A Resounding Success: Odour in the Environment 2023 VDI Conference in Leipzig Draws Praise from over 160 Attendees

   The recently concluded "Gerüche in der Umwelt 2023" conference, held on November 29-30, has been hailed as a resounding success, with approximately 160 participants gathering to explore the latest advancements and discussions in the realm of olfactometry and odour assessment.

   One of the standout features of the event was the keynote address delivered by Mr. Dietmar Mannebeck, a founding partner of Olfasense GmbH, Kiel. His presentation, a captivating summary of the history of TO olfactometers, provided attendees with valuable insights into the evolution of the TO olffactometer and of the olfactometry itself. Dietmar paid tribute to his father, Dr. Heinrich Mannebeck, a trailblazer in German olfactometry.

   Let's go a bit more into detail about the talks:

Day 1

   Mr. Uwe Strotkötter, a speaker with a recurrent presence in the VDI conference series, shed light on the Impact of the new TA Luft (Technical Instructions on Air Quality Control) on the determination and assessment of odour in ambient air. In his presentation, Mr. Uwe Strotkötter highlighted the significant impact of the new TA Luft regulations, in force for almost two years, on the assessment of odour in ambient air. Notably, the irrelevance criterion in Annex 7 now emphasizes potential negative additional loads and addresses cumulation testing. Also, Mr. Strotkötter commented on the positive influence of the VDI 3886 Part 1 standard on decision-making regarding the necessity of an odour report. Moreover, insights into the importance of accurate localization of ambient air assessment points and considerations for the full functionality of thermal oxidizers were also shared.

   Mr. Boris Zimmermann addressed the increased significance of the assessment of odour concentration in ambient air with the incorporation of the GOAA into Annex 7 of the new version of TA Luft. Amendments to TA Luft 2021 set an assessment threshold at 0.25 ouE/m3, and adjustments to parameters like soil roughness, boundary layer model, and plume rise calculation. Comparative case studies demonstrated minor deviations in dispersion calculation results between TA Luft 2002 (AUSTAL2000) and TA Luft 2021 (AUSTAL) for simple source structures. However, for more complex configurations, AUSTAL tended to exhibit higher relative odour hour frequencies, indicating potential overestimation of odour hours in ambient air in both the near- and the far-field as compared to AUSTAL2000.

   Dr Heike Hebbinghaus delved into the influence of buildings in odour dispersion calculations within the framework of TA Luft 2021. In her presentation, she outlined comparative calculations that assessed the effectiveness of substitute source approaches in accounting for the impact of buildings in dispersion calculations. Focusing on the sub-area where the diagnostic wind field model is applicable, the study concluded that employing vertical substitute sources from ground level to source height is generally deemed sufficiently conservative.

   In Mr. Uwe Hartmann's presentation, various model variants were scrutinized through a comparison with measurement data, specifically focusing on ammonia concentrations gathered 20 to 400 meters away from an agricultural facility. The dataset considered building influences and discharge conditions of the sources. The tested model variants, commonly employed in air pollution control, were evaluated for their predictive accuracy. The results revealed that barring two model combinations, the modelled concentrations closely aligned with the measured data. Discrepancies in concentration levels were observed in the vicinity of the plant, within the recirculation zone, while consistency prevailed in areas farther from the source. Mr. Hartmann's results suggest that, for odour dispersion calculations assessing odour in ambient air in designated areas, the standard model of TA Luft (diagnostic wind field model and Lagrangian particle model) is justifiable. However, for point-like assessments in the near-field, the model combination featuring the prognostic wind field model yielded higher values. The investigation did not provide conclusive support for the use of vertical line sources as a substitute source system or for the application of the prognostic wind field model with consideration of plume rise.

