CHAPTER 1
Introduction and scope of the study
Chapter -1
ABSTRACT
This chapter deals with general introduction to environmental pollution-Pollutant,
sources of pollution, classification of pollutants, principle pollutants, types of
environmental pollution, effect of pollution and scope of the study are given.
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Chapter -1
1.1 ENVIRONMENTAL POLLUTION AND THEIR EFFECTS
1.1.1 Pollutant
Pollutant is a substance which causes pollution. Pollution is caused by the
addition of substances by human activity to the environment. When these substances are
not removed, assimilated or decomposed by the nature (physical or biological process),
the accumulation of these pollutants causes pollution.[l] A pollutant may include any
activity (sound), chemical, geochemical (dust), substances, biotic component or product,
physical factor (light, heat) etc., that is released into the environment in such a
concentration that may have harmful or unpleasant effects[2].
Pollutant is also defined as “any liquid, solid or gaseous substance present in
such concentration as may be or tend to be injurious to the environment".
1.1.2 Sources of Pollution:
The sources of pollution is broadly classified into two groups.
Natural Sources: The pollution originates from the natural calamities and processes
such as volcanic eruptions (releases gases and ash), earthquake, forest fire, dust storm
(deserts), cysts and pollens, spores and bacteria, decay of organic matter [3]etc.
Man made (artificial) or Anthropogenic Sources: The pollution originate due
to the activities of man, anthropogenic sources cover a wide range of sources. Since man
as aggrevated the problem of pollution due to multiple activities for his comfort and
enjoyment[4]. The sources are deforestation, industrialization, automobiles, nuclear
explosions, over population, quarrying and mining, construction activities, wars,
agriculture (fertilizers and pesticides) etc.
1.13 Classification of Pollutants
Pollutants are classified as follows:
a) Based on the form they exist:
1) Primary Pollutants: These substances add directly from an identifiable source. These
substances exist as such in the environment.
Ex. Carbon dioxide, Sulphur dioxide etc.
2) Secondary Pollutants: These are the pollutants derived by the primary pollutants due
to the chemical reaction in the environment.
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Ex. Nitrogen oxides reacts in the presence of sunlight to form peroxy acetyl nitrate
(PAN) PAN is a secondary pollutant.
b) Based on biological degradability:
1) Biodegradable Pollutants: They are food waste, domestic sewage etc. These wastes
can decompose by the micro-organisms under natural conditions. However accumulation
in larger quantities may create pollution problems.
2) Non degradable pollutants: These pollutants are iron, mercury, aluminium, phenolic
compounds etc. These substances either do not degrade or degrade at very slow rate.
These pollutants are harmful even at ever low concentration. These pollutants
accumulate in the environment and often biologically magnified as they enter food chain
and biochemical cycle.
c) Based on their existence:
1) Quantitative Pollutants: These are the substances that normally occurring in the
environment and acquire the status of pollutant, when their concentration increased due
to the activities of man.
Ex. Carbon dioxide.
2) Qualitative Pollutant: These are the substances which do not occur in nature, but are
added due to the unmindful activities of man.
Ex. Pesticides.
1.1.4 Principle Pollutants
Various pollutants which cause environmental pollution are:
*
Deposited matter
Dust, smoke, sooth, grit, tar etc.
*
Gases
Carbon dioxide (CO2), Carbon monoxide (CO)
Sulphur dioxide (SO2), Halogens (Fluorine Chlorine,
Bromine, Iodine) Ozone, Ammonia etc.
*
Chemical compounds
Hydrogen fluoride, aldehydes, detergents, phosgene
etc.
*
Acid droplets
Nitric acid, Sulphuric acid, etc.
*
Metals
Iron, Zinc, Nickel, Cadmium, Chromium, Lead,
Mercury etc.
Agrochemicals (Poisons)
Pesticides, fungicides, herbicides, insecticides etc.
Organic substances
Acetic
Acid,
Benzene,
Ether,
Toluene,
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Benzopyrenes etc.
*
Photochemical oxidents
-
Photochemical Smog, Peroxy Acctyle, Nitrate,
(Pan), Nitrogen Oxides etc.
*
Fertilizers
-
Nitrogen, Phosphorous, Potash etc
*
Sewage waste, noise and heat, radioactive waste (iodine-131, cobalt-60, argon-41)
etc.
1.1.5 Types of Environmental Pollution
Pollution can be classified according to the medium in which it is added or
occurs. Types of pollution are.
Air pollution (atmospheric pollution)
Water pollution
Land/Soil pollution
Pollution can also be classified on the basis of the individual pollution. They are:
> Sewage pollution
> Noise pollution
> Metal pollution
> Oil pollution
> Population pollution
> Biological pollution
>• Thermal pollution
> Radioactive pollution
> Pesticide pollution
> Marine pollution
> Industrial pollution
1.1.6 Effect of pollution:
The pollution impact on the environment can be of short duration provided, if the
biosphere possesses enough capacity to assimilate, absorb or transport pollutants. Human
also assist in this process by treating the wastewater, recovering the pollutants,
reoxygenate water, destroy organic and disease organisms. Many times the pollutants are
diluted in river or lake water or hide them in land fills or store under sea. From there the
pollutants transform into the surrounding environment.
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Ex. Soil, Water, Air etc.
Pollution affects both the living and non-living component of environment [5],
Pollutants are increasing the assimilation capacity of the biosphere and often have long
term effect on the environment. The changes in physical environment (air, water and
land) adversely affects on the health of human and animals, and damaging plants and
property. Which directly affects on food production and depletion of forest resources?
Besides these are effects of noise pollution, radiation pollution, thermal pollution etc. As
the environment stress on the human being increases, it leads to infections disorders,
metal stress and causes cancer etc. The general effects observed are climatological
changes such as reduction in rain, increase in atmosphere temperature (green house
effect), change in quality of air etc. The change in atmosphere temperature leads to the
melting of snow consequently increases in sea level. Polluting the air causes depletion of
ozone in the atmosphere. By which UV radiation increases in the sun light and leads to
skin cancer.
The adverse effects on plants range from reduction in chlorosis (reduction of
chlorophyll), necrosis (dead area of leaf) and general growth of plant etc. pollution also
causes deterioration in the quality of materials such as steel, lime stone, paint etc.
1.2 Water Pollution
Water pollution is the contamination of water by foreign matters such as physical
matters, chemicals, micro-organisms, sewage, industrial waste or other wastes. All these
pollutants deteriorates the quality of the water and renders it unfit for its best uses [6].
Change is physical, chemical and biological characteristics of water which may
cause harmful effects on human, animal and acquatic biota.
In nature, water is available in its purest from (rain water). Many impurities are
added into it as it reaches the ground and percolates beneath the earth surface and also
when it used for the activities of human. Water pollution means alteration in the
physical, chemical and/or biological properties of water or contamination of water.
