BOD&COD.pdf

Winkler’s method (Determination of DO content)
Principle:
• DO oxidizes KI and liberates iodine (I2
). Liberated I2
is titrated against thiosulphate solution using starch
as an indicator.
• Amount of I2
liberated is equivalent to amount of DO present in of water.
• Since DO in water is in molecular state, it cannot oxidize KI as such. Hence manganese oxyhydroxide
(MnO(OH)2
) is used as an oxygen carrier, which is obtained by action of KOH on manganese sulphate
(MnSO4
).
Experimental procedure:
• Standardization of Sodium thiosulphate(Na2
S2
O3
): standardised using potassium dichromate
(K2
Cr2
O7
) by iodometric titration.
• Estimation of DO: Sample of water is filled in a stopper bottle up to brim, in order to exclude any air
column present in the closed flask which may increase actual DO leading to error.
• 2 mL each of MnSO4
and alkaline KI are added to get a brown colored floc of MnO(OH)2
which is
allowed to settle.
• Ppt. of MnO(OH)2
is dissolved using (1:1) H2
SO4
and clear solution is titrated against standardised
Na2
S2
O3
using starch as an indicator. End point is noted as disappearance of blue color.
Chemical reactions involved:
• DO reacts with Mn2+
ions in alkaline medium forming brown precipitate of basic manganese
oxyhydroxide (MnO(OH)2
)
Mn2+
+ 2 KOH + O2
→ MnO(OH)2
+ K2
SO4
• Brown precipitate of MnO(OH)2
dissolves on acidification and liberates nascent oxygen
MnO(OH)2
+ H2
SO4
→ MnSO4
+ 2H2
O + [O]
• When solution is treated with KI, iodide ions are oxidized by nascent oxygen to iodine, the amount of
which is equivalent to amount of DO.
2I-
+ 2H+
+ [O] → H2
O + I2
• Liberated iodine is finally estimated by titration with sodium thiosulphate (Na2
S2
O3
)
2S2
O3
2-
+ I2
→ S4
O6
2-
+ 2I-
• The stoichiometric expression relating DO and Na2
S2
O3
is
1 mL of 0.025 N Na2
S2
O3
= 0.2 mg DO.

Determination of BOD:
• It is measure of oxygen required by aerobic micro organisms during break down
of decomposable organic matter in the waste water.
• It is an important characteristic parameter to assess the self purification
capability of water.
• An average sewage has a BOD of 100-150 mg/L.
• Greater the concentration of decomposable organic matter, greater the value of
BOD, consequently more the strength of pollutant level.
• It is an indication of degree of pollution or in other words pollutants which are
amenable for degradation, and used as a guideline for the pollution regulatory
authorities to check the quality of discharged effluent into the water bodies.
• Based on the values, design of effluent treatment plant capacity is decided.
Principle:
• The test is based upon the determination of dissolved oxygen before and after a
5 days incubation period at 20 0
C under aerobic conditions.
• Decrease in the DO content after incubation is the measure of BOD and referred
as BOD5d
, in mg/L.
Procedure:
• A known volume of sample of sewage is diluted with a known volume of water,
containing nutrients for bacterial growth, whose dissolved oxygen is
predetermined.
• The difference in the original oxygen content in the diluted water and unused
oxygen of solution after 5 days gives BOD.

Chemical oxygen demand (COD):
• COD is the amount of oxygen required for the oxidation of
organic matter as well as oxidisable inorganic matter and
expressed in mg/L.
• It is a measure of the organic matter content of waste water that
is susceptible to oxidation by potassium dichromate (K2
Cr2
O7
).
• COD is measure of both bilogically oxidizable and biologically
inert organic matter such as cellulose, hence COD values are
generally higher than BOD.

Determination of chemical oxygen demand (COD):
• A known volume of water sample (250 mL) is refluxed with a known excess standard
potassium dichromate and dil. H2
SO4
in presence of AgSO4
catalyst for 1.5 hrs. (small
amount of mercuric sulphate added to eliminate interference of chlorides.
• Organic matter is completely oxidised to water, carbon dioxide and ammonia.
• Unreacted (remaining) K2
Cr2
O7
is then titrated against standard ferrous ammonium
sulphate (FeSO4
(NH4
)2
SO4
6H2
O,FAS) solution using diphenyleamine as an indicator.
• Blank titration is carried out using distilled water instead of the sample.
• The oxygen equivalent of K2
Cr2
O7
consumed is taken as a measure of COD.
• 1 mL of 1 N K2
Cr2
O7
= 0.008 g oxygen.
• COD = (Vblank
– Vsample
) N x 8 x 1000/ volume of waste water sample
Where, Vblank
and Vsample
= volume of FAS of normality N required for blank and test
sample.
• Measurement of COD gives pollution strength or extent of pollution in domestic and
industrial waste waters.
Blank titration
Distilled water
+
Excess K2
Cr2
O7
reflux
unreacted K2
Cr2
O7
titrated vs FAS
Sample/Back titration
Sample water
+
Excess K2
Cr2
O7
reflux
unreacted K2
Cr2
O7
titrated vs FAS

CARBONDIOXIDE CAPTURE
❖ Carbon Capture and Storage (CCS) is a technology that can capture up to 90% of the
carbon dioxide (CO2
) emissions produced from the use of fossil fuels in electricity
generation and industrial processes, preventing the carbon dioxide from entering the
atmosphere.
❖ Furthermore, the use of CCS with renewable biomass is one of the few carbon abatement
technologies that can be used in a 'carbon-negative' mode – actually taking carbon dioxide
out of the atmosphere.
❖ The CCS chain consists of three parts; capturing the carbon dioxide, transporting the
carbon dioxide, and securely storing the carbon dioxide emissions, underground
in depleted oil and gas fields or deep saline aquifer formations.
❖ First, capture technologies allow the separation of carbon dioxide from gases produced in
electricity generation and industrial processes by one of three methods: pre-combustion
capture, post-combustion capture and oxyfuel combustion.
❖ The carbon dioxide is then stored in carefully selected geological rock formation that are
typically located several kilometers below the earth's surface.

