Environment

Engineering Chemistry (revised edition)
ISBN: 978-81-265-4475-2
Copyright©2014 Wiley India Pvt. Ltd. All Rights Reserved

Nature of Environment
The plants, animals, human beings, forests, deserts, rivers and lakes, and the air
we breathe are beautifully woven together in an interdependent way, such that if
any one entity is disturbed, the effects are felt by all others. In a nutshell, the
nature of the environment could be envisioned as:
When one touches a flower, a star is disturbed.
The universe around is built atom by atom to its vastness, and man, being the
most supreme living organism, must learn to appreciate, cherish and preserve it
rather than harm it by exploiting natural resources for his own selfish motives.
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Natural Resources and their Overutilization
Natural resources are raw materials that occur naturally in nature and are
considered valuable in their original forms. The value of a natural resource
depends on its available quantity in nature and the mankind’s demand for it. This
demand is decided by its usefulness to production. Our natural capital thus
includes rainforests, biodiversity, genetic capital, fossil fuels, mineral deposits,
fertile soil, clean water, pure air, flora and fauna.
Overutilization of natural resources to the point of depletion results in oil
shortage, coal and mineral depletion, and environmental degradation which leads
to consequences such as deforestation, desertification, extinction of species,
climatic changes, water, land and air pollution. Conservation of these
irreplaceable natural resources is the major focus of nature capitalism,
environmentalism, ecology movements and green parties.
ISBN: 978-81-265-4475-2

Environmental Degradation
Environmental degradation is a process in which the natural environment is
compromised through destruction of ecosystems, extinction of wildlife and
air/water/soil pollution.
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There is sufficiency in the world for man’s need but not for man’s greed.
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The future impacts of climate change, identified by the Government of India’s
National Communications (NATCOM) in 2004 include:
1.Decreased snow cover, affecting snow-fed and glacial systems such as the
Ganges and Brahmaputra. About 70% of the summer flow of the Ganges comes
from melt water.
2.Erratic monsoon with serious effects on rain-fed agriculture, peninsular rivers,
water and power supply.
3.Drop in wheat production by 4–5 million tones, with even a 1°C rise in
temperature.
4.Rising sea levels causing displacement along one of the most densely populated
coastlines in the world, threatened freshwater sources and mangrove ecosystems.
5.Increased frequency and intensity of floods. Increased vulnerability of people in
coastal, arid and semi-arid zones of the country.
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Carbon monoxide
Source- vehicular emissions, incomplete burning of carbon based fuels, forest fires,
industrial processes , coal mining, refining of petroleum etc.
Health problems- lower the dissolution of O2 in our blood, drowsiness and
lethargy.
Over exposure affects vision and cause cardiovascular disorders.
Preventive measures- Developing more efficient internal combustion.
Using CNG and LNG

Carbon dioxide
Source- Burning of fossil fuels, vehicular emissions industrial processes etc.
Health Problems- Hinders the respiratory processes, if present in excess.
Environmental problems- green house gas responsible for causing global
warming.
Preventive measures- CNG and LNG.

Chlorofluorocarbons
Sources- Air- conditioners and refrigerators.
Problems- Ozone layer depletion.
LEAD
Sources- Fuels, batteries, paints , dyes etc.
Health problems – Damage nervous system especially in children.

OZONE
Sources- Industrial and vehicular discharge.
Health problems- Watering and burning of eyes .
Oxides of Nitrogen
It incude NO, N2O and NO2
Sources- Burning of fuels, explosives, fertilizers and nitric acid.
Environmental problems – Smog and acid rain.
Health problems- respiratory diseases, bronchitis.
Preventive measures- Using catalytic convertors.

Suspended particulate matters
These include small particles like smoke and dust or liquid droplets, having size
ranging from 0.002 microns- 500microns.
Inorganic particulate matters- metal oxides
Organic particulate matters- polycyclic hydrocarbons such as chrysene.
Health problems- oxides of lead, cadmium, mercury etc. causes respiratory problems.
Certain particulate accelerate metallic corrosion and damage the buildings.
Aerosols such as smoke, fog, dust lower visibility.

