EVS- GE6351-UNIT 2

*
Pollution:
* Definition – Causes, effects and control measures of: (a) Air Pollution, (b)
Water Pollution (c) Soil Pollution, (d) Marine Pollution, (e) Noise Pollution,
(f) Thermal Pollution (g) Nuclear Hazards
Solid Waste Management
* Causes, effects and control measures of municipal solid waste – role of
individual in prevention of Pollution – Pollution case studies
Disaster Management:
* Floods Earthquakes, cyclone and landslides
Field study of polluted sites:
* Urban / Rural / Industrial / agricultural

Definition:
 Pollution is the introduction of contaminants into the natural
environment that cause adverse change.
 Pollution can take the form of chemical substances or energy, such as
noise, heat or light.
 Pollutants, the components of pollution, can be either foreign
substances/energies or naturally occurring contaminants.
 Pollution is often classed as point source or nonpoint source pollution.
*

The major forms of pollution are listed below along with the particular contaminant
relevant to each of them:
 Air pollution - The release of chemicals and particulates into the atmosphere.
 Light pollution - Includes light trespass, over-
illumination and astronomical interference.
 Littering - The criminal throwing of inappropriate man-made objects,
unremoved, onto public and private properties.
 Noise pollution:- which encompasses roadway noise, aircraft noise, industrial
noise as well as high-intensity sonar.
a) Soil Pollution - Occurs when chemicals are released by spill or underground
leakage.
 Thermal pollution – It is a temperature change in natural water bodies caused by
human influence, such as use of water as coolant in a power plant.
 Visual pollution - Which can refer to the presence of overhead power lines,
motorway billboards, scarred landforms (as from strip mining), open storage of
trash, municipal solid waste or space debris.
 Water pollution - by the discharge of wastewater from commercial and industrial
waste (intentionally or through spills) into surface waters.
*

 Air pollution is the introduction into
the atmosphere of chemicals, particulates, or biological materials that
cause discomfort, disease, or death to humans, damage other living
organisms such as food crops, or damage the natural
environment or built environment.
 The atmosphere is a complex dynamic natural gaseous system that is
essential to support life on planet Earth. Stratospheric ozone
depletion due to air pollution has long been recognized as a threat to
human health as well as to the Earth's ecosystems.
*

Anthropogenic Sources / Man-made Sources:
 Stationary Sources" include smoke stacks of power plants,
manufacturing facilities (factories) and waste incinerators, as well
as furnaces and other types of fuel-burning heating devices.
 "Mobile Sources" include motor vehicles, marine vessels, aircraft
and the effect of sound etc.
 Chemicals, dust and controlled burn practices in agriculture and
forestry management.
 Fumes from paint, hair spray, varnish, aerosol sprays and other
solvents
 Waste deposition in landfills, which generate methane. Methane is
highly flammable and may form explosive mixtures with air.
 Military, such as nuclear weapons, toxic gases, germ
warfare and rocketry
*

Natural Sources:
 Dust from natural sources, usually large areas of land with little
or no vegetation
 Methane, emitted by the digestion of food by animals, for
example cattle
 Radon gas from radioactive decay within the Earth's crust.
 Smoke and carbon monoxide from wildfires
 Vegetation, in some regions, emits environmentally significant
amounts of pollutants on warmer days. These react with
primary anthropogenic pollutants—specifically, NOx, SO2, and
anthropogenic organic carbon compounds—to produce a
seasonal haze of secondary pollutants.
 Volcanic activity, which produce sulphur, chlorine, and ash
particulates
*

Effects on Human:
 Pollutants damage to human respiratory system
 Bigger particles – trapped and eliminated through nose hair & mucus
present in nose liner
 Smaller particles – reach tracheobronchial system – trapped by mucus –
eliminated by spitting or swallowing
Long term exposure:
 SO2 (coal): constriction of respiratory passage, bronchitis
 SO2 (with SPM): forms acid sulphate particles – affects lungs
 NOx (NO2): lung irritation, chronic bronchitis, emphysema
 CO: Binds with haemoglobin of blood – carboxyhaemoglobin – resulting
in suffocation due to non-transport of oxygen – dizziness,
unconsciousness, death
*

Long term exposure..
 Cigarette smoke - Lung, cancer, asthma, bronchitis, emphysema
(damage to air sacs – loss of lung elasticity & acute shortness of
breath)
 Suspended particle (with toxins) - lung tissue damage, asthma,
bronchitis & cancer
 Benzene, HCHO, Polychlorinated biphenyls, toxic metals, dioxins:
mutation, cancer, reproduction problems
 Hazardous materials - Asbestos, beryllium, mercury, arsenic,
radioactive materials cause lung diseases and/or affects kidney,
liver, spleen, brain etc.

 Air pollutants enter through stomata (leaf pores through with
gases diffuse) – destroying chlorophyll and affecting
photosynthesis.
 Pollutants – erode waxy coating of the leaves called cuticle,
which prevents excess H2O loss and damage from diseases,
pests, drought and frost.
 Damage to leaf structure causes necrosis (dead area of leaf),
chlorosis (loss or reduction of chlorophyll causes yellowing of
leaf) or epinasty (downward curling of leaf) & abscission
(dropping of leaves)
 Particulates - plug stomata thus reduces sunlight availability
 SO2 - bleaching, chlorosis, necrosis of leaves
*

Effects on Plants..:
 NO2 - increased abscission and suppressed plant growth
 O3 - flecks on leaf surface, premature aging, necrosis and
bleaching
 Peroxyacetyl nitrate (PAN) – silvering of lower surface of leaf,
damage to young and sensitive leaves, suppress growth
 Fluorides - necrosis of leaf tip;
 Ethylene - epinasty, leaf abscission and dropping of flowers
 Air pollutants (SO2 / NOx) mixes with rain resulting in high
acidity (low pH) in fresh water lakes – thus affecting fishes –
resulting in injuries & death.