The aim is to prevent the release of large quantities of CO 2
into the atmosphere from heavy
industry. It is a potential means of mitigating the contribution to global warming and ocean
acidification of carbondioxide emissions from industry and heating.
Carbon dioxide can be captured directly from the air or from an industrial source (such as
power plant flue gas using a variety of technologies,
including absorption, adsorption, chemical loopint, or membrane gas separation
technologies. Amines are used as solvents in the leading carbon scrubbing technology.
CCS applied to a modern conventional power plant could reduce
CO2
emissions to the atmosphere by approximately 80–90%
Capturing CO 2
is most effective at point sources, such as large fossil fuel or biomass energy
facilities, industries with major CO 2
emissions, natural gas processing, synthetic fuel plants
and fossil fuel-based hydrogen production plants.
Extracting CO 2
from air is also possible, although the far lower concentration of CO 2
in air
compared to combustion sources presents significant engineering challenges.

CARBON SEQUESTRATION AND ITS TYPES
CO2
is one of the main greenhouse gases that is causing global warming and forcing
climate change. The continued increased in CO2
concentration in the atmosphere is
believed to be accelerated by human activities such as burning of fossil fuels and
deforestation. One of the approaches to reducing CO2
Concentration in the atmosphere is
carbon sequestration.
CARBON SEQUESTRATION
Carbon Sequestration is the placement of CO2
into a depository in such way that it
remains safely and not released back to the atmosphere. Sequestration means something
that is locked away for safe keeping. the trapping of a chemical in the atmosphere or
environment and its isolation in a natural or artificial storage area.
OBJECTIVE
Developing technology to reduce rate of concentration of greenhouses gases in air
Reducing pollution in air as well as improving natural carbon content in soil
Improvement of soil structure and restoring degraded soil leading to increase yield in
crops

Source of carbon dioxide emission
1. Man made sources
2. Industries
3. Transportation
4. Land use change
5. Soil cultivation
6. Biomass burning
Natural sources
• Volcanoes
• Wild fires Decomposition
• Respiration
Ways that carbon can be sequestered
1. Geological sequestration : Underground
2. Ocean Sequestration : Deep in ocean
3. Terrestrial Sequestration : In plants and soil

1. Geological sequestration
Geologic Storage involves capturing anthropogenic CO2
before it enters the atmosphere
and injecting it into underground formations. Once CO2
is injected deep underground
(typically more than 800 meters) it is trapped in minute pores or spaces in the rock structure.
Impermeable cap rocks above the storage zones act as seals to ensure the safe storage of CO2
.
2.Ocean sequestration
Carbon is naturally stored in the ocean via two pumps, solubility and biological and there are
analogous man made methods, direct injection and ocean fertilization, respectively. At the
present time, approximately one third of human generated emission are estimated to be
entering the ocean.
3.Terrestrial Sequestration
The process through which CO2
from the atmosphere is absorbed naturally through
photosynthesis & stored as carbon in biomass & soils.

Chemical Toxicology
❖ Toxicology is the study of poisonous and harmful substances.
❖ Toxicity testing allows us to identify the toxicity of chemicals we use and gives information
about the potency of their effects.
❖ Of the Numerous chemicals in the environment some of them are highly toxic
❖ The toxic chemicals are released from the chemical industries.
❖ They get into the human food chain and once they get into there, they often lead to fatal
consequences.
❖ Many of these listed as environmental hazards are often essential ingridents for animal
growth Al, Ba. B, Co, Cu, Cr

Even well-known toxic elements as Pb, Cu, Cd are required in trace quantities for
Animal growth , The well Known Inert Al causes brain disorder.
Toxic chemicals can be classified according to environmental effects.
Elements Sources Effects
Arsenic By Products of Mining and Pesticides Toxic, Possibly carcinogenic
Boron Coal, detergent Toxic to some plants
Copper Metal Plating industrial and domestic
washings
Toxic to animals
Lead Industry, Mining Coal and Gasoline Anemia, wild life Destruction
Cadmium Industrial Discharge, Mining waste
and metal plating
High Blood pressure
Damage and Destruction to
testicular cells
Mercury Industrial Activites High Toxic in all forms
Zinc Industrial Waste Toxic plants at higher levels

IMPACT OF TOXIC CHEMICALS ON ENZYMES
Toxic Chemicals attack the active sites of the enzyme and thus inhibit enzyme
functioning. Divalent cations Hg2+ , Cd+2 , Pb +2 are effective enzyme inhibitors,
They have affinities for containing liquid SCH3
and SH which are the part of the
enzymes structure
These enzymes are called metalloenzymes contains metals in their structures and thus
inhibit the functioning of the enzyme. One metal ion is replaced by another metal ion of
similar size.
Thus Zn+2
in some metalloenzymes is replaced by Cd +2
leading to Cd+2
toxicity.

BIOCHEMICAL EFFECTS OF LEAD
❖ Lead is relatively abundant in nature and major source of lead is in the combustion of
Gases of petrol and gasoline.
❖ Lead is added primary as Lead tetraethyl and tetramethyl.
❖ Pb(C2
H5)4
, Pb(CH3
)4
along with the scavengers 1,2 dichloromethane .
❖ The major biochemical effect of lead is interference with the heme synthesis which leads
to biochemical heme damage.
❖ Pb inhibits several key enzymes. An important phase of heme synthesis is conversion of
Delta aminolevnic acid to porphobiugen
❖ Lead toxicity can affect every organ system.
❖ On a molecular level, proposed mechanisms for toxicity involve fundamental biochemical
processes. These include lead's ability to inhibit or mimic the actions of calcium
(which can affect calcium-dependent or related processes) and to interact with proteins
(including those with sulfhydryl, amine, phosphate, and carboxyl groups)
❖ Lead's high affinity for sulfhydryl groups makes it particularly toxic to multiple enzyme
systems including heme biosynthesis.