Oxides of Sulphur
Include sulphur dioxides and sulphur trioxide.
Sources- Volcanic erruptions, industrial processes, vehicular emissions.
Environmental effects- Causes acid rain, smog and effect marble buildings.
Health problems- Effect respiratory tarct and cause lung diseases.
Preventive measures- Removal can be done by combustion, using chemical
scrubbers like calcium carbonate that react with sulphur dioxide to form less
harmful calcium sulphate.

General Methods for Air Pollution Control
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Indoor Air Pollution
Indoor air pollution can arise from a range of activities, such as:
1.Due to incomplete combustion of gasoline, LPG, wood during cooking and
heating, NOx and carbon monoxide are released.
2.Due to incomplete combustion of petroleum-based products and gasoline,
benzene is released.
3.From fire-proofing and insulation, asbestos is released.
4.Tobacco smoke releases formaldehyde, hydrogen cyanide, acetone, toluene,
ammonia, nickel.
5.Photocopying machines and electrostatic air cleaners release ozone.
These indoor air pollutants can be controlled by proper ventilation using exhaust
pipes, chimneys, etc. Also, these can be removed by adsorption using silica gel
and charcoal as adsorbents.
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Solar Energy Flow
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Greenhouse effect
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Enhanced greenhouse effect caused by human activities.
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Causes
Production of excessive greenhouse gases is responsible for the enhanced
greenhouse effect. The following activities contribute to the production of
excessive greenhouse gases:
1.Carbon dioxide levels in the air are increased by the usage of petrol, diesel,
CNG, etc. by automobiles.
2.Some farming practices and land-use changes increase the levels of methane
and nitrous oxide.
3.Emissions from factories increase the greenhouse gases.
4.Deforestation also contributes to global warming. Trees clean the air by taking
up carbon dioxide and releasing oxygen. This ceases if trees are felled.
5.Increase in population results in more deforestation, more factories, more
usage of automobiles, etc.
All this contributes to the production of greenhouse gases and greenhouse effect.
ISBN: 978-81-265-4475-2

Effects
The enhanced greenhouse effect may have serious consequences such as those
described as follows:
1.Sea levels will rise due to rising temperatures, thus reducing supplies of
freshwater, as flooding will occur along coastlines worldwide and salt water will
reach inland.
2.Some species will become endangered and face extinction due to change in
habitat.
3.Increase in temperature will affect millions of people who might succumb to
the extremes in climate.
4.Diseases will spread fast as most microorganisms will flourish under the
warmer climate conditions.
ISBN: 978-81-265-4475-2

Solutions
1.Use of alternate sources of energy such as solar power, fuel cells, hydropower,
wind energy, geothermal energy, etc., which do not emit greenhouse gases.
2.Restrict use of electricity by using energy efficient devices and appliances.
Replace regular light bulbs with compact fluorescent light (CFL) bulbs.
3.Avoid vehicular emission of greenhouse gases by using public transport and
other alternatives such as car pools, walking, biking, etc.
4.Planting more trees is an effective way to counter the increases in carbon
dioxide caused by automobile traffic, manufacturing and other human activities.
During photosynthesis, trees and other plants absorb carbon dioxide and give off
oxygen. A single tree will absorb approximately one ton of carbon dioxide during
its lifetime.
5.Recycle and reuse paper, plastic, newspaper, glass and aluminum cans to reduce
waste and its disposal.
ISBN: 978-81-265-4475-2

