المحاضرة كاملة (air pollution)
TRANSCRIPT
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ProfessorProfessor DrDr..
Professor of Air and Soil Chemistry
Institute of Graduate Studies and Research
University of Alexandria
ElsayedElsayed AhmedAhmed ShalabyShalaby
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Air Pollution SourcesMonitoringAnd Control
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TODAYS MESSAGETODAYS MESSAGE
The air pollution we create also pollutes our
land and water.
ThereforeTherefore
In order to clean up our water, we must alsoclean up our air!
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Air Pollution DefinitionAir Pollution Definition
May be defined as any substances enters the
atmosphere in concentrations high enough
to cause adverse effect on Man Animals,
registration or materialsAir Pollutants ClassificationsAir Pollutants Classifications
Primary
Pollutants
CO
SO2NO
Secondary
Pollutants
O3NO2H2S
HNO3
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Air Po l lu t ion
Emission Man & animalsVegetation or material
Deposition or Chemical
reactions
AtmosphereEmission rate rate
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Why are we concerned about air pollution?Why are we concerned about air pollution?
AAir quality effects- air pollution can contribute to humanhealth problems and degrade visibility.
LLand effects- pollutants deposition saturates systems andoverloads vegetation
WWater quality effects- Air pollutants and toxic substances go
to water bodies as a final sink after emissions.
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Vocabulary for Airheads
Air Pollutants of Water Quality Concern
Where air pollutants come from and their impacts
What Still Needs to be Done
What Has Been Done to Date
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Volatilization: to pass off in vapor.
Emissions: pollution being released into the air from sources.
Particulate matter: includes dust, soot and bits of solidmaterials released into and move around in the
air.
Atmospheric Transport: air pollutants traveling short or
long distances.
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Vocabulary for AirheadsVocabulary for Airheads
Atmospheric Deposition: the process whereby airborne
particles and gases settle to the Earth's surface.
- Wet Deposition: pollutants deposited in rain, fog,and snow).- Dry Deposition: pollutants deposited with out rain,
fog or snow but in the form of airborne
particles.Atmospheric load: total amount of an air pollutant that
a water body receives.
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Air Pollutants of Water Quality ConcernAir Pollutants of Water Quality Concern
Nitrogen is a nutrient which all things need to grow.
However, human activities contribute more nitrogen
than an ecosystem needs.
Nitrogen Compounds
Nitrogen Oxides (NOx)
Ammonia/Ammonium (NH3/NH4)
Organic Nitrogen (Org-N)
Air Pollutants ofAir Pollutants of
Water Quality Concern continued...Water Quality Concern continued...
Chemical contaminants are natural or manmade
compounds that have the potential to become toxic:
Chemical contaminants
Metals (lead, cadmium, copper)
Mercury
Organic Contaminants
(pesticides, PCBs, PAHs)
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Where Air Pollutants Come FromWhere Air Pollutants Come From
What goes up
must come down
Stationary and area sources
Mobile sources
Agricultural sources
Natural sources
Stationary SourcesStationary Sources
do not move are thought of as large point sources
release relatively consistent quantities of
pollutants.Stationary Source
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Area SourcesArea Sources
Area sources:
smaller clustered stationary
sources
individual emissions may be low
collective emissions can besignificant.
Area Source
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Mobile SourcesMobile Sources
Mobile sources:
are capable of moving.
can be an on-roadcategory.
can be non-road or off-
road category.
On Road Mobile Sources
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Agricultural SourcesAgricultural Sources
Agricultural operations can
generate emissions of gases,
particulate matter, and
chemical compounds.These emissions come from:
animal housing
storage of animal waste
land-applied animal waste
crop production
Crops
Livestock 14
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Natural SourcesNatural Sources
Natural sources of air pollutants
include:
lightning
erupting volcano
weather-caused forest &
prairie fires
unconfined wild animals
Nature
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Atmospheric DepositionAtmospheric Deposition
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Acid rain
Smog (ozone and visibility)
Eutrophication
Accumulation in terrestrial ecosystems and in
drinking water
Nitrogen
IMPACTSIMPACTS OF AIRPOLLUTANTSOF AIRPOLLUTANTS
Bioaccumulate
Persist
Bind to sediments
Affect biological processes
Chemical Contaminants
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Removal ofGaseousPollutantsAnd Fugitive
Dust Control
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Removal of Gaseous Pollutants
and Fugitive Dust Control
themesMain
Absorption
Adsorption Catalytic & thermal oxidation
Fugitive dust control19
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Removal of gaseous pollutants by
liquid absorption
a basic chem. engg. unit operation.
usually carried out in a column or tower in which the gas to be
cleaned comes into contact with fresh liquid introduced at the top;
separation is achieved because of the solubility of the pollutants in
the liquid;
In many applications the absorbing liquid is water (water
scrubbing).
