The Odor Management Blog

Senior Odor Expert Ray Porter joins Odotech as Knowledge Leader

  

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NEWS RELEASE

February 18, 2013 - Montréal, Canada – Odotech Inc. (www.odotech.com), a smart odor tracking and monitoring company, announced today that Mr. Raymond Porter has been appointed to the position of Knowledge Leader. He brings extraordinary expertise in the field of environmental odor to help guide and accelerate the company’s success in the odor management market.

“With its game-changing electronic nose, Odotech has set a new standard in odor management solutions. OdoWatch - a dynamic odor monitoring and forecasting solution, solves long-standing problems that have plagued plant operators,” says Ray Porter.

 “Joining Odotech is an incredible opportunity for me to use my knowledge to reach new heights in solutions to odor problems, while offering massive cost savings for clients,” he adds.

Ray Porter brings more than 30 years of technical knowledge and experience to a diverse team of people committed to developing odor management solutions with the goal of improving the quality of life while optimizing the limited resources. Ray has served as a national technical resource for odor impact assessments and odor control projects. He has directed studies of odor emissions from wastewater treatment plants, compost facilities and solid waste management facilities. Ray has directed comprehensive air quality modeling analyses for power plants, petrochemical facilities and industrial plants to demonstrate compliance with applicable regulatory standards and limits. He has directed air sampling and ambient air monitoring studies for several clients. Ray has contributed to technical manuals of practice that address odor emissions and air quality compliance at wastewater treatment plants, he has also authored numerous papers and technical reports on odor assessment and control, as well as in other fields of expertise.

As an internationally well respected expert in the field of Odors, he was Chair of the Water Environment Federation’s (WEF) Air Quality and Odor Control Committee. He is currently a member of several professional association committees. “The best part of involvement, for me, is really just being  able to share my knowledge with other professionals. Not only teaching the skills and science of odor control and compliance, but also collaborating with other professionals from across North America and around the world,” said Porter.

Ray’s career has been spent at well-respected international consulting firms (CH2M HILL, WESTON Solutions, AECOM, CDM).  He holds a Master of Science Environmental Engineering — Georgia Institute of Technology and a Bachelor of Science, Meteorology—University of Lowell (University of Massachusetts – Lowell).

In this new position for Odotech, Ray will work with several teams providing knowledge, support and advice to various team members. Ray will have an active external role to engage dialog, promote and advocate for odor management solutions with customers and various stakeholders, in order to accelerate market penetration and technology adoption.

“We are thrilled to have Ray join our team, “says Thierry Pagé, Odotech CEO.  “His expertise will help us better understand the needs of the industries we service.  His technical knowledge will help us throughout the world by providing additional value to our clients and partners.”

About Odotech Inc.

ODOTECH is a leading provider of real-time smart odor management solutions for odor-emitting process industries. Founded in 1998, the company pioneered OdoWatch^® electronic nose for continuous odor monitoring, enabling organizations for the first time to See, Track and Control odors before they create a problem in the neighborhood. With over 500 customers throughout the world ODOTECH has established a global presence and continues to lead the way in the real-time odor management solutions market.

Online Educational Session: Odor Management for Municipalities & Industry

  

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Odotech invites you to join for the next GlobalSpec's Free Online educational sessions

Water Quality & Water Reclamation, January 25, 2012 see agenda

From 1:30 PM - 2:00 PM EST (10:30 AM - 11:00 AM PST) there will be a special session on Odor Management for Industry and Municipalities

• Learn how to right size odor abatement equipment and reduce documentation costs
• Understand how to set odor management priorities
• Learn how to save on investigations and government reporting
• Discover the benefits of an odor management master plan

Odor intensity using olfactometric analysis.

  

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Our laboratories are equipped with ODILE™ dynamic dilution olfactometers which allow objective quantification of odors.

Odor complaints, how to respond objectively

  

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You would like to respond objectively to odor complaints? Here is how to do it!

Several solutions are available to you, but the first stage must be a preliminary audit conducted by an engineer/odor expert. The object of the audit is to validate the parameters associated with regulatory documents, complaints or issues at stake. During the course of this audit, the following parameters will be identified, quantified and analyzed:

• Fugitive/channeled emissions

• Waste parameters such as stack height, emission rates, diameter, flow rates, etc.