Acid Rain
According to the US EPA (Environmental Protection Agency), acid rain is a
broad term referring to a mixture of wet and dry acidic depositions from the
atmosphere containing higher than normal amounts of nitric and sulphuric acids.
1.The wet deposition may be in the form of rain, snow, sleet, fog, and dew.
2.The dry deposition may be acidifying particles and gases.
Causes
1.Acid deposition due to natural processes
2.Acid deposition by human activities
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Acid rain caused by human activities
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Dry and wet deposition processes
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In the presence of rain, these acids dissolve in water, undergo hydrolysis and
cause wet deposition.
1.Sulphur dioxide undergoes oxidation by hydroxyl radical:
On further addition of oxygen sulphur trioxide is generated:
Sulphur trioxide reacts with water and gives sulphuric acid.
2.Nitrogen dioxide reacts with hydroxyl radical to give nitric acid:
3.Sulphuric and nitric acids undergo hydrolysis and form sulphate, nitrate and
ammonium ion.
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Effects
1.Raises the acidity levels in lakes and seas.
2.Causes damage to aquatic life.
3.Many ecosystems get disrupted on land and in sea.
4.Affects plant life on land by causing an imbalance in plant nutrients.
5.Monuments built by man undergo deterioration, for example, yellowing of the
Taj Mahal.
6.Statues may rust or deteriorate as shown in the picture.
7.Acid rain has destructive and long lasting effects.
Solutions
1.Use coal with low sulphur content.
2.Use scrubbers to remove sulphur from emissions.
3.Limit processes known to generate high levels of acid rain.
ISBN: 978-81-265-4475-2

Ozone Depletion
Ozone is a natural trace gas in Earth’s atmosphere. In the lower atmosphere
(troposphere), ozone helps trap heat to keep the Earth warm. In the upper
atmosphere (stratosphere), it plays an even more important role by filtering
harmful ultraviolet (UV) rays from the sun. Overexposure to UV rays destroys
skin cells, causes cancer and cataract, and can lead to macular degeneration.
Without a protective ozone layer, there would not be life on Earth as we know it.
Ozone depletion is described by two distinct, but related observations:
1.A slow, steady decline in the total volume of stratospheric ozone since the
late1970s.
2.A much larger, but seasonal, decrease in stratospheric ozone over the Earth’s
polar regions during the same period. The latter phenomenon is commonly
referred to as the ozone hole.
ISBN: 978-81-265-4475-2

Ozone Cycle
1.Oxygen molecule absorbs UV light and splits up:
2.The atomic oxygen then combines with oxygen molecule to give ozone:
3.Ozone molecules absorb UV rays and split up into a molecule of oxygen and
an oxygen atom. This oxygen atom then combines with an oxygen molecule to
regenerate ozone. This is a continuing process, which terminates when an oxygen
atom “recombines” with an ozone molecule to make two O2 molecules:
4.The overall amount of ozone in the stratosphere is maintained by a balance
between photochemical production and recombination.
ISBN: 978-81-265-4475-2

Reactions Involved
The CFCs emitted from the Earth’s surface rise to the stratosphere, where the
following reactions take place:
1.UV rays cause a chlorine molecule to break away from the CFC molecule:
2.The free Cl atom reacts with an ozone molecule and pulls one O atom away:
3.Chlorine monoxide reacts with free O atom from the stratosphere to again
release a free Cl atom:
4.This free Cl atom continues to react with ozone and deplete it in the
stratosphere.
ISBN: 978-81-265-4475-2

Effects
Depletion in the ozone layer allows UV rays to reach the Earth’s surface. This
causes the following problems:
1.Prolonged exposure to UV rays results in melanoma, a skin cancer, which if not
diagnosed early can prove fatal.
2.Immune system deteriorates on prolonged exposure to UV light.
3.Plant growth is retarded.
4.Marine life is destroyed.
Solutions
1.Injecting alkanes into the Antarctic atmosphere. These alkanes will immobilize
the notorious chlorine atoms of CFCs by forming haloalkanes with them.
2.Using hydrogen-containing CFCs like CHClF2, HFC, which are destroyed in
the troposphere itself and not taken to stratosphere for ozone destruction.
ISBN: 978-81-265-4475-2

Smog Formation
Smog is a combination of two terms, smoke and fog which is a consequence of
air pollution. Its presence in the air reduces visibility and causes harmful effects
on health.
Classical (London) Smog
Smoke produced in activities like burning of coal emits sulphur dioxide and
particulates. These get mixed with fog produced in chilly and damp climate to
form grayish smog. This type of smog, commonly called as London smog.
Causes
The air with smog is characterized by presence of high levels of carbon soot
arising from unburnt coal and sulphur dioxide arising from oxidation of sulphur
present in the coal. The reactions involved in smog formation are as follows:
ISBN: 978-81-265-4475-2