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Absorber types
3 types:Plate column;
Packed column;
Spray column
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Plate tower
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Pac e t erSpr
ay c lumn
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Practical applications
Removal of SO2 by water, amine, alkaline (FGD);
Removal of Nox by alkaline;
Removal of NH3 by water, acid;
Removal of odorous gases in oxidizing solutions;
Removal of CO2 and H2S in amine solutions;
Advantages
Relatively low capital cost, pressure drop and small space
requirements;
Capable of achieving relatively high mass-transfer eff. Increasing the height and/or type of packing or no. of plates
can improve eff. without using a new piece of equipment;
Ability to collect particulates as well as gases;
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Disadvantages
May create water (or liquid) disposal problem;
Wet product collected;
Particulates deposition may cause plugging of
the bed or plates;
Relatively high maintenance costs.
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Typical example of absorptive FGD
system used in Hong Kong
FGD in Lamma Power Station
small scale FGD system in industrial plants
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Adsorption
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Adsorption of air pollutants
A process by which residual molecular forces at the
surface of solids attract molecules of gases and
vapours;
Employed to remove low conc. gases from exhaust
by allowing the gaseous solutes (adsorbate) to
intimately contact a porous solid (adsorbent);
Pollutants
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For air pollution control, these gases and vapors are the pollutants which have to be separated from
the gas stream emitting into the ambient air;
Widely used industrially for odor control and for the removal of volatile solvents (such as benzene,
ethanol, trichloroethylene) from effluent streams.
Activated carbon is the most widely used adsorbents for air pollution control and is effective in
removing virtually all gas and vapors with molecular weights > 45.
Activated carbon is used industrially to remove flue gas SO2 by adsorption,
The adsorbed product will be brought to another plant (e.g. sulphuric acid plant) for extracting
the adsorbed SO2 by heating the adsorbent.
Adsorption can be greatly enhanced if the adsorbent possesses a large specific surface area.
Thus adsorbents such as charcoals, activated alumina, silica gel, and molecular sieves
(aluminosilicates) are particularly effective as adsorbing agents.
These substances have a very porous structure and their large exposed surface can take up
appreciate volumes of various gases.
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Types & applications of adsorbents
ApplicationAppearanceAdsorbent
Organic compounds &hydrocarbons, e.g. for solventrecovery, elimination of odour,purification of gases
Pellet, granuleActivated carbon
Small hydrocarbon molecules,water, e.g. for drying andpurification of gases
Granule, spheroidSilica gel
Oil vapours, water, e.g. for dryingof gases, air and liquidsGranule, spheroidActivated alumina
Molecules up to 10A in size,e.g. for selective removal ofcontaminants from hydrocarbons
Pellet, granule,spheroid
Molecular sieve
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Adsorber
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Advantages of adsorption
Product recovery may be possible;
Excellent control and response to process changes;
No chemical disposal problem when pollutant (product) recovered and return to
process;
Capability of systems for fully automatic, unattended operation;
Capability to remove gaseous/vapor contaminants from process streams to extremely
low levels.
Disadvantages
Product recovery may require an exotic, expensive distillation (or extraction) scheme;
Adsorbent progressively deteriorates in capacity as the number of cycles increases;
Adsorbent regeneration requires a steam or vacuum source;
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Techniques for removal of NOx from flue gas
Combustion modification
Catalytic decomposition
Selective catalytic reduction
Flue Gas Denitrification
NOx can be controlled by modifying the combustion
conditions(post-combustion control) or by removing it from
exhaust gases(exhaust aftertreatment);
Combustion and design modification techniques appear to be
the most economical means of reducing NOx but it is less
efficient than the exhaust aftertreatment;33
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Catalytic decomposition
Methodology:
Applicability:
This technique is of limited usesince no
catalyst was found toprovide sufficient activity
at reasonable temp.