 SO2 / NOx - with moisture (H2SO4 / HNO3) - corrosion
 Corrodes - metal parts of buildings, vehicles, bridges, railway tracks
etc.
 Disfigurement of statue and monuments made of marble and
limestone (e.g. Taj Mahal)
 Brittling of pages and leather binding
 SO2 affects leather, fabrics, paints and paper
 O3 - cracking of rubber, nylon
 NOx & O3 - Fading of cotton and rayon fabrics

Effects of Air Pollution on Materials:

 Setting of industries after proper environmental impact assessment studies
 Modification of process and/or equipment
 Use of appropriate materials
 Use of low sulphur coal in industries or removing sulphur from coal
 Removing NOx during combustion and controlling flow of air and fuel in industrial
boilers
 Vehicular pollution checking – catalytic converters – reducing carbon monoxide
and hydrocarbon emission
 Slow and cooler fuel burning – reduces NOx emission
 Use of mass transport system, bicycles etc
 Use of clean fuels (hydrogen gas)
 Use of non-conventional sources of energy
 Planting more trees
 Reducing pollution at its source
*

 Gaseous pollutants: Physical adsorption on porous solid materials – activated
charcoal, silica gel, fuller earth, etc.
 Effluent gases are trapped in liquid absorbent (SO2 trapped in NH3 solution)
 Combustion at optimal conditions of oxygen and temperature - reduces
pollution
 Particulate matters - Improved trapping devices with controllable flow rate,
collective efficiency, costs, particle characteristics.
 Devices used:
 Cyclones - for larger particles (>10 mm)
 Bag house filters - for smaller particles
 Wet Scrubbers - for toxic and acidic gases
 Electrostatic precipitator - nanosize particle
 parallel-plate type
 wire and pipe type
*

*
Atmospheric Chemistry and Physics: from Air Pollution to Climate Change

*
Climate Change
(>1990s)
Regional Air Pollution
(…1950s…)
Acid rain
(1970s…)
Stratospheric
Ozone depletion
(1985…)
Atmospheric
CHEMISTRY

Important gases in the Earth’s Atmosphere
(Note: Influence not necessarily proportional to % by volume!)
Composition of Earth’s Atmosphere

*
Important Aspects of Atmospheric Chemical Processes

*
Important Atmospheric Chemical Species
* Inorganic oxides: CO, CO2, NO2, SO2
* Oxidants: O3, H2O2, HO• radical, HO2• radical, ROO• radicals, NO3 radical
* Reductants: CO, SO2, H2S
* Hydrocarbons: Natural CH4, pollutant alkanes, alkenes, aromatics
* Oxidized organics: Aldehydes, ketones, acids, organic nitrates
* Photochemically active species: NO2, formaldehyde
* Acids: H2SO4, H2SO3, HNO3
* Bases: NH3
* Salts: NH4HSO4
* Unstable reactive species: Electronically excited nitrogen dioxide (NO2*), HO•
Solid and liquid particles in aerosols and clouds
* Sources and sinks for gas-phase species
* Sites for surface reactions on solids
* Aqueous phase reactions in water droplets

*
Two Very Important Factors in Atmospheric Chemistry:
(i) Radiant solar energy
* Photons put high energy into individual molecules
(ii) Hydroxyl radical, HO•
*Most important highly reactive intermediate

*
Photochemical Processes
*From photons of energetic solar electromagnetic radiation, h
*Produce electronically excited species designated *
NO2 + h  NO2*
*Excited species tend to be highly reactive in the atmosphere
*Two other reactive species
*Free radicals with unpaired electrons: H3C• , HO•
*Ions such as O+ (uncommon in lower atmosphere)

*
* Electronically Excited Species
* Absorption of a photon, usually of ultraviolet radiation, can energize
molecules, atoms, or radicals to electronically excited states
Electronically excited states where the arrows represent directions
of electron spin

*
Loss of Excitation Energy from Electronically Excited Species
(i) Emission of a photon (light): NO2*  NO2 + h
Called luminescence if instantaneous, phosphorescence if slower and
Chemiluminescence when the excited species that emits a photon is formed as the
result of a chemical reaction
O3 + NO  O2 + NO2* (luminescent species)
(ii) Direct reaction of an excited species
O2* + O3  2O2 + O
(iii) Dissociation
NO2*  NO + O (very important tropospheric reaction)
O2*  O + O (important in stratosphere leading to O3)
(iv) Photoionization (formation of ions in the ionsphere)
N2*  N2
+ + e-

*The word ‘smog’ comes from two words: smoke and fog.
*Characterize visible combination of smoke and fog
Smog
23
2
17
3
20
0
5
10
15
20
25
nitrogen
dioxide
benzene ozone aldehyde unreacted
carbon
No. of Classmates
Photochemical smog is a mixture of pollutants,

*
8
27
20
22
19
0
5
10
15
20
25
30
a b c d e
No. of Classmates
a. headaches b. eye, nose and throat irritation c. impaired lung function
d. coughing and wheeling e. damaging plants

*
Troposphere Ozone:
*NO2 + h NO + O
*O + O2 O3
Sources:
*Exhaust gases From Motor vehicles
*Unburnt Hydrocarbons

Peroxyacetyl Nitrates (PAN)
Are secondary pollutants formed from
peroxyacid radicals and NO2
*CH3CHO + OH• CH3C•O + H2O
*CH3C•O + O2 CH3C(O)OO• (acetylperoxy)
*CH3C(O)OO• + •NO2 CH3C(O)OONO2
(PAN)
*

*
*Ozone
*Cause acute respiratory problems
*Aggravate asthma
*Cause temporary decreases in lung function in
healthy adults
*Lead to hospital admissions and emergency room
visits
*Impair the body's immune system
*Peroxyacetylnitrate (PANs)
*Respiratory and eye irritants
*Mutagenic- causing skin cancer

*
*Formed when gases, such as CO2 and SO2 react with the water
in the atmosphere
*The pH of Rain drops
*As low as pH of 2
*Very harmful to our
living environment

*
*When CO2 reacts with water, carbonic acid is
formed.
CO2 (g)+H2O(l)-H2CO3(aq)
*When SO2 reacts with water, sulfurous acid is
formed.
SO2 (g)+H2O(l)-H2SO3(aq)
*When NO2 reacts with water, nitric acid is
formed.
2NO2(g)+H2O(l)-HNO2(aq)+HNO3(aq)

*
*It kills micro-organisms
*It poisons plants
*It damages metals and limestone
*It kills fish

*
PARTICULATE
Cyclones
Electrostatic Precipitators
Fabric Filter
Wet Scrubbers
GASES
Adsorption Towers
Thermal Incernation
Catalytic Combustion

*
*Use Flue Gas Desulfurization Systems
*Use Alternative Energy Sources, such as Hydro-Power or
Nuclear-Power

