AIR QUALITY AND POLLUTION (TKA 3301) LECTURE NOTES 8- Criteria Pollution

8/9/2019 AIR QUALITY AND POLLUTION (TKA 3301) LECTURE NOTES 8- Criteria Pollution

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Dr. Marzuki Hj. IsmailDr. Marzuki Hj. Ismail

Semester I 2009/10Semester I 2009/10

ENTECHENTECH

Dr. Marzuki Hj. IsmailDr. Marzuki Hj. Ismail

Semester I 2009/10Semester I 2009/10

ENTECHENTECH


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Ambient air is the air to which the general publichas access, i.e. any unconfined portion of theatmosphere.

The 2 basic physical forms of air pollutants areparticulate matter and gases.

Criteria pollutants - most common air pollutants inMalaysia

I

ntroductionI

ntroduction


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Primary pollutants - CO, SO2, NOx, HC, VOC, PM

Secondary pollutants - O3, nitrates, sulfates


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3 major sources of air pollution in Malaysia:3 major sources of air pollution in Malaysia:

Mobile sourcesMobile sources

Stationary sourcesStationary sources

Open burning sourcesOpen burning sources

Major Sources of Air Pollution

Open Burning

Stationary

Mobile

Mobile Stat ionary Open Burning


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Threshold level The pollutant level below which no ill effects are

observed

Dose The concentration multiplied by the time of

exposure

Synergistic Effect Combination of two things to produce a greater

effect than one.


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Sites in human body showing symptoms of air pollutioninclude:

Eyes, nose, throat and lungs

3 categories of impact:-

1. Chronic Pollutants cause gradual deterioration of a variety of

physiological functions over several years

2. Acute Pollutants cause life-threatening reactions within a period of

hours or days

3. Carcinogenic Pollutants initiate changes in cell that lead to uncontrolled

growth/ divisions of cancer


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1. Sources of CO

2. Effects of CO

3. CO standards for Malaysia4. Formation and fate of CO

5. CO emission control


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1. Natural Sources:

Anaerobic decomposition of carbonaceous material releases

methane (CH4)

Methane is oxidized by hydroxyl radical (OH) to form alkyl

radical (CH3)

CH4 + OH* CH3* + H2O

The reaction is followed by a complex series of reaction, which

can be represented as:

CH3* + O2 + 2 (hv) CO + H2+ OH

*

v = frequency of light

h = Planks constant


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2. Anthropogenic (man-made) sources:

Mobile sources automobiles (~ 60%)

Stationary sources (~ 40%) Burning of fossil fuels

Industrial processes

Solid waste disposal

Biomass burning


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Colorless, odorless, tasteless gas p Silent Killer

Nodetrimental effects onmaterial andplants.

High concentrationofCO cancause physiological

andpathological changesandfinallydeath.

CO isapoisonousinhalant.

CO reacts with hemoglobininthe bloodtoform

carboxyhemoglobin (COHb).


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People with cardiovascular disease, such asangina, are most at risk from CO.

People with marginal or compromisedcardiovascular and respiratory systems, fetusesand young infants, may also be at greater riskfrom CO

In healthy individuals, exposure to higher levelsof CO can affect mental alertness and vision.


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Ambient standard

Averaging time* Standard, ppm

8 h 9

1 h 35* average time is the period over which concentration

are measured and averaged

Emission standard for vehicles (petrol engine)

petrol engine in use (new model): 3.5% CO


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Formation of CO CO is formed as an intermediate product during combustion of

carbonaceous fuels

Co occurs as a final product during combustion of richmixtures

(insufficient oxygen)

The reaction is represented by the following equation:

CH4 + O2 CO + 2H2O

In lean mixtures(excessoxygen) CO is formed because of 2

reasons:

Poor mixing of the fuel and air resulting in some region beingfuel-rich

CO is formed in the high temperature region of the combustion

zone because at T>2000 0K, the oxidation of CO to CO2 is

negligible


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Summary of CO formation

3 main ways:

(i) Incomplete combustion ofcarbon to carbon containing compounds (2C + O2

2CO)

(ii) Dissociation of CO2 to CO and O at very high temperature (CO2 CO +

O)

(iii) High temperature reaction between CO2 and carbon containing compounds

(e.g. in blast furnace)

(CO2 + C 2CO)


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Fate of atmospheric CO

A large percentage of atmospheric CO is removed by biological process through

the action of soil microbes (fungi)

CO in the air may eventually oxidize into CO2 through reactions with free radical

present in the air:

CO + HO + O2 CO2 + HO2

(HO hydroxyl radical; HO2 hydroperoxyl radical)


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Mobile sources automobiles

3 types of engine:

the gasoline engine

the dieselengine

the jetengine

The gasoline engine:

4stroke engine (intake stroke; compression stroke; power stroke; exhaust

stroke):

Mixture of fuel & air is fed into a cylinder by the carburetor & is compressed & ignited

by a spark from the spark plug

1 kg of gasoline can burn completely when mixed with about 15 kg of air. However, for maximum power a lower air to fuel ratio is used resulting in incomplete

combustion.

