausea, and pulmonary congestion.

7. Death rates increase during extremely hot days, especially in cities. We can

prevent this by installing air conditionings and by acclimatising ourselves.

8. Diseases spread by insects are more prevalent during the warmer temperatures, for

example malaria, dengue fever, yellow ever, and encephalitis.

9. Global warming could have many impacts on fish and other aquatic species.

Water may become too warm for the fish to inhabit it, but warmer temperatures

may also enable fish in cold oceans to grow more rapidly.

10. Climate changes are likely to have both direct and indirect effects on birds. Higher

temperatures can directly affect their life cycles. The loss of their habitats could

have an indirect effect by making some regions less hospitable to birds.

Controls

1. Reducing the emission of gases those are responsible for green house effect.

2. Less burning crude oil and coal.

3. Use non renewable sources of energy.

4. Government should subsidies solar energy.

Sound Pollutions

In simple terms, noise is unwanted sound. Sound is a form of energy which is

emitted by a vibrating body and on reaching the ear causes the sensation of hearing

through nerves. Sounds produced by all vibrating bodies are not audible. The frequency

limits of audibility are from 20 HZ to 20,000 HZ.

A noise problem generally consists of three inter-related elements- the source, the

receiver and the transmission path. This transmission path is usually the atmosphere

through which the sound is propagated, but can include the structural materials of any

building containing the receiver.

Noise may be continuous or intermittent. Noise may be of high frequency or of

low frequency which is undesired for a normal hearing. For example, the typical cry of a

74

child produces sound, which is mostly unfavourable to normal hearing. Since it is

unwanted sound, we call it noise.

Noise is harmful. Damage caused by noise can range from bursting of eardrum,

permanent hearing loss, cardiac and cardiovascular changes, stress, fatigue, lack of

concentration, deterioration in motor and psychomotor functions, nausea, disturbance of

sleep, headaches, insomnia, and loss of appetite and much other damage is caused.

Pregnant women exposed to high noise levels may be at risk. Psychological

disturbances and emotional distress also occur - violent conduct by persons continuously

exposed to unbearable noise.

The National Physical Laboratory has found that Delhi, Bombay and Calcutta are

the noisiest cities in the world. Even the Election Commission has recognized the

harmful effects of noise and banned use of loudspeakers during the

elections. Widespread ill effects of Noise Pollution such as high blood pressure,

increased acidity and peptic ulcer formation, deafness, mental agitation and disturbance

of sleep generally became known to people in early 1980s. So far Bombay Police Act

1951 and Bombay Municipal Corporation Act 1888 considered noise as just a nuisance,

now it is known as major health hazard. We in India are exposed not only to noises,

common to most countries, but in addition we have to face misuse of loudspeakers, loud

and shrill vehicle horns, noisy crackers, etc, which are firmly put down in most countries.

Sound Pollution

The Human ear receives sound waves which setup oscillation in the ear drum

(tympanic membrane). These oscillation induce movements of three fossils or small

bones in the middle ear behind the ear drum.

The oscillation or sounds are identified and interpreted in the brain, which can

select mixed sounds into different categories – thus it can differentiate speech from

background noises.

The ear has the capacity to analyze sounds into frequency components. A person

with normal hearing has audio range between 20 Hz and 20,000 Hz (1 Hz = 1 cycle/sec. =

unit of frequency).

The audio sense is most sharp in the frequency range 2000-5500 Hz.

Sound waves travel through the medium from the source to the recipient or

listener. The rate of the oscillations of the medium is known as the frequency of the

75

sound, the unit being Hertz (Hz) or cycles per second. The frequency is a measure of the

pitch of the sound received by the listener. High frequency imply high pitched sounds

which are more irritating to the indeciduate than low frequencies. The second parameter

of sound is sound pressure, which is measured in Newtons per sq. meter (N/m2). The third

parameter of sound is its intensity, expressed in watts per sq. meter (W/m2) i.e., the

quantum of sound energy that flows through unit area of the medium is unit time. Sound

is also sometimes expressed in terms of loudness.

The common scientific acoustic unit is the Decibel (dB). It is not an absolute

physical unit like volt, meter etc., but it is a ratio expressed as a logarithacic scale relative

to a reference sound pressure level.

1 decibel (dB) = 10 log10 intensity measure/reference intensity.

The reference intensity used is the threshold of hearing which means sound which

can be first heard at a sound pressure of 2x10–5 Newton m2

or sound intensity of 10–12

watts m2.

The dB scale is limited in the sense that it is not related to the human ear

frequency response and environmental circumstances in which noise is produced. This

has necessitated design of noise measuring meters which reduce the response to low and

very high frequency, characteristics of Human ear capacity.

These meters record the dBA scale which is commonly used for measurement of

general noise levels.

Intensity Wm2–

Pressure (un2–

) dB Sound source

100 200,000 200 Satum rocket takeoff

1.0 20 120 Boiler shop

10–2

2.0 100 Siren at 5 m.

10–4

0.2 80 Heavy machinery workshop

10–6

0.02 60 Normal conversation at 1 m.

10–8

0.002 40 Public library

10–10

2 x 10–5

0 Threshold of hearing

Noise Classification

1. Transport Noise.

2. Occupational Noise.

3. Neighbourhood Noise.

The Central Pollution Board (India) has prescribed permissible sound levels for

cities divided into four zones :-

76

Table 3.1

ZONES DAY NIGHT

Industrial 75 dB(A) 65 dB(A)

Commercial 65 dB(A) 55 dB(A)

Residential 50 dB(A) 45 dB(A)

Sensitive areas upto 100m.

around hospitals

educational institutions.

50 dB(A) 40 dB(A)

Occupational noise levels are:

Table 3.2

PARTICULARS dB

Steel Plate riveting 130

Oxygen Torch 126

Boiler Maker‘s shop 120

Textile loom 112

Circular Saw 110

Farm Tractor 103

Newspaper press 101

Bench Lathe 95

Milling Machine 90

High Speed Drill 85

Key Press Machine 82

Super Market 60 (dBA)

Noise Pollution Hazards

Noise is air-borne mechanical energy shrinking the Human eardrum while 65

dB(A) is the noise level for conversation heard at a distance of one meter, 125 dB(A)

gives the sensation of plain in the ear and 150 dB(A) might kill a Human being.

In addition to progressive hearing loss there may be instantaneous damage or

aquatic trauma.

77

Sonic booms or over-pressure from supersonic air liners are impulse type noise,

which can have hazardous effects on the ears.

High frequencies or ultrasonic sound above the normal audible range can affect

the semicircular canals of the inner ear and make one suffer from nausea and dizziness.

Again very low frequency noise can produce resonance in the body organs giving

the effects of reduced heart beat, variants in blood pressure and breathing difficulties.

Mid-audible band frequencies can generate resonance in the skull and hence affect

the brain and nervous system having inspect on thinking and co-ordination of the limbs.

Moderate vibration can lead to pain, and cyanosis (blue-colouration) of fingers

while severe vibration results in damage to bones and joints in the hands with swelling

and stiffness.

One exposed to the constant tapping of a typewriter in office or the noise of a

generator on the streets runs the risk of physical and mental damage.

Children exposed to excessive noise show signs of behavioral disorders which in

later age manifest themselves in destructive nature.

Electroencephalogram records reveal distorted brainwaves and blurry of vision at

a level of 125 dBA.

The impact of noise pollution on migratory birds is exemplified in Alipore Zoo at

Kolkutta. The high-rise buildings near the Alipore Zoological Garden and the resultant

noise pollution is discouraging the annual visit of the migratory birds to the lake of the

zoo.

Sources of Noises

The noise pollution has two sources, i.e. industrial and non- industrial. The

industrial source includes the noise from various industries and big machines working at a

very high speed and high noise intensity. Non- industrial source of noise includes the

noise created by transport/vehicular traffic and the neighborhood noise generated by

various noise pollution can also be divided in the categories namely-natural and

manmade. Most leading noise sources will fall into the following categories: roads traffic,

aircraft, railroads, construction, industry, noise in buildings and consumer products.

78

1. Road Traffic Noise

In the city, the main sources of traffic noise are the motors and exhaust system of

autos, smaller trucks, buses, and motorcycles. This type of noise can be

augmented by narrow streets and tall buildings.

2. Air Craft Noise

The problem of low flying military aircraft has added a new dimension to

community annoyance, as the nation seeks to improve its nap-of the- earth aircraft

operations over wilderness areas and other areas previously unaffected by aircraft

noise has claimed national attention over recent years.

3. Noise from railroads

The noise from locomotive engines, horns and whistles, and switching and

shunting operation in rail yards can impact neighboring communities and railroad

workers.

4. Construction Noise

The noise from the construction of highways, city streets and buildings is a major

contributor to the urban scene. Construction noise sources include pneumatic

hammers, air compressors, bulldozers, loaders, dump trucks and pavement

breakers.

5. Noise in Industry

Although industrial noise is one of the less prevalent community noise problems,

neighbors of noisy manufacturing plants can be disturbed by sources such as fans,

motors and compressors mounted on the outside of buildings. Interior noise can

also be transmitted to the community through open windows and doors, and even

through building walls. These interior noise sources have significant impacts on

industrial workers, among whom noise- induced hearing loss is unfortunately

common.

6. Noise in building

Apartment dwellers are often annoyed by noise in their homes, especially when

the building is not well designed and constructed. In this case, internal building

noise from plumbing, boilers, generators, air conditioners and fans can be audible

and annoying. Improperly insulated walls and ceilings can reveal the sound off-

amplified music, voices, footfalls and noisy activities from neighbouring units.

External noise from emergency vehicles, traffic, refuse collection, and other city

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noises can be a problem for urban residents, especially when windows are open or

insufficiently glazed.

7. Noise from Consumer products

Certain household equipment, such as vacuum cleaners and some kitchen

appliances have been and continue to be noisemakers, although their contribution

to the daily noise dose is usually not very large.

Harmful effects

Annoyance: It creates annoyance to the receptors due to sound level fluctuations.

The aperiodic sound due to its irregular occurrences causes displeasure to hearing

and causes annoyance.

Physiological effects: The physiological features like breathing amplitude, blood

pressure, heart-beat rate, pulse rate, blood cholesterol are affected.

Loss of hearing: Long exposure to high sound levels cause loss of hearing. This

is mostly unnoticed, but has an adverse impact on hearing function.

Human performance: The working performance of workers/human will be

affected as they'll be losing their concentration.

Nervous system: It causes pain, ringing in the ears, feeling of tiredness, thereby

affecting the functioning of human system.

Sleeplessness: It affects the sleeping there by inducing the people to become

restless and lose concentration and presence of mind during their activities.

Damage to material: The buildings and materials may get damaged by exposure

to infrasonic / ultrasonic waves and even get collapsed.

Control

The noise pollution can be controlled at the source of generation itself by

employing techniques like-

1. Reducing the noise levels from domestic sectors: The domestic noise coming

from radio, tape recorders, television sets, mixers, washing machines, cooking

operations can be minimised by their selective and judicious operation. By usage

of carpets or any absorbing material, the noise generated from felling of items in

house can be minimised.

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2. Maintenance of automobiles: Regular servicing and tuning of vehicles will

reduce the noise levels. Fixing of silencers to automobiles, two wheelers etc., will

reduce the noise levels.

3. Control over vibrations: The vibrations of materials may be controlled using

proper foundations, rubber padding etc. to reduce the noise levels caused by

vibrations.

4. Low voice speaking: Speaking at low voices enough for communication reduces

the excess noise levels.

5. Prohibition on usage of loud speakers: By not permitting the usage of

loudspeakers in the habitant zones except for important functions. Now-a-days,

the Urban Administration of the metro cities in India, is becoming stringent on

usage of loudspeakers.

6. Selection of machinery: Optimum selection of machinery tools or equipment

reduces excess noise levels. For example selection of chairs, or selection of certain

machinery/equipment which generate less noise (sound) due to its superior

technology etc. is also an important factor in noise minimization strategy.

7. Maintenance of machines: Proper lubrication and maintenance of machines,

vehicles etc. will reduce noise levels. For example, it is a common experience that

many parts of a vehicle will become loose while on a rugged path of journey. If

these loose parts are not properly fitted, they will generate noise and cause

annoyance to the driver/passenger. Similarly in the case of machines, proper

handling and regular maintenance is essential not only for noise control but also to

improve the life of machine.