*
SO2 scrubbing, or Flue Gas Desulfurization processes can be
classified as:
 Throwaway or Regenerative, depending upon whether the recovered sulfur
is discarded or recycled.
 Wet or Dry, depending upon whether the scrubber is a liquid or a solid.
Flue Gas Desulfurization Processes
The major flue gas desulfurization ( FGD ), processes are :
 Limestone Scrubbing
 Lime Scrubbing
 Dual Alkali Processes
 Lime Spray Drying
 Wellman-Lord Process

*
 Lime and Limestone scrubbing lead to deposits inside spray tower.
 The deposits can lead to plugging of the nozzles through which the
scrubbing slurry is sprayed.
 The Dual Alkali system uses two regents to remove the sulfur
dioxide.
 Sodium sulfite / Sodium hydroxide are used for the absorption of
sulfur dioxide inside the spray chamber.
 The resulting sodium salts are soluble in water,so no deposits are
formed.
 The spray water is treated with lime or limestone, along with make-
up sodium hydroxide or sodium carbonate.
 The sulfite / sulfate ions are precipitated, and the sodium hydroxide
is regenerated.

*
*Lime Slurry is sprayed into the chamber
*The sulfur dioxide is absorbed by the slurry
*The liquid-to-gas ratio is maintained such that the spray dries
before it reaches the bottom of the chamber
* The dry solids are carried out with the gas, and are collected in
fabric filtration unit
* This system needs lower maintenance, lower capital costs, and
lower energy usage

*
Schematic process flow diagram – SO2 scrubbing and recovery system

*NOx control can be achieved by:
 Fuel Denitrogenation
 Combustion Modification
 Modification of operating conditions
 Tail-end control equipment
 Selective Catalytic Reduction
 Selective Non - Catalytic Reduction
 Electron Beam Radiation
 Staged Combustion
CONTROL OF NITROGEN OXIDES(NOX)

*
o One approach of fuel denitrogenation is to remove a large part of the nitrogen
contained in the fuels. Nitrogen is removed from liquid fuels by mixing the fuels
with hydrogen gas, heating the mixture and using a catalyst to cause nitrogen in
the fuel and gaseous hydrogen to unite. This produces ammonia and cleaner
fuel.
 This technology can reduce the nitrogen contained in both naturally
occurring and synthetic fuels.

*
*Combustion control uses one of the following strategies:
 Reduce peak temperatures of the flame zone. The methods are :
 increase the rate of flame cooling
 decrease the adiabatic flame temperature by dilution
Reduce residence time in the flame zone. For this we change the shape
of the flame zone
Reduce Oxygen concentration in the flame one. This can be
accomplished by:
 decreasing the excess air
 controlled mixing of fuel and air
 using a fuel rich primary flame zone

*
*The operating conditions can be modified to achieve significant
reductions in the rate of thermal NOx production. the various
methods are:
Low-excess firing
Off-stoichiometric combustion ( staged combustion )
Flue gas recirculation
Reduced air preheat
Reduced firing rates
Water Injection

*
oCombustion modification and modification of operating
conditions provide significant reductions in NOx, but not
enough to meet regulations.
 For further reduction in emissions, tail-end control equipment is
required.
 Some of the control processes are:
 Selective Catalytic Reduction
 Selective Non-catalytic Reduction
 Electron Beam Radiation
 Staged Combustion

*
Schematic process flow diagram – NOX control

*
*At higher temperatures (900-1000oC), NH3 will reduce NOX to
nitrogen without a catalyst.
*At NH3 : NOX molar ratios 1:1 to 2:1, about 40-60%reduction is
obtained.
*SNR is cheaper than SCR in terms of operation cost and capital
cost.
*Tight temperature controls are needed. At lower temperatures,
un-reacted ammonia is emitted. At higher temperatures ammonia
is oxidized to NO.

*
*This treatment process is under development, and is not
widely used. Work is underway to determine the feasibility of
electron beam radiation for neutralizing hazardous wastes
and air toxics.
 Irradiation of flue gases containing NOx or SOx produce nitrate and sulfate
ions.
 The addition of water and ammonia produces NH4NO3, and (NH4)2SO4
 The solids are removed from the gas, and are sold as fertilizers.

*
*PRINCIPLE
Initially, less air is supplied to bring about incomplete
combustion
Nitrogen is not oxidized. Carbon particles and CO are released.
In the second stage, more air is supplied to complete the
combustion of carbon and carbon monoxide.
30% to 50% reductions in NOx emissions are achieved.

*
 Control carbon monoxide formation.
Note : CO & NOx control strategies are in conflict.
 Stationary Sources
 Proper Design
 Installation
 Operation
 Maintenance
 Process Industries
 Burn in furnaces or waste heat boilers.

*
 Iron & Steel Mills, the blast furnaces, steel making furnaces.
 Petroleum Refineries, the catalyst regenerators, air-blown asphalt
stills, and sludge burners.
 Portland cement industry
 Asphalt batching plants
 Production of sulfuric acid
 Production of phosphoric acid
 Soap and Synthetic detergent manufacturing
 Glass & glass fiber industry
 Instant coffee plants

*
Primary Effects
• Reduction of visibility
• size distribution and refractive index of the particles
• direct absorption of light by particles
• direct light scattering by particles
• 150 micro g / m3 concentration ~ average visibility of 5 miles
( satisfactory for air and ground transportation )
• Soiling of nuisance
• increase cost of building maintenance, cleaning of furnishings,
and households
• threshold limit is 200 - 250 micro g / m3 ( dust )
• levels of 400 - 500 micro g / m3 considered as nuisance

*
* Five Basic Types of Dust Collectors :
Gravity and Momentum collectors
Settling chambers, louvers, baffle chambers
Centrifugal Collectors
Cyclones
Mechanical centrifugal collectors
Fabric Filters
Baghouses
Fabric collectors

*
Electrostatic Precipitators
Tubular
Plate
Wet
Dry
Wet Collectors
Spray towers
Impingement scrubbers
Wet cyclones
Peaked towers
Mobile bed scrubbers

*
 Gravity Settling
 Centrifugal Impaction
 Inertial Impaction
 Direct Interception
 Diffusion
 Electrostatic Effects

Tubular Dust Collector Arrangement for an
ESP

*
*Water is formed when two hydrogen atoms
bond to one oxygen atom.
*Not symmetrical
*Electrons spend more time near the (O) and
less time near the (H)
*Water molecule is polar
Water molecules are held together by a hydrogen bond

*
*There is a greater
concentration of
electrons around the
nucleus of the oxygen
than around the
hydrogen.
*Therefore, the
hydrogen end is
slightly positive and
the oxygen end is
slightly negative…...
Dipolar

*
*When water
molecules attract to
one another, the
hydrogen end of one
molecule is
attracted to the
oxygen end of
another.