CO is formed & discharged in the exhaust together with unburnt gasoline &

hydrocarbons


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The diesel engine:

Air supply is unregulated leading to higher air to fuel ratio. No

carburetor is required since fuel is injected directly into the

combustion chamber. No spark ignition is required since the air is

heated by compression.

A well designed, well maintained & properly adjusted diesel engine

will emit less CO hydrocarbons than the four stroke engine because

ofthe diesels high air to fuel ratio.

The jet engine:

Air drawn into the front of the engine is compressed & then heated

by burning fuel. The expanding gas passes through the turbine

blades which drive the compressor. The gas then exits the engine

through the exhaust nozzle.

The main pollutants is emitted are particulates % NOx


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Control of CO from mobile sources In general control strategies fall into 3 categories:

Engine modifications

Fuel system modifications

Exhaust treatment devices

The most significant control is the use of 3-waycatalytic

converter for exhaust treatment. A chemical catalyst made of

noble metals (platinum & rhodium) operating at around 800

C Oxidizes VOCs to CO2 & H2O & CO to CO2 while reducing NOx

to N2 at the same time.

catalyst

HC + CO + NOx H2O + CO2 + N2


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Motorcycle catalytic converter Catalytic converterfor Honda/Acura


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Control of CO from stationary processes

Sources of CO from non-combustion processes:

Steel & petroleum refining.

Co is usually collected & burnt in furnace or waste heat boilers. If CO

concentration is low, it can be catalytically oxidized in an afterburner or removed

by scrubbing in copper ammonium formate solution.

The most practical method of control from stationary combustion sources is by

proper design, installation, operation, & maintenance of the combustion

equipment.


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Nat al

Sea salt, soil dust, volcanic particles, smoke from forest fires, nitrates, sulfates,

terpenes (unsaturated hydrocarbons that give scent to lemon and pine),

photochemical reaction.

Anth p g nic ce (man-made) Fossil fuel burning, industrial processes, automobile, condensable

hydrocarbons, sulfates, nitrates

Reactions:

Conversion of H2S and SO2 to sulfates (SO4)

Conversion of NOx and NH3 to nitrates (NO3) Reaction of hydrocarbons to condensable products that form particulates at

atmospheric condition.


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Primary particulates:

Emitted directly from sources to atmosphere.

Secondary particulates: Formed from reactions with other substances, ex.

Particles formed from photochemical reactions havevery small diameters [< 0.4 microns)

Smoke and fly ash have diameters that range from0.05 to 200 microns.


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Particulates:

Any material, except uncombined water, that exists in the solid or liquid

state in the atmosphere or gas stream at standard conditions

Aerosol:

A dispersion of microscopic solid or liquid particles in gaseous media

Dust:

Solid particles larger than colloidal size capable of temporary suspension

in air

Fog:

Visible aerosol


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Inhalable particles: < 10 mm (PM10)

Coarse particulates: > 2.5 mm in diameter; normallycontain earth crusted materials and dust from industries

and vehicles

Fine particulates: < 2.5 mm in diameter; containsecondarily formed aerosols; combustion particles and

recondensed organic and metallic vapors


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Flyash:

Finely divided particles of ash entrained in flue gas. Particles may contain

unburned fuel

Fume

Particles formed by condensation (vapor to liquid); sublimation (solid to gas

without going to liquid phase), or chemical reaction, predominantly smaller

than 1 micron (tobacco smoke).

Mist

Dispersion of small liquid droplets of sufficient size to fall from the air.

Smoke

Small gas borne particles resulting from combustion

Soot

An agglomeration of carbon particles


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Many compounds are in PMPrim r Particl s(dir ctl mitt d)

c dar Particl s

(fr m r c rs r as s)

Other

(sea salt)

Crustal

(soil,dust)

Carbon

(Soot)

Metals

NOx

Ammoni

a

VOCs

Organic

CarbonSO2

Ammonium

Sulfate

AmmoniumNitrate

Composition of PM tells us aboutComposition of PM tells us about

the sources and formation processesthe sources and formation processes

Ga

s

Particle


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The most important characteristic of aerosol is particle size distribution.

