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SAMPLING PROCEDURE
FOR AIR AND SOLID
WASTE
SUBMITTED TO: Dr. MEENA
THAKUR
SUBMITTED BY: YASHPAL (F-14-21-M)

SAMPLING:
Sampling is the process of collection of represented
sample from the whole of the population.
SAMPLE:
Part of population consisting of one or more
sampling units, selected and examined as a
representive of whole.

SAMPLING OF AIR POLLUTANTS
First step in analysis of air pollutant.
May be present either alone or in
combinations.
Due to the difference in physical states and
the variability in ambient concentrations,
common devices cannot be applied for all
kinds of pollutant.

HOW TO HAVE A GOOD SAMPLE
Size of sample: 10 m3
Sampling rate : 0.003- 3.0 m3/min.
Sampling time : 3 hour

COLLECTION OF GASEOUS AIR POLLUTANTS
Four methods:
1.Grab sampling
2.Absorption in liquid
3.Absorption on solids
4.Freeze out sampling

GRAB SAMPLING
The sample is collected by filling an evacuated flask or an
inflatable bag.
Plastic bags , glass and stainless containers are widely used
for grab sampling.
The containers are evacuated and filled by allowing air to
enter. A container may be filled with water and then used as a
collector simply by draining away the water which is replaced by
a air.
Heating tapes and nichrome wires are used to prevent
condensation during sampling.

ABSORPTION IN LIQUID
Most common method of collecting the samples.
Separates the desired pollutants from air either
through direct solubility in absorbing medium or by
chemical reaction.
Collectors used:
to provide high degree of gas liquid contact.
 Fritted absorber
 Impingers

ABSORPTION ON SOLID
Based on tendency of gasses to be absorbed on
surfaces of solid material.
Sample air is passed through a packed column
containing a finely divided solid adsorbent on
whose surface the pollutants are retained and
concentrated.
Activated charcoal and silica gel are most
commonly used solid adsorbents.

FREEZE OUT SAMPLING
Contains a series of cold traps.
Maintained at low temp.
Used to draw the air sample whereby the
pollutants are condensed.
Traps are brought to lab and analyzed by
means of gas chromatography, IR & UV
spectrophotometry, mass spectrometry or by
wet chemical means.

SAMPLING OF PARTICULATE MATTER
Five methods:
1.Filteration
2.Sedimentation
3.Electrostatic precipitator
4.Thermal precipitator
5.Impingers.

FILTERATION
Most common technique used for sampling of particulate
matter.
The filter materials are:
Cellulose filter paper for determination of metals and
anions.
Glass fibers for analysis of organic compounds.
Silica felts for trace inorganic species and organic
compounds.
Optimum pore size of these filters is 0.45µ.

SEDIMENTATION
Suitable for comparatively larger particles having
size more than of 10µ.
Apparatus used is simple glass jar fitted with a
funnel.
A liquid is added to the collector so that solids are
prevented from being blown out of air.
Sample is deposited over a period of 1 month and
the material is dried and weighed.

ELECTROSTATIC PRECIPITATOR
Very efficient for collection of small particles.
Particles are collected on circular plate.
On entering the sampler, particles pick up charge as
they pass through an electric discharge between two
electrodes maintained at a potential differences of up to
3000 volts.
Small charged particle in gas stream loose their charge
in contact with electrode(oppositely charged) and get
accumulated on the electrode.

THERMAL PRECIPITATORTHERMAL PRECIPITATOR
Based on a principle of thermal force which
deflects the particles from the zone of lower temp.
to the zone of higher temp.
Used for the collection of particles of 0.001µ.

IMPINGERSIMPINGERS
It collect particles
from a relatively
high velocity air
stream directed at
a surface.
Device is a dry
impinger when
collecting surface
is dry and wet
impinger when
surface is wet.

SAMPLING OF GASES AND VAPOURSSAMPLING OF GASES AND VAPOURS
Four methods:
1.Bags and containers.
2.Absorption.
3.Adsorption.
4.Cold trapping.

COLD TRAPPINGCOLD TRAPPING
All particles from an air stream may be removed by
cold trapping i.e. freezing & liquefying gases and
vapours in collectors maintained at a low temperature.
Fractionation is achieved by using collector
maintained at progressively low temperature.
The first collector is maintained in an ice bath & the
last collector in a liquid nitrogen bath (-196C).

ABSORPTIONABSORPTION
Method of collection of gaseous pollutant is
absorption in a solvent, such as by bubbling the gas
through a liquid.
Pure water is adequate for collecting some
gaseous pollutants such as HF.
Alkaline solution for absorbing acidic gases, acidic
solution for absorbing alkaline gases and oils for
collecting hydrocarbons.

ADSORPTIONADSORPTION
Charcoal is efficient adsorber for gases and
vapours in air.
Air is pumped through the tube at a rate of
1L/min.
After adsorption charcoal is washed with suitable
solvent such as CS₂.
Beside charcoal silica gels, aluminium oxides are
also used as adsorber.

SAMPLE PRESERVATIONSAMPLE PRESERVATION AND STORAGEAND STORAGE
PURPOSE :
To minimize physical, chemical and biological changes
Three approaches:
1. Refrigeration
2. Use of proper sample container
3. Addition of preserving chemicals.

Refrigeration: to slow down loss processes
Container choice (material type and headspace) is critical
to reduce
– Volatilization
– Adsorption
– Absorption
– Diffusion
– Photodegradation
Addition of preservatives is critical to reduce losses due
to chemical reactions and bacterial degradation.

PROCEDURE:
1. Upload a truckload of wastes in a controlled area
away from other operations.
2. Quarter the wasteload.
3. Select one of the quarters and quarter the
quarter.
4. Select one of the quartered quarters and
separate all of the individual components of the
waste into preselected components.

5. Place the separated components in a container
of known volume and tare mass and measure
the volume and mass of each component.
6. Determine the percentage distribution of each
component by mass and the as-discarded
density.
 100-200 kg of waste should be sorted to obtain a
representative sample.

Prepare 100-200 kg of Waste from waste pit /
collection vehicle

Mix and
flatten the
waste
Divide into 4
blocks

Remove 2
blocks of
Waste
diagonally
opposite ends
Another
diagonal
opposite ends
waste are
remained

Remained
waste after 3-4
reduction
Prepare 2 buckets to
accommodate remained
waste

If the purpose of the waste analysis is for plan for
waste incineration system, then waste will be dried to
make it easy to proceed next steps.
But, in case of improvement of collection / final
disposal, waste component study will be made by wet
base (without drying).

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