المحاضرة كاملة (air pollution)

8/8/2019 (Air Pollution)

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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



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



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



year

1 Jan 2005


human healthcalendar year 40 Annual mean 1 Jan 2005


human health24 hours 50



year

1 Jan 2010


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.

المحاضرة كاملة (air pollution)

Documents