Photochemical Smog
Photochemical smog is the smog produced by reaction of sunlight with
chemicals like nitrogen oxides (NOx) and volatile organic compounds (VOCs)
found in polluted air to give particulates and tropospheric ozone.
Causes
The primary (NOx) and secondary pollutants (VOCs), found in polluted air cause
photochemical smog. The sources of these pollutants are as follows:
1.NOx: Exhausts of automobiles, coal-based power plants and commercial
industries emit NO, which gives NOx on subsequent reactions with atmospheric
oxygen.
2.VOCs: These are released from sources like petrol, organic paints and solvents,
etc. These pollutants are extremely reactive and form secondary pollutants such
as trophospheric ozone, aldehydes, peroxyacetyl nitrates, H2O2, •OH, HOO•,
ROO•, radicals, etc.
ISBN: 978-81-265-4475-2

Reactions
1.Formation of ozone:
•Nitric oxide released from automobile exhausts reacts with oxygen from
atmosphere to give brown colored nitrogen dioxide.
•Sunlight when incident on this NO2 releases the free radical of oxygen, which
being highly reactive sets off subsequent reactions.
•The oxygen free radical reacts with atmospheric oxygen producing ozone.
2.Formation of aldehydes and ketones:
3.Formation of peroxyacetyl nitrate:
ISBN: 978-81-265-4475-2

Effects
1.Photochemical smog is very harmful since it aggravates respiratory disorders
like bronchitis and asthma.
2.It causes a decrease in lungs’ capacity which results in shortness of breath,
wheezing, coughing, etc.
3.It decreases immunity, thus making the body susceptible to various infections.
4.It dries out eyes and nasal membranes.
Solutions
1.Using catalytic converters on motor vehicle exhausts.
2.Reducing commuter traffic and increasing public transportation. Using
telecommunication rather than face-to-face meetings.
3.Opting for a smaller, more fuel-efficient compact car; driving at or below the
speed limit and not letting vehicles idle unnecessarily.
4.Using a cleaner fuel to heat houses such as natural gas, solar power or wind
energy wherever available.
ISBN: 978-81-265-4475-2

Water Pollution
Water pollution refers to degradation of water quality.
1.Point sources
2.Non-point sources
Causes of Water Pollution
1.Sewage and domestic waste
2.Industrial effluents
3.Agricultural discharge
4.Siltation (small fragments of rocks and loose soil particles that get carried away
with moving water bodies)
5.Radioactive discharge (nuclear waste dumped by nuclear tests, nuclear reactors,
etc.)
6.Heat (thermal pollutants or discharges that raise the temperature of water)
ISBN: 978-81-265-4475-2

Point Sources
They discharge pollutants at specific locations through
pipes or sewers into bodies of surface water. Ex:
factories, sewage treatment
plants etc.

• Non-point Sources
Refers to pollutants that come from a widespread area and
cannot be tracked to a single point or source. Soil erosion,
chemical runoff, and animal waste pollution

BOD- It is the amount of water required by aerobic micro
organisms for biochemical decomposition process. It measures the
amount of oxygen consumed by micro organisms as they break
down organic matter within small water samples.
BOD high then dissolved oxygen content is too low to support life of
aquatic organisms.
When BOD is low then dissolved oxygen is more.
For polluted water BOD will be high and for non polluted water it
will be less.

COD -It is the amount of oxygen consumed in
oxidation of organic and oxidizable inorganic material
present in water sample.

Chemical Pollutants
1.Many inorganic chemicals such as arsenic, cadmium, lead, mercury, selenium,
etc., are responsible for water pollution.
2.Acids [HCl, H2SO4, HNO3 and H3PO4] and alkalis [NaOH, KOH, NH3 and
Ca(OH)2] that are discharged as effluents from various industries are important
inorganic pollutants.
3.Oil discharged into surface water, usually in the ocean as well on land and in
rivers, has caused major pollution problems.
4.Organic chemicals from the agricultural use of pesticides and herbicides and
industrial processes that produce dioxin have the potential to cause significant
ecological damage and human health problems.
5.Polychlorinated biphenyls (PCBs), used as dielectric and coolant fluids and in
fertilizers and detergents, affect the neurological behavior and are carcinogenic.
6.Synthetic detergents commonly used for washing and cleaning are made up of a
surfactant (alkyl benzene sulphonates) and a builder (sodium phosphate or
polyphosphate) along with some enzymes, bleaching agents, etc.
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Treatment of Sewage
• It consists of three steps:
1. Primary treatment
2. Secondary treatment
3. Tertiary treatment