Mostly used in automotive catalyst
2NO N2+ O2catalyst
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Selective catalytic reduction (SCR)
Methodology:
NOx is reduced by NH3over a catalyst in the presence of O2
4NO+4NH3 +O2 4N2 +6H2Ocatalyst
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Selective catalytic reduction
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Applicability:
Most applicable to flue gases from fuel-lean firing combustion
systems
Widely used in utility boilers.
Optimum temperature is at about 1300 K.
TiO2andV2O5are the most commonly used catalyst.
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FUGITIVE DUST CONTROL
MEASURES
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Sources of fugitive dust emissions
Coal yards.
Construction sites.
Unpaved road surfaces
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Sources of fugitive dust emissions
Raw material storage.
Demolition of building.
Renovation of building
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Met l f reduci fugiti e
dust emissi s
1. Wet suppressi
Spra f water f r dust suppressi ;
O l temp rar & must be repeated at regular i ter als.
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2. Chemical stabilization
Salt (CaCl, MgCl):absorb& retain moisture in the surface layer
Wetting agents & surfactants: lower the surface tension of water; rapid
penetration into the surface layer
Dust suppressants: bind fines to large particles in the surface layer
3. Physical stabilizationPlace cover on exposed surfaces to
prevent particles from
becoming airborne due to wind or
machinery action
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4. Vegetative stabilization
Deploy vegetation to control erosion
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5. Specialized techniques
A. Vehicle speed reduction less turbulence
B. Surface cleaning reduces re-entrainment
Manual cleaning Automatic
Cleaning system44
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Vehicular air pollution control
Control of indoor air pollution
Air Pollution ControlAir Pollution Control 33
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Methodologies of reducing vehicular emissionsMethodologies of reducing vehicular emissions
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General approaches of emission controlGeneral approaches of emission control
Good maintenance of vehicles
Good driving practice (e.g. stop engine while
waiting, avoid abrupt acceleration &deceleration)
Use proper fuel for vehicles
Post-combustion emission controls
Use clean fuel (electric car, alternative fuel,fuel cell)
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PostPost--combustion emission controlscombustion emission controls
3-way catalytic converter
Can reduce CO, HC and NOx> 90%
Mandatory.
GasolineGasoline vehiclevehicle
DieselDiesel vehiclevehicle
Great particulate emission (dark smoke)
High NOx HC (carcinogenic)
CO
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Common methods of controlCommon methods of control
Particulate trap )
Diesel oxidation catalyst (DOC) )
Catalyzed soot filter )
Alternative fuels (LPG, natural gas,
bio-diesel, alcoholic fuel)
) Post-combustion
Control
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Diesel vehicleDiesel vehicle
Particulate trap
Diesel oxidation catalyst (DOC)
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DifferentDifferent typestypes ofof alternativealternative fuelsfuels ForFor automobilesautomobiles
Fuel cellFuel cell
LPGLPG
EthanolEthanol
HydrogenHydrogen LNGLNG
CNGCNG BiodieselBiodiesel
MethanolMethanol
ElectricElectric
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Liquefied petroleum gas (LPG)Liquefied petroleum gas (LPG)
Widely used in light-duty vehicles in theworld for many years, current
population: 5 million
Mainly propane (95%) with a small
amount of butane
a non-toxic, colorless &odorless gas.
A clean-burning fuel
Produce fewer emissions than gasoline & diesel engine
Longer service life & reduced maintenance costs
No cold starting problem
Engine performance is almost the same as gasoline
No spillage problem
Closed filling system, so hardly contributes to filling pollution
which is a problem with both petrol & diesel.
Cost
LPG vehicle is more expensive than an equivalent gasoline-powered
vehicle (fuel cost is cheaper than diesel with tax relaxation.
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Alcoholic fuel:Alcoholic fuel: EthanolEthanol
Most widely used alternative fuel
Advantages:
Low pollution Improve air quality
- low emission & toxic compounds: emit almost no PM & much
less NOx than their diesel-fueled counterparts.
combust more completely than gasoline & diesel.
highly soluble & will disperse rapidly; biodegradable, & will
evaporate quickly if spilled on land.