*
*Water is the only
substance found on
Earth in all three
states (phases):
1. Liquid

*
*Water molecules are constantly moving
*Temperature increase = Increase in movement

*
*When water molecules move faster, they tend
to break their hydrogen bonds.
This is called
Evaporation

*
*When gas or vapor molecules slow down, they
clump or join together.
This is called
Condensation

*
*As water becomes cooler, it becomes less dense:
1 gram per cubic cm at 39.2
o
0.95865 gram per cubic cm at 212
o

*
*As water changes from a liquid to a solid,
molecules form crystals.
In ice crystals, molecules are spaced
further apart.
Liquid Solid (Ice)

*
*Since molecules are spaced further apart, ice is less dense than
water (it floats)
Helpful for aquatic organisms; forms a “blanket”
If ice was more dense than water, lakes would
freeze from the bottom upwards.

*
*Next to mercury, water has the highest surface tension of
all liquids.
This is a result of the tendency of water molecules to attract
to one another, or cohere, at the surface of any accumulation
of water.

*
*Surface tension allows insects to walk on water.
*Interaction between hydrogen bonding and the
earth’s gravitational pull

*
*Cohesion- the attraction between water
molecules to each other through Hydrogen
bonds (H)

*
*Adhesion- the attraction of water molecules to
another substance.

*
*Capillarity- the
movement of water
within the spaces of
a porous material
due to the forces of
surface tension,
adhesion, and
cohesion.Allows water to climb from
soil into plants

*
*The measurement of the H+ ions found in that particular
substance
*The scale goes from 0 to 14
*7 is neutral
*Below 7 is acidic
*Above 7 is alkaline (or basic)
*One pH unit represents a ten-fold change in H+ concentration

*
*Since water can dissolve more things than any other natural
substance, it is known as the “ Universal Solvent”
*Properties of Solvents include:
*Interacts with other polar compounds
*Is repelled by non-polar compounds
*Small size allows it to saturate areas
*Can convey other substances in solutions

*
*Water is especially good at dissolving salts
Salts form from the combination of particles with opposite
electrical charges (or ions)
EX. Na
+
+ Cl
-
= NaCl
*When salt is placed in water, the strongly charged salt ions
attract to the weaker charged water molecules.
*Water molecules surround each ion.
*Salt crystals fall apart, or dissociates, and the salt dissolves.

*
*Terrestrial habitats exhibit extreme ranges in temperature and
receive varying amounts of sunlight, precipitation, and wind.
*Additionally, they have other unique chemical and physical
properties that make them suitable places for one species to live,
but completely uninhabitable for another.
*So, too, oceanic habitats exhibit chemical and physical properties
that make certain ocean zones suitable or unsuitable places for
different species to live.
*In fact, chemical and physical properties of the ocean are crucial
to the survival of marine organisms.
* This chapter addresses the chemical (salinity and dissolved gases)
and physical (temperature, density, buoyancy, waves, tides, and
currents) properties of ocean water that are delicately
intermingled to produce one of the most self-sustaining life support
systems on earth

*A. Salinity
*The ocean is salty. But what makes it salty when the
water flowing into it is from freshwater rivers, streams,
and precipitation?
* Freshwater rivers and streams weather, or slowly wear
away, the rocks and soils they flow over as they make
their descent from mountainous and other inland regions
toward the ocean.
*Rocks and soils release inorganic salts and other chemical
compounds as they are weathered by this continuous flow
of water.
*These inorganic salts and other chemical compounds are
finally deposited in the oceans at the end of their
journey from far away inland places.
*Additionally, precipitation causes fresh water and
chemical compounds to be released from the atmosphere
into the oceans.

*B.Temperature
*Temperature is one of the most important
*physical factors affecting the distribution of life
*in the oceans. Additionally, temperature
*controls the rate at which organisms metabolize, or break
down, food items into nutrients
*that they can use. Exchange of gases, such as
*oxygen (O2) and carbon dioxide (CO2), in the
*marine environment is greatly affected by

*C. Density
*Variations in density, or the ratio of mass to volume, of the
ocean are a function of salinity and temperature.
*Oceanic waters with higher salinities are more dense than
oceanic waters with lower salinities.
* In other words, a liter of water with a salinity of 36‰ weighs
more than a liter of water with a salinity of 32‰.
* Additionally, waters that have cooler temperatures have
higher densities than waters with warmer temperatures.
*Ocean waters with higher salinities and cooler temperatures
have the greatest densities.
*Dense water masses actually “sink” toward the ocean floor,
while less dense ocean water masses “float” at or near the
ocean’s surface

*D. Buoyancy
*Just as water masses with different densities either
sink below or float on top of one another, objects that
are denser than water sink while objects that are less
dense than water float.
*Buoyancy is defined as the ability to remain afloat in a
liquid.
*Because salt water is more dense than fresh water, salt
water provides greater buoyancy to an object floating
on the surface than does fresh water.

*F. Waves
*Wind is a form of energy. Wind energy blowing along the surface of the
ocean is transferred to the ocean as waves and
*currents (also see Section H).
*Waves originate in the open ocean and, in many cases,the waves we see
along the coast were generated far away at sea (Fig. 2-7).
*The size of a wave depends on 3 factors: (1) the velocity of the wind, (2)
the wind’s duration,or the length of time the wind blows, and (3)fetch,
or the distance of the ocean over which the wind is blowing.
*The harder the wind blows and the longer it blows, the greater its
velocity and duration and the larger the waves.
*The longer the fetch, the larger the waves that are produced

*
Physical
* >Temperature
* >Light
* >Turbidity
Chemical
* >Dissolved oxygen (DO)
* >pH
* >Salinity
* >Co2
* >Ammonia
Biological

*
*Temperature affects physical, chemical, and biological
processes in water
*Chemical example: DO decreases as temperature increases
*Biological example: fish seek thermal refuges
*Temperature affected by depth
*Causes lake turnover
*Loss of streamside shade trees causes temperature to
increase

*
*Atmosphere consists of 21% O2
*Water consists of <1% O2
*When water and atmosphere come into intimate contact, O2
tends to diffuse into water
*Occurs as water passes over riffles, rapids, and falls and to a
lesser extent in still water
*Aquatic plants also pump O2 into water
*During daytime when they are undergoing photosynthesis

*
*Fish depend on DO in water
*O2 diffuses from water to
blood in gills
*When DO concentrations in
water drop below 5
milligrams per liter (mg/L)
most fish have trouble

*
*pH = power of 10 for the H ion concentration (drop the minus
sign)
*Pure distilled water has a pH of 7 (neutral)
*1 x 10-7 = 0.0000001 moles H+ per liter
*Most rivers and lakes have a pH of 4 to 9
*Fish have a narrow range that varies by species
*pH outside the range can cause damage to gills, eyes, skin, etc.

