Environmental Chemistry: Introduction, Chemical reactions, Pollution, control and Green Chemistry

1. Unit XIV : Environmental Chemistry

2. Content of UNIT XIV: Environmental Chemistry
• Introduction to Environment and Environmental Chemistry
• Introduction to Pollution in different Environment and
Ecosystems….
 Air or Atmosphere
 Water
 Soil
• Chemical reactions in Atmosphere….
 Smogs
 Major Atmospheric Pollutants
 Acid rain
 Ozone depletion
 Greenhouse effect and global warming
• Green Chemistry as an alternative tool for reducing pollution
•Strategy for control of Environmental Pollution

3. • The term environment has been derived
from a French word “Environia” meaning
“surroundings”.
• It refers to both biotic (living) and abiotic
(physical or non-living) materials in which
organisms live.
• Environment regulates the life of the
organisms including human beings.
• Ordinarily environment refers to the
materials and forces that surrounds the
living organism.
• It is comprised of the interacting systems
of physical, biological and elements
which are interlinked both individually and
collectively.
Meaning, Definition and Components of Environment
An ecosystem is a network of
interactions among organisms,
and between organisms and their
environment.

4. Components of Environment
• Environment mainly consists of
Atmosphere, Hydrosphere,
Lithosphere and Biosphere.
• It is divided into two types such as (a)
Micro environment and (b) Macro
environment.
• It can also be divided into two other
types such as (c) Physical and (d)
biotic environment.
• Physical environment refers to all
abiotic factors or conditions like
temperature, light, rainfall, soil,
minerals etc. It comprises of
atmosphere, lithosphere and
hydrosphere.
• Biotic environment includes all biotic
factors or living forms like plants,
animals, Micro-organisms.

5. •Environmental chemistry is the
scientific study of the chemical
and biochemical phenomena
that occur in natural
Environment.
•It can be defined as the study of
the sources, reactions,
transport, effects, and fates of
chemical species in the air, soil,
and water environments due to
anthropogenic activity and
biological activity.
•The impacts may be felt on a local
scale, through the presence of
pollutants or toxic substances
arising from a chemical waste
site, or on a global scale as global
warming.
Environmental Chemistry: Definition

6. Environmental Pollution: Definition
• Environmental pollution is the effect of undesirable changes in
environment due to introduction of contaminants that have
harmful effects on plants, animals and human beings.
• A substance, which causes pollution, is known as “pollutant”. Where
as, “contaminant” is pollutant causes irreversible damage or lethal
effect to air, water, soil and biotic communities.
• Pollutants can be solid, liquid or gaseous substances present in
greater concentration and are produced due to human activities or
natural happenings.
• Pollutants which are slowly degradable, remain in the environment in
an unchanged form for many decades. Substances such as
dichlorodiphenyltrichloroethane (DDT), plastic materials, heavy
metals, many chemicals, nuclear wastes etc.,
• Environmental pollution, pollutants originate from a source and get
transported by air or water or are dumped into the soil by human
beings.

7. Environmental Pollution
• Pollution has seen since the onset of the industrial revolution during the 19th
century.
• Technological progress facilitated by super efficiency, overproduction,
overconsumption are main causes of serious deterioration of natural
resources.
• Environmental pollution is a problem both in developed and developing
countries. Factors such as population growth and urbanization cause the use
of natural resources to the maximum.

8. Classification of Environmental Pollution
Pollution can be broadly classified according to the components of
environment that are polluted.
Major of these are:
Air or Atmospheric pollution , Water pollution, Soil pollution (land
degradation), Industrial pollution etc.,
Pollutants are generally grouped under two classes:
• Biodegradable pollutants – Biodegradable pollutants are broken
down by the activity of micro-organisms and enter into the
biogeochemical cycles. Ex: domestic waste products, sewage,
agricultural residue, paper, wood etc.,
• Non- Biodegradable pollutants – Non-biodegradable pollutants are
stronger chemical bondage, do not break down into simpler and
harmless products. Ex:- pesticides, Heavy Metals, plastics,
radioactive waste etc.