BIOCHEMICAL EFFECTS OF MERCURY
❖ Mercury is a toxic heavy metal which is widely dispersed in nature.
❖ Mercury occurs in several chemical forms, with complex pharmacokinetics.
❖ Mercury is capable of inducing a wide range of clinical presentations.
❖ Diagnosis of mercury toxicity can be challenging but can be obtained with
reasonable reliability
❖ Mercury is a heavy metal of known toxicity, noted for inducing public health
disasters in Minamata Bay, Japan
❖ Mercury in all forms poisons cellular function by altering the tertiary and
quaternary structure of proteins and by binding with sulfhydryl and selenohydryl
groups.

❖ Mercury can potentially impair function of any organ, or any subcellular structure.
❖ The chief target organ of mercury vapor is the brain, but peripheral nerve function,
renal function, immune function, endocrine and muscle function, and several types
of dermatitis
❖ Chronic exposure to clinically significant doses of mercury vapor usually produces
neurological dysfunction.
❖ At low-level exposures, nonspecific symptoms like weakness, fatigue, anorexia,
weight loss, and gastrointestinal disturbance
Mercurous Mercury
Calomel (Hg2
Cl2
) is still used in some regions of the world as a laxative. Although
poorly absorbed, some is converted to mercuric mercury, which is absorbed, and
induces toxicity as expected with mercuric mercury.

Mercuric Mercury
Acute poisoning with mercuric salts (typically HgCl2
) generally targets the gastrointestinal tract
and the kidneys.
Extensive precipitation of enterocyte proteins occurs, with abdominal pain, vomiting, and
bloody diarrhea with potential necrosis of the gut mucosa.
This may produce death either from peritonitis or from septic or hypovolemic shock. Surviving
patients commonly develop renal tubular necrosis with anuria.
Immune dysfunctions include hypersensitivity reactions to mercury exposure, including asthma
and dermatitis, various types of autoimmunity.
Brain dysfunction is less evident than with other forms of mercury. Thyroid dysfunction seems
associated with inhibition of the 5′ deiodonases, with decreased free T3 and increased reverse
T3

BIOCHEMICAL EFFECTS OF CYANIDE
❖ Cyanide poising is a poisoning that results from exposure of number of cyanides.
❖ Early symptoms include Headache, dizziness, fast heart rate and vomiting.
❖ Followed by slow heart rate , low blood pressure and cardiac arrest.
❖ Two cyanide - containing compounds including hydrogen cyanide gas and number
of cyanide salts.
❖ Cyanide ions interfere with the cellular respiration, resulting in the body tissues
being unable to use oxygen.
❖ Diagnosis is often difficult. It may be suspected in person following a house fire
who has decreased level of consciousness , low blood pressure or high blood
acetate.

CAUSES
❖ Acute hydrogen cyanide poisoning can result from inhalation of fumes from
burning polymer products that use nitriles in their production, such as polyurethane
or vinyl.
❖ It can also be caused by breakdown of nitroprusside into nitric oxide and
cyanide. Nitroprusside may be used during treatment of hypertensive crisis.

BIOCHEMICAL EFFECTS Carbon Monoxide
❖ CO, is a toxic gas that you cannot see or smell.
❖ CO is given off whenever fuel or other carbon-based materials are burned.
❖ CO usually comes from sources in or near your home that are not properly maintained or
vented.
RISK
All people are at risk for CO poisoning. Unborn babies, infants, the elderly, and people with
chronic heart disease, anemia, or respiratory problems are generally more at risk than others.
SYMPTOMS AND HEALTS EFFECTS:
Breathing CO can cause headache, dizziness ,vomiting, and nausea.
If CO levels are high enough, you may become unconscious or die.

❖ Each year, carbon monoxide leads the list of causes of poison-related deaths in the United
States.
❖ Thousands of people die annually from accidentally inhaling the tasteless and odorless gas.
Major exposures to deadly levels of CO are associated with house fires and faulty furnaces
and water heaters.
❖ Auto emissions and tobacco smoke account for much of the low-level exposures to which
people are bombarded everyday.
❖ The classic explanation for CO's poisonous action is that it binds to hemoglobin molecules
in the blood, impairing oxygen delivery to the body's cells. Eventually cells essentially
suffocate and die.
EVERYDAY EXPOSURES
In earlier studies, Thom found that blood vessels are a major site of damage in the brain due to
CO exposure, especially the cells that line the inner wall of the vessels, called the endothelium.
This damage occurs relatively early during exposure to CO.

BIOCHEMICAL EFFECTS OF OXIDES OF NITROGEN
❖ Nitrogen dioxide poisoning is the illness resulting from the toxic effect of nitrogen
dioxide (NO) . It usually occurs after the inhalation of the gas beyond the threshold limit
value.
❖ Nitrogen dioxide is reddish-brown with a very harsh smell at high concentrations, at lower
concentrations it is colorless but may still have a harsh odor.
❖ Nitrogen dioxide poisoning depends on the duration, frequency, and intensity of exposure.
❖ Nitrogen dioxide is an irritant of the mucous membranes linked with another air pollutant
that causes pulmonary diseases such as OLD, Asthma, chronic abstractive pulmonary
diseases and sometimes acute exacerbation of COPD and in fatal cases, deaths.
❖ Its poor solubility in water enhances its passage and its ability to pass through the moist oral
mucosa of the respiratory tract.