*
*Clarity of water
*Measured as light
penetration in
nephelometric turbidity
units (NTU)
*Also measured with a Secchi
disk
*Record the depth at which
you can no longer see the
banded colors on the disk

Secchi disk depth comparison from clear (left) to murky (right)
http://earthobservatory.nasa.gov/Study/WaterQuality/water_quality2.html

*
Water pollution is the contamination of water bodies
(e.g. lakes, rivers, oceans, aquifers and groundwater).
Water pollution occurs when pollutants are discharged
directly or indirectly into water bodies without
adequate treatment to remove harmful compounds.
Water pollution affects plants and organisms living in
these bodies of water. In almost all cases the effect is
damaging not only to individual species and populations,
but also to the natural biological communities.

*Water Pollution:-statistical data
 Water pollution is a major global problem which requires on-going
evaluation and revision of water resource policy at all levels
(international down to individual aquifers and wells).
 It has been suggested that it is the leading worldwide cause of deaths
and diseases, and that it accounts for the deaths of more than 14,000
people daily.
 An estimated 700 million Indians have no access to a proper toilet,
and 1,000 Indian children die of diarrheal sickness every day.
 Some 90% of China's cities suffer from some degree of water
pollution, and nearly 500 million people lack access to safe drinking
water.
 In the most recent national report on water quality in the United
States, 45 percent of assessed stream miles, 47 percent of assessed
lake acres, and 32 percent of assessed bays and estuarine square
miles were classified as polluted.

* Point Source:
 Point source water pollution refers to contaminants that enter a
waterway from a single, identifiable source, such as a pipe or ditch.
 Ex: Discharges from a sewage treatment plant, a factory, or a
city storm drain.

Non Point Source:
*Nonpoint source (NPS) pollution refers to both water
and air pollution from diffuse sources.
*Nonpoint source water pollution affects a water body
from sources such as
polluted runoff from agricultural areas draining into a
river, or wind-borne debris blowing out to sea.
*Nutrient runoff in storm water from "sheet flow" over
an agricultural field or a forest are also cited as
examples of NPS pollution.
*Contaminated storm water washed off of parking lots,
roads and highways, called urban runoff, is sometimes
included under the category of NPS pollution. However,
this runoff is typically channelled into storm drain
systems and discharged through pipes to local surface
waters, and is a point source

*Diagrammatic Representation :

*Ground Water:
 It constitutes to about 6.2% of total water available on earth – 30
time more than surface water
 Ground water is less prone to pollution – soil mantle acts as cation
exchanger to retain various contaminants.
 Potential sources of ground water pollution – septic tanks, industry
(textile, tanneries), deep well injection, mining etc.
 Ground water contaminated with arsenic, fluoride and nitrate is a
serious health hazard
*Surface Water:
 Sewage, Industrial effluents – toxic chemicals
 Synthetic detergents, Agrochemicals, Oil and
 Waste heat

*
Oxygen demanding wastes:
*Organic matters reaching water bodies are decomposed
by micro-organisms present in water
*Degradation is aided by the dissolved O2 in water
*Dissolved Oxygen (DO) – amount of oxygen dissolved in a
given quantity of water at a particular temperature and
atmospheric pressure
*Amount of DO depends on aeration, photosynthetic
activity in water, respiration of animals and plants and
ambient temperature
*Saturation value of DO varies from 8-15 mg/L
*Fishes require 5-8 mg/L and for species like crap – 3
mg/L
*Lower DO value harmful to species existence, oxygen
depletion (deoxygenation) releases phosphates from
bottom sediments – causing eutrophication.

Nitrogen and Phosphorous compounds (nutrients)
 Addition of nitrogen and phosphorous containing compounds –
aids growth of algae and other plants – die and decay consume
oxygen of water
 Anaerobic conditions produce foul smelling gases
 Excess growth or decomposition of plant material changes the
concentration of CO2 – alternation of water pH
 Changes in water pH, oxygen and temperature will change many
physico-chemical characteristics of water
 Pathogens
 Wastewater (sewage) contain many pathogenic (disease
causing) and non-pathogenic micro-organisms and many viruses.
 Water borne disease – cholera, dysentery, typhoid, jaundice
etc., are spread through contamination

Toxic compounds
 Pollutants such as heavy metals, pesticides, cyanides etc., are
harmful to aquatic organisms
 The demand of DO increases with addition of biodegradable
organic matter which is expressed as biological oxygen demand
(BOD)
 BOD – amount of DO required to aerobically decompose
biodegradable organic matter of a given volume of water over a
period of 5 days at 20 deg C
 More BOD value – poor water quality
 Non-biodegradable compounds like Pesticides and Mercury results
in bioaccumulation – subsequently to biomagnification. E.g. DDT
in food chain

Mercury toxicity (methyl mercury, lipid soluble) - minamata
disease to humans – through consumption of fishes – leading
to paralysis
Cadmium toxicity – Itai-Itai disease – consumed through rice
contaminated with Cd – irrigation water containing effluents
from smelters and mine drainage – bones, liver, kidney, lungs,
pancreas and thyroid are affected
Arsenic pollution in Bangladesh and West Bengal – Leprosy
like skin disease
Excess nitrate – Blue baby syndrome or methaemoglobinemia
Excess fluoride – Fluorosis – Defects in teeth and bones

*
Point source pollution control:
 Waste water treatment
 Advance sewage treatment
Non Point source pollution control:
Judicious use of agrochemicals – reduces surface runoff and leaching –
avoid using on sloped lands
Nitrogen fixing plants to supplement the fertilizer use
Adopting integrated pest management
Prevent run-off of manure – nutrient rich water can be used as
fertilizers in the fields
Separate drainage of sewage and rainwater
Planting trees – reduces pollution by sediments and also prevents soil
erosion