• Mapping complaints

• Number and frequency of complaints

  
  

              

Our odor experts will develop an odor diagnosis on the basis of these parameters (sampling odors directly at the source, followed by olfactory measurement in the laboratory) and an impact study that will provide you with a clear, accurate image of the odor impact of your activity. 

If you wish to pursue this further, within the framework of an odor nuisance management plan, our teams can establish an Odor Observer Committee. The participation of the residents in characterizing the odors around the site will create greater involvement of the community in the main aspects of the project and improve understanding and quantification of the odor issue. This also supports the emergence of constructive and cooperative dialogue between site managers and neighbors.

Is odor measurement subjective or based on science

  

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It is often said that odor measurement is subjective. This statement comes certainly because odor measurements are based on human odor panels that sniff the air to determine the presence of odor.

Odor measurement | Odor panel of an olfactometric analysis

It is likely also due to the variation in people's sensitivity to odor or personal appreciation of different odors. 

Odor measurement is, as a matter of fact, a dose-response relationship evaluation of an odorant substance. The dose-response relationships are commonly used in pharmacology, toxicology, biology and medical science. No one would think that these sciences are subjective. Olfactometry (odor measurement) is based on the same sound science.  

The dose-response relationship, or exposure-response relationship, describes the change in effect on an organism caused by differing levels of exposure (or doses) to a stressor (usually a chemical) after a certain exposure time. This may apply to individuals (eg: a small amount has no observable effect, a large amount is fatal), or to populations (eg: how many people or organisms are affected at different levels of exposure). (Source: Wikipedia).

Dose response curve from an olfacomtetric analysis

In the case of odor measurement:

• the change in effect on an organism is the odor perception
• the differing levels of exposure (or doses) are the dilutions of odor
• the stressor is the odor
• the population sample is the odor panel.

An olfactometric analysis is an analytical test of odor quantification or measurement of the odor concentration (according to established protocols). The goal of an olfactometric analysis is to determine the odor perception threshold. By definition, the perception threshold is when 50% of the population detects an odor because of the presence of odorant chemical compounds. The Odor unit, is by definition, 1 o.u./m3, the odor perceived (but not necessarily recognized) by 50% of a panel (1 o.u./m3 corresponds to the detection threshold). The Odor concentration (number of odor units) represent the number of dilutions (with odorless air) of the gas mixture required to obtain 1 o.u./m3.  The greater the number, the more "odorous" the sample is.

State of the art olfactometry will use panels that have been tested and selected according to the EN13725 standard and certified olfactometer operating in specific controlled conditions. This standard has been proven to provide reliable reproducible results.      

It is absolutely valid to consider the odors subjective in terms of the appreciation of their quality.  This belongs to the taste and experiences of each individual. On the other hand, the odor quantification is an objective method based on scientific fundamentals eliminating all the subjectivity related to odor perception.

Further readings:

http://blog.odotech.com/bid/56305/Odor-metrology-Olfactometry-vs-chemical-analysis

http://blog.odotech.com/bid/46953/Odor-diagnosis-how-and-why

Real-time Odor Tracking VS olfactometry

  

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Olfactometry is a great tool to translate into a quantitative and objective value the complexity of odor perception (see blog: Are odors additives in terms of the intensity?)

Dynamic dilution olfactometer

However, in some circumstances, real-time values are required to provide the dimension of odor fluctuations of a process that olfactometry can hardly provide. Indeed, olfactometric measurements require sampling and lab analysis that practically or financially limit the amount of values available to understand the odor fluctuations out of an odor source. 

Let's take the example of a biofilter exit treating composting odors. In this case, the process generates pulsed air flow for windrow forced aeration.

What do we see here?

First, using today’s standard ‘manual’ odor sampling and measurement method (blue dots), we measure three separate odor concentrations at different points in time, then connect the dots to obtain rectilinear segments.

In this case, looking at a biofilter designed to limit odor output to 400 odor units, the ‘manual’ method (olfactometry) would indicate that the biofilter is working fine and the neighbors would perceive no odor. However, there are still odor complaints; no one knows why.

