Dynamic Olfactometry Research Articles

Odour measurement in wastewater treatment plant by a new prototype of e.nose: Correlation and comparison study with reference to both European and Japanese approaches

In the modern world of wastewater treatment, control of odors has moved from an afterthought to a primary design consideration for most collection and treatment facilities. As development encroaches on our facilities and our new neighbours become less tolerant of nuisance odors, wastewater professionals have found the need to address odor as a primary concern in the design and operation of collection and treatment facilities.When facility odors affect air quality and cause citizen complaints, an investigation of those odors may require that specific odorants be measured and that odorous air be measured using standardized scientific methods. Odour intensity is one of main odour characterization parameters, and remarkably common and important sensory indicator of environmental odours. Odour intensity reflects people’s perception of odours and contributes to effective odour management.The “triangle odors bag method', which has been adopted for the offensive odors control law in Japan, and the dynamic olfactometry defined by EN 13725 has been adopted in Europe. These methods are the worldwide used for as reference methods for the sensorial measurement of odours. On these methods are also based the training of electronic nose (e.Nose).In this study odour samples were collected on municipal wastewater treatment plant located in south Italy at four different treatment units to determine the relationship between odour intensity assessed by Japanese “triangle odors bag method', odour concentration measured with dynamic olfactometry according to European standard EN13725:2003 and with odour concentration measured by a novel prototype of e.Nose patented by University of Salerno. A monthly sampling and relative measurements were carried out for consecutive 12 months at Laboratory of Sanitary Environmental Engineering Division (SEED) at University of Salerno (Italy). Results show when high odours were detected by Japanese standard, the odour concentrations measured according European standard were also high (e.g. emission from sludge line). Concentrations measured by e.Nose are strongly correlated with the measurements carried out by standard methods.

Improving recognition of odors in a waste management plant by using electronic noses with different technologies, gas chromatography–mass spectrometry/olfactometry and dynamic olfactometry

Odor emissions from waste management plants have long been an environmental and economic issue, but only recently regional authorities in Italy are regulating this sector by imposing control and mitigation of the phenomenon. Electronic noses, initially developed as cheap, easy tools to detect volatiles, may have the required time-resolved coverage of the odor emission phenomenon in a cheap and feasible way with respect to chemical analysis of air. One crucial issue to resolve is to evaluate the discriminant capacity of a sensor array in-field and under working conditions. In this paper the authors have studied the responses of electronic noses of different technologies to odors emitted from a waste management plant, by integrating results obtained with dynamic olfactometry and gas chromatography–mass spectrometry/olfactometry, in the aim to implement a monitoring system and improve cleaner production technologies. Three most impacting odor sources in the waste management plant were detected: biogas, a by-product of mechanical treatment of municipal solid wastes, with low organic fraction and a sludge pressed and dehydrated from treatment of urban wastewater. The most odor impacting source was the sludge and the major responsible of the odor impacts were aromatics (in particular 1,3,5-trimethyl benzene), aliphatic hydrocarbons, terpenes and sulphur volatiles (methyl disulphide, carbon disulphide, dimethyltrisulphide). Ten Metal Oxide Semiconductors and 32 polymer/black carbon (Nano Composite Array) sensors in two electronic noses, were tested for discrimination source capabilities. Results of linear discriminant analysis and cross validation give 86.7% successful recognition for Metal Oxide Semiconductors, 53.3% for Nano Composite Array and 93.3% for a selection of sensors belonging to both technologies chosen according to the selectivity towards the odor active molecules. The containment of odors could also be achieved by spraying a specific product and monitoring the process using selected sensors of the arrays. The results of the in-field work demonstrate strengths and weaknesses of different construction technologies in the e-noses arrays, to characterize and monitor in-site and in real time odor emissions from waste management plants.

Multivariate prediction of odor from pig production based on in-situ measurement of odorants

The aim of the present study was to estimate a prediction model for odor from pig production facilities based on measurements of odorants by Proton-Transfer-Reaction Mass spectrometry (PTR-MS). Odor measurements were performed at four different pig production facilities with and without odor abatement technologies using a newly developed mobile odor laboratory equipped with a PTR-MS for measuring odorants and an olfactometer for measuring the odor concentration by human panelists. A total of 115 odor measurements were carried out in the mobile laboratory and simultaneously air samples were collected in Nalophan bags and analyzed at accredited laboratories after 24 h. The dataset was divided into a calibration dataset containing 94 samples and a validation dataset containing 21 samples. The prediction model based on the measurements in the mobile laboratory was able to explain 74% of the variation in the odor concentration based on odorants, whereas the prediction models based on odor measurements with bag samples explained only 46–57%. This study is the first application of direct field olfactometry to livestock odor and emphasizes the importance of avoiding any bias from sample storage in studies of odor-odorant relationships. Application of the model on the validation dataset gave a high correlation between predicted and measured odor concentration (R2 = 0.77). Significant odorants in the prediction models include phenols and indoles. In conclusion, measurements of odorants on-site in pig production facilities is an alternative to dynamic olfactometry that can be applied for measuring odor from pig houses and the effects of odor abatement technologies.