9. Types of Pollution

10. Atmospheric or Air Pollution
• Definition: Air pollution is the introduction of particulates other harmful
substances such as gases into Earth's atmosphere. Air pollution may
come from anthropogenic or natural sources.
• The pollutant can be solid particles, liquid droplets, or gases.
• Air pollutants are classified as primary
or secondary.
• Primary pollutants are usually produced
from a process, such as ash from a
volcanic eruption, carbon monoxide
gas from motor vehicle exhaust, or the
sulfur dioxide and NOX released from
factories.
• Secondary pollutants are not emitted
directly. they form in the air when
primary pollutants react or interact. Ex:-
ozone, NO2 and NOX.

11. How atmospheric pollution is caused?
• Most of this air pollution results from the burning of fossil fuels (CO2
emission), such as coal, oil, natural gas, and gasoline to produce
electricity and power our vehicles.
Types Atmosphere
•The atmosphere that surrounds the
earth is not of the same thickness at
all heights. There are concentric
layers of air and each layer has
different density. They are…
Troposphere and Stratosphere
Troposphere
• The lowest region of atmosphere in
which the human beings along with
other organisms live. It extends up to
the height of ~ 10 km from sea level.
• This is the region of strong air
movement and cloud formation.

12. Stratosphere
It lies between 10 and 50 km above sea level. It contains dinitrogen
(N2), dioxygen (O2), ozone and little water vapour.
• Atmospheric pollution is generally
studied as tropospheric and
stratospheric pollution.
• The presence of ozone in the
stratosphere prevents about 99.5%
of the sun’s harmful ultraviolet
(UV) radiations from reaching the
earth’s surface.
• Protecting humans and other
animals from its effect.

13. Tropospheric pollution occurs
due to the presence of
undesirable solid or gaseous
particles in the air. The
following are the major gaseous
and particulate pollution in the
air.
Gaseous air pollutants: These are oxides of sulphur, nitrogen
and carbon, hydrogen sulphide, hydrocarbons, ozone and other
oxidants.
Particulate pollutants: These are dust, mist, fumes, smoke,
smog etc.,
Tropospheric pollution

14. Oxides of Sulphur
• Oxides of sulphur are produced when
sulphur containing fossil fuel is burnt.
The most common oxide among them is
sulphur dioxide.
Harmful effects of sulphur dioxide :
• This gas is poisonous for living
organisms and asthma, bronchitis and
emphysema in humans.
• In plants, a high concentration of sulphur
dioxide makes the flower buds stiff and
makes them fall off, hampering its
reproductive cycle.
2SO2(g) + O2(g) → 2SO3(g)
SO3 (g)+H2O(l) → H2SO4(aq)
• Sulphur dioxide is the main component in killer smog.
• The presence of particulate matter in polluted air catalyses the
oxidation of sulphur dioxide to sulphur.

15. Oxides of Nitrogen
• Mixture of gases that are composed
of nitrogen and oxygen. At high
altitudes when lightning strikes, they
combine to form oxides of nitrogen.
• Two of the most toxicologically
significant compounds are
nitric oxide (NO)
and nitrogen dioxide (NO2).
• Other gases belonging to this group
are nitrogen monoxide (NO)
nitrous oxide, N2O,
and nitrogen pentoxide (NO5).
N2 (g) + O2 (g) ⎯→ 2NO(g)
NO reacts instantly with oxygen to
give NO2
2NO (g) + O2 (g) → 2NO2 (g)
Rate of production of NO2 is faster
when nitric oxide reacts with ozone
in the stratosphere.
NO (g) + O3 (g) → NO2 (g) + O2 (g)

16. Harmful effects of Nitrogen oxides compounds
• The irritant red haze in the traffic and congested places is due to
oxides of nitrogen.
• Higher concentrations of NO2 damage the leaves of plants and retard
the rate of photosynthesis.
• Nitrogen dioxide NO2 is a lung irritant that can lead to an acute
respiratory disease in children.