*
*Preliminary treatment
*Primary(or)settling process
*Secondary (or)biological process
i)trickling filter process
ii)activated sludge process
*Tertiary treatment
*Disposal of sludge

*
 Soil contamination or soil pollution is caused by the presence
of xenobiotic (human-made) chemicals or other alteration in the natural soil
environment.
 It is typically caused by industrial activity, agricultural chemicals, or
improper disposal of waste.
 The most common chemicals involved are petroleum hydrocarbons,
polynuclear aromatic hydrocarbons (such as naphthalene and
benzo(a)pyrene), solvents, pesticides, lead, and other heavy metals.
Contamination is correlated with the degree of industrialization and
intensity of chemical usage.
 The concern over soil contamination stems primarily from health risks, from
direct contact with the contaminated soil, vapours from the contaminants,
and from secondary contamination of water supplies within and underlying
the soil.

*
Application of pesticides and fertilizers
Mining
Oil and fuel dumping
Disposal of coal ash
Leaching from landfills
Drainage of contaminated surface water into the
soil
Discharging urine and faeces in the open

*
Soil pollution by sewage and industrial effluents – affects
human health
Alkalis, pesticides, insecticides, heavy metal industrial
discharge affects soil fertility – by changing the physical,
chemical and biological properties of soil
Reduction in soil productivity – by inhibition of non-target
organisms, soil flora and fauna by persistent toxic chemicals
Accumulation of chemical in food chain
Sewage sludges contains pathogenic bacteria, viruses and
intestinal worms

Decomposing organic matter in soil produces toxic
vapours.
Radioactive fallout on vegetation – enters food chain.
Radio isotopes replaces essential elements resulting in
abnormalities
E.g. Sr-90 replacing Ca in bones and tissue results in
brittle bones – prone to fractures
Nitrogen and phosphorous from fertilizers in soil reaches
water bodies resulting in eutrophication
Ground water contamination – percolation of chemicals
in soil

*
Proper treatment of effluents before discharge
Proper collection and disposal of solid waste
Recovery of useful products from waste
Generation of biogas from biodegradable organic
waste
Methane generation from cattle dung – biogas plant
Microbial degradation of biodegradable substances

*OVERVIEW
*Kinds of Wastes
*Waste Generation
*Solid Waste in India
*Solid Waste management methods

*
Waste (also known as rubbish, refuse, garbage, junk) is unwanted
or useless materials. In biology, waste is any of the many
unwanted substances expelled from living organisms, metabolic
waste; such as urea and sweat.

*
Solid wastes: wastes in solid forms, domestic, commercial and industrial
wastes Examples: plastics , bottles, cans, papers, scrap iron, and other
trash
Liquid Wastes: wastes in liquid form Examples: domestic washings,
chemicals, oils, waste water from ponds, manufacturing industries and
other sources.
Bio-degradable :can be degraded (paper, wood, fruits and others)
Non-biodegradable :cannot be degraded (plastics, bottles, old machines,
cans, Styrofoam containers and others)
Hazardous wastes: Substances unsafe to use commercially, industrially,
agriculturally, or economically and have any of the following properties-
ignitability, corrosivity, reactivity & toxicity.
Non-hazardous : Substances safe to use commercially, industrially,
agriculturally, or economically and do not have any of those properties
mentioned above. These substances usually create disposal problems.

*
 Municipal Solid wastes: Solid wastes that include household
garbage, rubbish, construction & packaging materials, trade
refuges etc. are managed by any municipality.
 Bio-medical wastes: Solid or liquid wastes including
containers, products generated during diagnosis, treatment &
research activities of medical sciences.
 Industrial wastes: Liquid and solid wastes that are generated
by manufacturing & processing units of various industries like
chemical, petroleum, coal, metal gas, sanitary & paper etc.
 Agricultural wastes: Wastes generated from farming
activities. These substances are mostly biodegradable.
 Fishery wastes: Wastes generated due to fishery activities.
 E-wastes: Electronic wastes generated from any modern
establishments. They may be described as discarded
electrical or electronic devices. Some electronic scrap
components, such as CRTs, wires, circuits, mobile, computers
etc.

*STRUCTURE OF
SOLID WASTE
Solid Waste
Refuse Trash
Bulky wastes (TV, refrigerators
goods,
Broken furniture, etc.)
Garbage Rubbish
non-degradable (glass, rubber,
Metals, plastics non-metal set)
Vegetables, Meats, food
Wastes and other readily
Degradable organic wastes slowly degradable (paper, wood
Products, textiles etc.)

WASTE GENERATIONS RATES OF SOME ASIAN COUNTRIES

MSW GENERATION FROM THE METROPOLITANS OF INDIA

* Solid Waste in India
*7.2 million tonnes of hazardous waste
*One Sq km of additional landfill area every-year
*Rs 1600 crore for treatment & disposal of these wastes
*In addition to this industries discharge about 150 million tonnes of
high volume low hazard waste every year, which is mostly dumped on
open low lying land areas.
Growth of Solid Waste In India
*Waste is growing by leaps & bounds
*In 1981-91, population of Mumbai increased from 8.2 million to 12.3
million
*During the same period, municipal solid waste has grown from 3200
tonnes to 5355 tonne, an increase of 67%
*City like Bangalore produces 2000 tonnes of waste per annum.
*Waste collection is very low for all Indian cities.

* Waste Collection in India
*Primarily by the city municipality
-No gradation of waste product e.g. bio-degradable, glasses, polybags,
paper shreds etc
-Dumps these wastes to the city outskirts
*Local raddiwala / kabadiwala
* -Collecting small iron pieces by magnets
-Collecting glass bottles
-Collecting paper for recycling
How solid waste affected us in recent years?
* In Mumbai (2005) clogged the sewage line due to large no. of plastic bags.
* Blast in the Bhusan Steel factory at Noida, caused due to imported scrap
from Iran
* Reduction in the number of migratory birds due to consumption of
contaminated foods
* animals dying on streets and farmland due to consumption of plastic bags,
which blocks the food movement in their stomach

* HEALTH IMPACTS OF SOLID WASTE
*Exposure to hazardous waste can affect human health,
children being more vulnerable to these pollutants.
*Improperly operated incineration plants cause air pollution
and improperly managed and designed landfills attract all
types of insects that spread disease.
*Direct handling of solid waste results in chronic diseases
with the waste workers.