Dynamic Olfactometry and Potential Sample Toxicity. Guidelines for a Safe Occupational Health Approach

Dynamic Olfactometry and Potential Sample Toxicity. Guidelines for a Safe Occupational Health Approach

Odour Impact Assessment by Means of Dispersion Modeling, Dynamic Olfactometry and Mobile Electronic Nose around Agadir Fishing Port in Morocco

Odorous emissions emitted from various sources including industrial and commercial activities have particular concerns about human health. These malodors emissions are an environmental concern that affects health status and social life of the neighbors. That requires the local authority to set up a management strategy to control this nuisance. The evaluation of odour emissions from fishing port is complex because these emissions depend on several factors such as multiple sources of odor emissions, meteorological conditions, topography and others. That imposes the use of complementary approaches to monitor odours. In this paper, the case of Agadir fishing port is studied, which is adjacent to the tourist area and residential neighborhoods and which hosts a number of points that can generate odors. To assess this odour impact, three methods are used such as dynamic olfactometry, dispersion modeling and mobile electronic nose (e-nose). The use of these three methods in a complementary manner to assess odour impacts around a fishing port allowed both the quantification of the emissions using dynamic olfactometry and the evaluation of their impact on the study area with model dispersion. The results enabled also to identify the most affected areas of the city by odor emissions and to recognize the meteorological parameters maximizing odor impact. The other goal of this work is to compare the results of the odour dispersion modeling and e-nose measurements for one year in terms of frequency of overtaking the set alert thresholds over the same period. Comparison highlights the strengths and weaknesses of both approaches. Modeling can be used predicatively but it does not take into account fugitive emissions reliably in the absence of data on these emissions, modeling based on the hourly average misjudges the odor peaks, while e-nose made it possible to obtain validated data and provides accurate, affordable and real-time odour measurement capability tacking in to account the role of human perception without being able to characterize the extent of the odor nuisance caused by each source. We conclude that these three valuation methods provide complementary information about odor nuisance and reasonable estimates of odors.

Dynamic olfactometry and modelling as methods for the assessment of odour impact of public utility objects

Dynamic olfactometry and modelling as methods for the assessment of odour impact of public utility objects

How Does Dynamic Olfactometry Really Work?

How Does Dynamic Olfactometry Really Work?

Dynamic olfactometry and modelling as methods for the assessment of odour impact of public utility objects

Dynamic olfactometry and modelling as methods for the assessment of odour impact of public utility objects

RESEARCHES OF ODOUR EMITTED BY HOUSEHOLD WASTE / MAISTO ATLIEKŲ SKLEIDŽIAMŲ KVAPŲ TYRIMAI IR VERTINIMAS

The article deals with odour emitted by household waste, the chemical composition of household waste. The experiment was made with food waste (1000 g) placed in 5 litter containers. Food waste was containing products of animal origin (meat, fish, dairy products) and plant origin (vegetables, fruit) waste. Time of the experiment was 14 days 19±3 °C at environment temperature. Odour concentration is determined by dynamic olfactometry method. Studies have shown that the strongest odour of all household waste used in this experiment was emitted by meat and fish waste (76 444 OUE/m3). Meat and fish waste emits the strongest odour as waste contains proteins, their decomposition releases into the environment a strong unpleasant odour, hydrogen sulphide and ammonia. Protein degradation releases into the environment are, characterized by a strong unpleasant smell of hydrogen sulphide and ammonia gas. During the anaerobic decomposition of organic matter a variety of other fragrant compounds: alcohols (e.g., ethanol and methanol), vinegar, formic acid, etc. is found. Straipsnyje nagrinėjami eksperimentiniai tyrimai, susiję su kvapų išsiskyrimu iš biologiškai skaidžių maisto (virtuvės) atliekų. Eksperimentas atliekamas maisto atliekas (po 1000 g) sudėjus į 5 litrų talpas. Maisto atliekas sudaro gyvūninės (mėsa, žuvis, pieno produktai) ir augalinės (daržovės, vaisiai) kilmės atliekos. Eksperimentas vyko 14 parų 19±3 °C aplinkos temperatūroje. Kvapo koncentracija nustatoma dinaminės olfaktometrijos metodu. Tyrimais nustatytos stipriausią kvapą skleidžiančios virtuvės atliekos: mėsos ir žuvies atliekos (76444 OUE/m3). Mėsos ir žuvies atliekos skleidžia stipriausią kvapą, nes šių atliekų sudėtyje yra daug baltymų. Skylant baltymams į aplinką išsiskiria stipriu nemaloniu kvapu pasižyminčios sieros vandenilio ir amoniako dujos. Vykstant anaerobiniam organinių medžiagų skaidymui, taip pat susidaro daug kitų kvapnių junginių: alkoholiai (pvz., etanolis ir metanolis), actas, skruzdžių rūgštis ir kt.