8. Design of building: The design of the building incorporating the use of suitable

noise absorbing material for wall/door/window/ceiling will reduce the noise levels.

9. Green belt development: Green belt development can attenuate the sound levels.

The degree of attenuation varies with species of greenbelt. The statutory

regulations direct the industry to develop greenbelt four times the built-up area for

attenuation of various atmospheric pollutants, including noise.

10. Using protection equipment: The various steps involved in the noise

management strategy are illustrated. Protective equipment usage is the ultimate

step in noise control technology.

11. Exposure reduction: Persons who are working under such conditions will be

exposed to occupational health hazards. The schedule of the workers should be

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planned in such a way that, they should not be over exposed to the high noise

levels.

12. Hearing protection: Equipment like earmuffs, ear plugs etc. are the commonly

used devices for hearing protection. Attenuation provided by ear-muffs vary

widely in respect to their size, shape, seal material etc.

Measurement

A decibel is the standard for the measurement of noise. The zero on a decibel

scale is at the threshold of hearing, the lowest sound pressure that can be heard, on the

scale according to Smith, 20 db is whisper, 40 db the noise in a quiet office, 60 db is

normal conversation, 80 db is the level at which sound becomes physically painful.

The Noise quantum of some of the cities in our country indicate their pitch in

decibel in the nosiest areas of corresponding cities, e.g. Delhi- 80 db, Kolkata -

87,Bombay-85, Chennai-89 db etc.

WATER POLLUTION

Water Pollution

Water is an essential constituent for all types of life on earth. Next to air, water is

the most important substance for the existence of life on the earth. The pure water is one

which is free from impurities. Today water resources have been the most exploited

natural systems since man‘s existence on the earth. Pollution of water resources are

increasing due to rapid population growth, industrialization, urbanization, modernization

and wide spread human activities. Ground water, river, seas, lakes, ponds and streams are

founding it more and more difficult to escape from pollution.

Water pollution can be defined as the presence of some foreign substances or

impurities in water and by which lowing the water quality and making it unfit for use.

Thus ―Any physical or chemical changes in surface water or underground water that can

adversely affect living organisms is called water pollution.‖ The term water pollution is

also derived from latin word ‗pollus‘ which means before ‗wash‘. Before washing, water

contains impurities and hence the term water pollution is indicated contamination or

making foul the natural water resources like river, pond etc.

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Types of water Pollution – On the basis of nature of impurities, water pollution can be

classified into following four categories –

1. Physical Pollution.

2. Chemical Pollution.

3. Biological Pollution.

4. Physiological Pollution.

1. Physical Pollution – Physical pollution of water is due to the change in physical

properties of water such as colour, odour, taste, turbidity and thermal properties.

Colour of water is changed by industrial coloured waste materials like paper and

pulp, textile, and tanneries etc. Change of colour in water is harmful because it is

due to toxic chemicals.

Taste and odour is produced in water due to various salts, Fe, Mn, H2S,

Chlorine, Phenols and Unsaturated Hydrocarbons. Some micro organism like

bacteria and algae can also cause the taste and odour in water. Industrial water

containing Fe, Mn, free chlorine, phenols create bed taste and odour in water.

Decomposed organic matter, algae, fungi, bacteria and pathogens also cause bad

taste in water.

Turbidity of water comes from colloidal matter, fine suspended particles

and by soil erosion. This water becomes unsuitable for domestic and industrial

uses because it contains Fe, Mn, Co, Ni, Pb, Sb, Bi, etc which many cause stain on

cloths, sinks and baths.

The cooling water use in thermal power plants and nuclear power plants

discharges unutilized heat into the water which causes the depletion of dissolved

oxygen (D.O.) level.

Foam of water is also included in this category. The pollution of water by

foam may be serious because water containing foam is likely to carry suspended

matter and also includes pathogenic bacteria.

2. Chemical Pollution – Chemical Pollution of water is due to the change in

chemical properties of water like acidity, alkalinity or pH of water etc. It is caused

by presence of organic and inorganic chemicals, toxic dissolved and suspended

inorganic and organic compounds and gases like O2 or CO2. Organic pollutants

include fats, proteins and carbohydrates discharged from domestic and industrial

wastes. Inorganic pollution is caused by water of industrial use like fertilizers, gas

liquors, coke ovens, alkali producing industries, etc. toxic inorganic pollutants are

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free chlorine, chloramines, H2S, NH3 and salts of many metals such as Pb, Ni, Cu,

Hg, AS, Cr, U, Ba etc.

3. Biological Pollution – Biological pollution of water is mainly due to presence of

pathogenic bacteria, fungi, protozoa, viruses, parasitic worms, etc. The main

sources of biological pollutants are domestic sewage and industrial wastes, solid/

liquid human excreta and decomposable organic matter such as vegetables, fruits

etc. Contaminated water supplies frequently create infections of the intestinal

tract, polio and hepatitis, cholera etc.

4. Physiological Pollution - Physiological Pollution of water is caused by some

chemical agents like chlorine, sulphurdioxide, hydrogen sulphide, ketones,

phenols, amines, mercaptans and hydroxy benzene. Actually chlorine converts the

phenol to ortho or para chloro phenol which tastes like medicine and gives

offensive odour.

Sources of water pollution - Sources of water pollution can be divided into two

categories-

1. Point Sources.

2. Non Point Sources.

1. Point Sources – These sources are measurable discharge points. These are easily

identifiable at a single location. The point sources are industries, municipal

sewage, treatment plants, combined sewer overflow and raw sewage discharges.

This type of pollution sources can be controlled.

2. Non Point sources – These sources are diffused (plume) sources. These are the

sources of generalized discharge of water whose location can not be identified.

Ex. run-off from agriculture lands, forestry, mining, construction, urban off,

hydrologic modification and residual waste. This type of discharge of water

cannot be easily controlled.

Types of Water Pollutants and Their Adverse Effects

The Substances which are responsible for water pollution are known as water

pollutants. These pollutants can be organic, inorganic, radioactive, oxygen demanding

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wastes etc. These pollutants give adverse effect on environment. Various water pollutants

may be divided into following categories-

1. Organic pollutants.

2. Inorganic pollutants.

3. Suspended solids and sediments.

4. Radioactive pollutants.

5. Thermal pollutants.

1. Organic Pollutants – Most of the substances of which living things are composed

are organic compounds. The main source is food stuff (eg. Proteins,

carbohydrates, fats etc) a number of materials and substances necessary for

modern life style (e.g. cotton, petroleum, rubber, antibiotics etc) are organic

compounds. Their presence in water is not desirable as they impart taste, odour

and colour to water and some of them may be toxic and carcinogenic also. These

organic pollutants enter into the water system through domestic sewage, industrial

waste from paper mill, water from slughter house, meat packing plants, food

processing plants, run off from crop lands and decomposition products of organic

compounds. These pollutants may be suspended or dissolved from in water.

Suspended organic matter is due to presence of certain industrial waste or

vegetable or animals. Vegetable are in the form of algae, decayed leaves, fungi

etc, they impart acidity, green or brown colour and teste to water. Dead animals

and insects are responsible for growth of bacteria in water. This water contains

large quantity of albuminoidal ammonia, free ammonia, chlorides and different

types of bacteria and viruses. Organic pollutants may be divided as –

1. Natural organic pollutants - They came in water from decomposition of

naturally occurring organic compounds like leaves, plants, dead animals etc.

Various types of aquatic micro-organisms releasing organic compounds into a

water body through their metabolic processes also comes in this category.

All these wastes require dissolved oxygen (D.O.) for their degradation which

depletes the D.O. level of water. This reduction in D.O. level is harmful for

aquatic organization.

2. Sewage – Municipal and domestic sewage and effluents such as food processing

unit, paper mills, tanneries etc. contains a large number of organic pollutants

sewage makes water anesthetic , totally unfit for drinking domestic use sewage

contains various oxidizable and fermentable matter which cause lowing of

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anesthetic, totally unfit for drinking and domestic sewage. which affects the

aquatic for severely. Lowering of D.O. in also come objectionable odour in water.

When D.O. reaches 4-5 ppm fisher starts to die suspended matter of sewage create

a blanket on the water thereby interfering in the spawning of fish and reduces the

aquatic biota.

3. Industrial effluents- Industrial effluents are also contain various organic

compounds like tetrachloride (used as fire extinguisher), tetrachloroethylene (used

as solvent), pesticides, herbicides and many other chemicals use in industrial

process such as ethylbenzene, styrene and toluene. Most of these chemicals are

toxic to plants, animals and human beings. PCB‘s and dioxins cause cancer.

Industrial effluents containing methyl mercaptan and pentachloro phenol lowers

the photosynthetic rate of aquatic plants by hindering sunlight penetration.

Disinfectants added in water to kill algae and bacteria may persists in water bodies

and may cause mortality of fish, planktons and diatoms.

4. Synthetic organic pollutants - They are the man made materials such as

pesticides, detergents, food additives, insecticides, paints, elastomers, plasticizers,

plastics and other industrial chemicals. Most of these are toxic to plants, animals

and humans. DDT is highly stable and can persist for a long time in the

environment. It enters into the food chain becomes highly dangerous. It cause

heart, kidney etc. diseases in man. PCBs (Polychlorinated bi phenyls) are

generally used as dielectrics, lubricants and plasticizers are similar to DDT and

cause several physiological disturbances.

5. Disease-causing pollutants - They are pathogenic micro organisms which enters

into the water bodies through waste water coming from hotels, restaurants,

residential areas, human faeces matters, animal wastes, etc. They include bacteria,

viruses, protozoa, algae and helminthes. These pathogens are very dangerous for

human health and life. Various health problems caused by these pathogens are

listed below in Table 4.

Table 4.1 Health Problems Caused by Various Pathogens

S.No. Group/Name of Pathogen Disease Caused

(1) Bacteria

a. Salmonella typhosa.

Typhoid fever

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b. Salmonella Schottmulleri.

c. Vibrio Cholerae.

d. Enteropathogenic E.Coli.

e. Shigella.

f. Mycobacterium tuberculosis.

g. Other mycobacteria.

Gastroenteritis

Cholera

Gastroenteritis

Bacillary dysentery

Tuberculosis

Pulmonary illness

(2) Viruses

a. Polioviruses.

b. Coxsackie Viruses A and B.

c. Reoviruses.

d. Hepatitis A viruses.

Poliomoyelitis

Aseptic meningitis

Upper respiratory and

gastrointestinal illness

Hepatitis

(3) Protozoa

a. Balantidium Coli.

b. Entamoeba Histolytica.

c. Giardia lamblia.

Dysentery

Amoebic dysentery

Giardiasis

(4) Algae (blue green)

a. Anabaena flos-aquae.

b. Microcystis aeruginosa.

c. Schizothrix calciola.

Gastroenteritis

Gastroenteritis

Gastroenteritis

(5) Helminths

a. Dracunculus medinensis.

b. Echinococcus.

c. Schistosoma.

Dracontiasis

Echinococcosis

Schistosomiasis

6. Oil - Oil is a naturally occurring mixture of thousands of different hydrocarbon

compounds. Water pollution due to oil takes place because of oil spills from cargo

oil tankers on the seas, losses during off shore exploration and production of oil,

accidental fires in ships and oil tankers, and leakage from oil pipe lines. Insoluble

oils spreads over the water surface, and forms a layer which restricts light

transmission through surface waters, thereby reducing the photosynthesis of

marine plants. This reduces the D.O. level and cause a deleterious effect on

marine organisms. While soluble oil forms a milky emulsion which is quite stable

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and non-destroyable. These emulsion coat the gills of fish affecting their

respiration.

7. Organic pollutants - It can also be divided into two categories-

(i) Biodegradable (ii) Non-biodegradable

Biodegradable Organics - The organic compounds which degrade very rapidly in

a natural environment or man-made environment are called biodegradable

organics. Biodegradable organic pollutants include proteins, fats, carbohydrates,

polymers, resins, coal, oil and various other organic substances found in domestic

and industrial wastes.

Impact of Biodegradable Organics in Water - The most common biodegradable

organics are fats, proteins and carbohydrates. They are introduced into the water

through domestic sewage, industrial wastes from paper mills and tanneries, waste

from slaughter house, meat packing plants and food processing plants. They can

be either in the suspended from or dissolved from. Suspended vegetables such as

algae, decayed leaves, fungi, etc., impact acidity, green or brown colour and taste

to water. Suspended animals such as insects and dead animals are responsible for

the growth of bacteria and even viruses. This water contains large quantity of

albuminoidal ammonia, but small quantity of free ammonia and chlorides.