17. Hydrocarbons are composed of
hydrogen and carbon only and
are formed by incomplete
combustion of fuel used in
automobiles.
Hydrocarbons are carcinogenic,
i.e., they cause cancer.
They harm plants by causing
ageing, breakdown of tissues
and shedding of leaves, flowers
and twigs.
Hydrocarbons

18. Oxides of Carbon or Oxocarbon
• An oxocarbon or oxide of carbon is a chemical compound
consisting only of carbon and oxygen.
• Carbon forms two well-known oxides, Carbon monoxide (CO) and
Carbon dioxide (CO2). In addition, it also forms Carbon suboxide
(C3O2).

19. Carbon monoxide (CO)
• Carbon monoxide (CO) is one of the
most serious air pollutants. It is a
colourless and odourless gas.
• The natural concentration of CO in air
is around 0.2 ppm. Natural sources of
CO include volcanoes and
bushfires. Other sources are
incomplete combustion of carbon,
automobile exhaust. incomplete
combustion of coal, firewood,
petrol, etc.
• Effects of CO to human beings: It
binds to haemoglobin to form
carboxyhaemoglobin, which is about
300 times more stable than the
oxygen-haemoglobin complex. In
blood, when the concentration of
carboxyhaemoglobin reaches about
3–4 per cent, the oxygen carrying
capacity of blood is greatly reduced.
• This oxygen deficiency, results into
headache, weak eyesight,
nervousness and cardiovascular
disorder. In female smokers,
increased CO level in blood may
induce premature birth, spontaneous
abortions and deformed babies.

20. Carbon dioxide (CO2)
• CO2 is a colorless and odorless gas
vital to life on Earth. Exists in atmosphere
as a trace gas at a concentration of
about 380 ppm (0.038%) by volume.
• Sources: Burning of fossil fuels such
as coal, oil, and natural gas for energy,
It is also emitted during volcanic
eruptions.
• Increased use of fossil fuels, a large
amount of CO2 gets released into the
atmosphere. Excess of CO2 in the air is
removed by green plants by
photosynthesis.
• Deforestation and burning of fossil fuel
increases the CO2 level and disturb the
balance in the atmosphere. The
increased amount of CO2 in the air is
mainly responsible for global warming.

21. Global Warming and Greenhouse Effect
The average Earth surface temperature is 14° C. or 57.2° F
• Global Warming is the steady increase of Earth's average surface
temperature due to effect of greenhouse gases (CO2,CH4,N2O and
CFC etc.,)
• Global Warming: About 75 % of the solar energy reaching the
earth is absorbed by the earth’s surface, which increases its
temperature. The rest of the heat radiates back to the atmosphere.
Some of the heat is trapped by gases such as CO2, CH4, O3, CFCs
and water vapour in the atmosphere. Thus, add to the heating of the
atmosphere. This causes global warming.
• Greenhouse effect: Ozone Maintains the temperature and makes
the earth perfect for life. CO2 trapped for photosynthesis. If the
amount of CO2 crosses the ambient level of 0.03%, the natural
greenhouse balance may get disturbed and contribute to global
warming.

22. Sunlight's composition (Ground level/ per Sq/m) :
o Infrared radiation: 527 (W)
o Visible light: 445 (W)
o Ultraviolet radiation: 32 (W)

23. Atmospheric Methane (CH4)
• Atmospheric CH4 concentrations is one of the most potential
greenhouse gas in atmosphere. it traps 29 times more heat than
CO2. The concentration of CH4 in atmosphere is 1800 ppb.
• Sources: Methane emissions results from livestock, agricultural
practices, decay of organic waste in municipal solid waste landfills
and microbial degradation of organic matter.
• The waterlogged soil of rice paddies provides ideal conditions for
methanogenesis, and produced methane oxidized by
methanotrophs is the major source for atmospheric CH4.