Pollution is caused due to the discharge of sewage, industrial wastes, trade effluents,
radioactive waste, any other liquid or solid substances etc. in to the water. Water
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pollution affects on the normal uses of water for public water supply, commercial,
industrial, agricultural, or other ligitimate uses. Polluted water creates nuisance, render
water harmful or injurious to public health, animals, plants or aquatic life [7].
Fresh water available on the earth is used for various purposes[8]. It is used for
drinking, recreation, domestic and municipal uses, industries, irrigation, navigation. The
used water carries the residues of the activities with them and become contaminated [9].
The contaminated water is called waste water. The contaminated water becomes harmful
to plants, animals and human beings. The waste water generated are allowed to drain in
the natural drain or in pipe network (sewage pipe) and join stream or water bodies in the
downdward side [10]. Addition of the waste water to water bodies contaminates fresh
water flowing or available with them. Generally these waters added with chemicals
(organic and inorganic), degradable organis, pathogenic and non-pathogenic organisms,
suspended and floating soils, oil and grease etc. These water sources do not remain fit for
human consumption, life of plants and animals, industrial uses etc.
1.2.1 Sources of water pollution
The sources of water pollution are two types.
Non-point or natural source: Non point source is also called diffuse source of
pollution. The point of entry of pollutant is not identifiable. The pollutants generated
from a broad group of human activities and by natural processes. The pollutant sources
are decomposed vegetable and animals, agricultural run off. Weathering products etc.
Addition of these pollutants influence on the chemical characteristics, colour, odour,
biological properties etc.
Point or artificial sources: The pollutants are added at a known point. The pollutants
are collected and discharged at a single point. The sources are sewage, industrial, radio­
active, mining etc. The pollutant sources are generated due to the activities of man.[l 1]
1.2.2 Types of Water Pollution
Water pollution can be classified into the following three categories
*
Physical Pollution
■
Chemical Pollution
■
Biological Pollution
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Physical Pollution: The physical pollution of water is due to change in colour, turbidity,
odour, taste, foam, thermal properties and conductivity.
Colour change is not harmful, if it is not containing toxic chemicals. Most of the
waste waters contain colours due to organic dyes and inorganic compounds. Turbidity in
water is due to colloidal matters and finer suspended solids and soil erosion. Generally
higher the turbidity, stronger is the sewage and industrial wastewater, and the effects are
more. Unpleasent taste and adour are produced by industrial wastewater containing free
chlorine, phenols, Fe, Mn, etc. The presence of phenols produces medicinal taste.
Decaying of organic matter, fungi, algae etc., import peculiar taste towater. Odour is
mainly imported to water both by biological (fungi, micro organisms etc.) and chemical
compounds (Ammonia, Hydrogen Sulphide, Hydrocarbons, Free Chlorine etc.) Decaying
of organic matters and low pH, H2S will be produce, which can cause greater Adour
problems. Foam is formed by soaps, detergents, surfactants, untreated effluents etc. It
effects on reaeration capacity of stream and causes neusence. The thermal pollution is
mainly because of the discharge of heated and cooling water from industries and thermal
power plants. The heated water increases the degradability of organic matter and reduces
the dissolved oxygen in water.
Chemical Pollution : The chemical pollution of water is due to change in total solids
(Suspended, Settleable And Colloidal Solids), pH (Acidity And Alkalinity), chloride,
nitrogen, phosphorus, fats (includes Oil And Greases), sulphates (Sulphides and H2S),
dissolved oxygen, chemical oxygen demand (COD), bio-chemical oxygen demand
(BOD), gases, metals etc. Pollution is caused by organic or inorganic or by both.
Chemical analysis of water is carried out on wastewater in order to determine the
chemical characteristics, helps to indicate strength, stages of decomposition and type of
treatment required for making it safe for its ultimate uses.
Total Solids, suspended and precipitant solids: Sewage normally contains very
small amount of solids. It contains about 0.05 to 1.0 percent of (ie 500 to 1000 mg/1) of
solids. Industrial waste water contain total solids upto 7000 mg/L
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Chapter - 1
pH value: The pH value of sewage indicates the presence of alkaline or acidic salts or
acids. pH is the negative log of hydrogen ion concentration present in sewage. If the pH
is less then 7, the sewage is acidic, and if it is more than 7, the sewage is alkaline. The
industrial wastewater has the pH varying between 3 to 11. For any treatment method pH
is impotant.
Chloride Content: Chlorides are generally present in municipal sewage. The normal
chloride content of sewage is 120mg/L. However, large amounts of chlorides may enter
from industrial wastewater.
Nitrogen Content: Nitrogen indicates the presence of organic matter and it occurs in the
form of a ammonia nitrogen (free ammonia), organic nitrogen (albuminoid nitrogen).
Nitrate is the non-objectionable end product. The concentration of 45 mg/1 is allowed in
water. More than this causes “blue baby disease”, or methamoglobinemia” in childrens
(normally upto 6 months).
Fats, oils and greases: These are derived in sewage from the discharge of animal and
vegetable matter or from industries, garages, hotels etc. They interfere with the normal
treatment methods. These matters float in river water and cause visible pollution and
prevent reaeration capacity.
Sulphur Content: Sulphides and sulphates are formed due to decomposition of various
sulphur containing substances present in sewage and industries (tanneries, distilleries).
Hydrogen sulphide gas causes bad smell, odour and corrosion of materials (pipes and
concrete).
Dissolved oxygen (DO): The DO content of water is very important while discharging
sewage and industrial waste water or effluents into stream, it is necessary to ensure at
leant 4 ppm of DO in it. Lesser than 4 ppm (mg/L) will kill the fish and creating
nuisance.
Chemical Oxygen Demand (COD): This test allows measurement of a waste in terms
of the total quantity of oxygen required for oxidation to carbon dioxide and water. All
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the organic compounds oxidized by the action of strong oxidizing agents under acid
conditions. This test can do with in 3 hours.
Bio-chemical oxygen demand (BOD): This test allows fixing the amount of biologically
active organic matter present in wastewater.
Generally the BOD of water or wastewater during 5 days at 20°C is taken as
standard and is about 6.8% of the total demand. The standard 5 day BOD is written as
BOD5.
The organic pollutants are also be grouped as biodegradable or Non-biodegredable.
Biodegradable Organic Pollutants: These pollutants are those which are going to be
oxidized or fermented (hydrolyzed) in aerobic or anaerobic conditions. The end product
of aerobic condition is CO2, H2O and bacterial cells. Similarly the end products of
anaerobic conditions are CH4, CO2, H2 and bacterial cell (low). The bacterial cells are
called sludge. The pollutants are carbohydrates, sugars, proteins, starch, fats and oils,
other organic compounds (alcohols, acetate etc.) from sewage and industrial waste
waters. By treating in the engineered systems, this pollution load can reduce to the
maximum extent.