Thermal decomposition of fats, oils and glycerol forms various aldehydes

such as acetaldehyde, benzaldehyde, formaldehyde, furfural and vanillin, etc.

These compounds cause odour in water, inhibit algal growth and are toxic to fish

and other aquatic animals.

(i) Non-biodegradabie Organics - The organic compounds which do not degrade

naturally or degrade at a very slow rate are termed as non-biodegradable organics.

They remains in the aquatic ecosystem for a long time. They are pesticides,

fungicides, herbicides, insecticides, rodenticides etc. Theses non-biodegradable

organics are toxic and once they found their way from crops to nearby water

sources can cause a serious pollution problem.

8. Inorganic Pollutants - Inorganic water pollutants consist inorganic salts, metallic

compounds and complexes, mineral acids, organo metallic compounds and poly

phosphates detergents. Inorganic pollutants may be categorized in following

categories-

(i) Acids and Alkalis - Industries manufacturing hydrochloric, nitric, sulphuric,

phosphoric acids, sulphur dioxide, oxides of nitrogen, chlorine, ammonia and

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bases of Na, K, Ca etc., discharge a huge amount of acids and alkalis in water

system. These acids and alkalies destroy the bacteria and other micro organisms in

water.

(ii) Toxic Inorganic Compound - These are derived from industrial wastes of

industries producing fertilizers, coke ovens, gas liquors, alkalis, etc. They includes

salts containing anions of carbonate, acetate, nitrate, nitrite, fluoride, chloride,

sulphate, phosphate and sulphides of Cu, Cd, Zn, Mn, Pd, Sn, Fe and As etc.

Toxic compounds also include free chlorine, H2S, NH3.

(iii) Toxic Metals – Traces of heavy metals such as Hg, Cd, Pb, As Co, Mn, Fe and

Cr have deleterious effects on aquatic ecosystems and human health. They are

introduced into the water bodies from industrial processes, domestic sewage land

run off and fossil fuel burning. Detrimental effects of some toxic metals are

discussed below.

Mercury (Hg) is highly toxic, its compounds which are very volatile or

soluble cause potential hazards to man. It cause well known Minamata disease.

Lead (Pb) comes in water from steel and paint industries burning of

gasoline (containing TEL). Lead when enters into the food chain may cause death

of children and of infants due to brain damage. In adults it can cause anemia,

kidney, mental retardation, abnormal pregnancy, etc.

Cadmium even in concentrations less than 1 mg /l it is toxic. It presents in

water as suspended particles of hydroxides sulphates, etc. Cd can accumulate in

lever and kidney and can cause hypertension, emphysema, kidney damage and

weakening of bones.

9. Suspended solids and sediments - Soil erosion by natural and anthropogenic

processes (such as mining agricultural and constructional activities) deposits a

large amount of sediments in water. Industrial effluents contains various organic

and inorganic particles or immiscible liquids remains suspended in water and

effects its turbidity. The suspended solids effects taste, odour and colour of water

while bottom sediment can cause anaerobic conditions. Bottom sediments are

deposition of trace elements and heavy metal. These particles reduce direct

penetration of sunlight which reduces photosynthesis in aquatic plants and hence

decreases the D.O. in water. Toxic metals like Hg, Cd, Pb, can attack sulphur

bond in enzymes of aquatic and cause immobilizing effect.

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10. Radioactive pollutants - Radioactive pollutants enter into water bodies from

nuclear power plants, nuclear reactors, nuclear installations, fission and fusion

product nuclear tests etc. Extremely toxic radioactive Pu, Np, Cm, Cs, Zr, Ru, etc.

are produced from neutron bombardment of atomic fuel. Though all of radioactive

pollutants are carcinogenic the radio nuclides of most concern are Uranium 235,

238, Radium 226 and 228, radon and Thorium 230 and 232. In aquatic animals

radiation damage makes cell permeable membranes, which results in temporary or

permanent injury in them. The radioactive pollutant deactivate enzymes by

breaking S-H-S hydrogen bonds, due to this enzyme inhibition, cell division may

be stopped.

11. Thermal pollutants - Water is the most commonly used coolant in various

industries because of its low cost and good thermal properties. This heated water

when discharged to water bodies causes thermal pollution. These pollutant include

waste from atomic, nuclear and thermal power plants. The discharge of this

unutilized heat adversely affects the aquatic environment. The amount of

dissolved oxygen in water decreases with the rise in temperature, while activity of

biological life is more at higher temperature hence requires more D.O. This may

be fatal for aquatic life. Some animals and aquatic animals are killed outright by

hot water. It cause direct fish mortality due to failure of respiratory or nervous

system. High temperature accelerates the activities of pathogenic organisms,

which makes pathogens more virulent and fishes less resistant. It causes rapid

settling of sediments which affects the aquatic food supply.

Eutrophication

The phenomenon of becoming rivers and lakes highly productive is known as

eutrophication. The word eutriphication has been derived from the Greek word eutrophou

means well nourished or enriched. Entrophication of a water body may takes place by

both natural and anthropogenic sources.

Ponds and lakes during their early stage of formation are relatively barren and

nutrient deficient, thus supporting no or very poor aquatic life. In this state water bodies

are known as oligotrophic. Nutrient content of water body increases slowly by natural

processes such as surface run-off, organic debris plant's excreta and marine organisms

excreta. Bacteria and blue green algae fix atmospheric N and P in bottom rocks becomes

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soluble in water due to microbial activity. At this stage a moderate population of plants

animals and microbes develops in the system, which further increases with nutrient

enrichment. This process of natural eutrophication is accelerated by addition of domestic

and industrial sewage and agricultural run-off (mainly fertilizers containing phosphates

and nitrates). This accelerates the growth of algae and other water plants and the whole

system becomes highly productive i.e. eutrophic. Due to this accelerated eutrophication

water system turns into a shallow muddy pond, then to a marsh and finally into a dry

land.

CHARACTERISTIC OF WASTE WATER

Physical characteristics -Various physical characteristics of waste water are discussed

below.-

(i) Turbidity – Sewage in normally turbid resembling dirty dish water or waste from

baths, having other floating matter like pieces of paper, cigarette-ends, match –

sticks, greases, fruit skins etc. Turbidity of waste water shows that some amount

of solid matter is present in suspension it also indicates stag of sewage, the

turbidity increases as sewage becomes stronger.

(ii) Colour and Odour :- Colour and odour indicates the condition of sewage as it is

fresh stale or septic. Colour of fresh domestic sewage is grey. If the colour is

black or dark brown it indicate stale or septic sewage. Fresh sewage is practically

odourless. It starts to give offensive smell of hydrogen sulphide after 2 to 6 hours

when it become stale.

(iii) Temperature – The temperature of sewage is slightly higher than ordinary water.

The temperature effect on the biological activity of bacteria presents in sewage.

The average temperature of sewage is 20 to 25oC which is an ideal temperature for

the biological activities.

(iv) Solids – Generally sewage contains 99.9% of water and 0.1% solids in the form

of suspended solid dissolved soild colloidal solid and settleable solids. Suspended

solids are those solids which remains floating in sewage dissolved solids are those

which remains dissolved in sewage. Colloidal solid are finely divided solids

remaining either in solution or in suspension. Settles solids are that portion of

solid matter which settles out, if sewage is remain undisturbed for a period of 2

hours.

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Chemical characteristics - Various chemical characteristics of waste water are discussed

below-

(i) pH value – pH value determine whether sewage is acidic or alkaline. Fresh

sewage is generally alkaline having pH value in the range of 7.3 - 7.5 . But after

some time, its pH value lowers due to formation of acids by bacterial action.

However after oxidation, when sewage become relatively stable, it again

becomes alkaline. pH value of sewage helps in determination of amount of

coagulant and disinfectant needed and in its biological treatment.

(ii) Dissolved oxygen (D.O) – Oxygen is one of the most commonly dissolved gases

in water. Dissolved Oxygen (D.O) represents the amount of oxygen dissolved in

water. Oxygen can be dissolved in water through-

(a) Atmosphere , by natural aeration.

(b) Photosynthesis, by algae.

(c) Mechanical equipments during treatment of water.

Natural water always contains some amount of oxygen dissolved in it. The

solubility of oxygen is directly proportional to the pressure and inversely proportional to

the temperature. Solubility of oxygen also decreases with amount of salt contain in water.

The measurement of D.O. helps to determine purity of water. Clean surface waters

are generally saturated with D.O. while sewage generally has no D.O. presence of D.O. in

sewage indicates either it is fresh or its considerable oxidation has occurred due to sewage

treatment methods.

Dissolved oxygen (D.O.) is essential for the support of fish and other aquatic life

in water bodies. D.O. content in water can be determine by using Winkler‘ methods,

which is an oxidation- reduction process carried out chemically to liberate iodine in

amount equivalent to the dissolved oxygen.

All the wastes undergo decomposition and degredation due to bacterial activity

and deplete the dissolved oxygen (D.O.) from the water D.O. is a fundamental

requirement for the maintenance of aquatic life. Decrease in D.O. is an indication of

water pollution. Depletion of D.O. is disastrous as it destroys fish as well as other aquatic

animals including their habitat.

(iii) Biochemical oxygen demand (BOD) - BOD represents the quantity of oxygen

required by bacteria and other micro-organisms during the biochemical

degradation and transformation of organic matter present in waste under aerobic

conditions.

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The biochemical oxygen demand is a measure of oxygen utilized by the

micro-organisms during the oxidation of organic materials. BOD is a direct and

the most widely known measure for oxygen requirements and an indirect measure

of biodegradable organic matter. Inspite of its inherent limitations BOD test is still

valued as the best test for assigning organic pollution, it is considered as the major

characteristic used in stream pollution control. It gives very valuable information

regarding the purification capacity of streams and serves as a guideline for the

regulatory authorities to check the quality of effluent discharged into water bodies.

The BOD test essentially consists of measurement of dissolved oxygen

content of the sample before and after incubation at 200C for 5 days. if the sample

does not contain oxygen is supplied to it and BOD is measured.

= post O2/ million parts of sample

Limitations of BOD Test

1. Before BOD test the pre - treatment of sewage is necessary it is also contains toxic

wastes.

2. The test is applicable only in the case of biodegradable organic matter.

3. A high concentration of active bacteria is necessary to be present in the sample of

sewage.

4. Before applying BOD test the effects of nitrifying organisms are to be reduced.

5. The time required for the test is long as well as arbitrary.

6. There is no validity of the test after the soluble organic matter present in the

sewage sample is utilized.

Chemical oxygen demand (COD)

The chemical oxygen demand is a measurement of oxygen equivalent to that

portion of organic matter present is the waste-water sample that is susceptible to

oxidation by potassium dicromate.

The COD test is carried out to measure the content of organic matter of sewage

and natural waters. The test gives a good idea of the amount of organic matter present in a

stream.

The test involves the oxidation of organic matter in the sample with a known

excess of K2 Cr2 O7 in a 50% H2SO4 solution in the presence of AgSO4 (as catalyst) and

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HgSO4 (to eliminate interference to chlorine). It is then boiled for two hours. It is then

cooled and the excess dichromate is measured by titrating with a standard solution of

ferrous ammonium sulphate.

Sample + K2Cr2O7 AgSO4 (Catalyst) CO2 + Water + Ammonia

(From (in excess) HgSO4 (for suppression of chlorine)

Sewage) H2SO4 (for acidic medium)

K2Cr2O7 + Ferrous Ammonium Titration Salt

(remaining) Sulphate

(of normality N)

COD is measured (calculated) by the formula

COD in mg/L = (V1-V2)N x 8 x 100

X

Where V1 and V2 are volumes of Ferrous Ammouium Sulphate (of Normality N and X is

the volume of sample taken).