Complete nitrification–denitrification of swine manure in a full-scale, non-conventional composting system

A full-scale composting plant (track type, aerated by screws), treating liquid swine manure (94.8% on mass basis) with straw (<0.8%) and sawdust (4.4%), was monitored. The main objectives were testing the performance of the process and assessing its environmental sustainability. Particular attention was dedicated to verify the possibility that this process could determine significant mass reduction, along with Nitrogen reduction, mainly by denitrification. Emissions were evaluated by measuring NH3, N2O and CH4 (by static chamber), H2S and odor emissions (by dynamic olfactometry). Quality and quantity of inputs and outputs and process parameters (redox, oxygen, and temperature) were monitored. The process produced a mature, highly humified (Humification Index=0.27), solid product with 92.8% mass reduction (mainly evaporation), and nitrogen reduction (85.8% referred to input TN). The process was revealed to be environmentally sustainable: emissions of odors and H2S resulted negligible; emissions of N–N2O represented 0.18% of TN input, while emissions of N–NH3 represented 0.87% of input TN. Microbiological analyses determined the presence of 107 CFU/g of bacteria related to N cycle and real time PCR demonstrated the presence in the final product of 4.77⋅107 couples of genes of Bacterial amoA/gTS and 2.46⋅107 couples NosZ/gTS, indicating nitrification and complete denitrification. These results exhibit that nitrification and complete denitrification can efficiently occur in a composting process effectively transforming N2O into N2 as consequence of the optimized alternation of aerated and anoxic phases in the feedstock.

Environmental odor perception: testing regional differences on heterogeneity with application to odor perceptions in the area of Este (Italy)

One way to evaluate the hazard of environmental degradation of the quality of life in a place, because of bad odors, is to consider the heterogeneity of possible types and of possible sources of malodors. In the literature, the problem of comparing heterogeneities of types or of sources of odors in two geographical areas has not yet been dealt with the due attention. The main reason is that methodological proposals for tests for heterogeneity comparisons are very rare. We propose a permutation test based on the comparison of linear combinations of sampling indices of heterogeneity. The good power behavior, especially for small differences of the degrees of heterogeneity of the two compared areas, is proved through a Monte Carlo simulation study. The application of the test for heterogeneity comparisons on the data of the survey on odor perceptions in the region of Este (Italy) performed in 2010 shows the usefulness of the proposed methodology, which can be added, as a complementary analysis, to the classical established techniques for studying the environmental impact of odors like dispersion models, dynamic olfactometry, smell maps determination, and others. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Dynamic olfactometry and GC–TOFMS to monitor the efficiency of an industrial biofilter

Biofiltration is the most widely used technique for eliminating odours in waste treatment plants. Volatile organic compounds (VOCs) are among the odorous compounds emitted by waste management plants, and serve as variables to measure odour emissions depending on the type of aeration process used. In this work, we assess the performance of an industrial-scale biofilter where composting is the main source of VOCs and odour emissions. Dynamic olfactometry is the sensorial technique used to determine odour concentration, while gas chromatography–time of flight-mass spectrometry (GC–TOFMS) is used to perform the chemical characterization. This work examines a total of 82 compounds belonging to 15 odorous families of VOCs, particularly mercaptans, sulphur-containing compounds, alcohols and terpenes, among others. Principal component analysis (PCA) is used to assess the influence of each of these families of VOCs on the total variance of the measure with regard to both the input and output flow of the biofilter. Finally, partial least-squares (PLS) regression is used to estimate the odour concentration in each of the samples taken at the inlet and outlet of the biofilter in each of the samples based on the chemical information provided by chromatographic analysis. The study shows that there is an adequate correlation (r=0.9751) between real and estimated odour concentrations, both of which are expressed in European odour units per cubic metre (ouE·m−3).