Non-Biodegradable Organic Pollutant: These pollutants persist in the aquatic
environment for long time. These pollutants may degrade at very slow rate. This leads to
the accumulation of these pollutants and enters to the food chain and cause biomagnification. For Example, insecticides, fungicides, pesticides, herbicides, benzenes,
toluenes, heavy metals chloro organics etc. These pollutants are categorized as toxic
pollutants.
Biological pollution of water:
Biological pollution of water is caused by excretory
products of man, animal, birds, sewage and industrial waste water (tanneries, slaughter
house, dairy etc.) The main biological pollutants are bacteria, viruses, algae, protozoa,
parasitic worm, faecal coliform, streptococi etc. Contaminated water causes infection of
intestinal system (dysentery typhoid, cholera etc.) infectious hepatites, anthrax [12] etc.
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Chapter -1
1.2.3 Major Water Pollutants
The major water pollutants are:
Sewage: other terms used are domestic wastewaters, municipal waste water, waste water
generated from domestic activities. It adds, colour, taste, adour, organic and inorganic
compounds, heavy metals, suspended solids, floating solids etc.To reduce the pollution,
treatment of waste water is necessary [13].
Agricultural Waste: Agriculture is the single largest user of freshwater (surface and
groundwater) resources. Most of the agricultural water is recycled back to surface water
and groundwater. Modern agricultural practices are the main cause of water pollution.
Agricultural practices such as applying fertilizer, manure spreading, irrigation methods,
pesticides, animal farming, aquaculture, tillage etc. have wide impact on surface and
ground water quality [14],
Industrial Waste: Most of the rivers, lakes and ground water are polluted by
industrial wastewater or effluents. Industrial wastewater or effluents contain a variety of
organic and inorganic pollutants, such as suspended solids, metallic wastes, oil, grease,
phenols, toxic organic and inorganics, plastics, chemicals etc. Many of these pollutant
are not susceptible to degradation or slowly degrade to cause very serious environmental
pollution problems[15].
Radioactive substances: Radioactive substances are short lived or long lived products
which are released from nuclear power plants, nuclear fuel processing and nuclear
weapon tests. The long lived products (Uranium, Stomitum-90, Thorium, and Cesium137) will remain in the water for longer duration and contaminate the water for longer
time.
Petroleum products: These consist of hydrocarbons. These are slowly degradable.
Crude oil is the major pollutant of sea, when a large tanker spills the oil when
transporting. The major pollutants are oil, Benzene, Toluene, Chlorinated Solvents,
Biocides, Plastics, and Pesticides etc. Chlorinated solvents are toxic at very low
concentration [16].
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Thermal pollution: Release of heated water from chemical industries, thermal power
plants, nuclear power plants etc,, leads to the increase of temperature of water bodies.
Which effects on the utilization of water best uses and it effects on the entire aquatic
environment. (Increase in bacterial multiplication, consumption of DO, death of fish etc.)
1.2.4 Indicator of Polluted water
Following are the important indicators of water pollution:
Colour and bad taste of drinking water.
Increase in turbidity and floating solids (oil and grease).
Offensive odour from water bodies.
Growth of aquatic weeds (eutrophication) in water bodies.
Decrease in aquatic animals (fish).
Increase in temperature of water etc.
The polluted water cannot be used for public supply, industries recreation, agriculture,
aquaculture etc.
Radio active
Sewage domestic
Organic
^wastes
.Mineral
Oil
Increased fungicides, etc
temperature
‘ Products of
mining
Fig. 1.1 Pollutants responsible for water pollution
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Chapter -1
1.2.5 Water pollution control
Water pollution has become a global problem due to the industrialization and
population explosion. Industrial and domestic wastewaters have several undesirable
components [17]. (Organic and Inorganic). The wastewater treatment and its proper
management has become necessary to conserve the water resources. The pollution
problem in India is worse than same of the highly industrialized developed countries
(America, Europe etc.). The aquatic environment has been affected adversely by human
activities, improper sanitation and by unregulated enormous discharge of municipal and
industrial wastes. Some of the techniques to minimize the water polluted problem are
[18]-
1) Waste water treatment
The first step in controlling the water pollution is to treat the sewage and industrial
wastewater. There are several stages of treatment in the purification process. The
different method adopted is classified as:
I.
II.
III.
Physical units
Chemical process and
Biological process.
The other classification based on the above three is:
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Table 1.1 Different Treatment Processes
Physico chemical
Biological
Advanced
Physical
Aerobic
Electrolysis
Screening
Aerated lagoon
Reverse-osmosis
Grit chamber
Extended aeration
Ion exchange
Flotation
Oxidation pond
Adsorption etc.
Oil & grease trap
Activated sludge process
Plane sedimentation etc.
Stabilization pond
Physico-chemical
Oxidation ditch
Coagulation-sedimentation
Trickling filter etc.
Clarifier
Anaerobic
Anaerobic digestion
Anaerobic logoon
Anaerobic filter etc.
a. Primary treatment
b. Secondary treatment
c. Tertiary treatment or advance treatment
The primary treatment is to remove floating and suspended solids, oil and grease and
grit (sand or clay particles, egg cells, glass pieces etc.) by screening, grit chamber, oil
and grease tank, flotation and primary sedimentation (by gravity without chemicals). The
primary treatment is followed by secondary treatment. The secondary treatment is by
using chemicals (coagulants) or biological processes. Chemical processes are called
coagulation and sedimentation. The chemicals used are alum (aluminum sulphate) Lime,
Ferrour Sulphate, Ferric Chloride etc., to remove the finer suspended solids or to
precipitate the other chemicals or metals into sludge. The biological process uses micro
organisms to biodegrade (decompose) the degradable organic materials in the wastewater
under favorable conditions [19]. The growth of micro organisms utilizes the organic
matter as carbon source and nutrients and multiply the bacteria. After several hours, the
bacteria are settled as sludge (biological sludge) in secondary settling tank. The
remaining pollutant if required is removed in territory treatment. Territory treatment is a
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Chapter -1
complex chemical and biological process that removes metals, organic compounds,
minerals, viruses, inorganic compounds [20] etc.
The schematic flow diagram is shown in fig.
drying beds
Fig. 1.2 Flow diagram of Muncipal waste water treatment
The sewage sludge can be used as fertilizer since the liced bacteria, contain
nitrogen and phosphorus. The industrial waste water treatment sludges are very toxic and
handling is a problem. The effluent standard for disposal is given in table as follows.
