UNIVERSITY OF THI-QAR

Environmental Pollution

Faculty of Engineering
Oil and Gas Department
Dr. Saleem Ethaib Mohammad

2018-2019
 Environmental Pollution

Air pollution

Many forms of atmospheric pollution affect human health and the environment at levels
from local to global. These contaminants are emitted from diverse sources, and some of
them react together to form new compounds in the air. Industrialized nations have made
important progress toward controlling some pollutants in recent decades, but air quality is
much worse in many developing countries, and global circulation patterns can transport
some types of pollution rapidly around the world.

Atmospheric composition

Earth’s atmosphere contains mainly several different gases and additionally aerosol
particles. Atmospheric gases are generally classified by their amount and residence time.
The residence time (or removal time or lifetime) is an average amount of time that a
particle or substance spends in a particular system (as the atmosphere). The residence
time can be defined as the amount of the compound in the atmosphere divided by the rate
at which this compound removed from the atmosphere.
Based on the quantity, major components and trace gases, while according to residence
time, constant and variable (and sometimes highly variable) gases can be distinguished
(Table 1.1).
The amount of atmospheric gases can be expressed by different measures.
Generally used terms are the concentration (kg m–3), the volume ratio (m3 gas per m3 air)
and mole fraction (mol mol–1).
For trace gases, this mixing ratio are commonly given in units of parts per million volume
(ppmv or simply ppm), parts per billion volume (ppbv or ppb), or parts per trillion
volume (pptv or ppt); 1 ppmv = 10–6 mol mol–1, 1 ppbv = 10–9 mol mol–1 and 1 pptv =10–
12
mol mol–1.
The abundances of constant gases has remained the same over geological timescales,
while residence time generally means years in case of variable gases and days in case of
highly variable gases (Table 1.2).
The main constituents of the dry atmosphere are nitrogen (78.084% by volume), oxygen
(20.946% by volume) and argon (0.934% by volume), but much lower concentrations

Page 1
 Environmental Pollution

other noble gases can also be found (Table 1.2). Concentrations of these gases do not
vary substantially in time and space (in the lower 80 km layer of the atmosphere) and
therefore they are called permanent gases.
Table 1.1: Classification of atmospheric gases

Table 1.2: Composition of the Earth’s atmosphere

Page 2
 Environmental Pollution

Nitrogen (N2) is a relatively inert gas and fundamental to all living systems. Through the
nitrogen cycle nitrogen is removed from the atmosphere and becomes part of living
organisms. This process is realized by nitrogen fixation by soil bacteria, and by way of
lighting through precipitation. Nitrogen returns to the atmosphere mainly by biomass
combustion and denitrification.
As nitrogen, oxygen (O2) has also very important relations with life. Oxygen exchange
between the atmosphere and biosphere is realized by photosynthesis and respiration.
Argon (Ar) in the atmosphere is the third most abundant gas. Among noble gases, argon
was first detected in the atmosphere in 1894 by Lord Rayleigh and William Ramsay.
Water vapour (H2O) is a significant component of the atmosphere. Its concentration
varies over a wide range both spatially and temporally. Most of water vapour
concentrated in the lower atmosphere. The capacity of air to hold water vapour (called
saturation level) is a function only of the air temperature. The higher the temperature the
greater amount of water vapour can be held without condensation (Figure 1.1). The
highest atmospheric moisture content is observable over equatorial ocean area and
tropical rain forests, while the lowest water vapour concentrations can be measured over
cold, polar regions, and subtropical deserts.

Figure 1.1 Dependence of saturated water vapour pressure from air temperature.

Carbon dioxide (CO2) is an important greenhouse gas as it has a strong absorption

capacity in the infrared and near-infrared bands. It has a natural exchange between the
atmosphere and biosphere through the photosynthesis and respiration.

Page 3
 Environmental Pollution

The volume of other gases compared to the main components, are very low, and therefore
they are called trace gases. Despite their low concentrations, these tracers (e.g. ozone
both in troposphere and stratosphere, carbon, nitrogen, sulphur compounds etc.) can be of
critical importance for several environmental issues (for example: greenhouse effect,
atmospheric pollution etc.).

Next to the different gases, Earth’s atmosphere contains a huge number of aerosol
particles. Aerosols are generally defined as suspension of solid particles or liquid droplets
in a gas. Their size are very small, the particle diameters in the range of 10–9–10–4 m.

SOURCES OF AIR POLLUTION

Pure air is colourless and odourless. But various pollutants from natural and man-made
sources are entering the atmosphere daily and these disturb the dynamic equilibrium in
the atmosphere. This leads to air pollution when the normal properties of air are upset and
both man and environment suffer.
Natural sources of air pollution are:
• Volcanic activity, vegetation decay, forest fires emitting carbon monoxide, sulphur
dioxide and hydrogen sulphide and tiny particles of solids or liquids sprayed from the
seas and land by wind.
Man-made sources are:
• Gases, mist, particulates and aerosols emitted by industries and other chemical and
biological processes used by man.

Air Pollutants
In general, air pollutants, emitted from natural and anthropogenic sources, can be broadly
classified under two categories: primary and secondary pollutants.
The primary pollutants are those that are emitted directly from the sources. These are:
Inorganic gases – SO2, NO, CO, CO2, H2S. HF. Olefinic and Aromatic hydrocarbons;
Radioactive compounds.
The Secondary pollutants are those that are formed in the atmosphere by chemical
reactions among primary pollutants and atmospheric constituents. Examples are: SO3,
NO2, PAN (Peroxyacyl nitrate), O3, aldehydes, ketones, various nitrate and sulphate salts.

Page 4
 Environmental Pollution

The five major primary pollutants are:

Carbon monoxide CO
Nitrogen Oxides, NOx
Sulphur dioxide, SO2
Hydrocarbons, HC and
Particulate matter.

Carbon Monoxide, CO

It is a colourless, odourless and tasteless gas which is injurious to our health. Each year
350 million tonnes of CO (275 million tonnes from human sources and 75 million tonnes
from natural sources) are emitted all over the world in which USA alone shares 100
million tonnes. Transportation accounts for 70 per cent of CO emission. That is to say,
diesel and petroleum engines in automobiles are primarily responsible for about 70 per
cent of CO emissions. The sources of carbon monoxide, CO are the chemical reactions:

Control of CO Pollution

The petroleum and diesel-fed automobiles account for major share of carbon monoxide
emission. Hence efforts for carbon monoxide pollution control are mainly aimed at
automobiles. Use of catalytic converters in the internal combustion engines of
automobiles helps in cleaning up the exhaust emissions. Such converters built into the
automobile engines promote oxidation-reduction cycles and ensure complete combustion
of carbon monoxide, nitrogen oxides and hydrocarbons. The following figure and flow-
sheet illustrate the action of catalytic converters: Use of catalytic converters in two stages

Page 5
 Environmental Pollution

helps in elimination of pollutants from exhaust gases before they are discharged into the
atmosphere.

In the first converter nitrogen oxides are reduced to nitrogen (+ ammonia) in presence of
finely divided catalyst platinum, and the reducing gases, carbon monoxide and
hydrocarbons. The production of ammonia is kept at a minimum under carefully
controlled conditions. In the second converter, air is introduced to provide an oxidizing
atmosphere for complete oxidation of carbon monoxide and hydrocarbon into carbon
dioxide and water in presence of finely divided platinum catalyst.

Fig. 1.2: Catalytic converters for treating auto emissions

Nitrogen Oxides, NOx

It consists of mixed oxides, nitric oxide and nitrogen dioxide (NO and NO2 respectively),
the former is a colourless and odourless gas but the latter (NO2) has a reddish brown
colour and pungent smell. The formation of NO and NO2 is based on the chemical
reactions:

These reactions occur inside the automobile engines so that the exhaust gases consist of
NOx. The latter concentration in rural air is much less than in urban air. In air NOx is
converted into nitric acid, HNO3 by natural processes:

Page 6
 Environmental Pollution

This nitric acid is one of the constituents of acid rain discussed in a subsequent section.
From auto exhaust emissions NOx is removed as discussed above by means of catalytic
converters.

Hydrocarbons and Photochemical Smog

Natural processes, particularly trees emit large quantities of hydrocarbons in air.

Methane, CH4 is a major hydrocarbon. It is generated in large quantities by bacteria
formed by anaerobic decomposition of organic matter in water sediments and soil.

Domestic animals (cattle, buffaloes, etc.) contribute about 85 million tonnes of methane
to the atmosphere each year. Automobiles are significant sources of hydrocarbons.
In presence of ozone, carbon monoxide, nitrogen oxides and hydrocarbon participate in
photochemical reactions (in presence of sunlight). A chain reaction proceeds in which the
free radical R •CH2 is generated in the first step. Other free radicals which are formed are:
R CH2 •O2 in the second step by reaction with oxygen, R CH2 O; R CH2 •O in the third
step by reaction with nitric oxide; H•O2 in the fourth step by reaction with oxygen; a
stable aldehyde R CHO is another product at this stage; H•O• is formed in fifth step by
reaction with nitric oxide (nitrogen dioxide is another product here); and finally, the
starting free radical R •CH2 is regenerated by reaction with hydrocarbon, R CH3 thereby
sustaining the chain reaction.
The harmful products in the chain reaction are NO2 and aldehyde, R CHO. A side
reaction also follows by another route through the aldehyde, R CHO; it gives an injurious
end product, peroxy acyl nitrate (PAN) which is a strong eye irritant. These reactions lead
Page 7
 Environmental Pollution

to photochemical smog formation, which is characterized by brown hazy fumes which

irritate the eyes and lungs and also cause serious damage to plants.
Photochemical smog occurs in coastal cities in winter climate e.g., in Los Angeles, USA
which have the heaviest vehicular traffic.