❖ Nitrogen dioxide poisoning is not harmful to all forms of life just like "chlorine gas
poisoning" and carbon monoxide poisoning.
❖ It is easily absorbed through the lungs and its inhalation can result in heart failure and
sometimes death in severe cases.
❖ Individuals and races may differ in nitrogen dioxide tolerance level and individual tolerance
level for the gas may be altered by several factors, such as metabolic rate, barometric
pressure, and hematological disorders but significant exposure may result in fatal conditions
that could lead to shorter lifespan due to heart failure.
BIOCHEMICAL EFFECTS
❖ Chronic exposure to high level of nitrogen dioxide results in the allosteric
inhibition of glutathione and glutathione-S-Interface.
❖ Both of which are important enzymes found in the mucous membrane antioxidant defense
system, that catalyst nucleophilic attack by reduced glutathione (GSH) on non-polar
compounds that contain an electrophilic carbon and nitrogen.

❖ Glass is a non-crystalline often transparent amphorous solid, that has widespread practical,
technological, and decorative use in, for example, window panes, tableware, and optics.
❖ Glass is most often formed by rapid cooling (quenching) of the molten form, some glasses such
as volcanic glass are naturally occurring.
❖ The most familiar, and historically the oldest, types of manufactured glass are "silicate glasses" based
on the chemical compound silica (silicon dioxide, or quartz), the primary constituent of sand
❖ The refractive, reflective and transmission properties of glass make glass suitable for manufacturing
optical lenses and prisms, and optoelectroncis materials.
❖ Extruded glass fibres have application as optical fibres in communications networks, thermal
insulating material when matted as glass wool so as to trap air, or in glass-fibre reinforced plastic
(fibreglass).

Effects due to chemical pollution
Pollutants Effects
Fluoride Fluorosis
Chloride Hardness in water, laxative effects
Sulfates Affects human internal organs, carcinogenic
Phosphates Certain plants excessively grow on the surface of water bodies causing
eutrophication. Excessive growth reduces oxygen supply to aquatic organisms.
Toxic chemicals like As, Ba, Cd,
Cr, Pb, Zn, Cu, Ni
Serious health disorders may even cause death
Soluble organic Depletion of oxygen in water as they demand more oxygen for their stability
Suspended solids Change of taste, odour, increase in turbidity. Turbidity lowers the amount of light
reaching submerged plants and algae, reducing rate of photosynthesis
Trace organics Unaesthetic conditions
Colour and turbidity Affect photosynthesis
N, P Algal boom
Oil floating matter Retard re aeration of water
Acids, alkalies Affect aquatic life
Inorganic corrosion,
detergents Foam formation

Control measures of water pollution:
1. Adoption of proper, efficient and effective water management strategies
2. Enforcement of laws, water pollution control acts and standards. Practicing and monitoring to
meet the requirement.
3. Continuously monitoring the pollutant level at natural resources such as rivers, streams, lakes
etc. It evaluates the capacity of the resources to accept the pollutant load and regulates the
setting up of industries near by water sources.
4. Economics and appropriate treatment methods to practice i.e. industrial waste awareness to the
public.
5. Encouragement to industries for setting up the treatment plants.
6. Central and state pollution control boards jointly act to implement the rules and regulations to
control the pollution. By giving technical assistance, guidance, sponsoring, investigation, training
of personnel.
7. Emphasizing and encouraging the recycling and reuse of water. It reduces load on treatment
plants. Effective recycling and reuse reduce the water consumption.
8. Water quality monitoring at regular intervals at both domestic and industrial waste water
treatment plants.
9. Segregation of different type of water and treat it off with combination of physical, chemical and
biological process.
10. Treated waste water cane be used for cooling purpose.
11. Judicious use of agrochemicals like pesticides and fertilizers will reduce their surface run off and
leaching.
12. Adopting integrated pest management to reduce reliance on pesticides.
13. Advanced treatment for removal of nitrates and phosphates prevent eutrophication.
14. Public awareness.

Persistent organic pollutant
Persistent organic pollutants (POPs), sometimes known as "forever chemicals"
are organic compounds that are resistant to environmental degradation through
chemical, biological, and photolytic processes.
Many POPs are currently or were in the past used as pesticides, solvents,
pharmaceuticals, and industrial chemicals.
Organic pollutants include many insecticides and herbicides that have been used in
agriculture and pest control.
(DDT) is a pesticide, highly effective in controlling mosquitos.
Other pollutants were manufactured for use in various industries [e.g. polychlorinated
biphenyls (PCBs), phthalates], and others, such as dioxin, are unintended by-products of
manufacturing.
Phthalates are plasticizers used in bottles, toys and personal care products. PcBs are a
large group of similarly structured compounds with variation in toxicity and persistence
in the environment and in the body. Some forms are very similar to dioxin.

PCBs may affect endocrine function, physical growth, maturation and/or
cognitive or behavioral development of children and youth.

Thermal pollution:
• It is a common and widespread form of water pollution.
• Due to entry of unused heat generated by human activity.
• Power plants use water as a coolant and unused heat let into nearby water
sources which adversely affect aquatic plants and animals is called thermal
pollution.
• Cutting down of forest for developmental activities such as construction of
road, buildings etc. warming the water and the soil by 10 0
C.
• Effects of thermal pollution depend on temperature difference, rate of
dissipation of heat and the presence of downstream users.
Thermal pollution is the degradation of water quality by any process that changes
ambient water temperature. A common cause of thermal pollution is the use of
water as a coolant by power plants and industrial manufacturers.