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Table 1.2 Industrial effluent and sewage effluent discharge standards
into surface water sources
S.no
Characteristics of the effluent
Industrial effluents
discharge IS 2490-1974
1
BOD5
30mg/ L (20mg/ L)*
2
COD
250mg/ L
3
pH value
5.5 to 9.0
4
Total suspended solids (TSS)
lOOmg/L (30mg/ L )*
5
Temperature
40°C
6
Oil and grease
lOmg/L
7
Phenolic compounds (as phenols)
lmg/L
8
Cyanide (as CN)
0.2mg/ L
9
Sulphides (as S)
2mg/L
10
Fluorides (as F)
2mg/ L
11
Total residual chloride
lmg/ L
12
Insecticides
Zero
13
Arsenic (as As)
0.2mg/ L
14
Cadmium as (Cd)
2mg/L
15
Chromium, hexavalent (as Cr)
O.lmg/ L
16
Copper
3mg/ L
17
Lead
O.lmg/ L
18
Mercury
0.01 mg/ L
19
Nickel
3mg/ L
20
Selenium
0.05mg/ L
21
Zinc
5mg/ L
22
Ammonical nitrogen (as N)
50mg/ L
23
Radio active materials
a - Emitters
1 x 10"7/rc/ml
p - Emitters
1 x 10'6/ic/ml
* Sewage effluent discharge standard, except BOD5 and total suspended solids, all other
values are same (IS 4764-1973).
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Water is the main resource in all economic activities ranging from agriculture to
industry. The tanning industry is one of the oldest industries in India. Usually the tannery
wastes are characterized by strong colour, PH and high dissolved salts [21]. In the recent
years, the concentrated growth of this industry in certain localities has shown how the
waste from this industry can cause irreversible damage to the water environment in the
vicinity [21]. Leather production is a major industry in India, which makes significant
contribution to the country’s Foreign exchange earnings and provides employment
opportunities to about 3 million people. It is estimated that 30-35 litres of water is used
per kilogram of leather processed, generating about 680 million litres of effluent daily.
During the process of leather making, several chemicals like Chromium Sulphate,
Sodium Chloride, and Calcium Hydroxide etc are extensively used. Therefore, the
resultant effluent is enriched with chromium and salts. Indiscriminate disposal of
chemicals rich tannery effluent has resulted in extensive degradation of productive land,
surface and ground water. The industrial effluent standards are stringent as compared to
disposal on and for irrigation. Therefore industries, prefer to discharge their effluents on
land. Continuous irrigation using even treated effluents may lead to groundwater and soil
degradation through accumulation of pollutants. Apart from disposal of industrial
effluents on land and other surface water bodies, untreated / improperly treated effluents
are also injected into the groundwater through ditches and wells in some locations in
India to avoid pollution abatement costs. As a result groundwater resources of
surroundings areas become unsuitable for drinking and agricultural purposes. Continuous
application of polluted groundwaters for irrigation can also increase the soil salinity and
alkalinity problems in farmlands [22].
Ground water is said to be the safest water for drinking purpose and domestic
purposes among the various sources of water. Several factors such as discharge of
agricultural waste, domestic wastes and industrial wastes, land use practices, geological
formation, rainfall patterns and infiltration rate are reported to affect the quality of
ground water in an area [23]. As groundwater moves along flow lines from recharge to
discharge areas, its chemistry is altered by the effect of a variety of geochemical
processes [24]. In Karnataka there is no significant work on water quality except by
Jayanthi (1993) [25], Ayed (2002) [26] and Jayalakshmi Devi et.al (2005) [27]. T.Suresh
et.al (2009) [28], Water quality assessment studies in Karnataka, especially of Tumkur
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District are inadequate. Therefore the present study has been undertaken to assess the
water quality in this region.
Environment is the life support system that includes air, water and land, Nature is
the valuable asset possessed by earth, that provides all the basic requirements such as
food, air, water and shelter for the livelihood of living beings Nearly 75% of our rural
population is primarily dependent on ground water and about 25% of the people’s needs
in urban areas of our country are met by ground water. For obvious reasons, surface
water is unavailable everywhere and hence ground water becomes the only alternate
source of good quality of water. The ground water exploration and development have
gained momentum not only in our country, but also the world over, to cope up with the
increase in demand on the quality and quantity of fresh water due to population
explosion industrial expansion and rapid agricultural development.
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1.3 Air pollution
The atmosphere is the thin layer of gases (air) that surrounds the earth surface.
Air is defined as the invisible, tasteless and elastic mixture of gases. Air pollution is
assuming global magnitude and it is not confined to any particular part of earth or
country. Under ideal conditions, the air in the atmosphere has a qualitative and
quantitative balance that maintains the well being of human, plants and materials. When
the balance among the air components are disturbed, then the air is said to be polluted.
The definitions of air pollution are as follows:
Air pollution is the presence of ambient atmosphere of substances, generally
resulting from the activity of man, in sufficient concentration present for a sufficient time
and under circumstances which interfere significantly with the comfort, health or welfare
of persons or with the full use or enjoyment of property (Indian Standard Institution).
The presence in the outdoor atmosphere, of one or more contaminants such as
fumes, dust, gases, mist, grit, odour or vapours in considerable quantities and of duration
which is injurious to human, animal or plant life or which unreasonably interferes with
the comfortable enjoyment of life and property[29].
Substances introduced into the air by the activity of mankind in such
concentrations sufficient to cause serious effects on his health, plants, property or
interfere with the enjoyment of his property [30],
1.3.1 Components of Air
Various gases are present in the atmosphere. The nitrogen gas is biologically inert
but it is utilized by some bacteria and plants. The oxygen is essential for all living
beings. Carbon dioxide is utilized in photosynthetic process of plants. Trace gases
(Helium, Neon, Krypton, Xenon etc.) have little or no role with the living organisms.
Atmospheric pollution is the addition of harmful gases by human activities.
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Table 1.3 Normal Composition of Air
Gases
Percent (by volume)
Nitrogen
78.084
Oxygen
20.9476
Argon
0.934
Carbon dioxide
0.0314
Methane
0.0002
Hydrogen
0.00005
Other gases
Minute
1.3.2 Classification of Air pollutants
As the clean air in the troposphere moves across the earth’s surface, the products
of both natural (dust, volcanic eruptions etc.) and anthropogenic (man made-emissions of
vehicles and industry) activities are going to add to it. The pollutants which are going to
emits directly from the identifiable source are called “Primary Pollutants”. The primary
pollutants are going to react one another or with the basic components of air to form new
pollutants which are called secondary pollutants. The secondary pollutants are formed
due to chemical and photochemical reactions in the atmosphere[31]. The reaction
mechanisms involved in the processes are influenced by factors such as concentration of
reactants, the degree of photo activation, local topography, meteorological forces and
moisture content in the atmosphere. Examples of primary air pollutants are: Finer
particles (<100
fj,
m), coarse particles (>100
fd
m), carbon dioxides, oxides of nitrogen,
sulphur compounds, ammonia, halogen compounds, radio-active compounds and organic
compounds.
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Chapter - 1
Table 1.4 Emission sources of air pollutants
Natural sources
Man-made sources (artificial)
Pollen grins of flowers
Burning of wood
Sand and dust
Deforestation
Volcanoes
Nuclear tests
Forest fires
Mining
Marsh gases
Incineration
Cosmic dust
Power generation
Photochemical reactions
Air crafts
Vegetative decay
Vehicular emissions
Natural organic & inorganic decay
Industrialization
Soil debris
Burning of fossil fuels
Fungal spores etc.