Sulphur Dioxide, SO2

Sulphur dioxide is a colourless gas with a pungent odour. It is produced from the
combustion of any sulphur-bearing material. Sulphur dioxide, SO2 is always associated
with a little of sulphur trioxide, SO3.

Man-made sources—coal-fired power stations and other industries contribute about 33

per cent of SOx pollution while natural sources, viz. volcanoes provide about 67 per cent
of SOx pollution.
Soot particles containing metal oxides, catalyze the oxidation of sulphur dioxide to
trioxide.

The first reaction above occurs in presence of ozone and water vapour. The product,
sulphuric acid is formed on aerosol (fine particle suspended in air as in smoke, fog, mist,
etc.) droplet. Sulphuric acid is one of the constituents of acid rain.
In winter climate sulphur oxides from thermal power plants along with other gases leads
to smog formation e.g. London smog. This is known as reducing smog in contrast with
photochemical smog which is known as oxidising smog (consisting of hydrocarbons,
nitrogen oxides and ozone). London smog (1952) is well-known for its disastrous effect.

Page 8
 Environmental Pollution

Heavy smog (SO2) conditions prevailed in London for five days which killed about 4,000
people. The causes of death were bronchitis, pneumonia, and other respiratory troubles
particularly among aged people.

Control of SOx Pollution

SOx (sulphur oxides) from flue gases of industrial plants can be removed by means of
chemical scrubbers. The flue stack gases are led through a bed of (slurry) of limestone,
CaCO3 (calcium carbonate) which absorbs sulphur dioxide quite efficiently.

The method is economical but the disposal of solid waste, calcium sulphate is a problem.
Alternatively, sulphur dioxide in aqueous solution is treated with citric acid salt and the
resulting solution is exposed to a stream of hydrogen sulphide gas whereby sulphur is
deposited. This sulphur can then be recovered and utilised. Thermal power plants, major
sources of man-made SOx pollution, are normally constructed with tall chimneys to
disperse the emissions over a wide area. This reduces the local problem but creates
problems for far away areas through acid rains.

Acid Rain
It has been described above that much of nitrogen oxides, NOx and sulphur oxides, SOX
entering the atmosphere are transformed into nitric acid (HNO3) and sulphuric acid
(H2SO4) respectively. These combine with hydrogen chloride, HCl from HCl emissions
(both by man-made and natural sources) and generate acidic precipitation, known as acid
rain.
Acid rain is a major environmental issue as it badly damages the environment. It damage
buildings and structural materials of marble, limestones, slate and mortar. These materials
become structurally weak as calcium carbonate reacts with sulphuric acid to form soluble
sulphate, which is leached out by rain water:

Page 9
 Environmental Pollution

In Greece and Italy invaluable stones and statutes have been partly dissolved by acid rain.
Besides these, acid rain damaged forests in Germany and lakes in Sweden and Canada.
Acid rain originated from U.K. but far away in Sweden, it damaged some 8,000 lakes of
which 4,000 are dead. Similarly, acid rain from USA damaged lakes and forests in
Canada.
In India, Taj Mahal is threatened by acid rain from Mathura refinery and other industries.

Control of Acid Rain

Acid rain can be checked if its constituents sulphur dioxide and nitrogen oxide are
controlled as discussed above.
Particulate
Small solid particles and liquid droplets are collectively termed particulates. They
originate both from natural and man-made sources. Every year natural sources discharge
800–2,000 million tonnes and man-made sources 200–500 million tonnes of particulates.
Among manmade sources, fly ash from thermal power plants deserves mention.
Particulates range in size from 0.0002 μ (about the size of a molecule) to 500 μ (1 μ = 10–
6
meter). The number of particles in the atmosphere varies from several hundred per cm3
in clean air to more than 100,000 per cm3 in highly polluted air (urban/industrial area).

Soot
Soot particles originate from fuel combustion and consist of highly condensed product of
polycyclic aromatic hydrocarbon (PAH)—roughly 100 condensed aromatic rings. The
hydrogen content of soot is 1–3 per cent and oxygen content 5–10 per cent due to partial
surface oxidation. Due to large surface area, soot acts as a carrier for toxic organics e.g.,
benzo-α-pyrene and toxic trace metals e.g., beryllium, cadmium chromium, manganese,
nickel, vanadium, etc.
A soot particle has an average size 0.1–20 μ. The finer particles (< 3 μ) are the worst
causes of lungs damage due to their ability to penetrate deep in our respiratory tract and
thence in lungs where they remain for years and cause all sorts of diseases such as cough,
bronchitis, asthma, and finally cancer. Particulates cause increased corrosion of metals

Page 10
 Environmental Pollution

which assume serious dimensions in industrial and urban areas. They are responsible for
damage to buildings, sculptures, paintings, etc.

Particulates play key roles in the atmosphere. They reduce visibility by scattering and
absorption of solar radiation. They influence the climate through the formation of cloud,
rain and snow by acting as nuclei upon which water can condense into raindrops.
Atmospheric particulate levels can be correlated with the extent of precipitation over
cities and suburbs.

Control of Particulate Emissions

The removal of particulate matter from gas streams is an essential step for air pollution
control. There are four types of equipment used for this purpose.
(1) Gravity settling chamber: Effluent gases are led into a chamber which is large
enough to permit gas velocities to decrease and dust or droplets to settle. The chamber is
generally in the shape of a horizontal rectangular tank articles with a diameter > 50 μ are
ordinarily removed in this manner. The method is, however, not suitable for fine particles
which require longer setting time.
(2) Cyclone collector: A gas flowing in a tight circular spiral produces a centrifugal
force on suspended particles, forcing them to move outward through the gas stream to a
wall where they are collected. Thus, it is possible to remove 95% particles in the diameter
range 5-20 μ (Fig. 4.4).
(3) Wet scrubbers: These utilise a liquid (usually H2O) to help remove solid liquid or
gaseous contaminants. The extent of contact and interaction are increased by the use of
spray chambers or towers where· the liquid is introduced into the gas stream as fine
spray.
(4) Electrostatic precipitators: These are based on the principle that aerosal particles
acquire charges when subjected to an electrical field. The particles acquire a charge when
a gas stream is led through a high-voltage dccorona. The charged particles are attracted to
a grounded surface from which they are removed. Ozone is a possible product of the
corona discharge.

Page 11
 Environmental Pollution

GREENHOUSE EFFECT (GLOBAL WARMING)

A greenhouse gas is a gas that absorbs and emits radiant energy within the thermal
infrared range. Greenhouse gases cause the greenhouse effect. The primary greenhouse
gases in Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide and
ozone. Carbon dioxide is a non-pollutant gas in the atmosphere and a minor constituent
(356 parts per million) but it is of serious concern for the environment for its ability to
change the global climate.
The earth’s surface partly absorbs sun’s rays while emits long-wave infra-red radiation
(8000–25000 nanometres; 1 nanometre = 10–9 metre = 1 nm). Carbon dioxide and water
vapour in the atmosphere strongly absorb infra-red radiation (14,000–25,000 nm) and
effectively block a large fraction of the earth’s emitted radiation. The radiation thus
absorbed by carbon dioxide and water vapour is partly returned to the earth’s surface.
The net result is that the earth’s surface gets heated and the phenomenon is known as the
Greenhouse Effect (Fig. 4.6)

Fig. 4.6: The greenhouse effect

Carbon dioxide is not the only culprit responsible for greenhouse effect and global
warming.
Other greenhouse gases are: methane, chloroflurocarbons (CFC), nitrous oxide, ozone
and watervapour. The relative contributions of these gases to greenhouse effect are:
carbon dioxide 50 per cent; Methane 19 per cent; Chloroflurocarbons 17 per cent; ozone
8 per cent; nitrous oxide 4 per cent; water vapour 2 per cent.

Page 12
 Environmental Pollution

This shows that carbon dioxide accounts for 50 per cent of the greenhouse gases. The
shares of methane (19 per cent) and chloroflurocarbons (17 per cent) (gases from
refrigerators and air-conditioners) cannot be ignored.

OZONE HOLE
Ozone, (O3), triatomic allotrope of oxygen (a form of oxygen in which the molecule
contains three atoms instead of two as in the common form) that accounts for the
distinctive odour of the air after a thunderstorm or around electrical equipment. The
odour of ozone around electrical machines was reported as early as 1785; ozone’s
chemical constitution was established in 1872. Ozone is an irritating, pale blue gas that is
explosive and toxic, even at low concentrations. It occurs naturally in small amounts in
the Earth’s stratosphere, where it absorbs solar ultraviolet radiation, which otherwise
could cause severe damage to living organisms on the Earth’s surface. In the stratosphere,
the second region of the atmosphere, ozone is present in small quantities but it is
protective shield for the earth. Ozone strongly absorbs ultraviolet radiation from the sun
(295–320 nm) which is injurious for life on earth. Thus it protects living species on earth.
But recent human activities have injected some dangerous chemicals in the stratosphere
which consume ozone and reduce its concentration. This is the phenomenon of ozone
hole in the stratosphere.
Under certain conditions, photochemical reactions between nitrogen oxides and
hydrocarbons in the lower atmosphere can produce ozone in concentrations high enough
to cause irritation of the eyes and mucous membranes. Exhaust gases from jet aircrafts
and artificial satellites discharge nitric oxide (NO), nitrogen dioxide (NO2) etc., which
immediately react with ozone.

Chloroflurocarbons (CFC) are used as coolants in refrigerators and air-conditioners.

These slowly pass from troposphere and stratosphere and once there, they stay for 100
years.

Page 13
 Environmental Pollution

In presence of ultraviolet radiation (200 nm) from the sun, CFC breaks up into
chlorinefree radical (Cl) which readily consumes ozone.