Sources of Thermal Pollution:
1. Industries:
A common cause of thermal pollution is the use of water as a coolant by power plants and industrial
manufacturers:
(i) Hydro-electric power plants
(ii) Coal fired power plants
(iii) Nuclear power plants
(iv) Industrial effluents from power, textiles, paper and pulp industries
3. Domestic sewage:
Municipal sewage normally has a higher temperature.
4. Thermal pollution in streams by human activities
Industries and power plants use water to cool machinery and discharge the warm water into a stream
Stream temperature rises when trees and tall vegetation providing shade are cut.
Soil erosion caused due to construction also leads to thermal pollution
Removal of stream side vegetation
Poor farming Practices also lead to thermal pollution
5. 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.
6. 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.
7. 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. Reduction of DO:
• Concentration of DO at 0 0
C is 14.6 ppm and at 30 0
C is 6.7 ppm.
• Affects the aquatic life.
2. Change in quality parameters and toxicity:
• Physical properties like viscosity, density and solubility of gases decrease with rise
in temperature.
• 10 0
C rise in temp. increases toxic effect of substances and damages the enzyme
systems of aquatic fauna and flora.
• Metabolic activities such as respiration, food intake, mobility of fishes increase at
higher temp. which shorten the lifespan.
• e.g. crustacean daphnia (water fleas) lives for more than 100 days at 7-8 0
C, but only
for a month at 20 0
C.
• Increase in microbial population, change in activity of pathogens, susceptibility to
spreading of diseases.

Effects of Thermal pollution
Reduction in dissolved oxygen: Concentration of Dissolved Oxygen (DO) decreases with
increase in temperature.
Increase in toxicity: The rising temperature increases the toxicity of the poison present in
water. A 10 0
C increase in temperature of water doubles the toxicity effect of potassium
cyanide, while 80 0
C rise in temperature triples the toxic effects of o-xylene causing
massive mortality to fish.
Interference in reproduction: In fishes, several activities like nest building, spawning,
hatching, migration and reproduction depend on optimum temperature.
Direct mortality: Thermal pollution is directly responsible for mortality of aquatic
organisms. Increase in temperature of water leads to exhaustion of microorganisms thereby
shortening the life span of fish. Above a certain temperature, fish die due to failure of
respiratory system and nervous system failure.
Food storage for fish: Abrupt changes in temperature alters the seasonal variation in the
type and abundance of lower organisms leading to shortage of right food for fish at the
right time.

Control measures:
(1) Cooling Ponds:
❖ Cooling ponds or reservoirs constitute the simplest method of controlling thermal discharges.
❖ Heated effluents on the surface of water in cooling ponds maximize dissipation of heat to the
atmosphere and minimize the water area and volume.
❖ This is the simplest and cheapest method which cools the water to a considerable low temperature.
However, the technique alone is less desirable and inefficient in terms of air-water contact.
(2) Cooling Towers:
❖ Using water from water sources for cooling purposes, with subsequent return to the water body after
passing through the condenser is termed as cooling process.
❖ In order to make the cooling process more effective, cooling towers are designed to control the
temperature of water.
❖ In-fact, cooling towers are used to dissipate the recovered waste heat so as to eliminate the problems
of thermal pollution.
(i) Wet cooling tower:
❖ Hot water coming out from the condenser (reactor) is allowed to spray over baffles. Cool air, with
high velocity, is passed from sides, which takes away the heat and cools the water.
(ii) Dry cooling tower:
❖ Here, hot water is allowed to flow in long spiral pipes.
❖ Cool air with the help of a fan is passed over these hot pipes, which cools down hot water.
❖ This cool water can be recycled.

3) Artificial Lake:
❖ Artificial lakes are man-made bodies of water which offer possible alternative to once
through cooling.
❖ The heated effluents may be discharged into the lake at one end and the water for
cooling purposes may be withdrawn from the other end.
❖ The heat is eventually dissipated through evaporation.
❖ These lakes have to be rejuvenated continuously.
❖ A number of methods have been suggested and developed for converting the thermal
effluents from power plants into useful heat resources for maximising the benefits.

Radiation pollution/Nuclear pollution
Nuclear reactors
Nuclear explosion
EMR
Leakage from radioactive wastes

Radiation/Nuclear pollution:
• It is emission of radiation from radioactive substances such as uranium, plutonium etc.
Sources of radiation:
• Natural sources of radiation:
(a) High energy protons and electrons released from the sun as cosmic rays
(b) Radioactive isotopes, radioactive ores occurring in earth
• Anthropogenic sources:
(a) x-ray units used for medical diagnostics
(b) Nuclear tests
(c) Nuclear reactors
(d) Wastes from nuclear power plants
(e) Radioactive ore industries
(f) Electric fields created by usage of electronic devices
(g) Leakage from stored radioactive wastes
(h) Nuclear explosions
(i) Radiation from cell phones
(j) Microwave ovens
(k) Other electronic gadgets

Effects of nuclear pollution:
1. Direct contamination occurs through exposure of ionizing radiations and indirectly by
radionuclide reach through food chain.
2. UV, radiofrequency and microwave, non ionizing radiation on exposure cause skin cancer,
Leukemia, breast cancer
3. Eye irritation, fatigue, headache, dizziness, nausea, nervousness and other ailments occur when
at vicinity of radiation.
4. Electromagnetic radiation (EMR) from sun, TV, radio, cell phones, visible –UV lights also affect
human body.
5. Ionizing radiations penetrate into the living tissue and cause destruction of atoms and molecules
on its path creating instability. Unstable molecule or ions produce innumerable ions of other
species and start chain reaction which results in deactivation of enzymes and affect cell growth.
6. Radiation affects cell membrane and DNA leading to development of cancer, also can lead to
changes in genetic framework of an individual and cause genetic disorder.
7. Children with abnormalities, increased infant mortality, cardiovascular disorders, premature
ageing are some of the adverse effects of radiation pollution.
8. Certain diseases have been identified depending on the exposure time and strength of these
magnetic and electric fields.
9. People leaving close to cell tower experience dizziness, memory loss, asthma, epilepsy
(neurological disorder) etc.
10. EMR from cell phones have been linked to development of brain tumors, genetic damage.
11. Technician working in laboratory who are constantly exposed to radiation are under
occupational health hazard, at great risk of developing various types of cancers.
12. Certain plants and animals are known to die when exposed to radiations.

