Choosing the Most Effective Odour Measurement Technique

 

Introduction
  1. •Problem:
  2. There are many different methods for evaluating  odours
  3. Choosing the most effective technique is critical
  4. •Objective:
  5. Develop a method to solve your  odour problem
  6. •Sampling
  7. •Analysis, and
  8. •Quantification

 

Terminology• odour -perception experienced when one or more chemicals come into contact with receptors on the olfactory nerves • odourant -any chemical in the air that is part of the perception of  odour

 

 odour GenerationWaste Water SolidsCysteineMethionineOtherOrganics Organic SulfurHydrogenSulfideMethylmercaptanDimethylsulfideDimethyldisulfideOrganic NitrogenAmino AcidsAmmoniaAminesLimonenesOrganicAcids

 

 odour Characteristics
  1. •Character
  2. Mental associations, type of smell
  3. Subjective
  4. Hedonic tone
  5. •Intensity
  6. strength of smell
  7. butanol odour units or dilutions to threshold (D/T)
  8. •Duration
  9. •Frequency

 

Measurable  odour characteristics
  1. •Chemical Qualities
  2. Chemical composition
  3. Chemical concentration
  4. •Physiological Qualities
  5.  odour Threshold
  6. Recognition Threshold
  7. Complaint/Annoyance Threshold

 

Sampling methods
  1. •Ambient sampling
  2. •Flux chamber analysis
  3. •Headspace analysis

 

  1. •http://www.kassay.com/mopftir.htm

Ambient sampling

•Linking physiological response to the chemical  odourants that cause the problemFluxchamber

•Prepare TedlarBag•Transfer Sample to TedlarBag•Purge with Appropriate Gas•Allow Time for equilibration of HeadspaceHeadspace analysis

 

Sampling summary

Ambient

Flux Chamber

Headspace

 odour

 odourants

Two General Methods of Measuring  odours

 

Methods of  odour Analysis odourIntensity(strength) odourthreshold(detection) odourquality(descriptors)HedonicTone(annoyance)SensoryTestingGCanalysisGC/MSanalysisinidvidualgassensorsOpenPathFTIRAnalyticalTestingGas sample for odour analysis

 

Uses an  odour panel to determine intensity of  odour

Sample is introduced to trained panel members at different concentrations to determine the strength of the  odour

Concentrations are estimated based on statistical analysis during the testOlfactometry

 

  1. •http://www.fredericksburg.com/Photo/Gallery/020304%20week

 
  1. •Connect sample to cryoconcentrator

•Cryoconcentrator feeds sample to GC•GC separates compounds prior to analysis with Mass Spectrometer Analytical Analytical MethodsMethods

Lime Treated Class A Windrowed Biosolids2-Methyl-1-propeneTrimethylamineAcetoneDimethylsulfideTrimethylsilanol2-Butanone1-ButanolHexamethyldisiloxaneDimethyldisulfideTolueneMixed AlkanesAlpha-pineneDimethyltrisulfide

 

 odour Index Values (ODI)•Relates analytical concentration to referenced physiological responses•Used as a relative indicator of  odour intensityΣ−−=valuethresholdionconcentrat odourant odourIndex

 

Testing Protocol at Solids Handling Facilities
  1. •Eight facilities in the Mid-Atlantic Region participated
  2. •Represent a broad range of stabilization processes

051015202530Presence in # of samplesDimethyl Tetrasulfide2-PentanoneEthanolCarbon DisulfideMethanethiolTrimethylamineAcetic Acid2-ButanoneHydrogen SulfideAcetoneDimethyl TrisulfideDimethyl SulfideTolueneAmmoniaDimethyl Disulfide odourant

Commonly DetectedCompounds

 

 

Summary
  1. •Determine your objective
  2.  odours and/or  odourants
  3. •Base sampling methods on objectives
  4.  odour Modeling
  5. Process Evaluation
  6. •Determine the right level of analysis for your objective
  7. •Apply experience to data interpretation