Then we install an electronic nose OdoWatch (magenta curve); this gives us continuous measurement; and we now see that there are odor peaks up to 750 odor units.

The mystery is solved. Now we can act to deal with the problem. Measuring daily average odor concentration may doesn’t work. The human nose senses peak values not average values. Thus the monitoring system needs to measure odor concentration at very short intervals. OdoWatch measures odors every second.

Ever read a cartoon about olfactometry?

  

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Those of you following our blog on Odor management have seen us try to be serious about odors and olfactometry with people used to sniff out odors in olfactory port.

Please allow us a little prank, a joke on olfactometry. This cartoon is the gift of a friend portraying the concept of olfactometry in a comic.

What is the process of olfaction - odor perception ?

  

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The sense of olfaction is complex. Odor perception is influenced by many factors unique to each individual as well as external environmental factors. The basis of odor perception is the contact between chemical molecules, mainly in the gaseous state, which can be detected by the olfactory epithelium.

From : Pour la science # 218

The odorous molecules come into contact with the olfactory epithelium at the top of the nasal cavity and stimulate multiple chemically cell receptors (see figures).

From : Pour la science # 218

The electrical impulses generated by the olfactory epithelium cells are transmitted via the olfactory nerve (first cranial nerve which passes through the skull through the cribriform plate) in the central olfactory system located in the limbic system. A branch of the fifth cranial nerve, the trigeminal, is the vehicle for the perception of irritation at the nose, the nasopharynx and the oropharynx, as well as the sensation of taste and smell.

From: LAFFORT P., Aspects of the olfactory information, chap 6 dans Characterization and control of odours and VOC in the process industries, VIGNERON S., HERMIA J., and CHAOUKI J. Eds, Studies in Environmental Science, 61, Amsterdam, The Netherlands, 1994.

The trigeminal nerve also contributes to assess the odor perception magnitude even without irritation. It is interesting to note that some molecules are detected as well by irritation as by olfaction: ammonia, NOx, Ozone, ect.

The perception of an odor by humans results from a stimulus. It includes key information as the odor intensity and odor quality. Our ability to collect this information makes the olfaction a very complex sense.  All the biochemical parameters are not yet fully understood by specialists.

For the intensity, our sense of smell behaves much like our perception of hot or cold substances. The signal strength is very strong at the beginning then there is adaptation and gradual decline in signal strength (toe in a bath). In terms of odor quality, our sense of smell works similarly to taste: we can recognize, classify and assess the quality of an odor.

One of the quality of olfactometry is that a lot of the odor perception complexity is tied in a reproducible quantified parameter: the odor concentration.  

Related readings: 

• Odor metrology – Olfactometry vs chemical analysis
• Measurement of odor emissions – Olfactometry or chemical analysis?
• Similarities between the electronic nose and human odor perception

Odor metrology – Olfactometry vs chemical analysis

  

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We have seen the benefits of olfactometry in the blog Measurement of odor emissions – Olfactometry or chemical analysis?

In general, it is difficult to use the chemical analysis method for mixtures of odorous compounds due to the phenomena of synergy, inhibition and masking between different compounds (Gostelow et al., 2003).Complex mixtures, such as environmental air samples, contain many odorous compounds, generally at very low concentrations (Gostelow et al., 2001) (Schiffman et al., 2001) (Parker et al., 2002) (Filipy et al., 2006).  To analyze all the odorous compounds that are present, the composition of the sample must be known in advance, and the detection limits of the chemical analysis devices are often too high to identify and quantify all these odorous compounds (Gostelow et al., 2003).  Finally, the olfactory perception threshold values are not always available in the existing literature, the values reported vary by several orders of magnitude (AIHA, 1989) (US EPA, 1992), and the available references are not recent.

The effects of synergy and masking between different odorous compounds can be observed in samples. For example, in a sample of food odor, the volatile compounds were identified and regrouped in five key odorous families. This was done to study the effect on odor resulting from different combinations of the five groups of compounds (Hallier et al., 2004).  Synergy and masking effects were thus observed.