WASTE WATER TREATMENT

The objective of waste water treatment is removing the pollutants from water

before discharging it into a steam. After the treatment of waste water it can be reused or

discharged into a receiving stream. The waste water treatment processes are expensive

and depend upon the quality of water required. The waste water treatment processes are

usually classified as -

1. Primary Treatment (Physical treatment).

2. Secondary Treatment (Biological treatment).

3. Tertiary Treatment (Chemical treatment).

Primary treatment (Physical treatment) - It is a mechanical process in which waste

water passes through a screen for filtering sticks, stones and floating or suspended

materials. Suspended solids of waste water are settled down in the form of sludge in the

sedimentation tank. By this treatment 60% of suspended solid, 30% of oxygen demanding

waste, 20% of nitrogen compounds, 10% of phosphorus compounds are removed. This

process involves the following steps:

1. Screening. This process is used for removing suspended impurities. Grit- settling

chamber is used after screening. Removal of gross solids is generally

accomplished by passing waste water through mixed moving screens. These

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screens are present in the different forms such as screen hand raked screen, drum

screen etc. the raw water is passed through screen, having large number of holes

when floating matters retained by them. (fig. 4.1)

2. Sedimentation – Gravitational settling is employed to separate settle able solids.

The process is carried out in a large tank where the solids settle at the bottom in

the form of a sludge is removed either by various sections or mechanical means.

The clear liquid formed is known as the overflow which done not contain any

settle able solid.

Fig. 4.1 : Grit Chamber

Sedimentation is a process of allowing water to stand undisturbed in high tanks,

about 5 m deep, when most of the suspended particles settle down at the bottom, due to

the force of gravity. The clear supernatant water is then drawn from tanks with the help of

pumps. The retention period in sedimentation tank is from 2-6 hrs. When water contains

fine clay particle and colloidal matter, it becomes necessary to apply sedimentation with

coagulation for removing such impurities.

Fig. 4.2 : Sedimentation Tank

Parallel bar

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Sedimentation tanks

Sedimentation operation in waste treatment applications may be carried out in

rectangular, horizontal flow, circular radial flow or vertical basins. In first types tanks,

feed is introduced at one end along the width of the tank and the overflow is collected at

the surface. An endless conveyor scrapes the floating material into a screen through while

it also pushes the settled solids into a sludge hopper. The settling of particles in a

suspension depends upon their concentration and their flocculating properties.

1. Flotation - Flotation process is used for the treatment of industrial waste water. It

contains finely divided suspended solids and oily matter. Sedimentation process is not

allowed for all small particles whose densities are close to water. In this case the effluent

is aerated and the solid particles float to the surface and can be easily removed. Chemical

coagulants are used to help in this process.

Fig. 4.3 : Primary treatment

Secondary treatment (Biological treatment) - In a biological treatment, aerobic bacteria

is used to remove biodegradable organic wastes. It remove up to 90% of the oxygen

demanding wastes. The degraded material settles out in secondary settling tanks. The

96

sediment containing the microbial growths and their by product is called secondary

sludge or activated sludge. The treated water is then discharge in the nearby water bodies.

Some of the sludge is returned to aeration tanks where it is recycled with incoming waste.

Aerobic and anaerobic biological treatment are used to complete biological treatment.

Fig. 4.4 : Secondary treatment

Biological Treatment

Aerobic treatment Anaerobic treatment

Oxidation Aerated Trickling Activated Single digester Septic tanks

Pond lagoon filter sludge

(1) Aerobic Treatment – In this process micro- organism like bacteria, algae, fungi

etc. consume organic substances as a food and converted into biomass. In the

waste water different types of matters are present hence they need different

microbes for their proper treatment. Aerobic biological treatment may be

completed by the following process:

(a) Oxidation pond - Waste water is purified with the help of algae and aerobic

bacteria in the oxidation pond. In this pond aerobic bacteria decompose organic

matter where as algae consume the food and decrease BOD of waste water by

release of oxygen gas. This pond is not useful for Indian climate.

(b) Aerated lagoon - Effluents from primary treatment process are collected. Aerated

lagoon are aerated by floating aerators. Floating aerator maintains aerobic

97

environment for preventing the biomass to settle. By this method good flocculent

sludge is formed and 90% BOD can be removed. This process is oldest process.

Fig. 4.5 : Aerated lagoons

(c) Trickling filter - This consists bed of coarse material (stones, salts, PVC). The

waste water is distributed overt the surface of stone by a rotating arm. The filter is

arranged in a fashion by which air can entire at the bottom. Aerobic bacteria

purify sewage by forming a bacterial film around the particles of the filtering

media. Sufficient quantity of oxygen supplied for providing suitable aeration to

the filter. The microbial film formed is very sensitive to temperature and the

efficiency of the filter depends upon the composition of the waste, pH depth of the

filter etc. The effluent obtained from this is used by the secondary sedimentation

tank. Filter are effectively used for the treatment of dairy, distillery, food

processing, slaughter house, pharmaceutical wastes etc. The effluent of filter is

nitrified and removes about 70-80% of BOD.

Disadvantage

1. Decrease in efficiency by increasing load of waste water.

2. Cost of construction.

3. Need for ventilation ducts for the under-drain system.

(d) Activated Sludge process – In this process a mixture of waste water and

microorganisms are agitated and aerated. By this process an active mass of

microbes is formed which is called activated sludge. The aerobic bacteria bring

about biological digestion of the waste into CO2 and H2O, the effluent from the

98

aerated tank is separated from the sludge by setting and discharged from it. Some

part of this sludge is recycled to the aerated tank for further microbial process. A

BOD removed to the extent of 90-95% can be achieved by this process. It is best

method for biological treatment.

Fig. 4.6 : Trickling filter

Advantage

1. By this process no fly or odour nuisance occurs.

2. Minimum area required for this process.

3. It gives clear sparkling treated liquid.

4. By this loss of heat is minimum.

Fig. 4.7 Activated sludge plant

Disadvantage

1. It needs maintenance and careful attention.

2. It has high sensitivity to shock loads of toxic and organic substances.

(2) Anaerobic Treatment

In anaerobic process 95% biodegradable carbon is decomposed into biogas and

5% into biomass.

99

(i) Sludge Digesters - In this process complex organic matter of sludge is changed

into simple-compound through bio-chemical reactions. Sludge constituents

undergo slow fermentation process by anaerobic reaction. Microbes which are

responsible for anaerobic treatment are actinomycities, aerobector, lactobacillus

etc. By this process different fractions are obtained which are :

1. Digested Sludge . this is settled at bottom of the tank and used as a

2. Decomposition gases such as CH4 ,CO2, NO2,H2S and used as a fuel in

power generation.

3. Supernatant liquid –It is a solid matter present and used for irrigation.

Fig. 4.8 Anaerobic sludge digestion process.

60-70% of suspended smatter is settled as bottom of the tank. Organic matter of

sludge is decomposed interfere liquid, offensive smell occurs due to the digestion

process. It removes about 90% of BOD. Working of septic tank is unpredictable and the

uniform.

Advantage of anaerobic treatment

1. Anaerobic digestion reduces waste volume by 65%.

2. Digested sludge is used as manure.

100

Fig. 4.9 : Flow Chart of Secondary Treatment

3. Gases obtained from this treatment can be used as a fuel and for power generation.

4. The operation and maintenance costs are less in this treatment.

Tertiary Treatment (Chemical Treatment)

Tertiary treatment or advanced treatment is a process by which specific quantity

of pollutants can be reduced. By the tertiary treatment fine suspended solid particles,

microorganism, dissolved and solids inorganic and organic chemicals are removed. A

many techniques are available which depends upon the nature of pollutions . In the

tertiary treatment process following steps can be used -

(i) Coagulation : Certain chemicals are rapidly dispersed in waste water to change

the characteristics of the suspended particles. Due to this, particles coalesce and

from flocs which sink rapidly. Negatively charged colloidal suspensions are

removed by coagulation. Coagulation is most effective and economical means to

remove impurities.

For industrial waste water coagulation is used for oily emulsions, a settle

able solids such as pigments, paper, fiber, tannery effluents. The most widely used

coagulants for waste water treatment are Hydrated lime alum

(K2SO4.Al(SO4)3.24H2O) Ferric chloride, chlorinated coppers mixture of ferric

sulphate and chloride. At high pH these coagulants produce insoluble Al2 (OH)3

or Fe (OH)3flocs.

101

2 4 3 2 3 2 4

2 4 3 2 4 2 3

2 3 2 2

2 4 3 3 2 3 4 2

( ) 6 2 ( ) 3

3 3 ( ) 3 6

6 6 6

( ) 3 ( ) 2 ( ) 3 6

Al SO H O Al OH H SO

H SO Ca HCO CaSO H CO

H CO CO H O

Al SO Ca HCO Al OH CaSo CO

At low concentration of colloidal matter flock formation is difficult. In

these cases coagulants (Polyelectrolyte‘s) are added to promote flock formation.

Coagulation and flocculation can remove both suspended and colloidal solids.

After flock formation the solution is transferred to settling tank where

flocks are settled down.By the filtration flock can be removed. In this way several

filters of different porosity graded in the direction of water flow are used.

Fig. 4.10 : Tertiary Treatment

(ii) Chemical oxidation . In this method oxidizing agents such as chlorine, ozone etc.

are widely used for disinfection. Removing organic material which produces

hypochlorous acid which is powerful germicide. This hypochlorous acid reacts

with reducing agent and destroys pathogenic bacteria.

2 2

3 2 2

.

Cl H O HCl HOCl

NH HOCl NH Cl H O

Bacteria HOCl Killed pathogenic Bacteria

Ozone is also powerful oxidizing agent and acts and as an efficient disinfectant.

It is used for removal of colour, taste, odour of waste water. Ozone is effective in

the oxidation of many complex organic materials such pesticides, surfactants etc.

But this process is costly.

102

(iii) Ion Exchange - It is effectively used in removing hardness and Mn, Fe salts from

potable water. Trace metals Cu, Cr, Pb, Ni, etc. present in industrial waste water

can be removed by ion exchange method. It is economical only when the

recovered salts are reused in the process. Special ion exchangers are used for

retrieval of toxic metal ions from industrial waste water. Except these methods

some other methods are also used for advanced treatment of waste water. These

are Evaporation, Adsorption, Reverse Osmosis, Chemical precipitation method

etc.

Industrial Waste Water Treatment

Industrial waste water which mainly contents toxic and non-biodegradable

chemicals can be purified by two methods which are as follows:

(i) Filtration by Activated charcoal/Synthetic Resins – Activated charcoal with

large surface area is quite and effective filter medium for adsorption of organic

compounds. It can reduce concentration of chlorinated hydrocarbons by 99%.

Synthetic organic ion exchange resins are used for removal.

(ii) Membrane Techniques- The ion exchange membrane techniques are used for

removal toxic wastes by ultra filtration or reverse osmosis. In ultra filtration, the

solution is pushed under pressure through a membrane which contains pores of

size 2 to 10,000 mm, which stops big molecules make effluent free of them. In

reverse osmosis, the membrane pores are much smaller 0.04 to 600 mm in size.

These techniques are used for purification of waste from metal textile, paper, pulp

and food industries. Electro dialysis is another membrane technique which is used

to reduce concentration of ions.

Some common industries, pollutant contained in their waste water and their

treatment are discussed below-

(1) PAPER AND PULP INDUSTRY

Waste – The raw material for paper industries are cellulosic materials such as wood,

bamboo, cotton liners, bags , straw, jute and hemp. Various operations of these industries

such as raw materials preparation, pulping, washing bleaching, chemicals recovery,

screening of pulp and paper making utilizes, various chemicals such as sulphites, phenols,

free chlorine, methyl mercaptan, pentachlor phenol. All these chemicals are found is then

effluent. Waste water from paper industries is dark brown in colour, highly alkaline has

103

high content of suspended and dissolved solids high COD (about 1500 mg/l) and contains

lignin which is highly resistant to biological oxidation.

Harmful effects

(1) Chemicals present in waste water are harmful to flora and fauna of water streams.

(2) Dark brown colour of effluent due to lining compounds, inhibits photosynthesis

and other natural self purification processes of water stream.

(3) High oxygen demand depletes D.O. level to a dangerous value.

Treatment – First of all lignin is recovered as a useful by-product by chemical recovery.

The waste water is then chemically treated with lime for colour removal. Activated

carbon at pH lower then 3 can also be used for this purpose. Most of the suspended

particles can be removed by screening, coagulation, sedimentation and flocculation.

Dissolved organic matter can be removed by lagooning and activated sludge process.