The free radical (Cl•) is regenerated and continues the chain reaction. It is estimated that
one molecule of CFC consumes one lakh molecules of ozone. The damage by CFC
continues for 100 years. Even if CFC production is stopped now all over the world, the
CFC that is already there in the stratosphere will continue to damage the ozone layer for
the next 100 years.
In 1979 ozone hole was observed in the sky over Antarctica–here ozone layer thickness
was reduced by 30 per cent. Later on ozone hole was discovered in the sky over the
thicklypopulated northern hemisphere. Here in winter ozone thickness was reduced by 4
per cent and in summer by 1 per cent. Ozone hole allows passage of ultraviolet radiation
to the earth where it causes skin cancer, eyesight defect, genetic disorder, etc., in the
biosphere (man, animal and plant). In Europe and USA there is an increase in the cases of
skin cancer among people while some million people are suffering from eye cataract

Water Pollution
The normal uses of water for public supply are–recreation (swimming, boating, etc.),
fish, other aquatic life and wild life, agriculture (irrigation), industry, navigation, etc. Any
change in the dynamic equilibrium in aquatic ecosystem (water
body/biosphere/atmosphere) disturbs the normal function and properties of pure water
and gives rise to the phenomenon of water pollution. The symptoms of water pollution of
any water body/ground water are:
• Bad taste of drinking water,
• Offensive smells from lakes, rivers and ocean beaches,
• Unchecked growth of aquatic weeds in water bodies (eutrophication),
• Dead fish floating on water surface in river, lake, etc.

Page 14
 Environmental Pollution

• Oil and grease floating on water surface.

Chemical Characteristics of Water

Sea water is unfit for our consumption due to high mineral salt content. Chemically
speaking, sea water is a solution of 0.05 molar NaCI (Sodium chloride), 0.05 molar
MgSO4 (Magnesium sulphate) containing traces of all conceivable matter in the universe.
The oceans are the final sink for many substances involved in numerous geochemical
processes as well as the waste dumped as a result of human activities. They receive the
run-off of the continents and materials washed from the atmosphere. They are also the
important habitat of the bulk of the earth’s biosphere (sea plants, sea fish, etc.). The
chemical composition of sea water, river and lake water is shown:
Sea water: Sodium, chloride, magnesium 90 per cent, potassium, calcium, sulphate 3 per
cent, others 7 per cent.
River and Lake water: Carbonate 35 per cent, sulphate 12 per cent, chloride 5.7 per
cent, silica 11.7 per cent, nitrate 0.9 per cent; Calcium 20 per cent, sodium 5.8 per cent,
magnesium 3 per cent, potassium 2 per cent, iron, aluminium oxide 3 per cent.
Ground water (wells, tube wells) contains more mineral salts, nitrate and bicarbonate
than surface water (river, lake. water, etc.)

WATER POLLUTANTS
The large numbers of water pollutants are broadly classified under the categories:
1. Organic pollutants,
2. Inorganic pollutants,
3. Sediments,
4. Radioactive materials and
5. Thermal pollutants.
6. Biological pollutants
Organic Pollutants
These include domestic sewage, pesticides, synthetic organic compounds, plant nutrients
(from agricultural run-off), oil, wastes from food processing plants, paper mills and
tanneries, etc. These reduce dissolved oxygen (D.O.) in water. Dissolved oxygen (D.O.)

Page 15
 Environmental Pollution

is essential for aquatic life, the optimum level being 4–6 ppm (parts per million).
Decrease in D.O. value is an indicator of water pollution. The organic pollutants consume
D.O. through the action of bacteria present in water.
Oil pollution of the seas has increased over the years, due to increased traffic of oil
tankers in the seas causing oil spill and also due to oil losses during off-shore drilling. Oil
pollution reduces light transmission through surface water and hence reduces
photosynthesis by marine plants, decreases D.O. in water causing damage to marine life
(plants, fish, etc.) and also contaminates sea food which enters the human food chain.
Inorganic Pollutants
This group consists of inorganic salts, mineral acids, metals, trace elements, detergents,
etc. Acid mine drainage: Coal mines, particularly those which have been abandoned,
discharge acid (sulphuric acid) and also ferric hydroxide into local streams through
seepage. The acid on entering the waterbody destroys its aquatic life (plants, fish, etc.).
Sediments
Soil erosion, as a matter of natural process, generates sediments in water. Solid loadings
in natural water are about 700 times as large as the solid loading from sewage discharge.
Soil erosion is enhanced 5–10 times due to agricultural and 100 times due to construction
activities. Bottom sediments in aquatic bodies (streams, lakes, estuaries, oceans) are
important reservoirs of inorganic and organic matter, particularly trace metals e.g.,
chromium, copper, nickel, manganese and molybdenum.
Radioactive Materials
Radioactive pollution is caused by mining and processing of radioactive ores to produce
radioactive substances, use of radioactive materials in nuclear power plants, use of
radioactive isotopes in medical, industrial and research institutes and nuclear tests. The
discharge of radioactive wastes into water and sewer systems is likely to create problems
in future.
Thermal Pollutants
Coal-fired or nuclear fuel-fired thermal power plants are sources of thermal pollution.
The hot water from these plants is dumped as waste into nearby lake or river where its
temperature rises by about 10°C. This has harmful effect on aquatic life in the water body
whose D.O. is reduced and as a result, fish kill is quite common.

Page 16
 Environmental Pollution

Biological Pollutants
Bacteria (for example Salmonella, Shigella, Campylobacter, Vibrio cholerae), Viruses
(for example hepatitis A, rotavirus, enteroviruses), Protozoa (for example Entamoeba
histolytica, Giardia lamblia, Cryptosporidium parvum) and Parasites such as helminths
and their eggs (e.g. Ascaris (roundworm), Ancylostoma (hookworm), Trichuris
(whipworm)

Drinking Water Supply

Treatment of drinking water supply is a matter of public health concern. The water
treatment plants, in general, are simpler than sewage treatment plants. They operate in
three steps—(i) Coagulation and Flocculation; (ii) Sedimentation; (iii) Filtration and (iv)
Disinfection. The purified water is then supplied by municipalities through pipes for
domestic uses.
Drinking water sources are subject to contamination and require appropriate treatment to
remove disease-causing agents. Public drinking water systems use various methods of
water treatment to provide safe drinking water for their communities. Today, the most
common steps in water treatment used by community water systems (mainly surface
water treatment) include:
Coagulation and Flocculation
Coagulation and flocculation are often the first steps in water treatment. Chemicals with a
positive charge are added to the water. The positive charge of these chemicals neutralizes
the negative charge of dirt and other dissolved particles in the water. When this occurs,
the particles bind with the chemicals and form larger particles, called floc.
Sedimentation
During sedimentation, floc settles to the bottom of the water supply, due to its weight.
This settling process is called sedimentation.
Filtration
Once the floc has settled to the bottom of the water supply, the clear water on top will
pass through filters of varying compositions (sand, gravel, and charcoal) and pore sizes,
in order to remove dissolved particles, such as dust, parasites, bacteria, viruses, and
chemicals.

Page 17
 Environmental Pollution

Disinfection
After the water has been filtered, a disinfectant (for example, chlorine, chloramine) may
be added in order to kill any remaining parasites, bacteria, and viruses, and to protect the
water from germs when it is piped to homes and businesses.
Water Quality Standards
The analyses required of water samples depend on the intended use of the water. For
example, if its intended use is drinking, water should meet certain quality criteria with
respect to the appearance, (turbidity, colour), potability (taste, odour), health (bacteria,
nitrates, chlorides, etc.) and toxicity (metals, organics). These and similar criteria are
established by health or other regulating agencies to ensure that the water quality in a
resource is suitable for the proposed use.
Turbidity is a measure of the cloudiness or haziness in water caused by suspended solids
(eg sediment, algae). Turbidity is expressed in Nephelometric Turbidity Units (NTU) and
is measured using a relationship of light reflected from a given sample.
pH is an indicator of acidity or alkalinity. Neutral water has a pH of 7, acidic solutions
have values between 0-6 and alkaline solutions have values between 8-14.
Alkalinity is a measure of the buffering capacity of water, or the capacity of the water to
neutralise acids and resist pH change. Alkalinity within water bodies is consumed as acid
is released from acid sulfate soils. Adding limestone contributes alkalinity to waters,
helping to neutralise any acid released from the sediments. .
Salinity is a measure of the amount of dissolved salts in the water. Saline water conducts
electricity more readily than freshwater, so electrical conductivity (EC) is routinely used
to measure salinity. As salinity increases, it may become toxic to native freshwater
organisms.
Nutrients–Total nitrogen (TN) and total phosphorus (TP) are the total amount of
nitrogen and phosphorus present in the water body. Nitrogen can be present in different
forms (e.g. organic nitrogen in plant material, ammonia, nitrate and nitrite).
Chlorophyll a is the main photosynthetic pigment in green algae. The concentration of
chlorophyll gives an indication of the volume of aquatic plants present in the water
column.