Fire safety -much less flammable than gasoline.
less likely to ignite compared to gasolineFord
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Advantages (contd):Advantages (contd):
Fuel supply options
can be manufactured from a variety of carbon-based
feedstockssuch as natural gas, coal, & biomass
could diversify the country's fuel supply & reduce itsdependence on imported petroleum.
Economically attractive
with advances in technologies, could be produced,
distributed & sold to consumers at a competitive price
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SO2 Air Quality StandardsStandards of Ambient Air Quality and Emissions in Asian Countries and Others(Unit: mg/m3, unless otherwise indicated)
[a] 0.03 mg/m3 for "sensitive" areas, 0.08 mg/ms for "residential and mixed use" areas
[b] One-hour average
[c] Secondary based on environmental effects
[d] Primary based on health effects on humans
[e] Maximum of 3 hours once yearly
Country Annual Average 24-Hour Max Daily Average
China 0.06 0.50 0.15
India - 0.03-0.12 -
Indonesia - - 0.26 (0.1 ppm)
Phillipines - 0.85 (0.3 ppm) [ b] 0.37 (0.14 ppm)
Poland 0.032 - 0.2
Thailand 0.10 - 0.30
World Bank 0.10 0.5 (outside) 1.0 (inside)
USA0.06 (0.02 ppm) [c]
0.08 (0.03 ppm) [d]
0.26 (0.1 ppm) [c]
0.365 (0.14 ppm) [d]
1.3 (0.5 ppm) [c, e]
-
Germany 0.14 (0.05 ppm) - 0.40 (0.14 ppm)Japan 0.26 0.11 (0.04 ppm) -
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NOx Air Quality StandardsStandards of Ambient Air Quality and Emissions in Asian Countries and Others
(Unit: mg/m3, unless otherwise indicated)
CountryCountry Annual Average 24-Hour Max Daily Average
China 0.12 0.15 0.1-0.15
India 0.03-0.12 [a] - 0.0925
Indonesia - - 0.093 (0.05 ppm)
Phillipines - 0.19 (0.1 ppm) [ b] -
Poland 0.05 - 0.15
Thailand - 0.32 [ b] -
World Bank 0.1 (0.05 ppm) - 0.5
USA 0.1 (0.05 ppm) - -
Germany 0.1 (0.05 ppm) - 0.3 (0.15 ppm)
Japan - - 0.04-0.06
EU 0.2 - -
[a] 0.03 mg/m3 for "sensitive" areas, 0.08 mg/m3 for "residential and mixed use" areas
[b] One-hour average 58
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Particulates Air Quality StandardsParticulates Air Quality Standards
The most frequently used reference guidelines are those of the World Health Organization (WHO), the
European Union (EU), and the standards of the U.S. Environment Protection Agency (U.S. EPA). The WHO
and U.S. EPA guidelines/standards have been set based on clinical, toxicological, and epidemiological
evidence. Guideline values of ambient particulate concentrations were established by determining
concentrations with the lowest-observed-adverse-effect (implicitly accepting the notion that a lower threshold
exists under which no adverse human health effects can be detected), adjusted by an arbitrary margin of safety
factor to allow for uncertainties in extrapolation from animals to humans and from small groups of humans to
larger populations. Standards determined by the U.S. EPA also reflect the technological feasibility of
attainment.