24. Nitrous Oxide: (Laughing Gas)
• Nitrous oxide occurs naturally in the environment. The
atmospheric concentration of N2O is around 320ppb.
• In recent years, their quantities have increased significantly
due to the use of chemical fertilizers and the burning of
fossil fuels.
• If these trends continue, the average global temperature will
increase to a level which may lead to melting of polar ice
caps and flooding of low lying areas all over the earth.
Chlorofluorocarbon (CFC):
•CFC are man-made industrial organic chemical
compound that contains only carbon, chlorine, and
fluorine.
•The most common representative is
dichlorodifluoromethane (R-12 or Freon-12).
•Many CFCs have been widely used as refrigerants,
propellants (in aerosol applications), and solvents.
Because CFCs contribute to ozone depletion in the upper
atmosphere.

25. Acid Rain
• Acid rain, or acid deposition, is a broad term that includes any form
of precipitation with acidic components, such as sulfuric or nitric
acid that fall to the ground from the atmosphere in wet or dry forms.
This can include rain, snow, fog, hail or even dust that is acidic.
• Acid rain is a precipitation with unusually acidic due to possesses
elevated levels of hydrogen ions (low pH). Normally rain water has a
pH of 5.6 due to the presence of H+ ions formed by the reaction of
rain water with CO2 together to form carbonic acid.
H2O (l) + CO2 (g) ⇌ H2CO3 (aq)
Carbonic acid then can ionize in water forming low concentrations
of hydronium and bicarbonate ions:
H2O (l) + H2CO3 (aq) ⇌ HCO3
− (aq) + H3O+ (aq)

26. What Causes Acid Rain?
• Acid rain results when sulfur dioxide
(SO2) and nitrogen oxides (NOX) are
emitted into the atmosphere and
transported by wind and air currents.
• The SO2 and NOX oxidation reaction
with water, oxygen and other
chemicals to form sulfuric and nitric
acids. These then mix with water and
other materials before falling to the
ground.
Sources:
• Natural sources such as volcanoes eruption.
• Burning of fossil fuels to generate electricity. Two thirds of SO2 and one
fourth of NOX in the atmosphere come from electric power generators.
Vehicles and heavy equipment, oil refineries and other industries.
2SO2 (g) + O2 (g) + 2H2O (l) → 2H2SO4 (aq)
4NO2 (g) + O2 (g)+ 2H2O (l) → 4HNO3 (aq)
Particulate Pollutants

27. Taj Mahal was affected due to serious
levels of sulphur and nitrogen
oxides. It is because of large number
of power plants and industries set
up around this area. Acid rain
reacted with the marble (Calcium
Carbonate -CaCo3) of Taj Mahal and
damage the Marble structure.
•Bhopal gas disaster was occurred on
2–3 December 1984 at the Union
Carbide India Limited (UCIL)
pesticide plant in Bhopal, Madhya
Pradesh.
•Over 500,000 people were exposed to
Methyl Isocyanate (MIC) gas and
other chemicals emitted from industry.
Effect of Acid Rain in Taj Mahal:-
Bhopal Gas tragedy

28. Particulate Pollutants
oParticle pollution or Particulate matter (PM), is a complex
mixture of extremely small particles and liquid droplets that get
into the air.
oThese are outcome of vehicle emissions, smoke particles from
fires, dust particles and ash from industries.
oParticulates in the atmosphere may be viable or non-viable.
oThe viable particulates e.g., bacteria, fungi, moulds, algae etc.,
are minute living organisms.
oOnce inhaled, these particles can affect the Heart and Lungs and
cause serious health effects. Human beings are allergic to some
of the fungi found in air. They can also cause plant diseases
oNon-viable particulates may be classified according to their
nature and size such as Smoke particulates, Dust, Mists,
Fumes