Page 18
 Environmental Pollution

Metal During concentration events (ie evaporation and low inputs) the concentration of
metals are expected to increase, alternatively during flooding events the volume of metals
will be diluted and expected to reduce.
Based on the criteria, quality standards are set, which reflect the current state of
knowledge of various water constituents. These standards are continuously revised as
more and more is learnt about the effects of water constituents on proposed uses. Hence,
these standards should not be used as absolute limits, but only as guidelines that can be
used for preliminary judgements.
Table 5.1 summarizes several quality criteria and their standards for drinking water as
suggested by the following agencies:
(1) Indian Council of Medical Research (ICMR)
(2) World Health Organization (WHO)
(3) United States Public Health Service (USPHS)
Table 5.1: Standards for Drinking Water
A – Recommended maximum concentrationa (mg/L except where shown otherwise)
B – Maximum permissible concentrationb (mg/L except where shown otherwise)

Page 19
 Environmental Pollution

Wastewater Treatment
Water pollution is caused by municipal sewage (84 per cent) and industrial sewage (16
per cent). Though the latter has fewer loads on water body, it contains toxic matter
(inorganic and organic) which are more hazardous.
Wastewater Quality Indicators
Since all natural waterways contain bacteria and nutrients, almost any waste compounds
introduced into such waterways will initiate biochemical reactions (such as shown
above). Those biochemical reactions create what is measured in the laboratory as the
biochemical oxygen demand (BOD).
Such chemicals are also liable to be broken down using strong oxidizing agents and these
chemical reactions create what is measured in the laboratory as the chemical oxygen
demand (COD).

Page 20
 Environmental Pollution

Both the BOD and COD tests are a measure of the relative oxygen-depletion effect of a
waste contaminant.
Both have been widely adopted as a measure of pollution effect. The BOD test measures
the oxygen demand of biodegradable pollutants whereas the COD test measures the
oxygen demand of oxidizable pollutants.
Municipal Wastewater Treatment
Sewage treatment plants, in general, depend on biological decomposition of non-toxic
organic wastes using bacteria. Such biological decomposition is carried out under aerobic
conditions i.e., in presence of plenty of oxygen.

The process, commonly used for municipal waste water, is shown in Fig. 5.1.
In the first stage, solid wastes are removed from water by screening–any scum
(suspended matter) is removed and the sludge (muddy solid or sediment) allowed settling
at the bottom.
The residual liquid is exposed to biological oxidation of soluble organic materials
through a bed of microbes in activated sludge.
Then the solids are removed after sedimentation.
Finally the liquid effluent is subjected to chlorination for destroying pathogenic micro-
organisms. Now this effluent is fairly clean and suitable for domestic use.

Page 21
 Environmental Pollution

Fig. 5.1: Municipal waste water treatment (Primary and Secondary)

Wastewater and petroleum wastewater

Industrial wastes contain toxic chemicals which can damage environment (water, soil,
air) much more than domestic sewage. These waste liquids are named as effluents. The
composition of effluent in refinery wastewater depends on the crude quality. It
varies with the operating conditions.
In the refinery, non-hydrocarbon substances are removed and the oil is broken down into
its various components and blended into useful products. So, petroleum refineries
produce large volumes of wastewater including oil well produced water brought to the
surface during oil drilling, which often
contain a recalcitrant compound sand rich in organic pollutants therefore cannot
be treated easily and difficult to be treated biologically.
Petroleum wastewater are a major source of aquatic environmental pollution and are
wastewater originating from industries primarily engaged in refining crude oil,
manufacturing fuels and lubricants and petrochemical intermediates. It was reported

Page 22
 Environmental Pollution

that the volume of petroleum wastewater generated during processing is 0.4–1.6

times the amount of the crude oil processed. If the petroleum wastewater, which
contained high organic matter, discharged into the aquatic environment, which
required 2mgL-1from dissolved oxygen for normal life, results in decreased
dissolved oxygen by the bacteria. In anaerobic systems, the products of chemical
and biochemical reactions produce displeasing colors and odors in water. So, the
oxygen availability is important in water to reduce that.
These effluents are composed of grease and petroleum compounds which consists of
three main hydrocarbon groups; Paraffin [very few carbon atoms (C1to C4) such as
Methane (CH4), Ethane (C2H6) and Propane (C3H8)], Naphthene [such as
Cyclohexane (C6H12) and Dimethyl Cyclopentane (C7H14)] and Aromatics [The
more carbon atoms a hydrocarbon molecule such as Benzene (C6H6), Toluene
(C7H8) and Xylene (C8H10). In addition, Naphthenic acids (NAs) which are one
class of compounds in wastewaters from petroleum industries that are known to cause
toxic effects, and their removal from oilfield wastewater is an important
challenge for remediation of large volumes of petrochemical effluents. When a
crude oil contains appreciable quantities of Sulphur, it is called sour crude.
So, Sour water is a specific stream of petroleum refineries, which contains slowly
biodegradable compounds and toxic substances. Petroleum wastewater can vary greatly
depending on the plant configuration, operation procedures and type of oil being
processed.
Petroleum wastewater generation in refineries
Transforming crude oil into useful products such as Gasoline and kerosene was achieved
by the numerous refinery configurations. During these processes, the petroleum
wastewater was generated in the units such as Hydro-cracking, Hydro-cracker flare,
Hydro-skimming, Hydro-skimmer flare, sour water, Condensate, Condensate flare and
the desalter. In addition, the main sources of total phenols in the received waste streams
at the refinery wastewater treatment plant were the neutralized spent caustic (average 234
mg/l) waste streams, the tank water drain (average 11.8 mg/l) and the desalter effluent
(average 1.4 mg/l). Other units not directly involved with processing; Sanitary, crude
tank and laboratory water. The dominant pollutants in order of magnitude in

Page 23
 Environmental Pollution

petrochemical wastewater were normal-alkanes (C10-C21), aromatics, and polycyclic

hydrocarbons.
Current petroleum wastewater treatment techniques
The petroleum wastewater treatments are classified into three types; physical,
chemical and biological. However, the treatment required a typical application
of the integrated system due to the complexity of characteristics of petroleum
wastewater. Thus, the conventional treatment methods need multistage process treatment.
The first stage consisted of pre-treatment, which includes mechanical and
physicochemical treatments followed by the second stage which is the advanced
treatment of the pretreated wastewater.
Physical treatment methods
Physical treatment methods include processes where no gross chemical or biological
changes are carried out and strictly physical phenomena are used to improve or treat the
wastewater. Examples would be coarse screening to remove larger entrained objects and
sedimentation. The presence of sulphide and salts could inhibit biological operation in
excess of 20 mg L-1. Thus, the physical treatment system is a primary treatment step,
which is essential to remove or separate suspended solids (SS), immiscible liquids, solid
particles, suspended substances from petroleum wastewater by using sedimentation,
coagulation and flocculation and prolonged use of the secondary treatment unit. Most
physical treatment techniques are considered as conventional methods. However,
physical processes were relatively ineffective for the treatment of petroleum wastewater
because of its complexity and therefore, other processes might be used for pretreatment.
Nowadays, physical technologies such as sedimentation are used prior to biological
treatment in order to remove suspended solids. The sedimentation treatment, which is
used to separate oil from water, is mechanically achieved by gravity in API separators or
separation tanks.
An API oil–water separator is a device designed to separate gross amounts of oil and
suspended solids from the wastewater effluents of oil refineries, petrochemical plants,
chemical plants, natural gas processing plants and other industrial oily water sources. The
name is derived from the fact that such separators are designed according to standards
published by the American Petroleum Institute.

Page 24
 Environmental Pollution

A typical gravimetric API separator

Chemical treatment
Chemicals are used during wastewater treatment in an array of processes to expedite
disinfection. These chemical processes, which induce chemical reactions, are called
chemical unit processes, and are used alongside biological and physical cleaning
processes to achieve various water standards. There are several distinct chemical unit
processes, including chemical coagulation, chemical precipitation, chemical oxidation
and advanced oxidation, ion exchange, and chemical neutralization and stabilization,
which can be applied to wastewater during cleaning.
Chemical Precipitation
Chemical precipitation is the most common method for removing dissolved metals from
wastewater solution containing toxic metals. To convert the dissolved metals into solid
particle form, a precipitation reagent is added to the mixture. A chemical reaction,
triggered by the reagent, causes the dissolved metals to form solid particles. Filtration can
then be used to remove the particles from the mixture. How well the process works is
dependent upon the kind of metal present, the concentration of the metal, and the kind of

Page 25
 Environmental Pollution

reagent used. In hydroxide precipitation, a commonly used chemical precipitation

process, calcium or sodium hydroxide is used as the reagent to create solid metal
hydroxides. However, it can be difficult to create hydroxides from dissolved metal
particles in wastewater because many wastewater solutions contain mixed metals.
Chemical Coagulation
This chemical process involves destabilizing wastewater particles so that they aggregate
during chemical flocculation. Fine solid particles dispersed in wastewater carry negative
electric surface charges (in their normal stable state), which prevent them from forming
larger groups and settling. Chemical coagulation destabilizes these particles by
introducing positively charged coagulants that then reduce the negative particles’ charge.
Once the charge is reduced, the particles freely form larger groups. Next, an anionic
flocculant is introduced to the mixture. Because the flocculant reacts against the
positively charged mixture, it either neutralizes the particle groups or creates bridges
between them to bind the particles into larger groups. After larger particle groups are
formed, sedimentation can be used to remove the particles from the mixture.
Chemical Oxidation and Advanced Oxidation
With the introduction of an oxidizing agent during chemical oxidation, electrons move
from the oxidant to the pollutants in wastewater. The pollutants then undergo structural
modification, becoming less destructive compounds. Alkaline chlorination uses chlorine
as an oxidant against cyanide. However, alkaline chlorination as a chemical oxidation
process can lead to the creation of toxic chlorinated compounds, and additional steps may
be required. Advanced oxidation can help remove any organic compounds that are
produced as a byproduct of chemical oxidation, through processes such as steam
stripping, air stripping, or activated carbon adsorption.
Ion Exchange
When water is too hard, it is difficult to use to clean and often leaves a grey residue. An
ion exchange process, similar to the reverse osmosis process, can be used to soften the
water. Calcium and magnesium are common ions that lead to water hardness. To soften
the water, positively charged sodium ions are introduced in the form of dissolved sodium
chloride salt, or brine. Hard calcium and magnesium ions exchange places with sodium
ions, and free sodium ions are simply released in the water. However, after softening a

Page 26
 Environmental Pollution

large amount of water, the softening solution may fill with excess calcium and
magnesium ions, requiring the solution be recharged with sodium ions.
Chemical Stabilization
This process works in a similar fashion as chemical oxidation. Sludge is treated with a
large amount of a given oxidant, such as chlorine. The introduction of the oxidant slows
down the rate of biological growth within the sludge, and also helps deodorize the
mixture. The water is then removed from the sludge. Hydrogen peroxide can also be used
as an oxidant, and may be a more cost-effective choice.

