Practical Odour assessm ent Nigel Gibson Odour - the problem The - - PDF document

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Practical Odour assessm ent Nigel Gibson Odour - the problem The process of concern Local residents

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Topics covered

• Complaints
• Off-site survey
• Odour/ odorant sampling
• Odour/ odorant measurement
• Odour assessment

Objectives of odour m onitoring

• Establish whether nuisance exists
• Enable mitigation program to be defined

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Com plaints

• Sign of problems with a plant or process
• Level of complaints may not represent the

true feeling of the community

• Complaint level will vary with time

Factors affecting hum an response

• Physiological factors - age, sex, health...
• Social factors - custom, habit, attitude to

source, past experiences...

• Meteorological - temperature, humidity...
• Local politics

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Exam ple site - year 1

complants year 1 9 / 1 / 9 8 2 3 / 1 / 9 8 6 / 2 / 9 8 2 / 2 / 9 8 6 / 3 / 9 8 2 / 3 / 9 8 3 / 4 / 9 8 1 7 / 4 / 9 8 1 / 5 / 9 8 1 5 / 5 / 9 8 2 9 / 5 / 9 8 1 2 / 6 / 9 8 2 6 / 6 / 9 8 1 / 7 / 9 8 2 4 / 7 / 9 8 7 / 8 / 9 8 2 1 / 8 / 9 8 4 / 9 / 9 8 1 8 / 9 / 9 8 2 / 1 / 9 8 1 6 / 1 / 9 8 3 / 1 / 9 8 1 3 / 1 1 / 9 8 2 7 / 1 1 / 9 8 date complaint days complants

Exam ple site - year 2

complaints 2 / 1 / 9 9 3 / 2 / 9 9 1 7 / 2 / 9 9 3 / 3 / 9 9 1 7 / 3 / 9 9 3 1 / 3 / 9 9 1 4 / 4 / 9 9 2 8 / 4 / 9 9 1 2 / 5 / 9 9 2 6 / 5 / 9 9 9 / 6 / 9 9 2 3 / 6 / 9 9 7 / 7 / 9 9 2 1 / 7 / 9 9 4 / 8 / 9 9 1 8 / 8 / 9 9 1 / 9 / 9 9 1 5 / 9 / 9 9 2 9 / 9 / 9 9 1 3 / 1 / 9 9 2 7 / 1 / 9 9 1 / 1 1 / 9 9 2 4 / 1 1 / 9 9 8 / 1 2 / 9 9 month complaint day complaints

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Figure 4 odour control parameters v complaints

5 10 15 20 25 30 35 40 45 21/05/98 26/05/98 31/05/98 05/06/98 10/06/98 15/06/98 20/06/98 25/06/98 30/06/98 day bed temp. (deg C) 1 2 3 4 5 6 7 8 9 10 pH bed temperature complaints mex temp bed pH acidic pH

Odour Control Param eters v Com plaints

Figure1 showing wind speed, direction and complaints in June 1998

0.0 90.0 180.0 270.0 360.0 3600 3624 3648 3670 3694 3718 3742 3766 3790 3814 3838 3862 3886 3910 3934 3958 3982 4006 4030 4054 4078 4102 4126 4150 4174 4198 4222 4246 4270 4294 4318 4342 4366 Hour Wind direction (degrees from north) 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 windspeed (m/s) winddirection complaints WIND SPEED

W ind Speed Direction and Com plaints in June 1998

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Com m unity based techniques

• Diaries:
• useful, especially if the event is short-term, and out of

hours

• some discretion in assessing usefulness. (Validation

by complaints?)

• Care needed to interpret diaries (some exaggeration

possible, Validation by complaints?)

• Com m unity surveys:
• Expensive if done well
• Ideally large population base require
• Can differentiate between sources.

Boundary fence/ off-site survey 1

Many authorisations contain:

• general odour condition “ …

… ..no offensive

• dour…

… … … … . as perceived by the local authority inspector”

• routine boundary monitoring by operator

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Boundary fence/ off-site survey 2

Advantages:

• cheap
• easy (?)

Disadvantages:

• positive results only under extremes

conditions

• discrete test
• are the results believed?
• observer fatigue

Off-site survey m ethod 1

Method proposed in guidance to WML regulators (EA website) based on assessment of: Intensity + Extent + Sensitivity of Location

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Off-site survey m ethod 2 I ntensity

• 1. No detectable odour
• 2. Faint odour (barely detectable, need to stand still and

inhale facing into the wind)

• 3. Moderate odour (odour easily detected while walking

and breathing norm ally, possibly offensive)

• 4. Strong odour (bearable, but offensive odour - will m y

clothes/ hair sm ell?)

• 5. Very strong odour (this is when you really wish you

were som ewhere else)

Off-site survey m ethod 3

Extent ( assum ing odour detectable, if not then 0 )

• 1. Local and im persistent (only detected during brief

periods when wind drops or blows)

• 2. I mpersistent as above, but detected away from site

boundary

• 3. Persistent, but fairly localised
• 4. Persistent and pervasive up to 50 m from site

boundary

• 5. Persistent and widespread (odour detected > 50 m

from site boundary)

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Off-site survey m ethod 4

Sensitivity of Location w here Odour Detected ( assum ing detectable, if not then 0 )

• 1. Rem ote (no housing, com m ercial/ industrial

premises or public area within 500 m)

• 2. Low sensitivity (no housing, etc. within 100 m of

area affected by odour)

• 3. Moderate sensitivity (housing, etc. within 100 m of

area affected by odour)

• 4. High sensitivity (housing, etc. within area affected

by odour)

• 5. Extra sensitive (com plaints arising from residents

within area affected by odour)

Sam pling

• Point sources
• Open surfaces - with gas flow
• Open surfaces - without gas flow

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Point sources Open surfaces - w ith gas flow

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Open surfaces - w ithout gas flow Open surfaces - w ithout gas flow

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Odour m easurem ent/ quanitification

• Compound specific techniques
• Complex chemical analysis
• Olfactometry

Com pound specific techniques

• Specific odorants e.g. NH3, RNH2, H2S, RHS
• Marker compounds H2S, methane etc.