Numerous researchers have studied odorous mixtures and have created models to predict the effect that the mixtures’ composition has on the perceived odor (composition and concentration) (Gostelow et al., 2003). In general, the use of these models is limited and applies only to the experimental conditions of the study. As well, the mixtures of compounds are mostly studied in the laboratory because of the complexity of mixed odors.

Studies have identified dominant odorous compounds in environmental samples. For example, a positive relation can be established between the odor concentration determined by olfactometry and the odor principle identified in the odor samples of liquid hog manure (Hobbs et al, 2000) and odor samples of composting mushrooms (Noble et al., 2001).  However, these studies also show that a relation between the mixture composition and the odor concentration is still misunderstood and difficult to predict. For wastewater treatment processes, where H2S is the predominant odor, Gostelow and Parsons (2000, from Stuetz and Frechen 2001) show the values of r² between the H2S and the odor concentrations to be as low as 7 to 69%.

Odor Perception Threshold Values

The American Industrial Hygiene Association (AIHA, 1989) compiled numerous studies and established a critical analysis of odor threshold values. The AIHA document is a recognized reference today and is often used as a source for odor threshold values.  The scale of acceptable odor threshold values was established for H2S from 0,001 ppmv to 0,130 ppmv (1 µg/m³ to 181 µg/m³). The recommended value held by the AIHA (1989) is 0,0094 ppmv (13 µg/m³). H2S is a well-studied odorous compound and yet the AIHA proposes a scale of values for the threshold of two orders of magnitude, after their critical review. The example of H2S illustrates why it is often inappropriate to work with odor threshold values because reliable values are not always readily available. New studies with dynamic dilution olfactometers shows 0.0004 pmmv as perception threshold values.

Olfactometry analysis

Olfactometry generates standard sensory analyses, and the principal tool to measure odor characteristics is a trained jury of “noses” or a group of selected experts chosen according to rigorous and precise criteria.  An olfactometer is a device designed to dilute the odorous gas samples and to present these dilutions to the jury. After obtaining the responses of the jury, a statistical treatment of the data permits the olfactometric result to be calculated.

Olfactometric analyses are tested in the laboratory (EN 13725 and ASTM E679-04) or in the field during which the odor samples are gathered and then exposed to the target population in the study area. However, olfactometric analyses of ambient air in the field are not recommended because of frequent variations of odor concentrations in ambient air and the low resolution of these methods.

Applications

In England, the Environmental Agency published a guide on the measure of H2S and the reduced sulphur totals at the source of ambient air (Environment Agency, 2001).  This guide recommends that the measuring strategy be directly related to the objective of the measurement study. Thus, if the objective establishes the required abatement to eliminate the nuisance odor, it is specified in the guide that the odor concentration measurements expressed in odor units per cubic meter (o.u./m³) are more appropriate than the kind obtained through chemical measurement. 

Conclusion

The main advantage of olfactometry is the direct correlation between the odor and the sensitivity of the  detector used, i.e. the human nose.  

Despite the advantages of the classic analytical methods (accuracy, reproducibility, etc.), olfactometry remains the best available approach to measure odors directly, in order to objectively quantify the perception of odors.