Note: Adverse effect is defined as "any effect resulting in functional impairment and/or pathological lesions
that may affect The performance of the whole organism or which contributed to a reduced ability to respond to
an additional challenge" (see U.S. EPA, 1980). The EU guidelines have been determined by consultation and
legislative decision-making processes that took into account the environmental conditions and the economic
and social development of the various regions, and acknowledged a phased approach to compliance. A
potential trade-off was also recognized by the guidelines for the combined effects of SO2 and particulate
matter.59
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Country Air Quality Standards for ParticulatesCountry Air Quality Standards for Particulates
Standards of Ambient Air Quality and Emissions in Asian Countries
(Unit: mg/m3, unless otherwise indicated)
Country Annual Average 24-Hour Max Daily Average
China - 1.00 [a] 0.5 [ b] 0.30[a] 0.15 [b]
India 0.1-0.5 [c] - -
Indonesia - - 0.26
Phillipines - 0.25 [d] 0.15
Poland 0.05 - 0.12
Thailand 0.10 - 0.33
World Bank 0.10 0.50 -
USA 0.065 [e] 0.075 [f] 0.15 [e] 0.26 [f] -
Germany 0.1 [g] 0.2 [h] - 0.2 [g] 0.4 [h]
Japan - 0.20 0.1
[a] Total suspend [b] Fly dust
[c] 0.1 mg/m3 for "sensitive" areas, 0.2 mg/m3 for "residential" and "rural" areas, and 0.5 mg/m3 for "industrial and mixed
use" areas
[d] One-hour average [e] Secondary based on environmental effects
[f] Primary based on health effects on humans [g]
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EU Air Quality Standards
EU Guide Values:
Limit Values for Suspended Particulates, Sulphur Dioxide,
Oxides of Nitrogen, and Lead
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The Environmental Protection Agency Act 1992 (Ambient Air Quality Assessment and
Management) Regulations 1999 (S.I. No. 33 of 1999) and the Air Quality Standards
Regulations 2002 (S.I. No. 271 of 2002) transpose Council Directive 96/62/EC and the
first two daughter directives, Council Directive 1999/30/EC and Council Directive
2000/69/EC into Irish law. The 2002 regulations came into force on 17th June 2002; theydeal with sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter,
lead, carbon monoxide and benzene in ambient air.
A third daughter directive, Council Directive 2002/3/EC relating to ozone was published
in February 2002 and was transposed into Irish law by S.I. No. 53 of 2004. The fourth
daughter directive has not yet been finalised. It will deal with polyaromatic
hydrocarbons, arsenic, nickel, cadmium and mercury in ambient air. The tables below set
out the limit values or target values specified by the three published daughter directives.
LimitLimit ValuesValues forfor PollutantsPollutants MeasuredMeasured
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Limit Values of Directive 1999/30/EC
PollutantLimit Value
Objective
Averaging
Period
LimitValue
ug/m3
Limit Value
ppb
Basis of Application of the
Limit Value
Limit Value
Attainment Date
SO2Protection of
human health1 hour 350 132
Not to be exceeded more
than 24 times in a calendar
year
1 Jan 2005
SO2Protection of
human health24 hours 125 47
Not to be exceeded more
than 3 times in a calendar
year
1 Jan 2005
SO2Protection of
vegetationcalendar year 20 7.5 Annual mean 19 July 2001
SO2Protection ofvegetation
1 Oct to 31 Mar 20 7.5 Winter mean 19 July 2001
NO2Protection of
human health1 hour 200 105
Not to be exceeded more
than 18 times in a calendar
year
1 Jan 2010
NO2Protection of
human healthcalendar year 40 21 Annual mean 1 Jan 2010
NO + NO2Protection of
ecosystemscalendar year 30 16 Annual mean 19 July 2001
PM10 - Stage 1Protection of
human health24 hours 50
Not to be exceeded more
than 35 times in a calendar
year
1 Jan 2005
PM10 - Stage 1Protection of
human healthcalendar year 40 Annual mean 1 Jan 2005
PM10 - Stage 2Protection of
human health24 hours 50
Not to be exceeded more
than 7 times in a calendar
year
1 Jan 2010
PM10 - Stage 2Protection of
human healthcalendar year 20 Annual mean 1 Jan 2010
LeadProtection of
human healthcalendar year 0.5 Annual mean 1 Jan 2005 63
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Target Values and ozone daughter Long Term Objectives of Directive 2002/3/EC
The directive is different from the previous two in that it sets target values and long term
objectives
for ozone levels rather than limit values. They are as follows:
Target Values for Ozone from 2010
Objective Parameter Value
Protection of human
healthMaximum daily 8hour mean
120 ug/m3 not to be
exceeded more than 25 days
per calendar year averaged
over 3 years
Protection of vegetationAOT40, calculated from 1hour
values from May to July
18000 ug/m3-h averaged
over 5 years
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Conversion factors from ppb to ug/m3
Nitrogen dioxide 1 ppb = 1.91 ug/m3
Sulphur dioxide 1 ppb = 2.66 ug/m3
Ozone 1 ppb = 2.0 ug/m3
Carbon monoxide 1 ppb = 1.16 ug/m3Benzene 1 ppb = 3.24 ug/m3
List of Abbreviations
ug/m3 - micrograms per cubicmetreNO2 - Nitrogen Dioxide
NO - Nitric Oxide
SO2 - Sulphur Dioxide
PM10 - Particulate Matter with a diameter less than 10 microns
AOT40 : This is a measure of the overall exposure of plants to ozone. It is the sum of the
excess hourly concentrations greater than 80 ug/m3 and is expressed as ug/m3
hours. Only values measured between 08:00 and 20:00 Central European Time
each day from May to July are used for the calculation. (The name AOT40 refers
to 40ppb which is the same as 80 ug/m3).