Not necessarily a direct correlation with odour

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Marker com pounds- landfill Marker com pounds- STW

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Marker com pounds- brickw orks

Figure 1 Odour and H2S concentrations throughout one kiln cycle

0.E+00 5.E+05 1.E+06 2.E+06 2.E+06 3.E+06 3.E+06 4.E+06 4.E+06 5.E+06 5.E+06 6 : 1 8 7 : 2 8 : 1 5 9 : 1 4 1 : 1 3 1 1 : 1 3 1 2 : 1 4 1 3 : 1 4 1 4 : 1 6 1 5 : 1 6 1 6 : 1 5 1 7 : 1 7 1 8 : 1 6 1 9 : 1 5 2 : 1 7 2 1 : 1 5 time Odour concentration (ou/m3) 0.5 1 1.5 2 2.5 3 3.5 time H2S concentration (ppm) tot odour tot h2s

Com plex chem ical analysis

Adsorption followed by GC-FID or GC-MS ‘Electronic nose’

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Chem ical analysis - GC

Gas chromatography is a widely used analytical technique for characterising odour emissions Advantages:

• Provides quantitative analysis for a broad

range of chemicals

Chem ical analysis - GC

Disadvantages

• Does not detect inorganic species, e.g.

ammonia & hydrogen sulphide

• Poor detection of highly reactive species
• Time resolution of passive sampling is poor

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Chem ical analysis - GC Chem ical Analysis ( 3)

• Does not take into account additive effects,

e.g.

Compensation I ab< I a or I b (whichever smaller) Compromise I ab< I a or I b (whichever greater) Independence I ab= I a or I b (whichever greater) Partial addition I a+ I b> I a or I b (whichever greater) Complete addition I ab= I a+ I b Hyper-addition I ab> I a+ I b

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Electronic nose 1

Electronic sensors work in 1 of 2 ways: Chem ical reaction:

• responds to the products (or

starting materials) of reaction Micro- environm entally sensitive:

• functions by reaction changes occurring in

electrical properties. Mixture not substance specific

Electronic nose 2

In the future the electronic nose may offer a practical solution for objectively assessing

• dours.

Unlike gas chromatography the electronic nose measures all components in a mixture at any

• ne time.

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Electronic nose 3 Olfactom etry 1

It involves the step-wise dilution of a sample of odour-free air and subsequent presentation to a panel of observers in

• rder to determine the number of dilutions

required for odour to be perceived by 50%

• f the members of the panel.

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Olfactom etry 2 1 odour unit =

The amount of odorant(s) that, when evaporated into 1 cubic metre of odourless gas at STP, causes a physiological response from a panel (detection threshold) equivalent to that elicited by 40ppb (0.123mg/ m3) of n-butanol

Source: CEN TC264/ WG2 Olfactom etry 3

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Olfactom etry 4 Olfactom etry 5

% Negative response

50% 10 000 100 000 2 4 3 5 6 7 8

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45 000

Log10 (Dilution) Log10 (Dilution) Vs % Negative response

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I m pact assessm ent overview Screening or detailed m odelling?

• Screening

emission factor data, e.g. for pig farming: weaners 6 ou/ animal/ s dry sow 19.1 ou/ animal/ s boar 22.6 ou/ animal/ s simple model (dmax)

• Detailed - full measurement

(olfactometry) and modelling study (ADMS, AERMOD)

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Odour assessm ent criteria

• Two components:

a concentration component, and a percentage compliance component. E.g. Odour concentration shall not exceed X OU/ m 3 , corrected for the appropriate peak to m ean ratio, for m ore than Z% of the m eteorological conditions.

Criteria used in UK

5 ou/ m 3 as a 98th% ile of 1 hour averages

• set using pre-1995 Dutch data
• Dutch correction factor: 1 ouE/m 3 = 2 GE/ m 3

therefore criteria should now read: 2.5 ou/ m 3 as a 98th% ile of 1 hour averages

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Dutch criteria ( NER 2 0 0 0 )

Process Target 98th%ile Limit 98th%ile Bakeries 5 Breweries 1.5 Slaughterhouse 0.55 1.5 Meat processing 0.95 2.5 Grass drying 2.5 Coffee roaster 3.5 Animal feed plant 1 composting 0.5 1.5 wwtw 0.5-3.5

Exam ple output as a 98 th% ile

348000.00 348400.00 348800.00 349200.00 349600.00 350000.00 461000.00 461200.00 461400.00 461600.00 461800.00 462000.00 462200.00 462400.00 462600.00 462800.00 463000.00

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Sum m ary

complaints Off-site assessment Monitoring Impact assessment Nuisance assessment Yes Y es Possibly Yes Mitigation program Possibly Possibly Y es Yes