References

• AIHA (1989). Odor Thresholds for Chemicals with Established Occupational Health Standards. American Industrial Hygiene Association.
• ASTM (1997). E679-91 (reapproved 1997) - Standard Practice for Determination of Odor and Taste Thresholds By a Forced-Choice Ascending Concentration Series Method of Limits. American Society for Testing and Materials: p. 34-38.
• CEN (2003). EN 13725 - Air quality - Determination of odour concentration by dynamic olfactometry. European Committee for Standardization: p. 71.
• Environment Agency (2001). Technical Guidance Note M13: Monitoring hydrogen sulphide and total reduced sulphur in atmospheric releases and ambient air.  ISBN 1 857 05696 5.  Environment Agency’s National
• Compliance Assessment Service, England and Wales.   www.environment-agency.gov.uk/business/techguide/monitoring/m13.html  
• Filipy, J., B. Rumburg, et al. (2006). "Identification and quantification of volatile organic compounds from a dairy." Atmospheric Environment 40: 1480-1494.
• Gostelow, P., SA Parsons (2000). “Sewage treatment works odour measurements.” Wat. Sci.Technol. 41(6), 33-40.
• Gostelow, P., SA Parsons, RM Stuetz (2001). “Odour Measurements for Sewage Treatment Works.” Water Research 35(3): 579-597.
• Stuetz R. and Frechen FB (2001).  “ Odours in Wastewater Treatment. Measurement, Modelling and Control “. Gostelow, P., P.J. Longhurst, SA Parsons, RM Stuetz (2003). Sampling for Measurement of Odours. London
• UK, IWA, 80 pages. Hallier, A., P. Courcoux, et al. (2004). "New gas chromatography–olfactometric investigative method, and its application to cooked Silurus glanis (European catfish) odor characterization." Journal of Chromatography A 1056: 201-208.
• Hobbs, P. J., T. H. Misselbrook, T. Dhanoa and K. Persaud (2000). "Development of a relationship between olfactory response and major odorants from organic wastes." Journal of the science of food and agriculture Vol. 81: pp. 188-193.
• Noble, R., P. J. Hobbs, A. Dobrovin-Pennington, T. H. Misselbrook and A. Mead (2001). "Olfactory Response to Mushroom Composting Emissions as a Function of Chemical Concentration." Journal of environmental quality Vol. 30: pp. 760–767.
• Parker, T., J. Dottridge and S. Kelly (2002). R&D Technical Report P1-438/TR: Investigation of the Composition and Emissions of Trace Components in Landfill Gas, Environment Agency, England and Wales.
• Schiffman, S. S., J. L. Bennett, et al. (2001). "Quantification of odors and odorants from swine operations in North Carolina." Agricultural and Forest Meteorology 108: 213-240.
• US EPA (1992). “Reference Guide to Odor Thresholds for Hazardous Air Pollutants Listed in the Clean Air Act Amendments of 1990” (#EPA600/R-92/047).  TRC Environmental Consultants Inc., S. S. Cha, J. R. Mellberg, G. L. Ginsberg, K. E. Brown, K. Raab and J. C. Coco. US EPA, pp. 93.

Biosolid composting : Odor abatement monitoring using e-noses

  

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COMPOSTING PLANT DESCRIPTION AND ODOR SOURCES

The Toulouse-Ginestous composting site (in France) treats up to 60 tons per day of 30% solids dehydrated WWTP sludge. The sludge is amended with 25 to 50%v bark and screening residues (non degraded bark, recovered from the mature compost).  All composting operations are performed in a 10 000 m² building.

This mixture is composted as 6 m wide windrows with a height of 3 m.  Time-sequenced negative aeration is used over a 6 week residence time. The material is then transferred to another indoor platform where it undergoes an 8 week maturation period. The material is then screened to yield equal quantities of mature compost and screening residues.

Figure 1 Composting plan

The abatement equipment implemented at this facility was properly designed to provide effective reduction of anticipated odor emissions (combined scrubber/biofilters system). However, some processing upsets or operating conditions may trigger effectiveness reductions that can go unnoticed by the plant operator. Unfortunately, some processes can have low odor emissions most of the times and, under certain weather conditions or trigger events, become major nuisance sources.

In the summer of 2005, the plant acquired an electronic nose system in order to further their proactive approach towards odor management: in other words, to detect the potential of odor impacts before they actually affect the population.

Figure 2    View of the biofilter (a), weather station (b) and e-nose (c)

The system configuration was established to ensure monitoring of each key composting process and sources, not only those emitting to atmosphere: 1 e-nose monitors the co-products area, 1 e-nose analyses the air aspiration duct of the composting platform, 1 e-nose is located in the maturation area and 1 e-nose tracks the exhaust of the biofilter.

The composting plant does not operate in a steady state mode. The composition of the air sent to the odor treatment system will vary continuously depending on the operations, the overall composting situation (number of windrows, stage, etc.) and with the opening of doors. The following figure presents a log of the odor concentrations for the maturation and composting areas, the co-products building stack and the outlet of the biofilter for the first week of June 2006.