   Mr. Michael Kropsch's presentation dealt with the odour emission factors of livestock species. These factors determine the source strength, measured in odour units per second per livestock unit. Highlighting the importance of realistic dispersion calculations, the presentation underscored the central relevance of emission factors' accuracy for individual livestock categories. Setting emission factors too low could result in underestimating odour dispersion, leading to unforeseen odour impact in the surrounding area post-operation. Conversely, an overly cautious approach of adding an unreasonably high "safety cushion" to emission factors was deemed impractical. The presentation also addressed the need to incorporate laying hen and poultry fattening farms, as well as pig breeding and piglet rearing farms, into the analysis, considering the absence of odour surveys in certain Austrian areas and evolving barn construction practices aimed at emission reduction.

   Dr. Dietmar Öttl's presented the results of the Salu_T project. This research focused on odour and NH3 emissions from a pig-fattening barn designed for animal welfare. The study utilized odour surveys following the EN16841-1 and passive sampler measurements for ammonia. Emission factors, determined through dispersion calculations using the GRAL model, demonstrated significant reductions compared to the base factors used in Styria's pig fattening authorization procedures. The odour factor of 8 ouE/animal/s marked nearly a 95% reduction from the standard factor of 140 ouE/animal/s, while the corresponding factor for ammonia at 0.73 kg/TP/a reflected an approximately 80% reduction from the standard factor of 3.64 kg/TP/a. These substantial emission reductions, compared to conventional barn technology, were attributed to measures in barn and feeding technology, including multiphase feeding, an outdoor climate/open front stable, minimization of excrement areas, and faeces-urine separation.

   Mr. Fabian Krischke's presentation addressed the current challenge of insufficient information on emission behaviour and ambient air scenarios in animal welfare stables, causing delays in the approval process for desired shifts towards greater animal welfare in husbandry. The Bavarian State Office for the Environment initiated odour immission measurements on such farms, aiming to understand real odour immissions and provide enforcement recommendations. Previous approval practices inadequately differentiated emission factors for odours between conventional and animal welfare-oriented methods, resulting in higher predicted immission values for the latter due to the diffuse discharge situation. Comparisons with guideline VDI 3894 Sheet 1 revealed that the existing convention values tend to be too high for animal welfare-oriented farms, suggesting a need to revise emission factors for a more realistic control assessment in ambient air in line with AUSTAL forecasts and plume inspection measurements.

   In the last presentation of the first day, Ms. Kathrin Kwiatkowski addressed the growing importance of alternative housing methods for improved animal welfare, particularly those providing an outdoor climate stimulus. Emissions in these systems are diffusely discharged close to the ground over larger areas, unlike conventional housing with defined exhaust gas ducts. There's a concern that the relative odour frequencies, as per Annex 7 of TA Luft, are potentially overestimated in the broader environment of open-ventilated stables, impacting authorization procedures. The study involved plume measurements on freely ventilated dairy cattle facilities and pig pens with outdoor runs, employing back-calculation and dispersion calculations per TA Luft specifications. This allowed for an estimation of source strength, compared with convention values of VDI 3894 Part 1 (2011) guideline. Her presentation detailed plume measurement results according to EN 16841-2 on three fattening pig houses, explaining the back-calculation procedure and comparing the results obtained with those of the VDI 3894 Sheet 1 (2011) convention values.

At the end of the day, a touching moment occurred during the "Honors for the VDI/DIN Commission for Air Pollution Control (KRdL) – Standards Committee," where special awards were given to Dr. Heike Hauschildt, Dr. Isabelle Franzen-Reuter, and another lady that, I am sorry, but I did not know, nor I remember now her name.

This emotive event marked a recognition of their outstanding contributions to the VDI/DIN Commission for Air Pollution Control, acknowledging their commitment and achievements in the realm of odour standards and regulations. Both Heike and Isabelle are great professionals and they deserve this award. These awards not only celebrated individual excellence but also underscored the collective dedication to upholding air quality standards and advancing environmental stewardship.

Day 2

 On day 2 there were also many interesting presentations.