Chernobyl Accident 1986
(Updated December 2014)
•The Chernobyl accident in 26 April 1986 was the result of a flawed reactor design that
was operated with inadequately trained personnel.
•The resulting steam explosion and fires released at least 5% of the radioactive reactor
core into the atmosphere and downwind – some 5200 PBq .
•Two Chernobyl plant workers died on the night of the accident, and a further 28 people
died within a few weeks as a result of acute radiation poisoning.
•UNSCEAR says that apart from increased thyroid cancers, "there is no evidence of a
major public health impact attributable to radiation exposure 20 years after the
accident.“
•Resettlement of areas from which people were relocated is ongoing.
• In 2011 Chernobyl was officially declared a tourist attraction.

Fukushima Accident
(Updated February 2015)
•Following a major earthquake, a 15-metre tsunami disabled the power supply and
cooling of three Fukushima Daiichi reactors, causing a nuclear accident on 11 March 2011.
All three cores largely melted in the first three days.
•The accident was rated 7 on the INES scale, due to high radioactive releases over days 4 to
6, eventually a total of some 940 PBq (I-131 eq).
•Four reactors were written off due to damage in the accident – 2719 MWe net.
•After two weeks, the three reactors (units 1-3) were stable with water addition and by July
they were being cooled with recycled water from the new treatment plant. Official 'cold
shutdown condition' was announced in mid-December.
•Apart from cooling, the basic ongoing task was to prevent release of radioactive materials,
particularly in contaminated water leaked from the three units. This task became
newsworthy in August 2013.
•There have been no deaths or cases of radiation sickness from the nuclear accident, but
over 100,000 people had to be evacuated from their homes to ensure this. Government
nervousness delays their return.
•Official figures show that there have been well over 1000 deaths from maintaining the
evacuation, in contrast to little risk from radiation if early return had been allowed.

Control measures of radiation pollution:
1. Avoided by time, distance and shielding.
2. Exposure decreases with increase in distance from the source of radiation and time
of exposure.
3. Shielding between source and surroundings by the dense radiation attenuating
materials such as lead shields, air filters, wearing protective clothing, exhausts,
usage of radioactive indicators etc. minimize health hazards.
4. Proper management of nuclear waste should be ensured.
5. Various efforts including the process of site selection, design and construction of
nuclear power plants shall be considered.
6. Long term and short term effects of radiation due to accidental releases must be
anticipated and properly planned.
7. Nuclear stations must be located in a remote protected area with thick plantation
cover.

• Land pollution is the deterioration (destruction) of the earth’s land surfaces, often
directly or indirectly as a result of man’s activities and their misuse of land
resources.
• Soil pollution may be any chemicals or contaminants that harm living organisms.
Pollutants decrease soil quality and also disturb the soil's natural composition and
also leads to erosion of soil. Types of soil pollution can be distinguished by the
source of the contaminant and its effects of the ecosystem.
• Types of soil pollution may be agricultural pollution, Industrial wastes and urban
activities.
What is soil pollution?

Types of soil pollution
Agricultural Pollution
• Agricultural processes contribute to soil pollution.
• Fertilizers increase crop yield and also cause pollution that impacts soil quality.
• Pesticides also harm plants and animals by contaminating the soil.
• These chemicals get deep inside the soil and poison the ground water system.
• Runoff of these chemicals by rain and irrigation also contaminate the local water system and is
deposited at other locations.
Industrial Waste
• About 90% of soil pollution is caused by industrial waste products.
• Improper disposal of waste contaminates the soil with harmful chemicals.
• These pollutants affect plant and animal species and local water supplies and drinking water.
• Toxic fumes from the regulated landfills contain chemicals that can fall back to the earth in the
form of acid rain and can damage the soil profile.
Urban Activities
• Human activities can lead to soil pollution directly and indirectly.
• Improper drainage and increase run-off contaminates the nearby land areas or streams.
• Improper disposal of trash breaks down into the soil and it deposits in a number of chemical and
pollutants into the soil. These may again seep into groundwater or wash away in local water
system.
• Excess waste deposition increases the presence of bacteria in the soil.
• Decomposition by bacteria generates methane gas contributing to global warming and poor air
quality. It also creates foul odour and can impact quality of life.

Sources of soil pollution:
1. Industrial waste:
• e.g slag, ash, corroded metals
• Wastes from mining operations, manufacturing and construction industries,
demolished structures.
• Wastes discharged from paper and pulp industries, metal smelters, oil
refineries, chemical and cement factories etc.
• They are hazardous in nature when exposed to long duration.
2. Urban/Domestic waste:
• Household wasters, remains of food, vegetables garden wastes etc.
• Paper, plastics, metal objects generated by domestic activities
• Domestic and commercial refuse called Municipal Solid Waste (MSW)
3. Agricultural practice:
• Crop residues, processing wastes, animal wastes, feedlots, livestock yards,
bagasse from sugarcane and corn residues
4. Radioactive pollutants:
• Unused or spent fuels, wastes from nuclear plant industry, scrapped
electronic goods, medical equipment, releasing radioactivity.
5. Health care:
Biomedical, pathological wastes, potentially infectious wastes from hospitals,
clinics, laboratories.