Fertilizer Industries

Wastes- Fertilizer industrial waste contain various nutrients, e.g. P,N,K and their

salts and various acids (such as H2SO4, HNO3,H3PO4 and HCl). They also contains high

amount of F (over 1000 mg/l), Cr, Cyanide and NH3, AS and oils. Fertilizers such as urea,

ammonium sulphate, ammonium nitrate, super phosphate etc.

Harmful Effects

(1) Acids and alkalies can destroy the normal aquatic life.

(2) Arsenic, flourides and ammonia salts are toxic to the fishes.

(3) Amines besides being toxic to the fishes also deplete the dissolved oxygen of the

water body.

(4) Nitrogen and other nutrients present in waste water encourage growth of aquatic

life which further reduces D.O. level of water body.

(5) Make the water body unfit for use as a source of drinking water in the downstream

side.

Treatment - NH3 can be removed by sedimentation, neutralization, waste segregation

and biological methods. F and P can be removed by precipitating with chalk, lime or

double lime treatment. Cr can be removed by its reaction with SO2 in acid medium

followed precipitation of Cr(OH)2 by lime treatment. Urea can be removed by thermal or

enzymatic hydrolysis.

104

Sugar Industry

Wastes- Main wastes of sugar industries are carbonaceous matter, acids and suspended

solids. They comes into the effluent by spillage from sugarcane juice extraction, wash

water from filters, floor washing and spillage from pan boiling. The effluent has variable

pH, high B.O.D. and odour.

Harmful Effects

(1) High pH value disturbs the natural ecosystem of water.

(2) High B.O.D. results in depletion of D.O. Carbonaceous matter provides nutrient

for algae growth.

(3) Suspended solids impart turbidity.

Treatment - pH value can be balanced by neutralization, while B.O.D. can be remove by

aerobic oxidation. To remove various organic matters suspended or dissolved lagoons and

oxidation ponds can be used.

Leather Industry

Wastes - Effluent from leather tanning industries is highly acidic, contains a lot of NaCl.

It also contains alkalis, sulphides, lime, CaCO3. dirt, dung, organic matter such as animal

skin, flesh, hair etc. These organic matters and suspended solid impart dark colour and

bad odour. It has high B.O.D. in the range of 4000-9000mg/l and sometimes up to

12000mg/l.

Harmful Effects

1. The acidic or alkaline effluent are corrosive to concrete and metal pipes.

2. Water contains high NaCl can not be used for irrigation.

It imparts dull brown colour to receiving water, makes it anesthetic.

3. Suspended solids such as animal flesh, hair and CaCO3 may choke the sewage

pipes. They also interfere with the photosynthesis of aquatic flora.

4. Chromium and sulphide salts are highly toxic to micro organisms.

5. Dissolved protein such as albumin, imparts repulsive odour.

Treatment - Suspended impurities like animal hairs, flesh and CaCO3 can be removed in

primary treatment using screens and then sedimentation. Secondary treatment includes

chemical coagulation (without neutralization). This is followed by a biological treatment,

in which anaerobic lagoon may be followed by an aerated lagoon.

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Textile Industry

Wastes - Waste water from textile industries contains starch, polyvinyl alcohol, various

acids and alkalis, organic solvents, resigns, dyes, oils, phenols chromium salts, etc. This

water possesses a high B.O.D. and C.O.D.

Harmful Effects

1. This water has high pH value which is dangerous to aquatic life.

2. High B.O.D. due to of starch sulphides and nitrites, duplets the D.O. level.

3. Dyes impart colour and interfere with the photosynthesis of phytoplankton.

4 Oil film also interfere with oxygenation of water streams .

5 Colloidal and suspended impurities cause turbidity.

6. Dissolved impurities cause corrosion of metallic parts of the sewage treatment

plants.

Treatment - Coarse suspended matter can be removed by using screens while grease and

oil can be removed by using skimming tanks. Colour causing impurities can be removed

by chemical coagulation. Finely suspended and colloidal impurities can be removed by

aerobic biological treatment (e.g. trickling filter activated sludge process). Tertiary

treatment can also be given, if required to reduce the acidity or alkalinity of waste water,

it have to be neutralized. This is known as neutralization. Acidic wastes can be

neutralized by using lime stone or lime slurry or caustic soda while alkaline waste may be

neutralized by using H2SO4 or CO2 or boiler flue gases.

Distilleries

Wastes - Distilleries (wines alcohols and brandy producing industries) waste water is

highly brownish yellow coloured. It contains high concentration of chloride and

sulphates. Their BOD is very high.

Treatment - Waste contains very high polluted yeast sludge. It requires biological

anaerobic and aerobic treatment.

Pharmaceutical Industries

Waste - They producing antibiotics and synthetic drugs reject waste which may be either

acidic or alkaline. It contains high total solids, BOD and COD.

Treatment – It consists neutralization with lime, anaerobic digestion and conventional

aerobic biological processes.

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Some case studies of water pollution

The problem of water pollution due to discharge of domestic and industrial wastes

into an aquatic system has already become a serious problem in the country. Nearly 80%

of Indian‘s population is exposed to unsafe drinking water. In many capitals millions of

liters of sewage and industrial effluents are being discharged into the sea and water

courses without any treatment. In the last stretch of the Kally river near Kalyan town,

water becomes highly acidic with a pH of 1.5. Similar acute conditions prevail in many

rivers at other industrial zone e.g. Hooghly near Kolkata, Damodar near Asansol and

Durgapur, Gomati near Lucknow, Kanpur, and Yamuna near Agra and Delhi.

Water borne diseases such as infective hepatitis, poliomyelitis, cholera, diarrhea,

typhoid, dysentery etc. have been successfully controlled in the developed countries but

these are still assuming epidemic proportion in India. These diseases are due to the water

pollution.

Indian Drinking Water Standards

Indian standard for drinking water as per ISO: 10500- 1991 are given in Table 4.1

Table 4.1 Physical and Chemical Standards for Drinking Water

S.

No.

Characteristics Acceptable Tolerable in the absence of

alternative and better source up to

1. Turbidity (NTU units) <10 25

2. Colour (Hazen Scale) <10 50

3. Taste and odour Unobjectionable objectionable

4. pH 7.0-8.5 6.5-9.2

5. Total dissolved solids (TDS) 500 1500

6. Total Hardness (CaCO3)(Mg/l) 200 600

7. Chlorides (Cl-)(Mg/l) 200 1000

8. Sulphates (SO-4) (Mg/l) 200 400

9. Fluorides (F)(Mg/l) 1.0 1.5

10. Calcium (Ca)(Mg/l) 75 200

11. Nitrates (NO-3) (Mg/l) 45 45

12. Magnesium (Mg) (Mg/l) <30 Depends upon sulphates (Both are

related)

13. Iron (Fe) (Mg/l) 0.1 1.0

14. Manganese (Mn) (Mg/l) 0.05 0.5

107

15. Copper (Cu) (Mg/l) 0.05 1.5

16. Zinc (Zn) (Mg/l) 5.0 15.0

17. Phenolic compounds 0.001 0.002

18. Anionic detergents (MBAS) 0.2 1.0

19. Mineral oil 0.01 0.3

Toxic Materials

1. Arsenic (As) (Mg/l) 0.05 0.05

2. Cadmium (Cd) (Mg/l) 0.01 0.01

3. Chromium (Cr6+

) (Mg/l) 0.05 0.05

4. Cyanides (CN-) (Mg/l) 0.05 0.05

5. Lead (Pb) (Mg/l) 0.1 0.1

6. Selenium (Se) (Mg/l) 0.01 0.01

7. Mercury (Hg) (Mg/l) 0.001 0.001

8. Polynuclear aromatic

Hydrocarbon (PAH) (Mg/l)

0.2mg/l

(mg/l micro

gram/lit)

0.2mg/l

Radioactivity

1. Gross Alpha activity 3 pci/l 3 pci/l

2. Gross Beta activity 30 pci/l 30 pci/l

SAMPLING

The significance of a chemical analysis depends to a large extent on the sampling

programme. An ideal sample should be one which is both valid and representative. These

conditions are met by collection of samples through a process of random selection. This

ensures that the composition of the sample is identical to that of the water body from

which it is collected and the sample shares the same physiochemical characteristics with

the sampled water at the time and site of sampling.

Table 4.2 : Typical analysis of some surface and ground waters :

Constituents ppm A B C

Silica 9.5 1.2 10

Iron (III) 0.07 0.02 0.09

108

Calcium 4.0 36 92

Magnesium 1.1 8.1 34

Total hardness 14.6 123 169

Sodium 2.6 6.5 8.2

Potassium 0.6 1.2 1.4

Bicarbonate 18.3 119 339

Sulphate 1.6 22 84

Chloride 2.0 13 9.6

Nitrate 0.41 0.1 13

Total dissolved solid 34 165 434

The relevant factor for any sampling program are (a) Frequency of sample

collection (b) Total No. of samples (c) Size of each sample. (d) Site of sample

collection (d) Method of sample collection (e) Data to be collected with each sample

(f) Transportation and care of samples prior to analysis.

For analyzing of Natural and Waste water, two principal types of sampling

procedures are employed:

1. Spot or grab samples are discrete portions of water, samples taken at a given time.

A series of grab samples.

2. Composite samples are essentially weighted series of grab samples, the volume of

each being proportional to the rate of flow of the water stream at the time and site

of sample collection.

Preconcentration techniques:

1. Carbon absorption method.

2. Freeze Concentration.

3. Solvent Extraction.

4. Ion Exchange.

Treatment of extractable metal is done as follows : At the time of collection, the

water sample is acidified with conc. HNO3 (5 ml/l) before analysis the sample is well

mixed and 100 ml aliquot is taken in a beaker or flask. 5 ml of red distilled HCl is added.

The sample is heated to near boiling for 15 mins. and then filtered. The volume of the

filtrae is made up to 100 ml with distilled water and subsequently analyzed by AAS.

109

Preservation

It is essential to protect samples from changes in composition and deterioration

with aging due to various interactions. The optimum sample-holding times range from

few for parameters such as pH, temperature and D.O. to one week for metals.

These are essential for retarding biological action, hydrolysis of chemical

compounds and complexes and reduction of volatility of constitutes. It is desirable for

accurate results, that analysis must be undertaken within 4 hrs., for some parameters and

24 hrs for other from the time of collection, and it must be concluded within a week.

The bottles for sample collection should be thoroughly cleaned by water with 8M

HNO3, followed by repeated washing with deionized distilled water for bacteriological

examination.

Soil Pollution

Soil is defined as the naturally occurring unconsolidated mineral or organic

material at the surface of the earth. The word ‗soil‘ has derived from Latin word ‗solum‘

which means floor or ground. It is the top covering of the solid crust of the earth's land

mass, it is made up of broken down rock materials, of various kinds of changed in varying

degree from the parent rocks by action of different agencies. Soil is defined as more or

less loose and crumby part of the outer earth crust.

Soil is one of the most significant ecological factor. It is a store of minerals, a

reservoir of water, a conserver of soil fertility, a producer of vegetative crops, a home of

wild life and livestock. The food that we eat, the fiber which makes our cloths, the

materials used in making of house and buildings, all are originated from the plants, that

grow in the soil. It also provides nutrients, water, minerals to these plants. The soil

facilitates homes and environmental conditions for living beings. It also helps in

decomposition of organic wastes by various soil micro organisms. Thus all life essentially

depends upon the soil, there can be no life without soil.

Soil Pollution – Soil or land pollution refers to ―Alteration in physical /chemical

/biological properties of soil, which interferes its beneficial use. Thus soil pollution is

defined as the build-up in soils of persistent toxic compounds, chemicals, salts,

radioactive matter, disease causing micro organisms, which have adverse effects on plants

growth and animal health‖.

110

Soil pollution is the contamination of soil system by considerable quantities of

chemical or other substances, resulting in the reduction of its fertility or productivity with

respect to qualitative as well as quantitative yield of the crops.

Soil Profile

At any place where parent material is weathering over a period of time, here develop

layers of soil one over the other in progressive state of maturity. The vertical section of

such type of soil is called soil profile. This is characteristic of mature soil and are made

up of different horizons. These horizons vary in thickness, colour, texture, structure,

acidity, porosity and composition. Soil have mainly four horizontal layers. They are -

1. Horizone O or Litter zone - The uppermost horizon of soil is called O or litter

zone. It is usually not present in the soils of deserts, grassland, cultivated field, it

is present in soils of forests.