Effects of forage-to-concentrate ratio and dietary fiber manipulation on gas emissions and olfactometry from manure of Holstein heifers

The objective of this experiment was to determine the effects of differing ratios of forage to concentrate (F:C) and fiber levels on odor and gas emissions from manure. Eight Holstein dairy heifers (362.45±4.53 d of age and 335.6±7.41 kg of body weight) were randomly assigned to a split-plot, 4×4 Latin square design (21-d periods) with F:C as the whole plot (20 or 80% forage) and fiber level as sub-plot (0, 20, 40, or 60% inclusion of corn stover). Gas concentration was determined using an infrared photoacoustic analyzer over a 24-h period using a steady-state flux chamber setup. Odorous air samples were collected from chamber headspace and evaluated by 6h uman assessors using a forced-choice dynamic olfactometry technique. Emissions of CO2 were greater for the low than high concentrate diets, and no differences were observed for NH3 and CH4 emissions between F:C. Although F:C had no effect on NH3 emissions, as dietary fiber increased, a linear interaction with opposite effects was found for high and low concentrate diets. Nitrous oxide emissions were below minimum detectable levels. Neither F:C nor neutral detergent fiber level affected odor intensity. Odor emissions were successfully assessed, and manipulation of dietary fiber has the potential to influence CH4 and NH3 emissions.

Monitoring of pile composting process of OFMSW at full scale and evaluation of odour emission impact

In this study, the evolution of odour concentration (ouE/m3STP) emitted during the pile composting of the organic fraction of municipal solid waste (OFMSW) was monitored by dynamic olfactometry. Physical–chemical variables as well as the respirometric variables were also analysed. The aim of this work was twofold. The first was to determine the relationship between odour and traditional variables to determine if dynamic olfactometry is a feasible and adequate technique for monitoring an aerobic stabilisation process (composting). Second, the composting process odour impact on surrounding areas was simulated by a dispersion model. The results showed that the decrease of odour concentration, total organic carbon and respirometric variables was similar (around 96, 96 y 98% respectively). The highest odour emission (5224 ouE/m3) was reached in parallel with the highest microbiological activity (SOUR and OD20 values of 25 mgO2/gVS·h and 70 mgO2/gVS, respectively).The validity of monitoring odour emissions during composting in combination with traditional and respirometric variables was demonstrated by the adequate correlation obtained between the variables. Moreover, the quantification of odour emissions by dynamic olfactometry and the subsequent application of the dispersion model permitted making an initial prediction of the impact of odorous emissions on the population. Finally, the determination of CO2 and CH4 emissions allowed the influence of composting process on carbon reservoirs and global warming to be evaluated.

The Emission of Odor from LivestockBuildings for Dairy Cattle in Poland

Abstract. The aim of the study was to determine the momentary odor emission factors from two groups of free-stall dairy cattle barns (traditional and modern frame barns) with natural ventilation systems. The odor emission was measured in Poland (Greater Poland) from spring to autumn 2012. The researched six free-stall dairy cattle barns differed also in the type of resting area and manure removal system. The concentrations of odor were measured with the dynamic olfactometry method according to the European Standard EN 13725:2003 procedure. The concentration of odor in the monitored barns ranged from 101 to 825 ou E m -3 thus it characterized high variability. The mean momentary odor emission factors were lower (p≤0.05) for traditional designs barns than for modern frame barns and ranged from 0.04 to 0.061 ou E s -1 kg -1 and 0.127-0.171 ou E s -1 kg -1 , respectively. The housing system (deep litter, shallow litter, cubicles with floor mats or litter) did not influence on odor emission factors within modern frame barns group and also within the group of traditional designs barns (p≤0.05).

Evaluation of Abatement Technologies for Pig Houses by Dynamic Olfactometry and On-site Mass Spectrometry

The aim of the present study was to evaluate the effect of abatement technologies for pig houses on odour based on 1) on-site measurements of dynamic olfactometry and chemical odorants and 2) dynamic olfactometry with storage of air samples in sampling bags. The study was conducted at two facilities with growing-finishing pigs with either biological air cleaning or slurry acidification. Five measurements days were carried out at the facility with biological air cleaning and six days at the facility with slurry acidification. A mobile laboratory containing proton-transfer-reaction mass spectrometry (PTR-MS) and an olfactometer was applied for the on-site measurements. The mobile laboratory was connected to the odour sources by insulated and heated Teflon tubes that were flushed continuously with sample air. The sampling bags for dynamic olfactometry were collected simultaneously with the on-site measurements and were analysed after ca. 24 h. At each measurement day three repetition were performed before and after the biological air cleaner and in the pig house with slurry acidification and in an identical control pig house. Odour threshold values for the individual chemical odorants were used to estimate the odour activity value for each sample. The results demonstrated that evaluation of the abatement technologies based on the on-site measurements of dynamic olfactometry and the odour activity value based on chemical odorants were in agreement and showed the same trend in data. However, if the effect of the abatement technologies was evaluated based on dynamic olfactometry with storage in sampling bags the effect of the biological air cleaner was in general underestimated and the effect of the slurry acidification system was overestimated. In conclusion, the storage in sampling bags seems to bias the measurements of odour and this may influence the estimated effect of abatement technologies. More research is needed to limit the bias of sampling bags used for dynamic olfactometry.