Effects of solid wastes:
1. Accumulation of solid wastes increases the disease causing organisms such as
mosquitos, flies etc.
2. Bio degradable wastes decompose under uncontrolled and unhygienic
conditions, produce foul smell and breeds various types of insects and
infectious organisms, spoiling aesthetics of the site.
3. Prolonged usage of huge quantities of fertilizer, pesticides etc. alter quality of
the soil
4. Solid wastes run off with the rainwater and mixes with the nearby water
bodies resulting water pollution
5. Burning of solid wastes causes air pollution
6. Radioactive elements due to explosions of nuclear bomb, unspent fuel etc.
accumulate in the soil cause number of diseases in human beings.
7. Non biodegradable solid wastes such as plastic, rubber, metal etc. obstruct the
sewage systems, if burnt, cause air pollution.
8. Industrial wastes alter the chemical and biological properties of soil
9. Hazardous chemicals affect the human food chain leading to serious effects on
living organisms.

Control measures for soil pollution:
1. Control of soil erosion
2. Proper dumping
3. Awareness-creation and education about health hazards by pollution
4. Ban on toxic chemicals
5. Proper solid waste management system
6. Promotion of organic farming
7. Usage of an eco-friendly pest control devices
8. Recycling, reuse of wastes and reclaiming of soil
9. Reduction of wastes at source point and advisable to repair broken goods in
a cost effective manner

Monitoring techniques and methodology

Characteristics of water:
Physical characteristics:
1. Colour
2. Odour
3. Temperature
4. Suspended solid content
Chemical characteristics:
1. pH
2. Hardness
3. Total dissolved solids
4. Dissolved oxygen content (DO)
5. Chemical oxygen demand (COD)
6. Biological oxygen demand (BOD)
7. Total organic content
8. Trace metals
Biological characteristics:
1. Disease causing organisms
Determination of total organic carbon content and trace metal analysis is useful of
the selection of waste water treatment methods

Measurement of pH
• Using pH meter (glass electrode combined with reference electrode e.g. standard
calomel electrode (SHE)
• pH meter immersed in water sample generates a potential varying linearly with
the pH of the solution

Determination of total dissolved salts:
• It is determined by evaporating a known volume of sample water heated to
dryness in the pre-weighed china dish.
• Heating can be done by keeping it on a sand bath or heated and cooled to room
temperature by keeping in the desiccator.
• The weight of the china dish with the residue can be accurately measured.
• Dissolved salt content is calculated from the difference in weights and expressed
in mg/L
• Weight of empty china dish = W1
g
Weight of china dish with the residue after cooling = W2
g
Total dissolved salts = (W2
-W1
) g

Determination of dissolved oxygen (DO) content:
• DO content of water depend on the physical, chemical and biological impurities
• Can be measure by Winkler’s method or electrometric method
• Optimum DO content in natural water is 4-6 ppm which is essential for aquatic
life
• Fall in DO content is indication of water body polluted with organic matter.
• Important parameter to assess the purity of water.

Winkler’s method (Determination of DO content)
Principle:
• DO oxidizes KI and liberates iodine (I 2
). Liberated I2
is titrated against thiosulphate solution using
starch as an indicator.
• Amount of I2
liberated is equivalent to amount of DO present in of water.
• Since DO in water is in molecular state, it cannot oxidize KI as such. Hence manganese
oxyhydroxide (MnO(OH) 2
) is used as an oxygen carrier, which is obtained by action of KOH on
manganese sulphate (MnSO 4
).
Experimental procedure:
• Standardization of Sodium thiosulphate(Na 2
S2
O3
): standardised using potassium dichromate
(K2
Cr2
O7
) by iodometric titration.
• Estimation of DO: Sample of water is filled in a stopper bottle up to brim, in order to exclude any
air column present in the closed flask which may increase actual DO leading to error.
• 2 mL each of MnSO4
and alkaline KI are added to get a brown colored floc of MnO(OH) 2
which is
allowed to settle.
• Ppt. of MnO(OH)2
is dissolved using (1:1) H 2
SO4
and clear solution is titrated against standardised
Na2
S2
O3
using starch as an indicator. End point is noted as disappearance of blue color.
Chemical reactions involved:
• DO reacts with Mn2+
ions in alkaline medium forming brown precipitate of basic manganese
oxyhydroxide (MnO(OH) 2
)
Mn2+
+ 2 KOH + O2
→ MnO(OH)2
+ K2
SO4
• Brown precipitate of MnO(OH) 2
dissolves on acidification and liberates nascent oxygen
MnO(OH)2
+ H2
SO4
→ MnSO4
+ 2H2
O + [O]
• When solution is treated with KI, iodide ions are oxidized by nascent oxygen to iodine, the
amount of which is equivalent to amount of DO.
2I-
+ 2H+
+ [O] → H2
O + I2
• Liberated iodine is finally estimated by titration with sodium thiosulphate (Na 2
S2
O3
)
2S2
O3
2-
+ I2
→ S4
O6
2-
+ 2I-
• The stoichiometric expression relating DO and Na2
S2
O3
is
1 mL of 0.025 N Na2
S2
O3
= 0.2 mg DO.

Trace metal determination using atomic absorption spectroscopy
(AAS):
Atomic absorption spectroscopy (AAS)
• It is a spectroanalytical procedure for the quantitative determination of chemical
elements using the absorption of optical radiation (light) by free atoms in the gaseous
state.
• AAS can be used to determine over 70 different elements in solution or directly in solid
samples at trace quantities (0.1 – 100 ppm)
• used in pharmacology, biophysics and toxicology research.
• Based on the measurement of the decrease in light intensity from a source (hollow
cathode lamp) when it passes through a vapor layer of the atoms of the analyze element.