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The following is a worked example:
Local Time Ireland Central European Time Ozone Concentration ug/m3 Difference between previous
column and 80 ug/m323:00 00:00 63
Not counted before 08:00
00:00 01:00 70
01:00 02:00 65
02:00 03:00 63
03:00 04:00 45
04:00 05:00 5405:00 06:00 56
06:00 07:00 55
07:00 08:00 55 Only values greater than 80 count
08:00 09:00 62 0
09:00 10:00 51 0
10:00 11:00 70 0
11:00 12:00 92 12
12:00 13:00 90 10
13:00 14:00 82 2
14:00 15:00 87 715:00 16:00 91 11
16:00 17:00 90 10
17:00 18:00 89 9
18:00 19:00 84 4
19:00 20:00 85 Not counted after 20:00
20:00 21:00 83
21:00 22:00 70
22:00 23:00 60
AOT40 = sum of values in the 4th column = 65 ug/m3 hours 68
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WorldWorld bankbank
Background
In 1998, the World Bank Group has issued Thermal Power: Guidelines for New
Plants, which define procedures for establishing maximum emission levels for fossil-
fuel based thermal power plants with a capacity of 50 or more megawatts of electricity
(MWe) that use coal, fuel oil, or natural gas. The guidelines include emission limits for
particulate matter, SO2 and NOx for various types of power plants, including engine-
driven power plants. The guidelines also include ambient air quality standards, as well
as provisions applicable to noise, liquid effluents, and solid wastes from power plants.
The guidelines have been adopted to assist the World Bank in making funding
decisions for new power plants. However, internationally, the World Banks guidelines
have been widely used as the minimum norm if the host country does not have its own
specific legislation for engine-driven power plants. 69
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EngineEngine EmissionEmission StandardsStandards
BackgroundThe maximum emission levels are expressed as concentrations, to facilitate
monitoring. The emission limits are to be achieved through a variety of control and fuel
technologies, as well as through good maintenance practice. Dilution of air emissions to
achieve the limits is not acceptable.
The following are emission limits for engine driven power plants:
Particulate matter. PM emissions (all sizes) should not exceed 50 mg/Nm3.Sulfur dioxide. Total SO2 emissions should be less than 0.20 metric tons per day (tpd)
per MWe of capacity for the first 500 MWe, plus 0.10 tpd for each additional MWe of
capacity over 500 MWe. In addition, the SO2 concentration in flue gases should not
exceed 2,000 mg/Nm3, with a maximum emissions level of 500 tpd.
Nitrogen oxides. Provided that the resultant maximum ambient levels of nitrogen
dioxide are less than 150 g/m3 (24-hour average), the NOx emissions levels should beless than 2,000 mg/Nm3 (or 13 g/kWh, dry at 15% O2). In all other cases, the maximum
NOx emission level is 400 mg/Nm3 (dry at 15% O2).
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AmbientAmbient AirAir QualityQuality
Pollutant24-houraverage
Annual average
PM10 150 50
Total suspended particulates (TSP)a 230 80
NO2 150 100
SO2 150 80
a - Measurement of PM10 is preferable to measurement of TSP
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BasicAir Pollution Monitoring
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Why we need taking Air Pollution Monitoring?
How importance of getting Good Quality data.
Gas Pollutants Measurement.
Particulate Matter Measurement
IntroductionIntroduction
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How bad the air we breathe?
Setting up fixed air monitoring stations at
selected location for collecting air quality data
continuously.
Use of Database.
Review Air Pollution Control policy.