Primary Treatment
• The first step consists of screens, grit removal, oil and grease
trap and primary sedimentation.
Screens: The influent sewage water passes through a bar screen
to remove all large objects like cans, rags, sticks, plastic packets
etc. carried in the sewage stream
Grit removal: It includes a sand or grit channel or chamber,
where the velocity of the incoming sewage is adjusted to allow
the settlement of sand, grit, stones, and broken glass. These
particles are removed because they may damage pumps and
other equipment.
Oil & grease trap: Removal of oil and grease.
Primary Sedimentation: Gravitational settlement of suspended
and colloidal particles denser than water.

Secondary Treatment
• It consists of biological treatment for the removal
of organic matter. Use microorganism to
decompose organic waste. After several hours
bacteria are allowed to settle down as secondary
sludge.
• The sludge is further treated in 'sludge digesters':
large heated tanks in which its chemical
decomposition is catalysed by microorganisms.

Tertiary Treatment
• Complex biological and chemical process
removes the remaining pollutants like
minerals, metals and viruses.
Problem with Sewage water treatment
• Disposal of sludge,
• Treatment of sludge is costly and time
consuming process.

Noise Pollution
The unwanted noise dumped into the atmosphere that leads to discomfort
and health hazards is known as noise pollution.
Sources of Noise Pollution
•Natural phenomena such as violent volcanic eruptions,
thunder, fierce storms, etc.
•Domestic appliances such as mixers, washing machines,
telephones, etc.
• Industries such mills and
factories
• Automobiles
•Trains, ships, and aircrafts
•Bursting of crackers and playing
loud music during social
gatherings and festivals
• Entertainment devices
such as radio, television, etc.

The decibel (dB) is a logarithmic unit used to express the ratio
between two values of a physical quantity, often power or intensity
. One of these quantities is often a reference value, and in this case
the decibel can be used to express the absolute level of the
physical quantity.

Causes of Noise Pollution
Major sources that lead to noise pollution are vehicular traffic on land (roads, rail
and air), domestic and industrial noises, etc.
Some sources of noise and the level of noise produced by them
ISBN: 978-81-265-4475-2

Effects of Noise Pollution
1.The safe limit for sound for humans is 45–75 Db. Any sound measuring above
75 Db causes discomfort to the human ears and can lead to hearing impairment
when exposed for long duration. Sounds above 150 Db can cause instant
deafness in humans.
2.Noise is continuous if it is uninterrupted during the entire period of observation,
for example, a running fan sound. It is intermittent if it is interrupted by periods of
quiet for at least one second, for example, sound of a drilling machine. Impulse
noise is characterized by a change of at least 40 dB within duration of one second,
for example, the noise produced in the firing of a weapon. Impact noise, like
impulse noise, is produced by a sudden intense sound wave, for example, an
explosion.
3.Noise has ill effects on human physiological functions. It affects heartbeat,
peripheral circulation and breathing pattern. Excessive noise leads to temporary
or even permanent hearing loss. It also has effects on behavior such as
annoyance, irritability, headache, tiredness and insomnia. Noise also affects
productivity of humans.
ISBN: 978-81-265-4475-2

E-Waste
• Refers to the waste generated from electronic
products that are excessively used in
developed and developing countries.

Management of Solid Wastes
The management of solid wastes is very challenging as the wastes need to be
collected, transported, segregated, and safely deposited. The consequence of
haphazard disposal activities of the municipal solid wastes can be seen in the
form of rag pickers gleaning the filth for scrap and the proliferation of free-
ranging dogs. This in turn affects their health and well-being as well as of those in
contact with them, as they carry many contagious human diseases.
ISBN: 978-81-265-4475-2

Collection of NPK from anaerobic digester
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Environmental Management and Laws
Environment management plan
ISBN: 978-81-265-4475-2

Environment

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