Metallurgy
Refrigeration
Waste treatment plants
Wars etc.
Examples of secondary air pollutants: Ozone, formaldehyde, PAN (Peroxy Acetyl
Nitrate), photochemical smog, acid mists (H2SO4, HNO3).
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Table 1.5 The major classes of air pollutants
* Carbon oxides
-
Carbon dioxide and Carbon monoxide
* Nitrogen oxides
-
Nitric oxide , Nitrogen dioxide and nitrous oxide
* Sulphur oxides
-
Sulphur dioxide (SO2) and sulphur trioxide (SO3)
* volatile organic compounds (VOCs)
Methane, benzene, chloro-fluro carbon, solvents
* Photo chemical oxidants
-
Hydrogen peroxide, ozone (O3), PAN, aldehydes
* Suspended particulate matter
-
Solid particles such as dust, oil, lead, pesticides etc.
* Radio-active substances
-
Radon-222, Iodine-131, Plutonium-239 etc.
* Heat
-
Electricity from coal, oil etc.
etc.
1.3.3 Major Air pollutants and their effects
a) Particulate Matter
Air bom small solid and liquid droplets are known as particulates. Presence of
particulate matter makes up smoke. The particulate matter may be ashes or particulates
formed due to incomplete burning. Particulate matter are also emits from many
industries. Lead, Asbestos, Manganese, Arsenic, Copper and Zinc are some of the many
other particulate pollutants. The particulate matters stay in the atmosphere from a few
seconds to several months, depending on their size, density, settling velocity and
turbulence. Particles of size 1-10 fi m settles faster, 1.0 - 0.1 /am has small settling
velocity and particles of size below 0.1 /rm stays in the atmosphere for very long period.
The effects caused by the particulate matter are reduction in visibility change in
urban climatological characteristic and change in chemical characterstics of precipitation.
Air borne particles ie. Dust, soot, fume and mists are potentially dangerous for human
health. Accumulation of small particles can cause respiratory and cardiovascular
illnesses. Asbestos fibers can cause asbestosis [32],
b) Carbon monoxide
Carbon monoxide is a tasteless, odourless, colourless and non-irritating gas. The
chief sources are automobiles emissions due to incomplete combustion. The other
sources are stoves, furnaces, forest fires, open fire, factories, power plants etc. CO level
Page No. 21
Chapter -1
in the air is from trace to 0.5 ppm. Its level in urban area range from 5 to 50 ppm. Carbon
monoxide is very harmful to those persons who are exposed to the level of 100 ppm
(high ways). CO causes the effects such as difficulty in breathing, headache, irritation of
mucous membrane etc. The CO is fatal at higer concentration of 1000 ppm. Inhalation of
CO around 200 ppm in air causes carboxyhemoglobin i.e., combining of CO with blood
hemoglobin. This results in the decrease in oxygen carrying of blood to cells resulting in
oxygen deficiency (hypoxia). Inhalations for 6-8 hours result in headache and reduced
mental activity [33].
c) Carbon dioxide (CO2)
Carbon dioxide is release from respiration of organisms (natural). Major amount
is from burning of fossil fuel (coal, oil etc.) domestic cooking, industries, heating etc.
The CO2 concentration of atmosphere has rise more than 10 percent since from 1950s.
About half of the CO2 released into the atmosphere is utilized by plants for
photosynthesis or absorbed by the ocean water. The other 50% remain in the atmosphere.
The effect of CO2 is global warming and green house effect [34].
d) Sulphur Compounds
The sulphur containing pollutants in the atmosphere are carbon disulphide (CS2),
carbonyl sulphide (COS), dimethyl sulphide [(CHs^S], sulphur dioxide (SO2), Hydrogen
sulphide (H2S) and sulphate (SO4). Sulphur oxides are the most serious pollutants in the
atmosphere. Combustion of sulphur containing coal and petroleum products release the
oxides of sulphur. The major sources are thermal power plants, automobiles and smelting
plants.
e) Sulphur dioxide
It is colourless gas with pungent odour. Burning of fossil fuel in domestic,
industrial, power plants and furnaces releases around 75% of SO2 in atmosphere. Other
25% of the SO2 is from petroleum refineries and non ferrous smelters. SO2 emission in
India was around 13.9 Mt in the year 2000 against 6.76 Mt in 1979.
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f) Hydrogen Sulphide
It is a colourless toxic gas and has penetrating odour (rotten eggs). The sources of
H2S are decaying animal matter and vegetable matters. It is also released from sewers,
volcanic discharges coal pits etc.
Sulphur dioxide and its derivatives produce strong irritation of eyes and nasal
passegeways. SO2 causes significant brancho-constriction in asthematics at low
concentration (0.25-0.50 ppm). Fogs and moist air forms the H2SO4 and sulphate ions.
H2SO4 is a strong irritant than SO2 and causes deteriotation of materials. The plants are
more sensitive to SO2 than animals and human. This gas causes collaps of leaf area
(necrotic area). There is a bleaching of leaf pigments and impact on the plant
productivity. SO2 involve in the erosion of building materials such as limestone, slate,
mortar, marble and causes acid rain.
g) Nitrogen oxides (NO*)
Nitous oxide (N2O), Nitric oxide (NO) and Nitrogen dioxide (NO2) are different
form of NOx. They generally found in measurable concentration even in unpolluted
atomosphere. Out of these NO and NO2 are major pollutants. Oxides of nitrogen are also
produce due to the action of cosmic rays in the upper atmosphere (stratosphere). Man
made source of NOx are produced by the combustion of coal, natural gas, oil and petrol.
About 95% of NOx is produced as NO and remaining 5% as NO2. About 46% of NOx in
air comes from vehicular exhaust and 25% from electric generation and other sources is
urban area. NO is responsible for photochemical a reaction which forms PAN [35]. O3.
Carbonyl compounds etc. NO2 is the chief constituent of photochemical smoge. NO2
causes irritation, emphysema (inflammation), lung inflammation etc.
Smoker may suffer from lungs disease as the cigaretts contains 330-1500 ppm of
NOx. The plants growth is suppressed when exposed to 0.3-0.5 ppm for 10-20 days.
When the plants exposed for 4 hours to 4 to
8
ppm of NOx, visible injury of leaf can
observe, NOx reacts with moisture and then forms HNO3 (acid mist). The acid mist falls
on the ground as acid rain.
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Chapter -1
h) Ozone (O3)
Ozone is formed in the atmosphere through the chemical reaction involving NO2,
SO2 and aldehydes on absorption of UV radiation. Ozone near the earths surface creats
pollution problems. Ozone may also be formed by the reaction of NO2 under UVradiations effect.