29. Non-viable particulates
• Smoke particulates: solid or mixture of solid and liquid particles
formed during combustion of organic matter. Ex:-cigarette, smoke
from burning of fossil fuel and garbage.
• Dust: Fine solid particles over 1μm in diameter produced during
crushing solid materials, saw dust, pulverized coal, cement and fly
ash.
• Mists: Particles of spray liquids and by condensation of vapours
in air. Ex:- Sulphuric acid mist and Pesticides.
• Fumes: Condensation of vapours during sublimation, distillation,
boiling solvents and metallic oxides.
Effect of particulate pollutants:
• Particulate pollutants bigger than 5 μm lodge in the nasal passage,
whereas particles of about 10 μm enter into lungs easily.
• Lead used to be a major air pollutant emitted by vehicles. Lead
interferes with the development and maturation of red blood cells.

30. Particle pollution includes:
• PM10 : Inhalable particles, with diameters that are generally 10
micrometers and smaller.
• PM2.5 : Fine inhalable particles, with diameters that are generally 2.5
micrometers and smaller.

31. Smog
• Kind of air pollution originally named for the mixture of smoke and
fog in the air. There are two types of smog…
• Classical smog: occurs in cool humid climate. It is a mixture of
smoke, fog and sulphur dioxide (SO2).
• Photochemical smog: Photochemical smog is a mixture of
pollutants that are formed when nitrogen oxides and volatile
organic compounds (VOCs) react to sunlight, creating a brown
haze occurs in warm, dry and sunny climate. It produced by
automobiles and factories.
Formation of photochemical smog
• When fossil fuels are burnt, a variety of pollutants are emitted into
the earth’s troposphere.
• Sources: In nature bushfires, lightning and the microbial
processes are natural sources and combustion incomplete of fossil
fuels are anthropogenic sources of formation smog.

32. How is smog formed?
NO is converted into nitrogen dioxide (NO2). This NO2 in turn absorbs energy from
sunlight and breaks up into nitric oxide and free oxygen atom.
Oxygen atoms are very reactive and combine with the O2 in air to produce O3
The O3 reacts rapidly with the NO(g) formed in the reaction (i) to regenerate NO2
contribute to haze.
O3 is a toxic gas and both NO2 and O3 react with the un burnt hydrocarbons in the
polluted air to produce chemicals such as formaldehyde, acrolein and
peroxyacetyl nitrate (PAN).

33. Effects of photochemical smog
How can photochemical smog be controlled ?
• Control the emission of primary precursors NO2,O3 and
hydrocarbons
• Use of catalytic converters in automobiles reduce prevents the
release of nitrogen oxide and hydrocarbons to the atmosphere.

34. Stratospheric Pollution
Stratosphere is the layer just
above troposphere. The upper
stratosphere consists of
considerable amount of ozone
(O3), which protects us from the
harmful ultraviolet (UV)
radiations coming from the sun.
These radiations cause skin
cancer in humans. Therefore, it
is important to maintain.
Formation and Breakdown of Ozone
In stratosphere, the O2 is partially converted into O3. It is a two step
process.
Step 1: The UV radiation coming from the sun has sufficient energy to
split the O2 into 2 oxygen radicals.
O2 + UV 2O

35. Step 2: The oxygen radicals react with more oxygen molecules to form
ozone.
O3 thermodynamically unstable and decomposes to molecular O2
Thus dynamic equilibrium exists.
O3 + UV O2 + O
Depletion of ozone layer in stratosphere
In recent years, due to human activity two compounds NO and
CFC, are responsible for depletion of ozone layer.
Nitric Oxide
The NO reacts with O3 causing decrease the amount of O3 and forms
NO2 which reacts with oxygen radicals for regeneration of NO, while
amount of O3 decreases.
NO + O3 NO2 + O2
NO2 + O NO + O2