*1.LAND FILL
*It is the most traditional method of waste disposal.
*Waste is directly dumped into disused quarries, mining voids or borrow pits.
*Disposed waste is compacted and covered with soil
*Gases generated by the decomposing waste materials are often burnt to
generate power.
*It is generally used for domestic waste.

ADVANTAGES
 Landfill site is a cheap waste disposal option for the local council.
 Jobs will be created for local people.
 Lots of different types of waste can be disposed of by landfill in comparison to other
waste disposal methods.
 The gases given off by the landfill site could be collected and used for generating
power.
DISADVANTAGES
 The site will look ugly while it is being used for landfill.
 Dangerous gases are given off from landfill sites that cause local air pollution and
contribute to global warming.
 Local streams could become polluted with toxins seeping through the ground from
the landfill site.
 Once the site has been filled it might not be able to be used for redevelopment as it
might be too polluted.

LAND REQUIRED FOR DISPOSAL OF MSW EMMISION OF METHANE FROM LANDFILL

* 2. INCINERATION
*Incineration is a waste treatment process that involves the combustion of
solid waste at 1000C.
*waste materials are converted into ash, flue gas, and heat.
*The ash is mostly formed by the inorganic constituents of the waste and
gases due to organic waste.
*the heat generated by incineration is used to generate electric power.

* ADVANTAGES
 Minimum of land is needed compared to other disposal methods.
 The weight of the waste is reduced to 25% of the initial value.
 No risk of polluting local streams and ground waters as in landfills.
 Incineration plants can be located close to residential areas.
 Gases are used to generate power.
DISADVANTAGES
 Expensive
 Required skilled labour.
 The chemicals that would be released into the air could be strong
pollutants and may destroy ozone layer (major disadvantage).
 high energy requirement.

*
 The waste is compacted or compressed. It also breaks up large or fragile
items of waste.
 This process is conspicuous in the feed at the back end of many garbage
collection vehicles. Deposit refuse at bottom of slope for best compaction
and control of blowing litter.

*
*Pyrolysis is defined as thermal degradation of waste in the absence of air to
produce char, pyrolysis oil and syngas, e.g. the conversion of wood to
charcoal also it is defined as destructive distillation of waste in the absence
of oxygen. External source of heat is employed in this process.

*
* REDUCE
* You can help by PRECYCLING. 1/3 of all garbage is packaging.
* Buy things that are in packages that can be recycled or are made of recycled materials.
* When you buy something small, say no thanks to a bag.
* REUSE
* Many things can be reused before you throw them out.
* Use coffee cans and cottage cheese containers for storage
* Use backs of paper or backs of used envelopes for jotting notes
* Put leftovers in resalable containers instead of using wraps and foil
* Use old clothes as rags for cleaning instead of paper towels
* Have a garage sale or donate clothes, books or toys that you don't use anymore
* RECYCLE
* Each year we use:
* 25 billion plastic containers
* 30 billion bottles & jars
* 65 billion aluminum cans
* 100 billion pounds of paper

*
*It is found that with increase in the global population and the
rising demand for food and other essentials, there has been a
rise in the amount of waste being generated daily by each
household. Waste that is not properly managed, especially
excreta and other liquid and solid waste from households and
the community, are a serious health hazard and lead to the
spread of infectious diseases.

*
*The sea is indispensable to life on earth
*Coral reefs.
*Marine accidents potentially cause serious harm .

*What has Happened
&
What can happen

*Causes :
*Toxic Ocean Pollutants:
Sources : The leaking of landfills, dumps, mines and farms.
Enters our food chain .
Lead: Affects brain, kidneys.
Effects :
• Food poisoning.

*Causes:
*Marine Garbage :
• Virtual dumping ground for trash.
• Fishing nets, plastics, general household garbage.
• Animals sometimes eat trash products and die.
Effects :
• Depletes the oxygen

*Causes:
*Sewage Disposal in Ocean
• Great Stink of London
• Nutrient loading in the ocean ecosystem.
Effects :
• Poisoning of shellfish fisheries.

*Causes:
*Non-Point Pollutants
• Sources : Farmland, Industries, Urban & Atmospheric Runoffs .
• Eutrophication.
Effects :
• Contaminate coastal swimming areas and
seafood,
spreading cholera, typhoid and other diseases

The origin of various sources of pollution are listed below :

*
*Spills - Detection and Cleanup
• Strict discipline
• emergency contingency plan
• Oil spill clean up equipment

*Domestic sewage
• Green infrastructure approach
• Septic tank

*Industrial wastewater treatment
• Dissolved air flotation

*Urban runoff
• Best management practices

*
*Chemical company in SIPCOT
discharged effluents into River
Uppanar(cuddalore) in Tamil Nadu
*By Express News Service | Published: 19th June 2017
05:59 AM |
*Last Updated: 19th June 2017 05:59 AM

*Noise pollution
Noise pollution is a pleasing or excessive noise that may
disrupt the activity or balance of human or animal life.
The source of most outdoor noise worldwide is mainly
caused by machines and transportation systems, motor
vehicles, aircrafts, and trains.
Indoor noise is caused by machines, building activities,
music performances, and especially in some
workplaces. There is no great difference whether noise-
induced hearing loss is brought about by outside (e.g.
trains) or inside (e.g. music) noise.

Decibel (feeble sound, a human ear can hear)
is the standard unit for measurement of sound.
It is one tenth of “BEL” (Bel - named after
Alexander Graham Bell).
Decibel is a unit of measurement which is used
to indicate how loud a sound is.
Continuous exposure to sound above 80
decibels could be harmful.
Usually >100 db is the level at which sound
becomes physically painful.

*
By- products of industrialization,
urbanizations and modern civilization
Road Traffic Noise
Air Craft Noise
Noise from railroads
Construction Noise
Noise from Industries

*
 Hearing Problems:
 Exposure to noise can damage one of the most vital organs of the body,
the ear.
 When the sound level crosses the 70dB mark, it becomes noise for the
ear. Noise levels above 80 decibels produce damaging effects to the ear.
 When ear is exposed to extreme loud noise (above 100 decibels) for a
considerable period of time, it can cause irreparable damage and lead
to permanent hearing loss.
 Cardiovascular Issues:
 A noisy environment can be a source of heart related problems.
 Studies have shown that high intensity sound cause a dramatic rise in
blood pressure.