Increase in O3 concentration near the earth surface has adverse effect on human
health, and reduces crop yields significantly. At 0.02 ppm, O3 damages tomato, beans,
tobacco and other plants. O3 produces visible damage to leaves Ozone also reacts with
nylon, cotton, dyes etc. and damage them.
i) Hydrocarbons
The air pollutants are from petrol and petroleum products. Some of them are
Benzene, Benz-Pyrene, and Methane etc. The main sources are motor vehicles and
storage of hydrocarbons. The motor vehicles emittes by evaporation of petrol through
carburetors, crankcase etc. Evaporation from two and three wheels accounts for 65% of
the total hydrocarbons and the rest from unbumt fuel. They cause health hazard due to
the formation of photochemical reactions. PAN is the main product of photochemical
reaction.
Hydrocarbons + NO2 + O2
PAN + O3 + others
sunlight
------------------------ ►
Hydrocarbons have carcinogenic effect on lunges of human. PAN causes eye
irritation, respiratory distress, nose and throat irritation. Benzene and Benzpyrene causes
cancer. Aldehydes and ethylene products cause smog formation. Exposure of plants to
PAN, hydrocarbons and photochemical oxidents are injurious to plants and cause
chlorosis.
j) Metals
Mercury, Zinc, Lead and Cadmium are the common metals occurring in the
atmosphere. There are released from industries and human activities to the atmosphere.
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Chapter - 1
Mercury:
It is a liquid volatile metal found in rocks and soils. It addes to air due to human
activities. Mercury is used in the manufacture of paints, antiseptics, fungicides etc.
Inhalation of lmg/m3 of mercury in air cause mercury toxicity, fatique, headache,
leathergy, loss of apetitic etc. It damages nervous system, liver, eyes and may lead to
death (inhalation for three months)[36].
Zinc:
It occurs in the atmosphere around zinc smelters and scrap zinc refineries. Zinc
also emits from lead, copper and steel refining industries. Zinc occurs in air in the form
of white zinc oxide fumes and it is toxic to human.
Lead:
The consumption of leaded petrol contributes for lead in atmosphere. Lead
compound are added to petrol as anti-knocking agent. Lead emitted as volatile lead
halides (chlorides and Bromides). In air quality guide of WHO, the lead level is not to
exceed 2 //g/m . Lead inhalation causes reduced hemoglobin formation, and leads to
anemia. Other effects are liver and kidney infections in human.
Cadmium:
Occurs in air as a result of industrialization and human activities. Metal industries
engaged in extraction, refining, electroplating and welding of cadmium containing
materials, and refining of zinc, copper and lead are some of the major sources. The
vapours emitted are reacts to form oxide, sulphide or chloride compounds. Cadmium is
known to accumulate in human liver and kidney. It also causes hypertension,
emphysema and carcinogenic.
Other metals present in the atmosphere are, nickel, copper, beryllium, arsenic,
chromium, asbestos etc. Most of these metals are carcinogenic to human and animals.
k) Photochemical smog
There is much interlinking of NOx, O3 and hydrocarbons in the atmosphere.
These are major air pollutants. In presence of sun-light (UV) they react each other to
produces more toxic secondary pollutants in air. This reaction is called photochemical
reaction. The photochemical products are ozone, peroxy-acetyl-nitrate (PAN), olefins,
aldehydes, photochemical smog etc. These compounds cause irritation to skin, eyes and
upper respiratory tract. They are toxic to plants and causes silvering beneath the leaves
[37].
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Chapter -1
Photochemical smog is a mixture of pollutants such as nitrogen oxides, ozone,
PAN, aldehydes, hydrocarbon etc. The smog often has a brown haze due to the NO. This
smong is produced as a result of photochemical reaction among NOx, O2 and
hydrocarbon. This pollution causes reduced visibility and eye irritation. The smog is a
combination of smoke and fog. London smog (1952) is well known episodes of
industrial smog. The photochemical smog can be extremely toxic to human, plants and
minerals.
I) Chlorofluoroearbons (CFCs)
Chlorofluorocarbons (CFCs) are compounds belong to the group containing
Chlorine, Fluorine and Carbon. In general they are low flammable, unreactive, less toxic
and having low solubility in water. The major sources of CFCs are cleaning solvent,
refrigerants, aerosol propellants and plastic blowing agents. The CFCs are trieholorofluoromethane (CCI3F),
dichlaro-di-fluoromethane
(CCI2F2),
trichlorofluoroethane
(CCI2FCCIF2), etc. CFCs are used with materials like paint, insecticide, cosmetic
preparation etc., in pressuriesed containers. Once open they are going to add to air,
dichloro-di-fluoromethane is the most important one. These are used in refrigerants and
air conditioning units and foam plastic blowing agents. The series of CFCs are called
Freon. The release of CFCs leads to ozone depletion in the atmosphere [38].
1.3.4 Effects of Air pollutants
A healthy human breathes about 25,000 times a day, at a rate of 1-2 Its of air per
breath, ie about 25000 to 50000 lts/day. Hence air we breathe must be free from
pollutants and of good quality. Air quality surrounding human has a direct impact on
health and property. The health effects of air pollutants are classified as short term
effects and long term effects. Elderly people and children often suffer more from the air
pollution. The harmful effect of air pollution depends on the concentration of pollutants
and duration of exposure [39].
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Chapter -1
Table 1.6 Common Air pollutants their sources and effects
SI.
Sources
Pollutant
Effects
No
1
Carbon dioxide C02
Coal, petrol, oil, diesel,
Green house effect
combustion (Automobile
exhaust)
2
Carbon monoxide CO
Burning of coal petrol,
Reduce oxygen carrying
diesel, automobile
capacity of blood, causes
exhaust
headaches and drowsiness
fatal in high concentration
3
Sulphur dioxide S02,
Coal and oil combustion
Acid rain: which damages
trees, plants, water bodies,
so3
materials, causes headache,
aggrevates asthma,
vomiting and causes
irritation of eyes, nose and
throat.
4
5
Oxides of nitrogen N02,
High temperature
Acid rain formation, effects
NO
burning in automobiles,
plants, building, lakes,
burning of coal
aggrevates asthma
Burning of leaded petrol
Neural effect in children,
Lead compounds
effect on plants
6
7
8
Nuclear waste
Nuclear weapon testing,
Radioactivity, cancers,
nuclear power plants
mutations etc.
Suspended particles
Burning of coal
Eye irritation, aggrevation
(ash, fly ash soot etc.)
manufacturing process
of asthma etc.
Ozone (03)
Atmospheric chemical
Global warming, damage to
reaction of N02 and
plants and materials
aldehydes
9
Hydrocarbons
Burning of petroleum
Carcinogenic effect on
products, benzene,
human causes eye irritation
benzepyrene etc.
respiratory distress, throat
Page No. 27
Chapter -1
irritation, formation of
PAN, effect on plants
10
Chlorofluro carbons
Refrigerants, aerosole
(CFCs)
propellents, cosmetics
Ozone depletion
etc
The short term effects include irritation of eyes, nose and throat and upper
respiratory infections such as pneumonia and bronchities, allergic reactions, headaches
and nausea. Long term health effects are lung cancer, chroinc respiratory disease and
damage cause to liver, nerves system, kidneys and brain. The continues exposure to air
pollutants can aggrevate or complicate the medical conditions in children and elderly
persons.