A novel tool for odor emission assessment in wastewater treatment plant

Odor emissions are one of the major environmental impact generated by wastewater treatment plants (WWTPs) perceived by exposed population. Consequently, the control of odor emissions is a relevant aspect that must be considered in the management of the WWTPs. Any efficient strategy for odor control was based on direct and/or indirect monitoring and characterization of odor emissions. The presented work focuses on the identification of new indirect indicators for the measurement of the odors emitted by different treatment units in a full-scale wastewater treatment plant, as to reduce the cost of environmental monitoring and the environmental impacts of the plant. The work focuses on the existing correlation in each treatment unit between the odor emission capacity (OEC) of wastewater and the odor concentration measured by dynamic olfactometry according to EN13725:2003 in ambient air. In addition the research shows the correlation between the organic contents measured by BOD5 and COD and the OEC of the wastewater by analyzing different treatment units.

Odour in composting processes at pilot scale: monitoring and biofiltration

Although odour emissions associated with the composting process, especially during the hydrolytic stage, are widely known, their impact on surrounding areas is not easily quantifiable. For this reason, odour emissions during the first stage of composting were evaluated by dynamic olfactometry at pilot scale in order to obtain results which can be extrapolated to industrial facilities. The composting was carried out in a commercial dynamic respirometer equipped with two biofilters at pilot scale filled with prunings (Populus) and mature compost obtained from the organic fraction of municipal solid waste. Given that the highest odour emissions occur in the first stage of the composting process, this stage was carried out in a closed system to better control the odour emissions, whose maximum value was estimated to be 2.78 ou E s −1 during the experiments. Odour concentration, the dynamic respiration index and temperature showed the same evolution during composting, thus indicating that odour could be a key variable in the monitoring process. Other variables such as total organic carbon (C TOC) and pH were also found to be significant in this study due to their influence over odour emissions. The efficiency of the biofilters (empty bed residence time of 86 s) was determined by quantifying the odour emissions at the inlet and outlet of both biofilters. The moisture content in the biofilters was found to be an important variable for improving odour removal efficiency, while the minimum moisture percentage to obtain successful results was found to be 55% (odour removal efficiency of 95%).

Estimating odour impact range of a selected wastewater treatment plant for winter and summer seasons in Polish conditions using CALPUFF model

Odour emission from wastewater treatment plants (WWTP) is a common cause of odour nuisance to neighbouring areas. The analysed object was mechanical biological WWTP designed for 1,200,000 population equivalent. Collection of the samples was carried out in accordance with the methodology described in VDI 3880 and PN-EN 13725 during the rainless weather. Odour concentration measurement was made using the method of dynamic olfactometry, in accordance with the procedures described in EN: 13725 ‘Air Quality: Determination of odour concentration by dynamic olfactometry’. For selected emission sources model calculations were conducted using CALPUFF dispersion model for neighbouring residential areas, which are exceptionally exposed to odours. This study presents results of modelling in local scale, for different meteorological scenarios, respectively for winter and summer seasons.

Ammonia diffusion through Nalophan double bags: effect of concentration gradient reduction.

The ammonia loss through Nalophan bags has been studied. The losses observed for storage conditions and times as allowed by the reference standard for dynamic olfactometry (EN 13725:2003) indicate that odour concentration values due to the presence of small molecules may be significantly underestimated if samples are not analysed immediately after sampling. A diffusion model was used in order to study diffusion through the bag. The study discusses the effect of concentration gradient (ΔC) across the polymeric membrane of the analyte. The ΔC was controlled by using a setup bag called “double bags.” Experimental data show a reduction of ammonia percentage losses due to the effect of the external multibarrier. The expedient of the double bag loaded with the same gas mixture allows a reduced diffusion of ammonia into the inner bag. Comparing the inner bag losses with those of the single bag stored in the same conditions (T, P, u) and with equal geometrical characteristics (S/V, z), it was observed that the inner bag of the double bag displays a 16% loss while the single bag displays a 37% loss. Acting on the ΔC it is possible to achieve a gross reduction of 57% in the ammonia leakage due to diffusion.