 Dr. Jörn Hameister's presentation delved into a critical aspect often overlooked in discussions on odour assessment — the evaluation of odours indoors. His presentation highlighted the importance of considering odour assessment within indoor environments where people spend approximately 90% of their time. Dr. Hameister emphasized that existing guideline values for substances in indoor air, established by the Committee for Indoor Air Guide Values (AIR), focus on health assessments derived from toxicological data but do not specifically address protection against odour nuisance. He discussed the challenges of odour assessment indoors, where complaints may arise due to unusual or unpleasant odours, potentially impacting occupants' well-being and work performance. Dr. Hameister introduced the concept of "odour conductance values" (GLW, for its acronym in German), an attempt to objectively evaluate complaints about odour nuisance based on measured values. The GLW concept, initially published in 2014 and revised in spring 2023, aims to distinguish between minor and significant odour nuisances, providing a framework for addressing indoor odour concerns beyond traditional health-related guidelines.

 Dr. Kirsten Sucker's presentation delved into the nuanced realm of odours within indoor spaces, where concerns about potential health consequences often arise. She discussed the evolved concept of odour guide values developed by the Committee for Indoor Guide Values. This concept, rooted in quality-assured odour thresholds, aims to provide a robust framework for assessing odorous substances in indoor air. Dr. Sucker's talk addressed the intriguing question of whether odour thresholds, determined directly through olfactometer-based assessments, reliably reflect the perception of odours within indoor environments.

   Dr. Kirsten Sucker's investigation unfolded in three distinct stages. First, a group of ten healthy, non-smoking individuals, aged between 19 and 50, possessing normal olfactory capacity, was selected following EN 13725: 2022. The second phase involved measuring odour thresholds for two distinct substances, namely n-butanol and benzaldehyde. These measurements were conducted both in an olfactometer and in a normal room under standard ambient conditions. The final stage of the investigation focused on exploring the impact of five environmental stressors (temperature, noise, light, CO2 concentration and relative humidity) on the determination of the odour threshold of n-butanol. The results showed that the odour thresholds determined in the room air were always lower than on the olfactometer and the dispersion of the odour thresholds was lower in the room air. Another interesting result was that the uncomfortable environmental conditions had no systematic influence on the odour threshold measurements of n-butanol. However, under the influence of street noise and the increased temperature, the dispersion of the odour thresholds was significantly greater and individual persons reacted with very high or very low odour thresholds.

   Dr. Ralf Petrich presented an innovative approach leveraging collaborative filtering, a method commonly employed in platforms like Netflix for personalized recommendations. In this application, the system was designed to learn the occurrence of odour events and their specific wind directions at various points around a source. The methodology involved a statistical analysis of inspection data obtained from a grid measurement. The primary objective was to establish a streamlined statistical procedure, post a learning process, capable of analyzing grid measurement results minimally. In his talk, he described the construction of two matrices (U and V). With the the information stored in them, Mr. Petrich was able to predict odour events that had occurred at the measurement points that had not been walked on.

 In the following talk, Dr. Jannik Hüls delved into the exploration of employing deep learning, specifically the U-Net model, for predicting odour in ambient air. In this investigation, data derived from dispersion calculations using AUSTAL were translated into images and employed for training and validating the U-Net model. The primary objective was to leverage the U-Net model to segment areas where an odour hour frequency surpassing 2 per cent was prevalent. To evaluate the model's performance, a comparison was made with the established AUSTAL software. The results showcased promise, suggesting that deep learning could emerge as a valuable tool for forecasting odour in ambient air.

 Then, Mr. Gorden Bruyn presented findings from a comprehensive odour measurement initiative conducted at the sewage sludge drying facility at the Bottrop sewage treatment plant. The project, initiated by the VDI working group on olfactometry aimed to validate the new method outlined in EN 13725:2022 for determining measurement uncertainty in odour emission measurements. The study involved comparative measurements on real environmental samples, comparing them with several other methods. The results indicated that adhering strictly to normative requirements for odour measurement yielded comparable results. Notably, the method employed in the past (VDI 3884 Sheet 1) provided narrow confidence ranges, while the DIN EN 13725:2022 method exhibited the highest measurement uncertainties. The presentation also highlighted the differences in measurement uncertainty between various methods, including DIN EN ISO 20988:2007 method A7 and DIN EN ISO 20988, method A6. In practical terms, these results suggest the need for a possible revision of the uncertainty calculation methodology detailed in the existing EN 13725:2022.