Main global air pollution problems are ozone depletion, aerosol scattering, green
house effects, acid rain, long range transportation of air pollutants and heat islands.
Significant and devastating effects of air pollutants have been identified on plants. Some
of the visible injury on plants and leaves are necrotic patterns, chlorosis, tissue collapse,
growth alterations and colour patterns. Air pollution can cause economic loss by
damaging the property. The air pollution damage to property is corrosion of metals,
eroding or soiling of building surfaces, rubber cracking, fading of paints etc. Air
pollutants have a direct or indirect effect on climate, human, vegetation and materials.
1.3.5 Air Quality Standards
The ambient air quality standards given by central pollution control board of
India is given below.
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Chapter -1
Table 1.7 Indian Ambient Air Quality Standards
Concentration in ambient air (//g/m3)
Time
Pollutant
Residential,
weighted
Industrial area
rural & other
Sensitive area
average
areas
Sulphur dioxide
Annual
80
60
15
S02
24 hours
120
80
30
Oxides of Nitrogen
Annual
80
60
15
no2
24 hours
120
80
30
Suspended
Annual
360
140
70
particulate matter
24 hours
500
200
100
Respirable
Annual
120
60
50
particulate matter
24 hours
150
100
75
Annual
1.0
0.75
0.50
24 hours
1.5
1.0
0.75
8 hours
5.0
2.0
1.0
1 hours
10.0
4.0
2.0
(SPM)
(<10//m)
Lead (Pb)
Carbon
monoxide
(CO)
Air quality monitoring may done by measuring, emissions from point sources
(stack), ambient air and metrological. Ambient air is monitored to provide background
values with which to compose results of emissions monitoring and to assess pollutant
levels in the atmosphere. The most common particulate matter monitoring equipment is
high volume sampler. Devices used for gas monitoring are gas specific. Hence different
equipments are required for different gases. Instruments applied for monitoring gaseous
emissions are wet chemistry techniques, electrochemical, ultraviolet light and infrared
analysis techniques.
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Chapter -1
1.3.6 Air pollution control
The atmosphere has several mechanisms of self cleaning such as dispersion,
flocculation, absorption, agglomeration, gravity settling, rain wash etc. Today air
pollutants are emitting at higher rate than the self cleanising and they started to
accumulate. So control of air pollutants at source is a more desirable and effective
method through preventive or control technologies [40],
a) Source control
First approach to reduce air pollution is through source reduction. Some of the source
reduction methods are:
> Substitution of high sulphur coal to low sulphur coal in thermal power plants.
> Substitute coal by natural gas.
> Substituting petrol with ethanol or oxygenated fuel.
> Use alternative energy sources.
> Use only unleaded petrol.
> Use catalytic converters to control the emissions of CO and HC.
> Planting trees along busy streets. They can remove particulates, CO and absorb
noise etc.
Air pollutants are mainly:
a. Particulate matter
b. Gaseous emission and
c. Automobile exhaust
d. The different techniques used to control are:
e. Particulate control
f.
Gaseous pollutants control
g. Automobile emission control
Particulate Control
The particulate size ranging from 0.1 to 100 micron. It is important to realize the
sizes of air pollutants range that have to be controlled. In addition, the types of chemicals
in the emissions will often dictate the use of a particular devices and the efficiency of
removal is also important. Everyday around 0.5 Mt of particulates are released into the
atmosphere by athropogenic sources. Particulates released into atmosphere in the form of
dust, mist, smoke, smog, aerosoles etc. The equipments used for particulate matter
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Chapter -1
control are settling chambers, cyclons, bag filters, and scrubbers (wet and dry)
electrostatic precipitators [41].
Control of Gaseous Pollutants
Principle gaseous pollutants responsible for air pollution are sulphur oxides,
nitrogen
oxides,
carbon
oxides,
organic
and
inorganic
acidic
fumes
and
hydrocarbons[42]. For the control of these gases chemical processes such as absorption,
adsorption, condensation and combustion are used.
Absorption
Absorption is the processes used to remove gaseous air pollutants by dissolving
into a liquid medium (water, solvent, acid or alkaline solution). This method is used to
remove NOx, SOx, chlorine, ammonia, H2S, hydrocarbon etc. Processes like packed and
spray towers are used.
Adsorption
Adsorption occurs when the contaminant becomes attached to the surface of
adsorbing media. The adsorbing solid is called adsorbant and the adsorbing material is
the adsorbente or sorbate. Adsorption means of concentrating gaseous pollutants. This
process may employ for recovery or disposal. Some of the commonly used adsorbents
are activated carbon (granular or powdered), activated alumina, silica gel etc. Adsorption
is effective in removing aromatic and aliphatic organic chemicals (VOCs and dioxins)
and heavy metals like Lead, Mercury etc. Generally packed columns are used.
Combustion
This is a process used to remove organic compounds (VOCs) by destroying the
combustible air pollutants such as vapours, gases and odours into carbon dioxide and
water. Incineration systems are designed to oxidate the pollutants as close as possible to
completion. Complete combustion can be achieved by proper oxygen, temperature
(500°C to 1300°C), turbulence and giving sufficient time period. Combustion may be
divided into direct flame combustion, thermal combustion and catalystic combustion.
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Chapter -1
Condensation
Condensation of vapours from the gas stream using water at temperature serves
as effective removal method before treating the gases by combustion or adsorption. This
is method if recovery. It is applicable only if the vapour gas is rich with the recoverable
compound. Normally acid vapour are recovered by this method.
Tumkur city has Hemavathi River as major water resource in its neighbourhood.
The city has been heading towards fresh water crisis mainly due to improper
management of water resources and environmental degradation, which has led to lack of
access of safe water supply.
The department of Mines and Geology carried out investigations to evaluate the
ground water quality in Tumkur city. It has reported that 51% of the samples were found
to be non-potable due to the presence in excess of one or more water quality parameters.
But in our irrigation Nitrate was found to be the major cause, accounting for 45% of non
potability.
Air pollution may be defined as any atmospheric condition in which certain
substances are present in such concentrations that they can produce undesirable effects
on man and his environment. These substances include gases (sulphur oxides, nitrogen
oxides, carbon monoxide, hydro carbons, etc.), particulate matter (PM) (smoke, dust,
fumes, and aerosols), radioactive materials and many others. Most of these substances
are naturally present in the atmosphere in low (background) concentrations and are
usually considered to be harmless.