AirAir PollutionPollution MonitoringMonitoring
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Garbage In Garbage Out (GIGO).
Prepare Standard Operating Procedure (SOP) forconcerned station staff to perform selected task
work.
Setting up QA/QC program.
GettingGetting GoodGood QualityQuality DataData
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Sulfur Dioxide (SO2).
Oxide of Nitrogen ( NO - NO2 - NOx).
Ozone (O3).
Carbon Monoxide (CO)
GasGas PollutantsPollutants MeasurementMeasurement
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Pulsating UV Light used as
exciting source.
Absorbs light in 230 nm-190 nm
region.
Excited SO2 emit a characteristicradiation from higher state back
to ground state.
Photomultiplier tube converts the
radiation into electrical signal
proportional to the SO2concentration.
SulfurSulfur DioxideDioxide AnalyzerAnalyzer
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Gas-phase reaction of nitric oxide (NO) and ozone (O3) produces a characteristic
luminescence. (NO + O3 ---> NO2 + O2 + hv).
Light emission take-place when excited NO2 decay to lower energy state.
Nitrogen dioxide (NO2) must first be transformed into NO before it can be measured using
the chemiluminescent reaction. A molybdenum converter heated to 325 degree C to
convert NO2 to NO via the reaction: (3 NO2 + Mo ---> 3 NO + MoO3)
OxideOxide ofof NitrogenNitrogen AnalyzerAnalyzer
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UV photometer determines ozone concentration by measuring the attenuation of light due
to ozone in the absorption cell.
Absorption wavelength is 254 nm.
The concentration of ozone is directly related to the magnitude of the attenuation.
OzoneOzone AnalyzerAnalyzer
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Total Suspended Particulate (TSP).
Respirable SuspendedParticulate (RSP).
PM10 Sampling System
PM2.5 Sampling System
Type of Filter Media
Criteria for Filter Selection
ParticulateParticulate MatterMatter MeasurementMeasurement
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Total Suspended Particulate (TSP) High
Volume Air Sampler (particle size < 100
um): flow-rate adjustable ranging from 20
to 60 cubic feet per minute (cfm).
Mass flow controller and Volumetric Flow
Controller are widely used for keeping
constant flow-rate during collecting
particulate matter.
ManualReference Method Sampling Equipment (I)ManualReference Method Sampling Equipment (I)
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Respirable Suspended Particulate (RSP) PM10
High Volume Air Sampler: design flow-rate is
40 cfm (1.13 cmm). Flow controllers used as
same as TSP sampler.
ManualReference Method Sampling Equipment (II)ManualReference Method Sampling Equipment (II)
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PM2.5 Fine particulate standard is
published in the Federal Register dated
July 18, 1997.
Four types of samplers are currently inuse including Single channel,
Sequential, Portable Audit and
Speciation sampler.
ManualReference Method Sampling Equipment (III)ManualReference Method Sampling Equipment (III)
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Cellulose Fiber Filter (TSP) 8 x 10
Glass Fiber Filter (TSP) 8 x 10
Quartz Fiber Filter (PM10) 8 x 10
Quartz Fiber Filter (PUF) 102 mm Circle
Teflon Filter
Pallflex TX40 Filter
TypeType ofof FilterFilter MediaMedia
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www.cse.polyu.edu.hk/~airlab
www.epa.gov/ttn
Federal Register, 40CFR part 50,51,52,53 and 58,
Reference Method for the Determination ofSuspended Particulate Matter in the Atmosphere
(High Volume Method).
Quality Assurance Handbook for Air Pollution
Measurement System, Volume II, Ambient Airspecific Methods.
ReferenceReference MaterialMaterial
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Indoor and outdoor air pollution
Air Pollution Control
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Air Pollution Control
Topics to be covered:
Approaches of air pollution control.
Considerations in selecting APC equipment Different types of dust control equipment
Fugitive dust control
Gaseous pollutants control
Vehicular pollutants control
Indoor air pollutants control
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LONG-TERM CONTROL:
Involves a legislated set of measures to be adopted over a multi-
year period
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Comprehensive air pollution
control strategy
Figure 1 Elements of a comprehensive air pollution control strategy for a region
Sort-term controlLong-term Control
Urban
planning and
zoning
Rescheduling
of activities
Programmed
reduction in the
quantity of
material emitted
Rescheduling of
activities
Immediatereducti
on in emissions
Requirements for long-term planning Requirements for real-time control
Air quality objective
Airshed model
Survey of control techniques and costs
Meteorological probabilities
Air quality objective
Dynamic model
Rapid communications
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19901990 LevelLevelCountryCountry
-8%EU countries
-7%U. . .