 The next talk was supposed to be carried out by Dr. Dominik Wildanger, but he was substituted by Dr. Ralf Both. His talk dealt with the application of the grid method in a large project encompassing an area with multiple odour-emitting plants. The findings of the EN 16841-1 were compared with the observations of public officers patrolling the area and the actual odour-related complaints lodged by residents. The outcomes of this systematic assessment that incorporated citizen complaints, results from the odour reporting tool Ortelium, on-site investigations, and the assessment of odour hour EN 16841-1, concluded that:

  • Identified relevant sources of odour emissions include a metal processing plant, a composting plant, a processing plant for lightweight packaging materials, and one for household waste.
  • Several odour sources on different systems were identified for which no relevance to emissions could be determined.
  • No clear indications of possible sources of disgusting odours were found.
  • The existing odour nuisance is considered significant, constituting a harmful environmental impact within the meaning of Section 3 (1) BImSchG, regardless of the actual odour levels in ambient air.

   In conjunction with biofilters and thermal methods, the standard VDI 2441, "Process gas and waste gas purification using cold plasma processes," has acknowledged UV technology as a state-of-the-art solution for treating pollutant and odour emissions. Dr Heinz Hiegemann's presentation highlighted the Emscher case in Essen. The authorities, recognizing the advantages in terms of space, cost, operational stability, and flexibility, transitioned from biofilter processes to UV irradiation technology. This change was implemented as part of the "Emscher conversion" generation project, resulting in the operation of 53 photo-oxidation plants (FOA) for odour treatment along the approximately 51 km Emscher wastewater canal.

   Dr. Gerald Jödicke's presentation focused on the evaluation of odour filter system efficiency in the context of flavours and fragrances production, where odorous exhaust air is inherent. The odour intensity of the exhaust air can vary significantly based on production volume, process steps, and the product portfolio, exhibiting rapid changes within minutes. Dr, Jödicke proposed a new, simple approach to assess odour concentration involving an olfactometric screening, where a dilution series of the odorous air sample is prepared, ranging from 1:1 to 1:100,000. Test subjects sniff the bags filled with odorous air, noting the sample in which an odour is first detected. According to Dr. Jödicke, this process, repeated independently by at least 10 individuals, yielded aggregated results compared with measured values following EN 13725 standards.

   Mr. Matthias Rau's insightful presentation concluded the second day, addressing the surge in complaints from city centre residents regarding smoke and odour issues from restaurants employing charcoal barbecues and kebab grills. Focusing on a specific case with six restaurants in a confined street section, samples were collected from kitchen and grill exhaust air sources, analyzed olfactometrically, and exhaust air parameters recorded. Dispersion calculations were then carried out with the MISKAM model to assess ambient air scenarios at various heights, guiding the determination of the impact on neighbouring residents. The study prompted the identification of necessary mitigation measures, integrated into dispersion calculations as additional scenarios, raising discussions on the procedure's applicability within local conditions and relevant immission values.

  The day concluded with a very interesting poster presentation, which we've previously detailed here

  The following day there was a course dealing with complaint and conflict management.

   All in all, it was a round conference with many attendees this year. I have 2 recommendations for olores.org readers. Firstly, try to purchase the proceedings of this conference. Secondly, if you speak some German, consider attending the next VDI conference scheduled to take place in 2 years at a location yet to be determined.


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Carlos Nietzsche Diaz Jimenez's Avatar

Carlos Nietzsche Diaz Jimenez

Carlos is the editor-chief of olores.org and has been in the odour world since 2001. Since then, Carlos has attended over 90 conferences in odour management, both national and international and authored a few papers on the subject. He has also organized a few international meetings and courses. Carlos owns a small company named Ambiente et Odora (AEO). He spends his free time with his wife and his twins, Laura and Daniel, and of course, writing on olores.org.

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