Those air pollution episodes were the results of exceptionally high concentrations
of sulfur oxides and particulate matter, the primary constituents of industrial smog
(smoke+fog=smog) or sulfurous smog. Sulfurous smog is caused almost entirely by
combustion of fossil fuels, especially coal, in stationary sources such as power plants and
smelters. In contrast, the air pollution problem in many cities is caused by emissions of
carbon monoxide, oxides of nitrogen and various volatile organic compounds, which
swirl around in the atmosphere reacting with each other and with sunlight to form photo
chemical smog. Although stationary sources also contribute to photochemical smog, the
Page No. 32
Chapter -1
problem is most closely associated with motor vehicles. A major effect of efforts in the
United States to control both sulfurous smog and photochemical smog has been the
elimination of those dramatic, peak concentrations of pollution that were responsible for
air pollution. The human toll is much more difficult to document, but estimates place the
current excess deaths caused by air pollution (mostly small particles) at several tens of
thousands per year in the United States alone.
Much of the work on air pollution in the last few decades has centered on a small
set of six substances, called criteria pollutants, that have been identified as contributors
to both sulfurous and photochemical smog problems. The sources, transport, effects and
methods of controlling these criteria pollutants will be the principal focus of this chapter.
More recently attention has been shifting towards the characterization and control
of a growing list of especially hazardous air pollutants, many of which we are exposed to
at our homes and work places, where we spend roughly 90 percent of our time. Modest
improvements in indoor air quality can improve public health as much as major
reductions in the traditional outdoor sources.
Atmospheric dispersion modeling is the mathematical simulation of how air
pollutants disperse in the ambient atmosphere. The atmospheric dispersion models are
also known as atmospheric diffusion models, air dispersion models, air quality models
and air pollution dispersion models. The dispersion models are used to estimate or to
predict the downwind concentration of air pollutants emitted from sources such as
industrial plants (point sources) and vehicular traffic (line sources).
One of the early air pollutant plume dispersion equations was derived by
Bosanquet and Pearson [43]. Their equation did not assume Gaussian distribution nor did
it include the effect of ground reflection of the pollutant plume. Sir Graham Sutton
derived an air pollutant plume dispersion equation in 1947[45] which did include the
assumption of Gaussian distribution for the vertical and crosswind dispersion of the
plume and also included the effect of ground reflection of the plume. The basis for most
of those models was the complete equation for Gaussian Dispersion Modeling of
continous, Buoyant Air Pollution Plumes [44],
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Chapter -1
The widely used Gaussian air pollutant dispersion equation requires the input of
effective stack height H which is the pollutant plume’s centerline height above ground
level. The difference between the actual stack height h and the effective height H is
called the plume rise Dh. Plume rise is caused by a combination of factors the most
important ones being the buoyancy and momentum of exhaust gases and stability of the
atmosphere itself. Buoyancy results when exhaust gasses are hotter than ambient air or
when the molecular weights of the exhaust is lower than that of air (or a combination of
both factors) momentum is caused by mass and velocity of the gasses as they leave the
stack.
1.4 ENVIRONMENT STUDIES: IMPORTANCE
Importance of Environment Studies: The environment studies enlighten us, about
the importance of protection and conservation of our indiscriminate release of pollution
into the environment.
At present a great number of environment issues, have grown in size and
complexity day by day, threatening the survival of mankind on earth. We study about
these issues besides and effective suggestions in the Environment Studies. Environment
studies have become significant for the following reasons:
a. Environment Issues Being of International Importance
It has been well recognised that environment issues like global warming and ozone
depletion, acid rain, marine pollution and biodiversity are not merely national issues but
are global issues and hence must be tackled with international efforts and cooperation.
b. Problems Cropped in The Wake of Development
Development, in its wake gave birth to Urbanization, Industrial Growth, Transportation
Systems, Agriculture and Housing etc. However, it has become phased out in the
developed world. The North, to cleanse their own environment has, fact fully, managed
to move ‘dirty’ factories of South. When the West developed, it did so perhaps in
ignorance of the environmental impact of its activities. Evidently such a path is neither
practicable nor desirable, even if developing world follows that.
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Chapter -1
c. Explosively Increase in Pollution
World census reflects that one in every seven persons in this planted lives in India.
Evidently with 16 per cent of the world's population and only 2.4 per cent of its land
area, there is a heavy pressure on the natural resources including land. Agricultural
experts have recognized soils health problems like deficiency of micronutrients and
organic matter, soil salinity and damage of soil structure.
d ENVIRONMENTAL SCIENCE
Need for An Alternative Solution
It is essential, specially for developing countries to find alternative paths to an alternative
goal. We need a goal as under:
(1) A goal, which ultimately is the true goal of development an environmentally sound
and sustainable development.
(2) A goal common to all citizens of our earth.
(3) A goal distant from the developing world in the manner it is from the over­
consuming wasteful societies of the “developed” world.
e. Need To Save Humanity From Extinction
It is incumbent upon us to save the humanity from exinction. Consequent to our
activities constricting the environment and depleting the biosphere, in the name of
development.
f. Need For Wise Planning of Development
Our survival and sustenance depend. Resources withdraw, processing and use of the
product have all to by synchronised with the ecological cycles in any plan of
development our actions should be planned ecologically for the sustenance of the
environment and development.
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Chapter -1
g. Misra’s Report
Misra (1991) recognized four basic principles of ecology, as under:
(i) Holism
(if) Ecosystem
(iii) Succession
(iv) Conversation.
Holism has been considered as the real base of ecology. In hierarchical levels at which
interacting units of ecology are discussed, are as under:
Individual<population<community<ecosystem<biome<biosphere.
Misra (1991) has recognised four basic requirements of environmental management as
under:
(0 Impact of human activities on the environment,
(if) Value system,
(iii) Plan and design for sustainable development,
(iv) Environment education.
Keeping in view the of goal of planning for environmentally sustainable development
India contributed to the United Nations Conference on Environment and Development
(UNCED), also referred to as “Earth Summit” held at Rio de Janeiro, the Capital of
Brazil, 3rd-14th June, 1992.
1.5 Scope of environmental Pollution
Pollutants may be chemical, biological, thermal, radioactive, or even mechanical.
Environmental engineering is a diverse field, which emphasizes several areas: process
engineering,
engineering),
environmental
waste
chemistry,
water
reduction/management,
and
and
sewage
pollution
treatment
(sanitary
prevention/cleanup.
Page No. 36
Chapter -1
Environmental engineering is a synthesis of various disciplines, incorporating elements
from the following:
Agricultural engineering
Geology
Biology
Hydrogeology
Chemical engineering
Public health
Chemistry
Solid waste
Civil engineering
Hazardous waste
Ecology
Water treament
Geography
Wastewater treatment
Physics
Statistics
Environmental engineering is the application of science and engineering
principles to the environment. Some consider environmental engineering to include the
development of sustainable processes. There are several divisions of the field of
environmental engineering.
Page No. 37
Chapter -1
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edition, p 62-69, 1983
2. Fuller E.D, Physics and Man’s Environment, Houghton Miffin Co., Boston p 102106, 1974.
3. Keith Bucher, Global Climate, Wiley, New York p 76-79,197
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Chapter -1
15. T.G.Mulligan and R.D.Fox, Treatment of industrial waste waters Chem. Engg.
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