• In order to analyze a sample for its atomic constituents, it has to be atomized.
• The atomizers most commonly used nowadays are flames and electro thermal
(graphite tube) atomizers.
• The atoms should then be irradiated by optical radiation, and the radiation source
could be an element-specific line radiation source or a continuum radiation source.
• The radiation then passes through a monochromator in order to separate the
element-specific radiation from any other radiation emitted by the radiation source,
which is finally measured by a detector.
Instrumentation:

1. Formation of homogeneous ground state atomic vapor of metal atoms from the salt solution of
the metal. This is done by aspirating the solution by use of atomizer, nebulizer or by the use of
flame.
2. Metallic compound decomposed in the flame, produced by oxyacetylene/hydrogen that will
raise the temperature in the range of 1800-3000 0
C. In some cases, graphite furnace may be used
instead of flame to produce the vapor
3. In AAS, the key component if the hollow cathode lamp. It consists of a glass tube containing
mobile gases, primarily argon, (Ar) at several mm pressure, an anode and a hollow cathode
which is inside coated with the metal to be analyzed. A high voltage across the electrodes
generates and electrical current ionizes the argon gas. Ar+ ions produced inside the tube impinge
in the cathode with a very energy, leading to sputtering of metal atoms from the cathode
surface. These energized metal atoms emit radiations with a very narrow wavelength
characteristics of the metal
4. The radiation from the hollow cathode lamp passes through a flame into which the sample is
aspirated. The metallic compounds are decomposed in the flame and the metal is reduced to
elemental state forming a cloud of atoms.
5. The cloud of metal atoms absorb the fraction of radiation in the flame. The decrease in radiant
energy increases with the concentration of the element in the sample according to the Beer’s
law. The fraction of absorbed radiation results in a decrease in intensity of the transmitted
radiation reaching the photo detector.
• Principle (AAS):

• Determination of metal ions such as Cd, Cr, Co, Cu, Fe, Pb, Mg, Mn, Ni, Ag and Zn
by direct aspiration into air oxyacetylene flame.
• Hg can be determined by flameless AAS.
• Methodology:
• The instrument is calibrated with a distilled water as blank solution making
absorbance value is 0.
• Series of standard solution of metal to be analyzed prepared for making calibration
curve, a straight line plot of absorbance with concentration of metal ions.
• The unknown concentration of the metal ions sample solution is aspirated under
same identical experimental conditions, and noting down the absorbance value.
• From the calibration curve, the value of concentration can be determined.

Determination of trace metal using inductively coupled plasma
atomic emission spectroscopy (ICP-AES):
• Used for analyzing the metals, non metals in all samples e.g. biological, clinical
metallurgical and environmental at a concentration level in the range of ppm to ppb.
• Used for multi-element analysis since 1975.
• The flame consists of an incandescent plasma (ionized gas) or Ar heated inductively
by radio frequency energy at 4 -50 MHz and 2 -5 kW.
• The energy is transferred to a stream of Ar through an induction coil, whereby
temperature up to 10,000 0
C is attained.
• The sample atoms are subjected to temperature around 7000 0
C, twice that of
temperature used in AAS (3200 0
C)

Principle of ICP-AES:
1. Excitation of aerosol containing ground state atoms is carried out using a high
temperature gas plasma, so that temperature is in the order of 8000 – 9000 0
C.
2. The sample solution is aspirated into the nebulizer and the aerosol formed is
carried by stream of argon gas into ICP assembly at a higher velocity.
3. A high voltage discharge ignites argon gas into a plasma which is containing a
high amount of both ions and electrons, maintaining at temperature in the
range of 6000 0
C.
4. The temperature is further increased to 8000 – 10,000 0
C, by induction heating
arrangement. Under this condition, sample aerosol forms a plume containing
the sample elements free from any molecular association.
5. The excited ions come to the ground state emitting characteristics radiation
and analyzed by photo multiplier tube or spectrometer set up.
6. At a time more than 70 metals can be scanned and analyzed. Elements P, B, W,
Zr, U etc. can be detected where AAS fails.

• Example of biodegradable pollutant Is
a) Phenolic compounds b) Domestic washings c) Mercury d) DDT
• Harmful effects of fluoride in air are
a) Brain malfunction b) reduces visibility c)respiratory infection d) affect the teeth
• Source of chlorofluoro carbon is
a) aerosols b) fossil fuel burning c) fertilizers d) volcanic eruption
• One of the major component of atmosphere is
a) Sulphur dioxide b) nnitrogen c) carbon dioxide d) water
• Ozone is present in ---- layer
a) troposphere b) mesosphere c) thermosphere d) sratosphere
• Carbon dioxide traps ---- radiation from sun
a)infrared b) UV c) X-ray d) radio waves
• Which of the following air pollution control device is suitable for removal of gaseous pollutants
a) Cyclone separator b) electrostatic precipitator c) fabric filter d) wet absorption
• BOD measures
a) Industrial effluents b) amount of organic compounds in water c) air pollution d) radioactive pollution
• Peroxy acetyl nitrate belongs to
a) Primary pollutant b) secondary pollutant c) natural pollutant d) none of the above
• Which of the ecological pyramid is always upright
a) Pyramid of energy b) pyramid of biomass c) pyramid of number d) pyramid of ecosystem
Part A

• ---- is key component of nature’s thremostat
a) Ozone b) CO2 c) water d) O2
• Electrostatic precipitator are used to remove
• a) gases b) liquids c) particulates d) odour
• Photochemical smog is combination of
• a) smog and fog b) smoke and fog c) ozone and fog d) smog and peroxyacyl nitrate
• The main atmospheric layer near the surface of the earth is
• a) troposphere b) mesosphere c) lithosphere d) stratosphere

• In auatic ecosystem phytoplanktons can be considered as
a) Consumer b) producer c) macroconsumer d) saprotrophic organisms

Part B
How is photochemical fog formed what are its effects?
Describe formation of ozone layer and its depletion in the atmosphere
Any two methods of removal of particulate matter in air pollution control
What are effects of acid rain
How ozone layer is depleted? What are its effects?

Part c
• Reasons and effects of acid rain
• What is green house effect
• Enumerate effects of air pollution

BOD&COD.pdf

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