In a typical situation, to reduce health impact, the right thing to do is to

remove and reduce the particulates in the size range < 1Qm which may

make up > 90% of the total number of particles but which mayconstitute only 3% of the total mass.


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Coagulation: Part c s c d and st ck t th r.

Cond nsation: Gas s c nd ns nt a small s lid article

t f rm aliquid dr let.

Chemical Reaction: Gases react t f rm articles.

Cloud/FogProcesses: Gases diss lveina water dr let and chemically

react. A articleexists when the waterevaporates.

ulfate


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Substance Size range (micron)

Said grain 20 to 200

Paper 75

Human hair 50

Particle causing air pollution 0.01 to 10

Typical crushing operation > 10

Combustion, evaporation, orcondensation process

0.1 to 10

Tobacco smoke 0.01 to 1

(Note: 1 micron = 1Qm = 10-4 cm = 10-6m)


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Respiration is gas exchange between anorganism and the environment

Respiratory structures include the nose,

pharynx

, larynx

, trachea, bronchi, bronchiolesand alveoli

Mechanics of Breathing

Respiratory Diseases

Exhalation

Inhalation


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Nasal Passage

Pharynx

Trachea

Bronchus

Larynx

Bronchioles

Alveoli


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PM can accumulate in the respiratory system and areassociated with numerous health effects.

Adverse health effects have been associated withexposures to PM over both short periods (such as a

day) and longer periods (a year or more). People with existing heart or lung are at increased

risk . The elderly also are sensitive to PM exposure. PM can increase susceptibility to respiratory infections

and can aggravate existing respiratory diseases.


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PM increases the risk of respiratory death in infantsunder 1 year, affects the rate of lung functiondevelopment, aggravates asthma and causes otherrespiratory symptoms such as cough and bronchitis inchildren;

PM2.5 seriously affects health, increasing deaths fromcardiovascular and respiratory diseases and lungcancer. Increased PM2.5 concentrations increase therisk of emergency hospital admissions forcardiovascular and respiratory causes; and

P

M10

affects respiratory morbidity, as indicated byhospital admissions for respiratory illness.


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Wheezing and coughing

Heart attacks and death

TSP (Total Suspended Particles)

In presence of SO2, direct correlation betweenT

SP andhospital visits for bronchitis, asthma, emphysema,pneumonia, and cardiac disease

~60,000 deaths from PM (AHA)

1% increase in mortality for every 10 mg/m3 increase in PM(AHA)

Respiratory mortality up 3.4% for the same (AHA) Cardiovascular mortality up 1.4% for the same

(AHA)

Wide Range


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Asthma 14 Americans die/dayofasthma

3x reater than 20 yrs ago

Increased health care costs

Particulateepisodes Inversions

Inpresenceof 2 1930: euse Valleyin elgium- 60 deaths

1948: Donora,PA- 20 deaths

1952: LethalLondon mog- 12,000 deaths


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Cement-dust coating on apple leaves and fruit. The dust hadno injurious effect on the foliage, but inhibited the action of apre-harvest crop spray.


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Viainhalation/respiratoryas well

as eye/skin

Threeparts of respiratory system

Naso-pharyngeal (HAR)

Tracheo- ronchial (TBR)

Pulmonary-Alveolar (GER)

Lungs p portalofentry

Purpose

GER A > 75 m2


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Naturalprotection mechanisms

Naso-pharyngeal (HAR)

Tracheo- ronchial (TBR)

ucociliaryescalator

Bronchial constriction

Pulmonary-Alveolar (GER)

acrophages (phagocytosis)

No ciliaryaction


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Human airways are lined with a ciliarymembrane. These cilia are 5 m in length, andas the cilia beat, they engage with, and propel,

a thin overlying layer of mucus.


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A type of white blood that ingests (takes in) foreign material.

Macrophages are key players in the immune response to foreigninvaders such as infectious microorganisms.

Once a white cell has left the blood vessel and migrated to the

enemy, the next job is to EAT the microbe. This human macrophage, is a professional "phagocyte" or eating

cell (phago = "eating", cyte = "cell").

But eating the organisms is not enough.

To insure that the organisms not grow and divide within the

macrophage, the white cell must kill the organisms by somemeans such as the OXIDATIVE BURST.


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The macrophage is using its internal cytoskeleton to envelop cellsof the fungus Candida albicans.


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AIR QUALITY AND POLLUTION (TKA 3301) LECTURE NOTES 8- Criteria Pollution

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