36. Chlofofluoro carbons (CFC) or freons
CFC used in refrigerators, air conditioners as propellants and by
the electronic industry for cleaning computer parts etc. Once CFCs
are released in the atmosphere, they mix with the normal atmospheric
gases.
In stratosphere, they get broken down by powerful UV radiations,
releasing chlorine free radical.
The chlorine radicals are continuously regenerated and cause the
breakdown and damaging of ozone layer.
One molecule of CFC can destroy more than one thousand O3
molecules in stratosphere.
Hypochlorite
Californium dichloride

37. Effects of Depletion of the Ozone Layer
• Due to depletion of O3 layer, more U.V. radiations fall on the
earth surface.
• UV radiations lead to ageing of skin, cataract, sunburn, skin
cancer, killing of many phytoplankton, damage to fish
productivity etc.
• The UV radiations affect plants proteins and thus reduce the
chlorophyll.
• UV radiations also tend to damage the immune system.
• Increases evaporation of surface water through the stomata of
the leaves and decreases the moisture content of the soil.

38. WATER POLLUTION
• Water is essential for life. Without water there would be no life.
• Water pollution is the process of contamination of water of natural or
artificial water resources with harmful substances.
• Pollution of water mainly originates from Human activities.
• Sources of Water Pollution:
Point Source: Easily identified place or source of pollution. Ex;-
Municipal wastes and industrial discharge.
Non point sources:- Pollution are those where a source of
pollution cannot be easily identified, e.g., agricultural run off
(from farm, animals and crop-lands), acid rain, storm-water
drainage.

39. Major Water Pollutants
Causes of Water Pollution
Pathogens: Disease causing agents includes bacteria, virus and other
organisms that enter water from domestic sewage and animal excreta. Ex;-
Amoebiasis, Botulism, Cholera, E. coli Typhoid, Hepatitis A etc.,
Organic wastes: organic matter such as leaves, grass, trash etc. as
a consequence of run off. Excessive phytoplankton growth. These
are biodegradable.

40. Biochemical Oxygen Demand (BOD)
• The polluted water contain large amount of inorganic and organic
compounds. Some of these can be oxidised by microorganisms.
• Organic matter is added to water, all the available oxygen is used up. This
causes oxygen dependent aquatic life. Anaerobic bacteria begin to
break down the organic waste and produce chemicals that have a foul
smell and are harmful to human health.
• Bacteria degrade these organic wastes and keep the water depleted in
dissolved oxygen.
• Biochemical Oxygen Demand (BOD): Amount of dissolved oxygen needed
by aerobic biological organisms to break down organic material present in a
given water sample at certain temperature over a specific time period.
• The BOD is taken as a realistic measure of water quality – clean water
would have a BOD value of less than 5 ppm whereas highly polluted river
water could have a BOD value of 17 ppm or more.
• Chemical Oxygen Demand (COD) is the amount of oxygen required to
oxidise and stabilize the organic and inorganic matter present in a certain
volume of water.

41. Chemical Pollutants
• Heavy Metals: Cd, Pb & Hg are known as heavy metals. These may be
present in industrial or mining waste. They are highly toxic and cause
damage to kidney, liver, brain and central nervous system.
• Detergents & Fertilizers: These may contain phosphate. The addition
of phosphorus to water, encourages the formation of algae, which
reduces the DO concentration of water. The process is known as
eutrophication.
• Acid- polluted water (pH < 3) : This is deadly to most forms of aquatic life.
Industrial wastes and acid rain contribute to the acidity of natural water.
International Standards for Drinking Water
Fluoride: Soluble fluoride is added to drinking water limits to a concentration
of 1 ppm. High concentrations are poisonous and are harmful to bone and
teeth at levels over 10 ppm.
Lead: Drinking water gets contaminated with Pb when lead pipes are used
for transportation of water. The limit for the concentration for lead ions in
drinking water is 50 ppb.
pH: The pH of drinking water should be between 5.5 and 7.5. A decrease in
the pH of the water increases the solubility of metal ions.