*
 Sleep Disturbances:
 This is one of the noise pollution effects that can deter your overall
well being.
 Noise can interrupt a good night's sleep, and when this occurs, the
person feels extremely annoyed and uncomfortable.
 People deprived of uninterrupted sleep show a sharp dip in their energy
levels which often results into extreme fatigue. This can considerably
decrease a person's ability to work efficiently.
 Interference in Verbal Communication:
 A noisy environment that produces more than 50-60 decibels simply
does not allow 2 people to communicate properly.
 Interpreting the speech of a second person becomes quite difficult and
may lead to misunderstandings.

*
 Mental Health Problems:
 Exposure to loud sound can lead to elevated stress levels as
well as stimulate violent behavior. A constant noise in the
vicinity can also trigger headaches, make people tense and
anxious, and disturb emotional balance.
 Other Problems:
 Digestive spasms and stomach disorders
 Dilation of the pupil of the eye
 It causes headache, irritability and nervousness, feeling of
fatigue and decreases work efficiency.
 Noise also affects the developing embryo in mothers uterus.

*
 People living in the heart of city or near the airport, often have to bear the
brunt of high noise levels. To decrease noise, one can install dual-paned
windows. Offices, too can use windows to curb noise levels. Soundproofing is
another alternative that can be looked at to reduce excessive sound levels.
 Use of music systems and television sets with high volumes can cause noise
pollution at home. Instead, using these appliances with the volume kept at a
moderate level is a better option.
 An effective way to manage noise would be to wear ear protection while
working in noisy conditions. Animals should be moved to some other place,
away from the noise source, thereby decreasing their noise exposure time.
 Vehicles and factory machines need to be maintained properly and checked
from time to time. Lack of maintenance will not only increase noise levels,
but also decrease the efficiency of these machines.
 Making a change in design and operation of machines, vibration control,
sound proof cabins and sound-absorbing materials can reduce. it.

*
 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.
 When water used as a coolant is returned to the natural environment at a higher
temperature, the change in temperature decreases oxygen supply, and
affects ecosystem composition.
 Urban runoff–stormwater discharged to surface waters from roads and parking lots–
can also be a source of elevated water temperatures.
 When a power plant first opens or shuts down for repair or other causes, fish and
other organisms adapted to particular temperature range can be killed by the abrupt
change in water temperature known as "thermal shock."

*
*Warm water:
 Elevated temperature typically decreases the level of dissolved oxygen of water. This
can harm aquatic animals such as fish, amphibians and other aquatic organisms.
 Thermal pollution may also increase the metabolic rate of aquatic animals - result in
fewer resources
 Some fish species will avoid stream segments or coastal areas adjacent to a thermal
discharge. Biodiversity can be decreased as a result.
 High temperature limits oxygen dispersion into deeper waters, contributing
to anaerobic conditions. This can lead to increased bacteria levels when there is
ample food supply. Many aquatic species will fail to reproduce at elevated
temperatures.

*Cold water:
Releases of unnaturally cold water from reservoirs can
dramatically change the fish and macro invertebrate
fauna of rivers, and reduce river productivity.

*
Cooling Ponds
Spray Ponds
Cooling Towers (video lecture)

ADDITION OF EXCESS OF UNDESIRABLE HEAT TO WATER
THAT MAKES IT HARMFUL TO MAN, ANIMAL OR AQUATIC LIFE
*

*
*Nuclear power plants use water as a
cooling agent.
*After the water is used, it is put back
into a water supply at 9-20oC warmer
This 1988 thermal image of the Hudson River
highlights temperature changes caused by
discharge of 2.5 billion gallons of water each
day from the Indian Point power plant. The
plant sits in the upper right of the photo — hot
water in the discharge canal is visible in yellow
and red, spreading and cooling across the
entire width of the river. Two additional outflows
from the Lovett coal-fired power plant are also
clearly visible against the natural temperature
of the water, in green and blue.

Red – reservoirs Yellow – Fossil Plants Purple – Nuclear Plants

*CAUSES
DISCHARGE OF HEATED WATER OR HOT WASTE
MATERIAL INTO WATER BODIES FROM
*NUCLEAR POWER PLANTS
*INDUSTRIAL EFFLUENTS
*DOMESTIC SEWAGE
*HYDRO-ELECTRIC POWER
*COAL FIRED POWER PLANTS

*NUCLEAR POWER PLANTS
 Nuclear power plants use water as a cooling agent.
 After the water is used, it is put back into a water
supply at 9-20oC
 Emissions from nuclear reactor increase the
temperature of water bodies.

*Coal-fired power plants
 Coal is utilized as a fuel
 Condenser coils are cooled with water from nearby
lake or river
 The heated effluents decrease the DO of water
 Damages the marine organisms

*Coal-fired power plants-process

*Industrial Effluents
Discharged water from steam-electric power industry
using turbo generators will have a higher temperature
ranging from 6 to 9˚C than the receiving water
In modern stations, producing 100 MW, nearly one
million gallons are discharged in an hour with increase
in temperature of the cooling water passing by 8 to 10 ˚C

*Domestic sewage
Sewage is commonly discharged into lakes,canals or
streams
Municipal sewage normally has a higher temperature
than the receiving water
Increase in temperature of the receiving water
decreases the DO of water.
The foul smelling gases increased in water resulting in
death of marine organisms

*Hydro electric power
generation
Generation of hydroelectric power sometimes results
in negative thermal loading in water systems
Creates less heat on water sources less than nuclear
power plant

*
Solid dot:
Upper lethal
Limit for a
Given species
Open dot:
Best T for
spawning
Solid blocks:
Preferred
Temperature
Range

*
1. The Water Quality Board requests TDEC
conduct a study of the cumulative water quality
impacts of the thermal pollution caused by
existing and proposed power generating plants
on the Tennessee River, including the climatic
scenarios of prolonged drought and warmer
temperatures.
2. The Water Quality Board requests that TDEC
participate in the environmental scoping of the
impacts upon the waters of the State of TN of
the proposed TVA Bellefonte, AL nuclear power
plants and report periodically to the Board.

*
*Cooling towers
*Cooling ponds
*Spray ponds
*Artificial lakes

EVS- GE6351-UNIT 2

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