Biological treatment
Use microorganisms, mostly bacteria, in the biochemical decomposition of wastewaters
to stable end products. More microorganisms, or sludges, are formed and a portion of the
waste is converted to carbon dioxide, water and other end products. The petroleum
wastewater was treated by various biological methods successfully such as activated
sludge reactors or biofilm-based reactor to remove the organic pollutants. The biological
oxidation processes depend on the compositions of the petroleum wastewater. However,
these processes have some disadvantages such as the extreme sludge production, and low
capacity to COD removals. Generally, biological treatment methods can be divided into
aerobic and anaerobic methods, based on availability of dissolved oxygen. In anaerobic
systems, the products of chemical and biochemical reactions produce displeasing colors
and odors in water. Thus, the oxygen availability was important in water to reduce
displeasing colors and odors.

Page 27
 Environmental Pollution

Soil pollution
Soil pollution is defined as the presence of toxic chemicals (pollutants or contaminants)
in soil, in high enough concentrations to pose a risk to human health and/or the
ecosystem. In the case of contaminants which occur naturally in soil, even when their
levels are not high enough to pose a risk, soil pollution is still said to occur if the levels of
the contaminants in soil exceed the levels that should naturally be present.

The soil pollution sources are:

1) Indiscriminate solid waste disposal on land;
2) Random discharge of industrial waste effluents on land and water courses;
3) Excessive use of pesticides, herbicides and chemical fertilisers, in agriculture;
4) Excessive irrigation;
5) Radioactive materials from radioactive fall-out arising nuclear explosion tests,reactor
accidents etc.
6) Oil spills include any spill of crude oil or oil distilled products (e.g., gasoline, diesel
fuels, jet fuels, kerosene, Stoddard solvent, hydraulic oils, and lubricating oils) that can
pollute the surface of the land, air, and water environments.
An oil spill on the land may penetrate underground and move downward reaching
eventually the groundwater. However, such vertical movement may be slowed done if not
prevented by the presence of paved surfaces, natural clay layers or other natural or
anthropogenic barriers. Oil may also move laterally along less permeable layers
(including surface pavements) or with groundwater and surface waters.

Some the effects of soil pollution are:

• Disturbance in the balance of flora and fauna inhabiting in the soil.
• Contaminated soil decreases soil fertility and hence there is decrease in the soil yield.
• Loss of natural nutrients in soil and reduced nitrogen fixation.
• Increased soil erosion.
• Increase in soil salinity, makes it unfit for cultivation.
• Creation of toxic dust.

Page 28
 Environmental Pollution

• Foul odor due to industrial chemicals and gases.

• Alteration in soil structure can lead to death of organisms in it.
.
Effects on humans
• Soil pollution has major consequences on human health. Consumption of crops and
plants are grown on polluted soil cause health hazards. This could explain small and
terminal illness.
• Long term exposure to polluted soil affects the genetic make-up of the body and may
congenital illnesses and chronic health diseases.
• Chronic exposure to heavy metals, petroleum, solvents and agricultural chemicals can
be carcinogenic.

CONTROL OF SOIL POLLUTION

A number of ways have been suggested to curb the pollution rate. Attempts to clean up
the environment require plenty of time and resources. Some the steps to reduce soil
pollution are:
• Ban on use of plastic bags below 20 microns thickness.
• Recycling of plastic wastes.
• Ban on deforestation.
• Encouraging plantation programmes.
• Undertaking awareness programmes.
• Reducing the use of chemical fertilizer and pesticides.
• Recycling paper, plastics and other materials.
• Ban on use of plastic bags, which are a major cause of pollution.
• Reusing materials.
• Suitable and safe disposal of including nuclear wastes.
• Chemical fertilizers and pesticides should be replaced by organic fertilizers and
pesticides.

• Undertaking many pollution awareness programs.

Page 29
 Environmental Pollution

Solid-waste treatment and disposal

Solid waste disposal methods are actually the methods for control of soil pollution.
Improper disposal of municipal solid waste can create unsanitary conditions, and these
conditions in turn can lead to pollution of the environment and to outbreaks of vector-
borne disease—that is, diseases spread by rodents and insects. The tasks of solid-waste
management present complex technical challenges. They also pose a wide variety of
administrative, economic, and social problems that must be managed and solved.

Incineration
Burning is a very effective method of reducing the volume and weight of solid waste. In
modern incinerators the waste is burned inside a properly designed furnace under very
carefully controlled conditions. The combustible portion of the waste combines with
oxygen, releasing mostly carbon dioxide, water vapour, and heat.
Incineration can reduce the volume of uncompacted waste by more than 90 percent,
leaving an inert residue of ash, glass, metal, and other solid materials called bottom ash.
The gaseous by-products of incomplete combustion, along with finely divided particulate
material called fly ash, are carried along in the incinerator airstream.
Fly ash includes cinders, dust, and soot. In order to remove fly ash and gaseous by-
products before they are exhausted into the atmosphere, modern incinerators must be
equipped with extensive emission control devices. Such devices include fabric baghouse
filters, acid gas scrubbers, and electrostatic precipitators. (See also air pollution control.)
Bottom ash and fly ash are usually combined and disposed of in a landfill. If the ash is
found to contain toxic metals, it must be managed as a hazardous waste.

Energy recovery
The energy value of refuse can be depending on the paper content, and the heat given off
during incineration can be recovered by the use of a refractory-lined furnace coupled to a
boiler. Boilers convert the heat of combustion into steam or hot water, thus allowing the
energy content of the refuse to be recycled. Incinerators that recycle heat energy in this
way are called waste-to-energy plants. Instead of a separate furnace and boiler, a water-
tube wall furnace may also be used for energy recovery. Such a furnace is lined with

Page 30
 Environmental Pollution

vertical steel tubes spaced closely enough to form continuous sections of wall. The walls
are insulated on the outside in order to reduce heat loss. Water circulating through the
tubes absorbs heat to produce steam, and it also helps to control combustion temperatures
without the need for excessive air, thus lowering air pollution control costs.
Waste-to-energy plants operate as either mass burn or refuse-derived fuel systems. A
mass burn system uses all the refuse, without prior treatment or preparation. A refuse-
derived fuel system separates combustible wastes from noncombustibles such as glass
and metal before burning. If a turbine is installed at the plant, both steam and electricity
can be produced in a process called cogeneration.
Waste-to-energy systems are more expensive to build and operate than plain incinerators
because of the need for special equipment and controls, highly skilled technical
personnel, and auxiliary fuel systems. On the other hand, the sale of generated steam or
electricity offsets much of the extra cost, and recovery of heat energy from refuse is a
viable solid-waste management option from both engineering and an economic point of
view. About 80 percent of municipal refuse incinerators in the United States are waste-to-
energy facilities.

Composting
Another method of treating municipal solid waste is composting, a biological process in
which the organic portion of refuse is allowed to decompose under carefully controlled
conditions. Microbes metabolize the organic waste material and reduce its volume by as
much as 50 percent. The stabilized product is called compost or humus. It resembles
potting soil in texture and odour and may be used as a soil conditioner or mulch.

Composting offers a method of processing and recycling both garbage and sewage sludge
in one operation. As more stringent environmental rules and siting constraints limit the
use of solid-waste incineration and landfill options, the application of composting is
likely to increase. The steps involved in the process include sorting and separating, size
reduction, and digestion of the refuse.

Sorting and shredding

Page 31
 Environmental Pollution

The decomposable materials in refuse are isolated from glass, metal, and other inorganic
items through sorting and separating operations. These are carried out mechanically,
using differences in such physical characteristics of the refuse as size, density, and
magnetic properties. Shredding or pulverizing reduces the size of the waste articles,
resulting in a uniform mass of material. It is accomplished with hammer mills and rotary
shredders.

Digesting and processing

Pulverized waste is ready for composting either by the open windrow method or in an
enclosed mechanical facility. Windrows are long, low mounds of refuse. They are turned
or mixed every few days to provide air for the microbes digesting the organics.
Depending on moisture conditions, it may take five to eight weeks for complete digestion
of the waste. Because of the metabolic action of aerobic bacteria, temperatures in an
active compost pile reach about 65 °C (150 °F), killing pathogenic organisms that may be
in the waste material.
Open windrow composting requires relatively large land areas. Enclosed mechanical
composting facilities can reduce land requirements by about 85 percent. Mechanical
composting systems employ one or more closed tanks or digesters equipped with rotating
vanes that mix and aerate the shredded waste. Complete digestion of the waste takes
about one week.

Sanitary landfill
Land disposal is the most common management strategy for municipal solid waste.
Refuse can be safely deposited in a sanitary landfill, a disposal site that is carefully
selected, designed, constructed, and operated to protect the environment and public
health. One of the most important factors relating to landfilling is that the buried waste
never comes in contact with surface water or groundwater. Engineering design
requirements include a minimum distance between the bottom of the landfill and the
seasonally high groundwater table. Most new landfills are required to have an
impermeable liner or barrier at the bottom, as well as a system of groundwater-
monitoring wells. Completed landfill sections must be capped with an impermeable cover

Page 32
 Environmental Pollution

to keep precipitation or surface runoff away from the buried waste. Bottom and cap liners
may be made of flexible plastic membranes, layers of clay soil, or a combination of both.