2. Horizon A or Top soil - After O zone top soil of Horizon A is present in the

soil which contains under composed partially decomposed and completely

decomposed humus. It is generally sandy.

3. Horizon B or Subsoil - It is formed by clay soil and contains little humus.

4. Horizon C Weather land - It is at the bottom of soil profile and contains

weathered rock of parent material. It is light coloured and is virtually lacking in

organic material.

5. Horizon R unweathered land - It includes unweathered bad is rocks and

present below the C Horizon.

Fig. 4.11 : Soil Profile

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Sources of soil pollution

Soil Pollution is an extremely complicated process. It may occur-directly by dumping

and disposal of wastes. and application of agro-chemicals indirect effect of air pollution

Ex. acid rain. The main soil pollutants are-

1. Industrial Wastes - Both solid and liquid wastes of industries are dumped over

the soil. The wastes contain a number of toxic chemicals like Hg, Pb, Zn, Cd, Cu,

cyanides, thiocynates, cromates, acids, alkalies and other organic substances.

Some toxic chemicals added in the soil by mining operations also.

2. Pesticides - In present time a number of chemicals are used to kill insects, fungi,

algae, rodents, weeds, herbs etc. to improve agriculture, forestry and horticulture.

They are sprayed on the plants in the form of fine mist or powder. Most of the

pesticides has a broad spectrum and effect all types of life. Thus they are therefore

also called biocides. Pesticides reduce the number of species of living as well as

micro organisms, thus effect the structure and fertility of soil. Some pesticides and

their degraded products are absorbed by plants which in turn may affect the entire

food chains and food webs.

3. Fertilizers and Manures - Fertilizers are added to the soil for increasing crop

yield. Excessive use of these chemicals and fertilizers decreases strength of useful

bacteria and crumb structure of the soil. It also increases salt content of the soil

and reduces productivity of the soil.

The excretory products of people and live stock and digested sewage sludge used

as manure which pollute the soil. A number of pathogens are present in these type

of wastes contaminate the soils and their crops and cause serious health hazards

for man and animals.

4. Discarded Materials - Most of the discarded materials are dumped on the soil by

man. These include concrete, asphalt, ruged, leather, cans, plastics, glass,

discarded food, paper and carcasses.

5. Radioactive waste - Radioactive elements from mining and nuclear power plants

find their way into water and than into the soil.

6. Other Pollutants - Many air pollutants (acid rain) and water pollutions ultimately

becomes part of the soil. The soil also receive some toxic chemicals during

weathering of certain rocks.

112

Adverse Effects of Soil Pollution

The effect of pollution on soil are quite alarming and can cause huge disturbances

in the ecological balance and health of living creatures on earth. Nearly 80% of the

diseases, can be limited with soil and water. The solider highly polluted by several

pathogenic organism and hazardous industrial effluents. Soil pollution is the result of

urban – technology revolution and speedy exploitation of every bit of natural resources.

Some of the most serious soil pollution effects are mentioned below -

1. Decrease in soil fertility and soil yield.

2. Loss of soil and natural nutrients present in it and result in soil erosion.

3. Disturbance in the balance of flora and fauna residing in the soil.

4. Increase is in salinity of the soil thus cause salination of soil problem, which

makes it unfit for vegetation, thus making it useless and barren.

5. Crops can not grow and flourish in a polluted soil, if some crops manage to grow,

then those would be poisonous.

6. To cause health problems in consuming people.

7. Creation of toxic dust leading is another potential effect of soil pollution.

8. Unpleasant smell due to industrial chemicals and gases might result in headaches,

fatigue, nausea, vomiting etc.

9. Changed soil structure cause death of many essential organisms.

10. Soil pollution runs off into rivers and cause water pollution by which kills the fish,

plants and other aquatic life.

11. May poison children playing the soil polluted area.

Controlling measure of soil pollution

The following steps have been suggested to control soil pollution –

1. Reducing chemicals use - Fertilizers and pesticides use. Other biological

methods of pest control can also reduce the use of pesticides.

2. Reusing of materials – Materials such as glass containers, plastic bags, papers,

cloths etc. can be reused at domestic levels instead of disposed, reducing solid

waste pollution.

3. Recycling and recovery of materials - Materials such as papers, plastics and

glass can and are being recycled. Thus can minimize the volume of refuse and

helps in the conservation of natural resource Ex. Recovery of 1 tone paper can

save about 17 trees.

113

4. Reforesting – Control of land loss and soil erosion can be attempted by restoring

forest and grass cover to check west lands and soil erosion.

SOCIETY AND ETHICS

Impact of Waste on Society

Solid waste generation in one form is associated with human activities. Among

the various problems resulting due to consequences of urbanization, management of solid

waste is one of them. Management of solid waste in urban centers is becoming very

complex. Solid is the material generated from various human activities and which is

normally disposed as unless and unwanted. Thus ―Any unwanted or discarded material

from residential, commercial, industrial, mining and agricultural activities that cause

environmental problem may be termed as solid waste.‖ It consist of the highly

heterogeneous mass of discarded materials from the urban community as well as the more

homogeneous accumulation of agricultural, industrial and mining wastes. Improper

handling of this solid waste can pose direct threats to both the public health as well as

quantity of environmental resources.

Increasing urbanization, industrialization and population growth, the solid waste

has been a problem in past has become a serious threat in recent years and situation is

going to be worse if appropriate measures are not taken immediately. Dumping the waste,

has two negative points. One is it pollutes the air, water and soil resulting in diseases and

destruction of human habitat and other one is, it deprives us of a powerful resource

material for producing energy, electricity and manure etc.

Urban solid waste management continuous the remain as one of the most

neglected areas of urban development in India. Unplanned land fills have caused an

environmental disaster poising health hazards both to workers and to other population. It

is to be expect that only 1 cubic meters of garbage can produce more than two million

flies, which is the carrier of many diseases, eg. bacillary dysentery. Second most

important vector of human diseases due to solid waste is rat. Rats, destroy property as

well as infect by direct bite, they are dangerous as carrier of insects and cause various

human diseases.

Solid waste are also responsible for water and soil pollution. It generate from a

refuse dump enters surface and ground water and pollute it. Uncontrolled burning of these

wastes in open dumps can contribute to air pollution. Besides all these adverse effects

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open dumps of solid waster are also responsible for spoiling aesthetic beauty of the local

area.

Thus every activity of the man from birth to death has its impact on the

environment. Some of the major impacts are listed below-

Solid Waste Management

As solid waste can neither be transported any where nor can be dispersed in the

atmosphere. If it has to be dumped on land which besides occupying precious land

resources destroys the aesthetic beauty of the region. It is also an open food source for

various rodents and parasites, which cause a number of diseases. Disposal of solid waste

has many problem like technical, environmental, administrative, political and economical

difficulties. To overcome this type of difficulties the concept of solid waste treatment is

generated called as "solid waste management‖. The main aim of this is to minimize the

adverse effects caused by solid wastes to reduce difficult is of future. Solid waste

management comprises of purposeful and systematic control of the generation, storage,

collection, transport, separation, processing, recycling, recovery and disposal of the solid

waste.

Classification of Solid Waste

Waste produced in the society is from different sources and are of various types

depending upon their physical, chemical and biological properties. On the basis of their

source and nature wastes are classified mainly into following categories -

1. Nuclear Waste.

2. Thermal Waste.

3. Plastic Waste.

4. Bio- Medical Waste.

5. Agricultural waste.

6. Domestic waste.

7. E - waste.

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Table – 5.1 Man-made activities and their impact on environment.

Activity Impacts

Agricultural Water pollution, soil erosion discharge of nutrients and water

burden on water resources. Discharging of pesticides, fertilizers

and other chemicals to environment and ecosystem.

Transportation Deforestation for constructing roads and railways, decreased the

agriculture land. Air pollution, noise pollution disruption of wild

life habitats.

Industries Water pollution, air pollution and noise pollution. Pressure on

land, natural resources and transport system.

Energy power plants Thermal power plants create water, air and thermal pollution, they

require coal, oil, etc. Hydropower plants submerged of valuable

lands deforestation, disturbances in wild life. Nuclear power

plants create air and water pollution and risk of radioactive

hazards.

Mining Global warming, acid rain deforestation, water pollution and soil

erosion.

Urbanization Solid waste generation, water burden, environmental problems

like air water and noise problems. Sanitation problem, traffic

related and social problems.

Religions Spread of disease, water burden transport and sanitation problems

1. Nuclear waste - Nuclear waste comprises a variety of material that contains

radioactive nuclei, such as C-14, U-235, U-238, U-239, Ra-226 etc. The emission

of energy from radioactive substances in the environment is often called as

―Radioactive or nuclear pollution‖.

The sources of radioactivity are classified into natural and man-made. The natural

sources includes -

i. Cosmic rays coming from outer space.

ii. Emission from radioactive material from earth‘s crust.

Low level of radiations are exposed from these natural sources but man-made

sources are very poising to mankind which produced during the -

i. Mining and processing of radioactive ores.

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ii. Use of radioactive material in nuclear power plants.

iii. Use of radioactive isotopes in medical industrial and research applications.

iv. Use of radioactive material in nuclear weapons.

The effect of radioactive pollutants depend upon the half life, energy releasing

capacity, rate of deposition of contaminants. According to the amount and types

of radioactivity in them, they are classified as-

i. Low level waste – It contains small amounts of short lived radioactive it is buried

in shallow landfill sites. Its sources are hospitals, laboratories, industries etc.

World wise it comprises 90% of the volume but only 1% of the radioactivity

present in of all waste.

ii. Intermediate level waste – It contains higher amount of radioactivity and may

require special type treatment. Usually short lived waste is buried, but long lived

waste will be disposed at deep underground. It comprises resins, chemical sludge

and reactor components. World wise if makes up 7% of the volume and has 4% of

the radioactivity of all waste.

iii. High level waste – It contains the highly fission products and some heavy

elements with long lived radioactivity. It requires special shielding during

handling and transportation. Only 3% of the volume of all waste holds 95% of the

radioactivity.

Four main technical processes are available for treatment of waste are-

evaporation, chemical precipitation, flocculation solid phase separation and ion

exchange. These treatment are well established and widely used. Evaporation is a

proven good method for the treatment of liquid radioactive waste.

2 Thermal waste – It refers to the release of heat into any of the component of

environment. The pollution related with this heat is called thermal or heat

pollution. Thermal pollution can be sudden, long term or acute event process.

Sudden heat releases due to some natural events like forest fires and human

created like fire storms. The main sources of thermal waste are –

(i) Nuclear Power Plants – The emissions of nuclear reactors, fission and fusion

reactions, processing, are responsible for rising temperature of nearby water

bodies. Out of this drainage from hospitals, research centre etc. emit a large

amount of unutilized heat and traces of nuclear radio substances into nearby water

body and pollute them thermally.

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(ii) Industrial Effluents – Power generating industries like hydro electric power plant,

coal power plant etc. require large amount of water as a coolant and other

industries like textile, sugar, paper and pulp also release heat in water.

(iii) Domestic Sewage – The municipal water sewage has a increased temperature as

compared to receiving water. These increased temperature of receiving water,

causes decrease in D.O. and hence anaerobic conditions will setup and create foul

and offensive gases in water.

Increased temperature decreases the level of D.O., the decrease in D.O. can harm

aquatic animals like fish, amphibians etc. Higher temperature of water can change the

natural conditions and finally disturb the aquatic ecosystem. Fish spawning cycles may be

disturbed and fishes may be susceptible to the diseases.

3. Plastic waste – Plastic has many advantages – It is durable, light weight,

economic etc., these quality makes its increased demand but due to its non

biodegradable nature, plastic is now a serious environmental problem. The growth

in the consumption of plastics is to such an extent that plastic is now considered as

environmental hazardous due to the throw away culture. In India it is estimated,

about 10,000 tones of plastic waste is generated daily.

The sources of plastic wastes are. House hold (carry bags, bottles,

containers etc), Hospitals and Medicals (disposable syringes, glucose bottles,

surgical gloves, blood and euro packets etc), Hostels (packaging items, minerals

water bottles plastic plates, glasses, spoons etc) Air or rail travels (mineral water

bottles, plastic plates, glasses, plastic bags etc.).