42. SOIL POLLUTION
• Soil pollution is caused by Chemicals such as pesticides ,
insecticides, herbicides and fungicides are used for protection of
food crops from damage.
• Chemical fertilizers are used for improving crop yield.
• Apart from this, polybags and other type of polymers are used for
packaging and storage of food items. Most of the things are non-
biodegradable
Pesticides:
• They synthetic toxic chemicals and are used to stop the
reproduction and growth of unwanted organisms.
• Synthetic pesticides has possible effect upon human health. For
example DDT, Aldrin and Dieldrin.
• They transferred from lower trophic level to higher trophic level
through food chain
• They causes serious metabolic and physiological disorders.

43. Herbicides:
• Herbicides are used to kill weeds.
Sodium chlorates, NaClO3 and
sodium arsenite Na3AsO3 were
commonly used as weed killers.
• Organic herbicides now used.
They are much more toxic to certain
type of plants than to others.
• Organic herbicides such as trizines
are presently widely used to kill
weeds in cornfields.
Fungicides:
• Fungicides are the pesticides used to check the growth of fungi.
• Fungi, are plants without chlorophyll, they cannot use solar
energy for preparing their food. They live as saprophytes.
• Organic compounds of mercury have been used as fungicides and
this has detrimental effect

44. INDUSTRIAL WASTES
oIndustrial wastes are contribute to
major sources of Environmental
pollution.
oChemical and other wastes polluting
the air, water, and land and causing
pollution and climate change which is
dangerous for earth’s biodiversity.
oIndustries discharges biodegradable
and non-degradable wastes.
Biodegradable wastes are generated by
cotton mills, food processing units,
paper mills, Pharmaceuticals and
textile factories.
oNon-biodegradable wastes are
generated by power plants, steel
plants, metallic industries, Fertilizer
industries etc.,

45. Strategies to control Environmental Pollution
• Pollution prevention methodology to reduces the amount of pollution
generated by industry, agriculture or consumers.
Waste Management
• It is the activities and actions required to manage waste from its
inception to its final disposal like collection, transport, segregation,
treatment and disposal.
• It includes Municipal, agricultural, and hazardous wastes.
• Waste management is intended to reduce adverse effects of waste
on health and environment.
Collection and Disposal
• Domestic wastes are collected carried to the disposable site sorted
out and separated. Non-biodegradable materials are sent for
recycling. Biodegradable wastes are deposited in land fills and are
converted into compost.

46. Disposal solutions
Landfill: Dumping and burial of solid wastes. It categorized into…..
•Municipal solid waste (MSW) landfills - uses a synthetic (plastic) liner to isolate
the trash from the environment
•Construction and demolition waste landfills - consist of the debris generated
during the construction, renovation, and demolition of buildings, roads, and bridges.
•Industrial Waste Landfills- nonhazardous solid waste, consists of nonhazardous
waste associated with manufacturing and other industrial activities.
Incineration: Incineration is a disposal method of solid organic wastes subjected
to combustion so as to convert them into residue and gaseous products.
Incinerators convert waste materials into heat, gas, steam, and ash. Ex;-
Hazardous waste materials.
Recycling: It’s method of collection and reuse of waste materials such as
consumer products include aluminium, copper wire, steel from food, rubber
tyres, polyethylene materials, paperboard cartons, newspapers, magazines
and light paper.
Re-use: Recoverable materials that are organic in nature, such as dead biological
materials, Energy recovery from wastes including Pyrolysis, into usable heat,
electricity, or fuel and chemical refinery.

47. GREEN CHEMISTRY or SUSTAINABLE CHEMISTRY
• Green chemistry is the design of utilising the existing knowledge
and principles of chemistry and other sciences to reduce the
adverse impact on environment.
• Green chemistry is a production process that would bring about
minimum pollution or deterioration to the environment.
The principles cover such concepts as:
• The design of processes to maximize the amount of raw material
that ends up in the product.
• The use of renewable energy sources
• The use of safe, environmentally benign substances, including
solvents, whenever possible.
• The design of energy efficient processes
• Avoiding the production of waste, which is viewed as the ideal form
of waste management.