Recycling
Separating, recovering, and reusing components of solid waste that may still have
economic value is called recycling. One type of recycling is the recovery and reuse of
heat energy, a practice discussed separately in Incineration. Composting can also be
considered a recycling process, since it reclaims the organic parts of solid waste for reuse
as mulch or soil conditioner. Still other waste materials have potential for reuse. These
include paper, metal, glass, plastic, and rubber, and their recovery is discussed here.

Separation
Before any material can be recycled, it must be separated from the raw waste and sorted.
Separation can be accomplished at the source of the waste or at a central processing
facility. Source separation, also called curbside separation, is done by individual citizens
who collect newspapers, bottles, cans, and garbage separately and place them at the curb
for collection. Many communities allow ―commingling‖ of nonpaper recyclables (glass,
metal, and plastic). In either case, municipal collection of source-separated refuse is more
expensive than ordinary refuse collection.
In lieu of source separation, recyclable materials can be separated from garbage at
centralized mechanical processing plants. Experience has shown that the quality of
recyclables recovered from such facilities is lowered by contamination with moist
garbage and broken glass. The best practice, as now recognized, is to have citizens
separate refuse into a limited number of categories, including newspaper; magazines and
other wastepaper; commingled metals, glass, and plastics; and garbage and other
nonrecyclables. The newspaper, other paper wastes, and commingled recyclables are
collected separately from the other refuse and are processed at a centralized material
recycling facility, or MRF (pronounced ―murf‖ in waste-management jargon). A modern
MRF can process about 300 tons of recyclable wastes per day.
At a typical MRF, commingled recyclables are loaded onto a conveyor. Steel cans (―tin‖
cans are actually steel with only a thin coating of tin) are removed by an electromagnetic

Page 33
 Environmental Pollution

separator, and the remaining material passes over a vibrating screen in order to remove
broken glass. Next, the conveyor passes through an air classifier, which separates
aluminum and plastic containers from heavier glass containers. Glass is manually sorted
by colour, and aluminum cans are separated from plastics by an eddy-current separator,
which repels the aluminum from the conveyor belt.

Reuse
Recovered broken glass can be crushed and used in asphalt pavement. Colour-sorted
glass is crushed and sold to glass manufacturers as cullet, an essential ingredient in
glassmaking. Steel cans are baled and shipped to steel mills as scrap, and aluminum is
baled or compacted for reuse by smelters. Aluminum is one of the smallest components
of municipal solid waste, but it has the highest value as a recyclable material. Recycling
of plastic is a challenge, mostly because of the many different polymeric materials used
in its production. Mixed thermoplastics can be used only to make lower-quality products,
such as ―plastic lumber.‖
In the paper stream, old newspapers are sorted by hand on a conveyor belt in order to
remove corrugated materials and mixed papers. They are then baled or loose-loaded into
trailers for shipment to paper mills, where they are reused in the making of more
newspaper. Mixed paper is separated from corrugated paper for sale to tissue mills.
Although the processes of pulping, de-inking, and screening wastepaper are generally
more expensive than making paper from virgin wood fibres, the market for recycled
paper should improve as more processing plants are established.
Rubber is sometimes reclaimed from solid waste and shredded, reformed, and remolded
in a process called revulcanization, but it is usually not as strong as the original material.
Shredded rubber can be used as an additive in asphalt pavements, and discarded tires may
be employed as swings and other recreational structures for use by children in ―tire
playgrounds.‖ In general, the most difficult problem associated with the recycling of any
solid-waste material is finding applications and suitable markets. Recycling by itself will
not solve the growing problem of solid-waste management and disposal. There will
always be some unusable and completely valueless solid residue requiring final disposal.

Page 34
 Environmental Pollution

Thermal pollution
Thermal pollution is defined as sudden increase or decrease in temperature of a natural
body of water which may be ocean, lake, river or pond by human influence. This
normally occurs when a plant or facility takes in water from a natural resource and puts it
back with an altered temperature. Usually, these facilities use it as a cooling method for
their machinery or to help better produce their products.

Causes of Thermal Pollution

1. Water as Cooling Agent in Power, Manufacturing and Industrial plants: Production and
Manufacturing plants are biggest source of thermal pollution. These plants draw water
from nearby source to keep machines cool and then release back to the source with higher
temperature. When heated water returns to the river or ocean, the water temperature rises
sharply. When oxygen levels are altered in the water, this can also degrade the quality
and longevity of life in wildlife that lives underwater. This process can also wipe away
streamside vegetation, which constantly depends on constant levels of oxygen and
temperature. By altering these natural environments, industries are essentially helping
decrease the quality of life for these marines based life forms and can ultimately destroy
habitats if they are not controlled and careful about their practices.

2. Soil Erosion: Soil erosion is another major factor that causes thermal pollution.
Consistent soil erosion causes water bodies to rise, making them more exposed to
sunlight. The high temperature could prove fatal for aquatic biomes as it may give rise to
anaerobic conditions.

3. Deforestation: Trees and plants prevent sunlight from falling directly on lakes, ponds
or rivers. When deforestation takes place, these water bodies are directly exposed to
sunlight, thus absorbing more heat and raising its temperature. Deforestation is also a
main cause of the higher concentrations of greenhouse gases i.e. global warming in the
atmosphere.

Page 35
 Environmental Pollution

4. Runoff from Paved Surfaces: Urban runoff discharged to surface waters from paved
surfaces like roads and parking lots can make water warmer. During summer seasons, the
pavement gets quite hot, which creates warm runoff that gets into the sewer systems and
water bodies.

5. Natural Causes: Natural causes like volcanoes and geothermal activity under the
oceans and seas can trigger warm lava to raise the temperature of water bodies.
Lightening can also introduce massive amount of heat into the oceans. This means that
the overall temperature of the water source will rise, having significant impacts on the
environment.

Effects of Thermal Pollution

1. Decrease in DO (Dissolved Oxygen) Levels: The warm temperature reduces the levels
of DO (Dissolved Oxygen) in water. The warm water holds relatively less oxygen than
cold water. The decrease in DO can create suffocation for plants and animals such as fish,
amphibians and copepods, which may give rise to anaerobic conditions. Warmer water
allows algae to flourish on surface of water and over the long term growing algae can
decrease oxygen levels in the water.
2. Increase in Toxins: With the constant flow of high temperature discharge from
industries, there is a huge increase in toxins that are being regurgitated into the natural
body of water. These toxins may contain chemicals or radiation that may have harsh
impact on the local ecology and make them susceptible to various diseases.

3. Loss of Biodiversity: A dent in the biological activity in the water may cause
significant loss of biodiversity. Changes in the environment may cause certain species of
organisms to shift their base to some other place while their could be significant number
of species that may shift in because of warmer waters. Organisms that can adapt easily
may have an advantage over organisms that are not used to the warmer temperatures.

Page 36
 Environmental Pollution

4. Ecological Impact: A sudden thermal shock can result in mass killings of fish, insects,
plants or amphibians. Hotter water may prove favorable for some species while it could
be lethal for other species. Small water temperature increases the level of activity while
higher temperature decreases the level of activity. Many aquatic species are sensitive to
small temperature changes such as one degree Celsius that can cause significant changes
in organism metabolism and other adverse cellular biology effects.

5. Affects Reproductive Systems: A significant halt in the reproduction of marine wildlife

(although this may be true, reproduction can still occur between fish – but the likelihood
of defects in newborns is significantly higher) can happen due to increasing temperatures
as reproduction can happen with in certain range of temperature. Excessive temperature
can cause the release of immature eggs or can prevent normal development of certain
eggs.

6. Increases Metabolic Rate: Thermal pollution increases the metabolic rate of organisms
as increasing enzyme activity occurs that causes organisms to consume more food than
what is normally required, if their environment were not changed. It disrupts the stability
of food chain and alter the balance of species composition.

7. Migration: The warm water can also cause particular species of organisms to migrate
to suitable environment that would cater to its requirements for survival. This can result
in loss for those species that depend on them for their daily food as their food chain is
interrupted.

Page 37
 Environmental Pollution

Marine Pollution
Marine environment is submitted to contamination that comes in many different forms,
such as toxic chemicals (e.g., organic compounds, DDT, PCB, metals, pharmaceuticals,
gas), solid waste (e.g., plastics), increased nutrient (e.g., nitrates and phosphates) and
sediment inputs due to human activities (e.g., industry, agriculture, deforestation, sewage
discharge, aquaculture), radioactivity, oil spills, and discarded fishing nets. Marine
contamination changes the physical, chemical, and biological characteristics of the
oceans and coastal zones, and potentially threatens marine organism, ecosystems, and
biodiversity and affects thus the quality and productivity of marine ecosystems. In this
context, the contamination causing damage or negative impact on marine ecosystem is
called pollution. The ultimate effect of pollution on marine resources depends on the
form, intensity (acute or chronic), and location of the contamination, with some marine
environments, ecosystems, and species being more sensitive than others to pollution.

Sources and Pathways

Pollution is often classed as point source or nonpoint source pollution. Point source
pollution occurs when there is a single, identifiable, localized source of the pollution. An
example is directly discharging sewage and industrial waste into the ocean. Pollution
such as this occurs particularly in developing nations. Nonpoint source pollution occurs
when the pollution comes from ill-defined and diffuse sources. These can be difficult to
regulate. Agricultural runoff and windblown debris are prime examples.
There are many ways to categorize and examine the inputs of pollution into our marine
ecosystems. Generally there are three main types of inputs of pollution into the ocean:
direct discharge of waste into the oceans, runoff into the waters due to rain, ship
pollution, and pollutants released from the atmosphere and deep sea mining.