Plastic is a high molecular weight polymer compound, it is of two types –

Thermoplastics and Thermosets. Thermoplastics soften and melt on heating and

they are recyclable. Ex. Polyvinyl chloride (PVC), Polytetrafluroethylene or

Teflon (PTFE) etc. Thermosets not soften on heating they stay solid and cannot be

recycled.

Various environmental problems are increases due to this plastic waste

like; it reduce rate of rain water percolating, thus resist the recharge of

underground water. On burning of plastic waste, they emit polluting gases and

cause air pollution. The soil fertility is also affected when plastic bags form part of

manure. If animals feed garbage containing plastic, sometimes die. Plastics also

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infected water bodies. Plastics present an ugly and unhygienic seen and thus spoil

beauty of the landscape and make polluted public places.

4. Biomedical waste - The waste generated from hospitals, health centers, medical,

veterinary, laboratories, nursing homes, funeral homes and other associated areas

constitute biomedical wastes. The above material are considered as biomedical

waste like biological cultures, anatomical wastes, discarded medicines, bandages

human excreta, blood cells, organs and tissues, chemotherapeutic wastes,

pathological wastes, waste from surgery and autopsy used syringes, gloves,

blades, instruments and gas containers, stocks of infectious agents etc.

Medical waste is generated during the diagnosis, treatment or

immunization of human beings or animals. This waste is highly infectious and

can be a serious threat to human health if it is not managed in a scientific manner.

It has been estimated that 4 kg of waste generated 1 kg would be infected of them.

Biomedical waste should be strictly classified as infectious or bio-

hazardous and they spread of infectious diseases. Hence biomedical waste should

be placed in specially labelled bags and containers for removal by bio- medical

waste transporters. Another waste should not be mixed with it. Generally

incineration method is used for the treatment.

5. Agricultural waste – Agricultural waste is waste, that produce as farm as a result

of farming activities. Nowadays agricultural practices have also been modernized,

to create a revolution in agriculture huge quantity of chemicals, fertilizers and

pesticides are used. The long term effects of these chemicals have proved very

dangerous and undesirable. They pollute environment in the term of soil and water

pollution to a great extent. Agricultural wastes are -

(i) Fertilizers – They contain plant nutrients like N, P, K etc and its derivatives.

Excessive use of these in the soil, they can reach the ground water by leaching and

can wash out to surface water (river, lakes etc.) by natural draining.

(ii) Pesticides – There are chemicals, used to kill pests. Pests are undesirable parasites

are worms or insects or birds like nematodes (that feed on roots and plant tissues)

bacteria, fungi and viruses weeds (flowering plant with crops) vertebrates ( that

feed on fruit and grain).

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Pesticide can be classified as –

1) Insecticides –It use to kill or suppress unwanted insects. Ex. DDT, Malathian,

Aldrin, Endrin etc.

2) Fungicides – These are used to kill fungi. Ex. FOPLET, CAPTAN etc.

3) Herbicides – It used to suppress the growth of weeds. Ex. Atrazine, mounuron

etc.

4) Rodenticides – These are used to kill rodents. Ex. Norbomide, Strychnine etc.

These different types of pesticides are polluting the natural environment. The

residues of these chemical substance remains in soil and reach in other life form

through food chain and affect them.

iii) Soil Conditioners and other chemical effects- They are used to increase and

protect the soil fertility. They contain some toxic metals like Cd, Hg, As, Pb etc.

When used these compounds to a land, they will accumulate in the soil

permanently and introduced into a food chain through growing crops.

6. Domestic waste – These wastes are generated after household activities of human

beings. It includes-

i) Garbage – All kind of solid waste from household. It can be recycled and reused.

To prevent creation of these waste it should be thrown into the dustbins by

community.

ii) Organic waste – It includes kitchen waste, vegetables, flowers, leaves, fruits etc.

iii) Toxic waste – Chemicals, paints, containers, fertilizers, pesticides, batteries, old

medicines etc.

iv) Recyclable – Like paper, glass, metals, plastic etc.

v) Soiled – Hospital waste i.e. cloth soiled with blood and other body fluids.

As population is increased, the amount of waste generated is also increasing. In

India, it is estimated in 1997 solid waste was about 48 million tones. About 30%

of municipal solid waste is not collected, and now it becoming unmanageable. The

local corporations have adapted different methods for the disposal of waste – open

dumps, landfills, incineration, landfills etc. But composting treatment is good out

of these.

8. E – waste – E – waste is electrical and electronic products nearing the end of their

―useful life‖. It describe loosely discarded, surplus, obsolete or broken electrical

and electronic devices like T.V. sets, VCRs, stereos, copiers, fax machine,

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computer monitor, digital cameras, laptops, scanners, printers, telephone, mobile

phone, CD – Rom, refrigerators, plastics, wires and other high tech goods and

sophisticated medical equipments are the major sources of e –waste. Generally in

working condition these equipments are not risky but these products contain Hg,

CD, Pb, Sb, Ag, Cr, Zn, As, plastic and other toxic compounds and cause serious

health problems when released in landfill disposal and incineration. These e-

waste is largest contributor of heavy metals.

Thus all E – waste is toxic and hazardous. If it dispose in landfill, toxic

chemicals of e-waste can leach in to the land and then atmosphere and impact

nearby communities and the environment. If incineration method is used for the

treatment of e-waste. It having heavy metals like Pb, Hg, Cd etc. thus they spread

into the air. Adverse effects from the E- waste include DNA damage, asthmatic

bronchitis, mental retardation in children. Contaminated soil and water are

becoming carcinogenic and toxins and cause birth defects, infant mortality,

tuberculosis, blood diseases and other respiratory problems.

If incineration method used to dispose waste they released into the

atmosphere and can accumulate in the food chain. Plastics, PVC, released toxic

dioxins and furan pollutes the environment. Reuse and recycling are good

methods to minimize the e-waste many old products are exported to developing

countries and can increase a products lifespan.

Solid Waste Management:

a) Bio-Concentrative Wastes: Industries using Cadmium, Mercury or Polychlorinated

biphenyl (PCB) expelled these as wastes. These are bio-concentrative and hot

readily adjustable to atmosphere.

b) Toxic Wastes: These are waste that may affect living organisms either by ingestion

through the food chain, respiratory system or through the surface of skin.

c) Flammable wastes: They are those materials which are at specific conditions

become flammable and cause hazards.

d) Explosive wastes: It may be any material which would have possibility of explosive

determination with or without ignition.

e) Reactive wastes.

f) Irritating or sensitizing wastes.

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Some common Industrial wastes:

Fertilizers - Ammonia, Arsenic

Coke ovens - Phenol, Cyanide, Thio-cyanide, Ammonia

Metallurgical - Heavy metals e.g., Copper, Cadmium

Electroplating - Hexa-valent chromium, Cadmium, Copper & Zinc

Synthetic Wool - Acrylonitrile, Acetonitrate

Petrochemicals - Phenol, Heavy metals, Cyanide

Any unwanted or discarded material from residential, commercial, industrial,

mining and agricultural activities that cause environmental problems may be termed as

solid waste.

3Rs & 4Rs of solid waste management:

Recovery Reduction

Recycle Recovery

Reuse Recycle

Reuse

Solid waste management comprises of purposeful and systematic control of the

generation, storage, collection, transport, separation, processing, recycling, recovery, and

disposal of solid waste.

Fig. 5.1 : Material flow

Collection of Municipal Solid Wastes (MSW):

a) Community storage Point: The municipal refuse the taken to fixed storage bins

and stored tile the waste collection agency collects it daily for disposal in a

vehicle.

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b) Curbsides Collection: In advance of the collection time, the refuse is brought in

containers and place on the footway.

c) Block collection: Individuals bring the waste in containers and hand it over to the

collection staff that empties it into the waiting vehicle and returns the container to

the individuals.

Fig. 5.2 (A) : Separation of MSW

Before the solid waste is ultimately disposed off it is processed in order to

improve the efficiency of solid waste disposal system and to recover unable resources out

of the solid wastes.

Before disposal collection of municipal solid wastes and industrial solid waste:

collection, transportation, transfer station, storage discharge state activities are performed

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due to heterogeneity of the city refuse it is important to select the most appropriate solid

waste disposal method keeping in view the following objectives:

Fig. 5.2 (B) : Separation of MSW

a) It should be economically viable i.e., the operation and maintenance costs must be

carefully assessed.

b) It should not create a health hazard.

c) It should not cause adverse environmental effect.

d) It should not be aesthetically unpleasant i.e., it should not result in offending

sights, odours and noises.

e) It should preferably provide opportunities for recycling of materials.

The methods of reduction commonly used are:

1. Salvage or manual separation.

2. Compaction or mechanical volume reduction.

3. Stationary compactor.

4. Incineration or thermal volume reduction.

Fig. 5.3 : Incineration of MSW

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If solid waste will burn it can be incinerated. Highly combustible wastes like

plastics, cardboard, paper, rubber and combustible wastes like cartons, wood, scrap, floor

sweepings, food wastes etc. are subjected to incineration i.e., burning at very high

temperatures.

Incineration results in air pollution and so proper control equipment need to be

installed to avoid contamination of environment. The heat generate during incineration is

usefully utilized by generating steam or by putting a waste heat boiler on the incinerator

thereby partly recovering the lost of waste collection and disposal.

1. Open dumping: Open dumping of solid wastes is done in low lying areas and

outskirts of the towns and cities.

2. Sanitary land filling or controlled tipping: Sanitary land filling involves the

disposal of municipal wastes on or in the upper layers of the earth‘s mantle

especially in degraded areas in need of restoration.

In land filling, the solid wastes are compacted and spread in thin layers, each layer

being uniformly covered by a layer of soil. The layer is covered by a final cover of about

one meter of earth to prevent rodents from burrowing into the refuse and scattering.

This is a biological method of waste treatment and bacterial refuse digestion

results in decomposition products like CO2, CH4, NH3, H2S and H2O which can be

harnessed as renewable sources of energy.

Advantages of land filling:

1. Simple

2. Economical

3. Cheap equipment and plant is required.

4. Skill labour not required.

5. Separation of different types of solid wastes is not required.

6. No residue or by product.

7. Low lying areas can be reclaimed and put to better use.

Disadvantages

Large land area is required continuous evolution of foul smell at the site of

disposal. Use of insecticide is required. Covering of waste solid with good earth may

sometimes difficult. It may also cause ground water pollution.

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Pyrolysis or Destructive Distillation

It is the process in which certain waste can be pyrolysed. If it can yield valuable

gases or liquids as by products, pyrolysis might be suitable in under anaerobic conditions.

The organic components of the solid wastes split up into gaseous liquid and gaseous

fractions (CO, CO2, CH4, Tar, Charred Carbon). Unlike the highly exothermic process of

combustion, pyrolysis is a highly endothermic process and that is why it is also called

destructive distillation.

Composting or Biodegradation

It includes waste like organic refuse such as kitchen waste, leaves, grass and

handling these wastes in such a way that naturally occurring bacteria and other micro-

organisms will break these down and produce safe, clean and soil like material called

compost. It can occur in the presence of air or in a closed container or underground.

Receiving Pits - Send to hopper - Rotary vibrating screens --- Magnetic separator

---- Sorting belt / table ------- Mixing of sludge -------- window pits ----------

Rolls --------- Screen -------- Market.

Preparation of fine intermediate and coarse humus. Bacterial decomposition of the

organic compound of the municipal solid wastes result in formation of humus or compost

and the process is known as composting. It consists of waste preparation, Digestion and

Product up gradation. Types of composting covers by trenching, open window

composting, mechanical composting.

Shredding: Preparation of solid waste requires, reduction and uniformity in size for

future use for this a process called shredding is devised. Shredded waste can be best

utilized every use, There are number of different types of size reduction machines which

can handle industrial wastes. They are rolling ring crushes, jar crushes, hammer mills,

shredder and hags. The rolling ring crushes and roll crushes use impact shearing and

compression, and hammer mills use impact and shearing.

Hammer Mills: This is most common type of industrial size reduction equipment. The

hammer mill consists of large motor driven rotor to which are hinged a number of heavy

hammers that pivot on these hinges and turn with the motor like to many blades of a saw.

Hammer mills can have rigid or flexible hammers, light or heavy hammers according to

the desirability of work. Breaker plate used to bear or absorbed crushing force and it is

manufactured in a way to promote shearing action.

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Bio-methanisation Technology

The organic portion is removed this position goes into bioreactor which are closed

with bacteria in it. The bacteria in the garbage produce organic manure and biogas.