-6%Japan
0Russia, New Zealand
+8%Australia
+10%Ireland
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SHORT-TERMCONTROL (episode control):
involves shutdown & slowdown procedures that areadopted over periods of several hours to several days
under adverse meteorological conditions
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Meteorological
prediction
Prediction -
simulationEmergency
Controlprocedures
Automatic air
monitoring network
Atmosphere
Emissionstandard
enforcement
StackMonitoring system
Emission
sources
Element of a real-time air pollution control system.
Air quality
Alert level
Emission
standards
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2. PREVENTION
Approaches of Air Pollution control (cont.)What
means are available to prevent air pollution fromoccurring?
Aside from shutting down all polluters, there are
means available or potentially available to remove
all or part of the pollutants to the extent necessary to
prevent serious atmospheric contamination. Airpollution control devices
Approaches of Air Pollution control (cont.)
Air pollution control devices
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What are the driving forcesfor controlling air pollution?
1) Environmental protection
2) Occupational health consideration in workplace3) Social consideration
4) Legal limitation imposed by government
What considerations should be
Taken When selecting air pollution
control equipment?
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1. Environmental
Ambient conditions
Maximum allowable emissions (emission standard)
Contribution of APC system to wastewater, land
pollution and noise pollution problems
Aesthetic considerations (visible steam etc.)
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2. Engineering Contaminant characteristics.
Gas stream characteristics.
Design & performance characteristics of the
particular control system.
3. Economic
Capital cost (equipment, installation, engineering, etc.).
Operationcost (utilities, maintenance, etc.).
Expected equipment lifetime and salvage value
The final choice of equipment is usually dictated by that
equipment capable of achieving compliance with regulatory
codes at the lowest cost (total cost include capital cost,
maintenance and operation costs).
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Different Types of Air Pollution Control Equipment
1) Mechanical Collector.
2) Baghouse.
3) Electrostatic Precipitator
4)Wet Scrubber
Particulates
removal
5) Absorber.
6) Adsorber.
7) Incinerator
8) Condenser
Gaseous removal
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Commonly used air pollution control
methods/techniques
Industrial application.
- particulate matter (PM)
- gaseous pollutant
Fugitive emission control.
Vehicular emission control.
Indoor air pollution control
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AdvantagesHigh removal efficiency (>99%) for coarse and fine particulate
Very small particles can be collected
Dry dusts can be collected for recovery of valuable material (e.g. fly ash)
Small pressure and temperature drops
Designed to operate continuously with little maintenance over long periods of
time
Few moving parts reduce maintenance
Can be used at high temp. (700C) & high pressure ( 2 x 106m3/hr)
Low power consumption and hence low operating cost106
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High capital cost
Not easily adaptable to variable condition
(i.e. flows, temp., particulate loadings)
Some particles with extremely high or low
resistivity are very difficult to be collected
Disadvantages Application area
Incinerator,
utility boiler,
furnaces,
refineries, smelters,
paper mills,
small household air-conditioning
system
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PM Removal
Fabric filter
It is one of the most common techniques for collecting dust. A filter generally is any porous structure composed of granular or fibrous material
which tends to retain the particulate as the carrier gas passes through the voids of the
filter.
Two basic types of filters are usually used:-
Disposable and non-disposable (more commonly used industrially)
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A typical baghouse
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Advantages
Extremely high collection eff. on both coarse
and fine particulates (> 99.9%).
Collected dust is recovered dry for
subsequent processing/disposal
Disadvantages
Temp. > 300C require special refractory
mineral or metallic fabrics that are still in the
developmental stage.
Conc. of some dusts in the collector (~59 g/m3)
may cause explosion hazard if a spark or flame
is admitted by accident. Fabrics can burn ifreadily oxidizabledust is being collected
Application area
Vacuum cleaner,
air conditioning system, ash and material handling plant,
power plant,
cement plant, etc.