Direct discharge
Pollutants enter rivers and the sea directly from urban sewerage and industrial waste
discharges, sometimes in the form of hazardous and toxic wastes.
Inland mining for copper, gold, etc., is another source of marine pollution. Most of the
pollution is simply soil, which ends up in rivers flowing to the sea. However, some

Page 38
 Environmental Pollution

minerals discharged in the course of the mining can cause problems, such as copper, a
common industrial pollutant, which can interfere with the life history and development of
coral polyps. Mining has a poor environmental track record. For example, according to
the United States Environmental Protection Agency, mining has contaminated portions of
the headwaters of over 40% of watersheds in the western continental US. Much of this
pollution finishes up in the sea.

Land runoff
Surface runoff from farming, as well as urban runoff and runoff from the construction of
roads, buildings, ports, channels, and harbors, can carry soil and particles laden with
carbon, nitrogen, phosphorus, and minerals. This nutrient-rich water can cause fleshy
algae and phytoplankton to thrive in coastal areas; known as algal blooms, which have
the potential to create hypoxic conditions by using all available oxygen. In the coast of
southwest Florida, harmful algal blooms have existed for over 100 years. These algal
blooms have been a cause of species of fish, turtles, dolphins, and shrimp to die and
cause harmful effects on humans who swim in the water.
Polluted runoff from roads and highways can be a significant source of water pollution in
coastal areas. About 75% of the toxic chemicals that flow into Puget Sound are carried by
stormwater that runs off paved roads and driveways, rooftops, yards and other developed
land.

Ship
Ships can pollute waterways and oceans in many ways. Oil spills can have devastating
effects. While being toxic to marine life, polycyclic aromatic hydrocarbons (PAHs),
found in crude oil, are very difficult to clean up, and last for years in the sediment and
marine environment.
An oil spill in the sea will undergo a series of chemical, biological, and physical
processes which will lead to the degradation of the oil. The speed of these processes
depends to a large extent on the character of the oil, the ambient temperature, and other
environmental conditions. Heavy oils, i.e., oils with a high portion of hydrocarbons with
high molecular weight, will degrade more slowly than lighter oils. In addition, at high

Page 39
 Environmental Pollution

temperatures, the degradation processes will go faster than at low temperatures.

Important processes leading to the breakdown of an oil spill are evaporation, dispersion,
dissolution, and sedimentation. Evaporation is a process where lighter compounds
(molecules with four or fewer carbon atoms) enter a gaseous state. This process often
removes significant portions of
Oil spills are probably the most emotive of marine pollution events. However, while a
tanker wreck may result in extensive newspaper headlines, much of the oil in the world's
seas comes from other smaller sources, such as tankers discharging ballast water from oil
tanks used on return ships, leaking pipelines or engine oil disposed of down sewers.

Discharge of cargo residues from bulk carriers can pollute ports, waterways, and oceans.
In many instances vessels intentionally discharge illegal wastes despite foreign and
domestic regulation prohibiting such actions. An absence of national standards provides
an incentive for some cruise liners to dump waste in places where the penalties are
inadequate. It has been estimated that container ships lose over 10,000 containers at sea
each year (usually during storms). Ships also create noise pollution that disturbs natural
wildlife, and water from ballast tanks can spread harmful algae and other invasive species

Atmospheric pollution
Another pathway of pollution occurs through the atmosphere. Wind-blown dust and
debris, including plastic bags, are blown seaward from landfills and other areas.

Deep sea mining

Deep sea mining is a relatively new mineral retrieval process that takes place on the
ocean floor. Ocean mining sites are usually around large areas of polymetallic nodules or
active and extinct hydrothermal vents at about 1,400 – 3,700 meters below the ocean's
surface. The vents create sulfide deposits, which contain precious metals such as silver,
gold, copper, manganese, cobalt, and zinc. The deposits are mined using either hydraulic
pumps or bucket systems that take ore to the surface to be processed. As with all mining
operations, deep sea mining raises questions about environmental damages to the
surrounding areas

Page 40
 Environmental Pollution

Because deep sea mining is a relatively new field, the complete consequences of full-
scale mining operations are unknown. However, experts are certain that removal of parts
of the sea floor will result in disturbances to the benthic layer, increased toxicity of the
water column, and sediment plumes from tailings. Removing parts of the sea floor
disturbs the habitat of benthic organisms, possibly, depending on the type of mining and
location, causing permanent disturbances. Aside from direct impact of mining the area,
leakage, spills, and corrosion would alter the mining area's chemical makeup.

Types of pollution
Acidification
The oceans are normally a natural carbon sink, absorbing carbon dioxide from the
atmosphere. Because the levels of atmospheric carbon dioxide are increasing, the oceans
are becoming more acidic. The potential consequences of ocean acidification are not fully
understood, but there are concerns that structures made of calcium carbonate may
become vulnerable to dissolution, affecting corals and the ability of shellfish to form
shells.

Eutrophication
Eutrophication is an increase in chemical nutrients, typically compounds containing
nitrogen or phosphorus, in an ecosystem. It can result in an increase in the ecosystem's
primary productivity (excessive plant growth and decay), and further effects including
lack of oxygen and severe reductions in water quality, fish, and other animal populations.

Plastic debris
Marine debris is mainly discarded human rubbish which floats on, or is suspended in the
ocean. Eighty percent of marine debris is plastic – a component that has been rapidly
accumulating since the end of World War II. The mass of plastic in the oceans may be as
high as 100,000,000 tonnes.

Toxins

Page 41
 Environmental Pollution

Examples of persistent toxins are PCBs, DDT, TBT, pesticides, furans, dioxins, phenols,
and radioactive waste. Heavy metals are metallic chemical elements that have a relatively
high density and are toxic or poisonous at low concentrations. Examples are mercury,
lead, nickel, arsenic, and cadmium. Such toxins can accumulate in the tissues of many
species of aquatic life in a process called bioaccumulation.

Underwater noise
Marine life can be susceptible to noise or the sound pollution from sources such as
passing ships, oil exploration seismic surveys, and naval low-frequency active sonar.
Sound travels more rapidly and over larger distances in the sea than in the atmosphere.
Marine animals, such as cetaceans, often have weak eyesight, and live in a world largely
defined by acoustic information. This applies also to many deeper sea fish, who live in a
world of darkness. Between 1950 and 1975, ambient noise at one location in the Pacific
Ocean increased by about ten decibels (that is a tenfold increase in intensity).

Page 42
 Environmental Pollution

Noise Pollution
Noise is part of our environment. With progress in industrialization, the noise level has
been rising continuously. In the 19th century the development of the steam engines,
petrol engine and machines in factories resulted in increasingly noisy environment. In the
20th century this was further accelerated by introduction of diesel engine, jet engines,
turboprop, high tech machineries, construction site machineries and automobile traffic.
Noise has been recognized as one of the dimensions of pollution which brings about
degradation of the environment and creates health and communication hazards.
SOUND AND HUMAN ACOUSTICS
Sound consists of wave motion in an elastic medium such as air, water or solids (e.g.,
metals, plastics, wood, bricks, etc.). Sound waves travel through the medium from the
source to the recipient or listener.
The rate of the oscillation of the medium is known as the frequency of the 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 frequencies mean high pitched sounds which are
more irritating to the individual than low frequencies. The second parameter of sound is
sound pressure which is measure in Newton per sq. meter (N/m2). The third parameter on
sound is its intensity, expressed in watts per sq. metre i.e., the quantum of sound energy
that flows through unit area of the medium in unit time.
The human ear receives sound waves which set tip oscillations in the ear drum (tympanic
membrane). These oscillations cause movement of three small bones in the middle ear
behind the ear drum. These then pass through the fluid in the inner ear to the auditory
nerve and finally transmitted to the brain. The oscillations or sound are identified and
interpreted in the brain, which can select sounds into different categories—speech, music,
noises, etc.
The sensitivity of the ear varies from person to person. With ageing, people lose hearing
power gradually. A young person, 18 year old, with normal hearing, has audio range
between 20 Hz and 20,000 Hz. The audio sense is sharpest in the frequency range 2000
8500 Hz.

NOISE MEASUREMENT UNITS

Page 43
 Environmental Pollution

As mentioned before, sound pressure and sound intensity are two important parameters of
noise. The common scientific acoustic unit is the Decibel (dB). It is not an absolute
physical unit like volt, meter, etc. but is a ratio, expressed in logarithmic scale relative to
a reference sound pressure level.

The reference intensity used is the threshold of hearing which means sound which can be
first heard at a sound pressure of 2×10–5 Newton per sq. meter or sound intensity of 10–12
watts per sq. meter. Noise meters have been designed for noise measurement from low to
high frequencies, characteristic of human ear capacity. These meters record the dB scale
for routine measurement of general noise levels. Refined noise meters have been
developed to take care of peak noise levels, duration of noise exposure and quality of
noise which are aspects of specified noise situation.

Table 8.1: Sound Measurement (Intensities, Pressures and Decibels) in Air

at Room Temperature and Sea Level Pressure

NOISE CLASSIFICATION
There are broadly three categories of noise:
(i) Transport noise,
(ii) Occupational noise, and
(iii) Neighbourhood noise.
Transport Noise
Transport noise can be further sub-divided into (i) Road traffic noise, (ii) Aircraft and
(iii) Rail traffic noise.