Organic manure is used as inputs in chemical fertilizers and biogas can be used to

produce electricity.

Ethics and moral values

Ethics is also known as moral philosophy. Ethics word has originated from ‗ethos‘

means character or manners. The term ‗ethical‘ as concerning principle of human

conduct. It can be understand by the following ways-

Ethics as a matter of fact, deals with certain standard of conduct and moral.

Ethics is an indirect governing force behind every human conduct.

Ethics is human behavior and differentiate between proper/improper, right/wrong

or fair/unfair human actions. It can be defined as a theory or a system of moral

values. It can be used as synonymous for morally correct. Ethics is an activity and

area of inquiry. It involves defining, analyzing, evaluating and resolving moral

problems and developing moral criteria to guide human behavior. Ethics is

basically used to use the knowledge for the protection of safety and welfare of

public and also to treat all others in a way similar to now you and yourself would

like to be treated.

Morals

Morals refers to personals behavior. It refers to any aspect of human action.

Morals are those customs, the violation of which is regarded in the community as

definitely wrong in the word, they are Morals. The moral code is that of body of rules in

which the individual conscience upholds as constituting right or good. The physician who

destroys a monstrously deformed baby, for example may violate the community‘s moral

code, but he remains true to his own moral convictions. For most of morals codes vary

from person to person, but the morals characterize the group or the community.

Values

Man had social nature is his fundamental attribute. Human values are conceptions

of basic categories of desires. Values are needs/desires. Values are the rules by which we

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make decisions about right and wrong, should and shouldn‘t, good and bad. It is the link

that ties together the personal perceptions, judgments, motives and actions. These needs

are not necessarily self- centered and some of them might be abstract like liberty,

conformity, prosperity etc. Values are more important and primary than facts in forming

and understanding all kinds of human purpose. Five human values (Truth, Care, Peace,

Duty and Justice) are universal, though values are not always held in the sense of being

followed, they are everywhere held in esteem.

Ethical Situations – Some doing our best is not good enough, we must do what is

required. A variety of situation can occur that require a consideration for possible ethical

consequences of an action or practice. The most frequently cited ethical dilemmas fell in

to the following categories.

Meta Ethics Normative Ethics Applied Ethics

Situation 1: You are applying for a job. Would you put on your resume that you had been

debarred for three years by the university in a cheating case.

Situation 2: Your employer has called you to enquire about the role of a particular

person in an undesirable incident occurred in the organization. You know that the person

was responsible for the incident. Do you answer only the questions asked or tell the whole

truth. The person is a good friend of yours and everyone loves him.

Situation 3: You, as the Principal of the institute, have been solicited by a new vending

machine company and, in return, offered a free holiday trip. Would you accept the offer?

Situation 4: By mistake, the teacher has given you a higher grade in the Exam. It is

unlikely that it would ever be discovered. Would you report it to the teacher?

Situation 5: A teacher is a tough grader. Would you, as the principal, change a grade for

an outstanding student who is seeking a scholarship?

There are many ways for making decision, but few guides to indicate when

situation might have an ethical implication. These examples show how ethical problem

arise most often when there is difference of judgment or exceptions as to what constitutes

the true state of affairs or a proper course of action.

The simple way to act in typical situation, after recognizing it is to use generic

indictors as compelling guides for an active conscience. Strictly say this is not absolute

rules or values. Instead, they are more like a rough measurement where an exact one is

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not possible. They often conflict with each other and some will trump with each others in

some conditions. According to principle, that need to be considered, they should constant.

Objective of Ethics and its study

Ethics is a code of values to guide our actions. They are related with each field of

human life like personality, education and occupation. Ethics, in its full range of meaning

includes developing the appropriate sensibilities – moral, cultural spiritual and the ability

to make proper judgment and decision in life. Ethics an activity and act on enquiry.

Resolving moral issues and justifying moral judgment to guide professionals.

How should be live life well?

How to find happiness?

How to make others happy?

How to make decisions in diverse situations?

How to behave and communicate with others?

How to manage all kind of people with happiness?

The study of ethics, thus, is essentially ‗man making and ‗character building‘.

Take the case of two brilliant and very qualified scientists- one invents a life – saving

drug, both have a great deal of academic brilliance but the scientist with ethics and high

moral values creates something that can save thousands of lives; whereas, on the contrary,

the other scientist creates something that can take thousands of lives and cause pain and

deformities even in future generations.

There is only one fundamental alternative in the universe existence or non

existence. The existence of inanimate matter is unconditional, the existence of life is not,

it depends upon the specific course of action. Matter is indestructible, it changes, its

forms, but it cannot cease to exist. It is only a living organism that faces a constant

alternative- the issue of life or death. Life is a process of self – sustaining and self

generated action. If an organism fails in that action, it dies, its chemical element remains,

but its life goes out of existence.

Preliminary Studied Regarding Environmental Protection Act

It is a moral responsibility for and looking after the environment for ourselves, our

family, friends and society. The act places a general environmental duty on every one in

not to harm the environment.

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Indian constitution has a number of provisions directing the responsibility of the

central government and state for ―Environmental Protection‖. The state‘s responsibility

has been laid down under article 48 – A which states- The state shall endeavor to protect

and improve the environment and safeguard the forests and wildlife of the country.

Environmental Protection has been made a fundamental duty of every person under

article 51 –A which states. It shall be the duty of every person of India to protect and

improve the natural environment like wildlife, forest, lakes, rivers etc. Article 21 reads as

– No person shall be deprived of his life or personal liberty.

According to section 2 (a) of Environmental Protection Act (1986). It

includes - (i) water air and land (ii) the inter relationship which exists among and between

(1) water, air and land (2) human beings, other living creatures, plants, micro organisms

and property. It Includes-

Water and air pollution

1. The water (prevention and control of pollution) Act, 1974.

2. The water (prevention and control of pollution) Rules, 1975.

3. The Air (prevention and control of pollution) Act, 1981.

4. The Air (prevention and control of pollution) Rules, 1982.

5. The Air (prevention and control of pollution) (union territories) Rules, 1983.

6. Environment protection.

7. The Environment (protection) Act, 1986.

8. The Environment (protection) Rules, 1986.

9. Environment (sitting for industrial projects) Rules, 1999 Coastal stretches.

10. Declaration of coastal stretches as Coastal Regulation Zone (CRZ).

11. Hazardous process and organisms.

12. The rules for the manufacture, use, import, export and storage of hazardous.

13. Microorganism genetically engineered organisms or cells 1989.

14. The manufacture, storage and import of Hazardous chemical rules, 1989.

15 The Hazardous waste (management and handling) Rules, 1989.

16. Dumping and disposal of fly ash discharged from coal of lignite based thermal

power plants on land, 1999.

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Noise Pollution

1. The noise pollution (Regulation and control) (Amendment) Rules.

2. Noise pollution (Regulation and control) Rules, 2000.

Wild life and Forests

1. The Indian wildlife (protection) Acts, 1972.

2. The wildlife (protection) Rules, 1995.

3. Forest (conservation) Acts, 1980.

4. The Indian forest Act, 1927.

5. Guidelines for diversion of forests lands for non – forest purpose under the forest

(conservation) Act, 1980.

Forest Conservation act, 1980

‗Non Forest Purpose‘ means the breaking up of cleaning of any forest, land or

portion there of for the cultivation of tea, coffee, spices, rubber, palms, oil bearing plants,

horticultural crops, medicinal plants or plantation crops.

It is well known that breaking up the soil or clearing of the forest land affects

seriously reforestation up the soil or clearing of the forest land affects seriously

reforestation or regeneration of forests and therefore, such breaking up of soil can only be

permitted after advantages and disadvantages to the economy of the country.

Environmental conditions, ecological imbalance that is likely to occur, its effect on the

flora and the fauna in the areas, etc., it was therefore thought that the entire control of the

forest areas should vest in the central government. With that end in view, Section 2

provided that prior approval of the central government should be obtained before

permitting the use of the forest land for non- forest purpose.

Current Requirements that should be met before declaring an area into a wild Life

Sanctuary/ National Park under Forest Act.

1. The state government may by notification in the office declare the provision of

their chapter to any forest land or waste land which is not include in a reserve

forest, but which is the property of government.

2. The forest land and waste land included in any such notification shall be called a

‗protected forest‘.

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3. No such notification shall be made unless the nature and extent of the rights of

government and of private persons in or over the forest land or waste land

comprised therein have been enquired into and recorded at a surveyor settlement,

or in such other manner as the state government thinks sufficient.

Environmental Impact Assessment (EIA)

Environmental Pollution has become a global problem and random urbanization

and industrialization have made the situation critical. Recent estimate shows that coal

based power generation units in India alone contribute about 13 million tones of fly ash,8

million tones particulates, 4,80,000 tones of COx, 2.80 .000 tones of NOx, 1600 tones

CO and 5.000 tones of HCs to the atmosphere annually. Water pollution and solid waste

disposal are also causes for great concern. The situation in mainly due to the lack of

proper planning before project implementation.

EIA is an effort to anticipate, measure and weight the socio economic and

biophysical change that may result from a proposed project. This involves a multi-

disciplinary approach. Ex. for EIA study of a dam, the team may include expertise from

the areas of geology. forestry, wildlife, anthropology, chemistry, engineering, economics,

agricultural science and social Science.

In 27th

Jan 1994, EIA was carried out under administrative guidelines which

required the proponents of major irrigation. Projects, River Vally Project, Power valley

Project. Power station Ports etc. to secure a clearance from the union ministry of

Environment Forest (MOFE).

Natural environment is balanced in itself. Ecological ethics limit social as well as

individual freedom. The belief in environment is governed by the following laws-

1. Role of man in nature is to create final order, harmony and balance.

2. Man can engineer nature and modify it for his benefits.

3. Man has a moral obligation to protect and preserve the environment.

4. A life support system in its wilds state is necessary for the survival of human

begins.

5. Environment is beautiful, magnificent powerful and un predictable.

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Steps involved in EIA – The following steps are involved in EIA process-

1. Project Screening – In this step planner studied the plan and decide whether to

conduct a comprehensive EIA study or not. The world Bank has placed all the

projects in following categories, on the basis of environmental impacts-

(i) Water resources developmental project.

(ii) Highway Project.

(iii) Thermal power project.

(iv) Petrochemical project.

(v) Fertilizers project.

(vi) Residential construction project.

(vii) Minining project etc.

Comprehensive studies of EIA have to be conducted for identifying the significant

environmental impact. If impact are negative, such projects are screened off right in the

beginning.

2. Scope of Assessment – It is stressed on determining, at an early stage and project

specific issues and impacts are to be assessed.

3. Consideration of Alternatives – In this step it has to ensure that the promoter has

also considered on other alternative project locations, scales, processes, layouts,

operating conditions etc.

4. Identification of Impact – It includes the both present and future state of the

environment. It also ensures that all the significant EIA are identified and taken

into account in the process.

5. Prediction of Impacts – It identify the magnitude and other dimension of

identified change in the environment with a project by comparison with the

situation without that project.

6. Interpretation and Evaluation of Impacts – Object of this is to assess the

relative significance of the predicted impacts to allow a focus on main adverse

impacts.

7. Mitigation – It involves the introduction of measures to avoid, reduce, remedy or

compensate for any significant adverse impacts.

8. Public Consultation – It aims to assure the quality and effectiveness of the EIA

to consider in decision making process.

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9. EIS Reporting – It is a vital step of the process. It EIS done badly, much good

work in the EIA may be.

10. Review – It is a systematic appraisal of the quality of the EIS, as a contribution to

the decision making process.

11. Decision making – It involves a consideration by the relevant authority of the EIS

together with other material considerations.

12. Post decision monitoring – In this step involves the recording of out comes

associated with development impact, after a decision to proceed.

13. Auditing – It follows from monitoring. It can provide actual out comes and the

effectiveness of mitigation.

Benefits of EIA

EIA offered a many benefit some of them are-

(1) Reduced time and cost of project implementation.

(2) Increased projected acceptance.

(3) Improved project performance and quality.

(4) Lost saving modifications in project design.

(5) Avoiding impacts of law and rules regulations.

(6) Avoiding waste treatment.

(7) It provide healthy environment.

(8) It reduces pollution in some extent.

(9) Improved human health.

(10) It decreased resource over use.

(11) It increased community skills and knowledge about environment.