Page 44
 Environmental Pollution

Road Traffic Noise

Traffic noise is increasing over the years with increase in the number of road vehicles.
Traffic speed is the major cause of noise. The noise volume is enhanced with increase in
traffic speed. Modern highways and traffic system encourage higher speeds.
In general, on urban roads there are distinct traffic peaks in the morning and evening
(10 A.M. and 6 P.M.) as people travel to and fro workplaces. Heavy diesel-engined
trucks are the noisiest vehicles on roads at present. For instance, the permissible noise
levels for cities are prescribed by the Central Pollution Control Board, India:

Aircraft Noise
The noise levels have peak values when aircrafts fly low and overhead or take off and
land at airports.
Rail Traffic
It is less of a nuisance as compared to the previous types of traffic noise.
Occupational Noise
Industrial workers are exposed to noisy working environment for 48 hours a week (8 hrs.
a day for 6 days a week). Some typical occupational noise levels are given below:
Table 8.2: Occupational Noise Level

Millions of workers suffer from progressive hearing damage and become prone to

Page 45
 Environmental Pollution

accidents under their working conditions. Their working efficiency is also affected.
Neighbourhood Noise
Loud TV and radio sets, loud cassettes, loudspeakers in public functions, disco music,
etc., are sources of neighbourhood noise which disturb and irritate the general public and
alsoharm the patients.
NOISE POLLUTION HAZARDS
The human ear drum is struck by noise in the form of airborne mechanical energy. While
the tolerable conversation level is 65 dB at a distance of 1 metre, 125 dB gives the
sensation of pain in the ear and 150 dB might be a killer.
High intensity noise for continuous periods is the major cause for ear damage. If a noise
level exceeding 90 dB in the mid-frequency range reaches the ear for more than a few
minutes, then the sensitivity of the ear is reduced.
Noise pollution can cause pathological or psychological disorders. High frequencies or
ultrasonic sound above the audible range can affect the semi-circular canals of the inner
ear and make one suffer from nausea and dizziness. Mid-audible frequencies can lead to
resonance in the skull and thereby affect the brain and nervous system. Moderate
vibration can also cause pain, numbness and cyanosis (blue colouration) of fingers while
severe vibration results damage to bones and joints in the bands with swelling and
stiffness.
In industrial and other establishments the general impact of noise pollution is lower
efficiency, reduced work rate and higher potential for accidents and injuries.
In residential areas even low frequency noise of 50–60 dB at night disturbs sleep,
particularly among the aged people, causing adverse effect on health.
Children, exposed to excessive noise, show signs of behavioural disorder which in later
age develop into destructive nature and neurotic disorders in the adult.
Excessive noise is one of the major factors for chronic exhaustion and tension in our
daily lives. This may explain why more and more people tend to become addicted to
alcohol, tobacco and drugs.
Noise pollution has also impact on travel of migratory birds from winter to tropical
climate.
PERMISSIBLE NOISE LEVELS

Page 46
 Environmental Pollution

In this age many people work and live in environment where the noise level is not
hazardous. But over the years they suffer from progressive hearing loss and
psychological hazards. The maximum permissible noise levels are summarised as
follows:
Table 8.3: Maximum Permissible Noise Levels

Noise pollution can be effectively controlled by taking the following measures:

(1) Control at Receiver’s End:
For people working in noisy installations, ear-protection aids like ear-plugs, ear-muffs,
noise helmets, headphones etc. must be provided to reduce occupa-tional exposure.
(2) Suppression of Noise at Source:
This is possible if working methods are improved by:
(a) Designing, fabricating and using quieter machines to replace the noisy ones.
(b) Proper lubrication and better maintenance of machines.
(c) Installing noisy machines in sound proof chambers.
(d) Covering noise-producing machine parts with sound-absorbing materials to check
noise production.
(e) Reducing the noise produced from a vibrating machine by vibration damp-ing i.e.
making a layer of damping material (rubber, neoprene, cork or plas-tic) beneath the
machine.
(f) Using silencers to control noise from automobiles, ducts, exhausts etc. and convey
systems with ends opening into the atmosphere.
(g) Using glass wool or mineral wool covered with a sheet of perforated metal for the
purpose of mechanical protection.
(3) Acoustic Zoning:

Page 47
 Environmental Pollution

Increased distance between source and receiver by zoning of noisy industrial areas, bus
terminals and railway stations, aerodromes etc. away from the resi-dential areas would go
a long way in minimising noise pollution. There should be silence zones near the
residential areas, educational institu-tions and above all, near hospitals.
(4) Sound Insulation at Construction Stages:
(a) Sound travels through the cracks that get left between the door and the wall. For
reducing noise, this space (jamb frame gap) should be packed with sound absorbing
material.
(b) Sound insulation can be done by constructing windows with double or triple panes of
glass and filling the gaps with sound absorbing materials.

(c) Acoustical tiles, hair felt, perforated plywood etc. can be fixed on walls, ceil-ings,
floors etc. to reduce noise (especially for sound proof recording rooms etc.)
(5) Planting of Trees:
Planting green trees and shrubs along roads, hospitals, educational institutions etc. help in
noise reduction to a considerable extent.
(6) Legislative Measures:
Strict legislative measures need to be enforced to curb the menace of noise pol-lution.
Some of these measures could be:
(a) Minimum use of loudspeakers and amplifiers especially near silence zones.
(b) Banning pressure horns in automobiles.
(c) Framing a separate Noise Pollution Act.

Page 48
 Environmental Pollution

Radioactive Pollution
Radioactive pollution occurs when there is presence or depositions of radioactive
materials in the atmosphere or environment, especially where their presence is accidental
and when it presents an environmental threat due to radioactive decay. The destruction
caused by the radioactive materials is because of the emissions of hazardous ionizing
radiation (radioactive decay) like beta or alpha particles, gamma rays or neurons in the
environment where they exist.

Radioactivity
The process by which certain elements undergo spontaneous disintegration, accompanied
by emission of radiations, is known as radioactivity. The elements are called radioactive
elements. Examples are: uranium, thorium, radium etc.

Radiations—Nature and Types

The radioactive substances generally give rise to three types of radiations—alpha (α),
beta (β) and gamma (γ).
Alpha particles (α): These are positively charged particles carrying a charge of +2 unit

and mass 4 units so that they are identical with helium nuclei . Alpha particles have
ionizing power i.e., they produce ion pairs their course in air.
Beta particles (β): These are identical with electrons. They are more penetrating than α-
rays i.e., they travel a little further than the latter in air but are absorbed by a thin layer of
metal e.g., aluminium foil. The ionizing power of the β-particles is less than that of α-
rays.
Gamma rays (γ): These consist of short-wave electromagnetic radiation or photons
emitted by a nucleus in an excited state. Gamma rays, being electromagnetic in nature,
have no mass and so cannot be thought of as particles. Their penetrating power is greater
than those of α- and β-particles. Thus while α-particles are stopped in air (3–9 cm) or thin
Al-foil (5 mm thick), γ rays can pass through 25cm of iron and 8 cm of lead.

Radioactive Decay: Radioactive elements undergo spontaneous transformation of one

atom to another and radiations are emitted in the process.

Page 49
 Environmental Pollution

Causes of Radioactive Pollution

1. Nuclear accidents from nuclear energy generation plants
2. The use of nuclear weapons as weapons of mass destruction (WMD)
3. Use of radio isotopes
4. Mining
5. Spillage of radioactive chemicals
6. Tests on radiation
7. Cosmic rays
Effects of Radioactive Pollution
1. Genetic mutations
Radiation has adverse effects when it comes to genetics. It leads to damage of DNA
strands leading to genetic break up in the course of time.
2. Diseases
Cancer is the most dominant radiation related disease. It has developed over the years and
poses great risk in global health.
3. Soil infertility
Radioactive substances in the soil react together with the various nutrients leading to
destruction of those nutrients, thus rendering the soil infertile and highly toxic.
4. Cell destruction
Radioactive pollution has diverse effects such as the alteration of cells. The bodies of
living organisms are unique in that there are millions of cells in one single body, where
each has its purpose to fulfill. Radiation distorts the cells present leading to permanent
damage of the various organs and organ systems. In the face of too much radiation,
permanent illnesses and death are inevitable.
5. Burns
Radiation is not easy to feel but it is easy to realize that you have been affected by it. The
immediate presence of burns, red lesions and sores is evidence. To make it worse, this
can lead to skin cancer.

Solutions of Radioactive Pollution

Page 50
 Environmental Pollution

1. Proper method of disposing radioactive waste

Radioactive waste still has some level of radiation. Accordingly, it cannot be disposed in
the same way as normal waste. It cannot be incinerated or buried. Since there is
likelihood of seepage, this waste should be stored in heavy and thick concrete containers.
Another option is to dilute the radiation since storage may not be possible. Since there are
no easy ways of disposing of radioactive material, professional assistance should always
be sought.
2. Proper labeling
It is necessary for any material with radioactive content to be labeled and the necessary
precautions advised on the content of the label. Containers with such elements should be
well labeled in order for one to use protective gear when handling them.
3. Banning of nuclear tests
It has already been proven that nuclear power has a lot of latent power that is very
destructive. Nevertheless, the tests done to perfect the energy contribute greatly to the
overall presence of radioactive substances. Moreover, these tests though done in the
deserts end up escaping from one ecosystem to another eventually affecting the lives of
many people.
4. Alternative energy sources
The evolution and use of nuclear power was not a bad thing initially. However,
considering the damage and threats it has on the environment, it is high time for its use to
be discontinued and for the world to perhaps focus on alternative and environmentally
friendly energy sources – like renewable sources of energy namely Solar, hydro-electric
and wind power.
5. Proper storage
It is mandatory for containers carrying radioactive material to be stored properly. For
starters, such substances should be stored in radiation proof containers to ensure no
seeping or leakage during handling. Proper storage means no harm and can minimize
cases of accidental leakage.
6. Reusing
Since it is not easy to store or dispose the waste, it can be recycled and used for other
purposes like in another reactor as fuel thereby protecting the environment.

Page 51