Evaluation of Occupational Exposure Risk for Employees Working in Dynamic Olfactometry: Focus on Non-Carcinogenic Effects Correlated with Exposure to Landfill Emissions

This work aims to evaluate the non-carcinogenic health effects related to landfill odor emissions, therefore focusing on workers involved in dynamic olfactometry. Currently, the most common technique to quantify odor emissions is dynamic olfactometry, a sensorial analysis involving human assessors. During the analysis, assessors are directly exposed, at increasing concentrations, to odor samples, and thus to the hazardous pollutants contained therein. This entails the need to estimate the associated exposure risk to guarantee examiners’ safety. Therefore, this paper evaluates the exposure risk for olfactometric examiners to establish the minimum dilution level to be adopted during the analysis of landfills’ odorous samples to guarantee panelists’ safety. For this purpose, an extensive literature review regarding the pollutants emitted by landfill odor sources was conducted, comparing compounds’ chemical concentrations and threshold limit values (TLVs) to calculate the Hazard Index (HI) and thus establish a minimum dilution value. The data collected indicate that a non-negligible non-carcinogenic risk exists for all landfill emissions considered. However, from the data considered, the minimum dilution factor to be adopted is lower than the typical odor concentration observed for these sources. Therefore, the olfactometric analysis of landfill samples can be generally conducted in safe conditions.

Experimenting with Odour Proficiency Tests Implementation Using Synthetic Bench Loops

Uncertainty in the quantification of odour measurements is a difficult (but needed) task. Critical aspects include panel selection (required by dynamic olfactometry), sampling, and stability of the samples. Proficiency tests (PTs) can help evaluate such contributions; however, the classical approach to PTs, in which laboratories analyse real samples taken from the field, are not as applicable in this field, and are often implemented by only using dry gas cylinders containing stable compounds. Consequently, uncertainties related to the sampling activity cannot be assessed. In particular, high odour levels and the presence of water vapour in emission sources can create significative biases due to sampling techniques used and chemical reactions that can occur before analysis. In this work, we present experimental notes, developed using the experimental facility ‘LOOP’, realised at the RSE research centre in Italy, in order to “help” the definition, in an upgraded protocol for implementing PTs for odour determinations. Using this bench loop is advantageous as it involves the possibility of implementing samples in conditions very similar to reality (i.e., high temperatures, high water content, and the presence of chemical interferents).

Evaluation of a Wet Acid Scrubber and Dry Filter Abatement Technologies in Pig Barns by Dynamic Olfactometry

Livestock activities, in particular swine farms, are sources of odorant compounds that cause conflicts with the neighboring population. Beside the effects on the neighborhood, excessive odor emission can cause discomfort to farm workers. In this context the APPROAch project, aims to test the application of two different air cleaning technologies (a wet acid scrubber and a dry filter) to reduce dust, ammonia and odors, in naturally ventilated pig facilities. The aim of the present study is to evaluate, in a pig farm, the odor removal efficiency of the two tested abatement technologies, based on air samples analyzed by dynamic olfactometry. Odor sampling was carried out at a pig facility involved in the project and brought to the lab within 30 h from sampling, as established by the European Standard EN 13725:2004. Odor concentration was evaluated by dynamic olfactometry using an Olfaktomat-n 6 (PRA-Odournet B.V.—Amsterdam, The Netherlands). The results show that the wet acid scrubber prototype presents an average odor removal efficiency of 16%, whereas dry filter has from limited to no effect. This efficiency could be considered as a good result for a prototype even if further analysis, with longer sampling periods are needed.

INFLUENCE OF MODELLING CHOICES ON THE RESULTS OF LANDFILL ODOUR DISPERSION

Landfills are an important source of odour pollution, potentially causing nuisance to adjacent populations. The most commonly used odour impact assessment for this type of plants usually involves a combination of dynamic olfactometry with dispersion modelling. Despite the advantages associated with the use of dispersion models, there are still some important issues related to their uncertainty. The dispersion model requires the Odour Emission Rate (OER) as input, expressed as units of odour emitted per unit time. Source term characterization and the estimation of the OER are typically the most important steps in the model’s implementation, accounting for the highest contribution to the overall uncertainty. Another important element of uncertainty when modelling emissions from landfill surfaces is the geometrical implementation of the emission source in the dispersion model. This entails the definition of the initial dimensions of the emission, which is critical in the case of large area sources. This paper discusses issues related to uncertainty in the use of dispersion models for the evaluation of landfill odour impacts, particularly focusing on the estimation of the OER and the emission’s initial vertical dimension. This study shows that modelling choices may lead to a variance in the resulting modelled odour concentrations at receptors differing by up to a factor 3. This variability should not cause distrust in the method, but rather indicates the importance of having odour dispersion modelling studies carried out by experts with deep knowledge of the physical-chemical mechanisms underlying atmospheric emissions.

Odour Assessment for a Pig Farm Through Dynamic Olfactometry and Air Dispersion Modelling in Order to Reduce the Odour Pollution Using Biotechnologies

Odour represents one the most actual topics in terms of industrial pig farming pollution effects, mainly because of the increasing number of settlements build in traditional farming areas but also because of the overpopulation of pigsties. The odour impact assessment was requested by a big pig farm in order to comply to the request of the Environmental Agency to reduce the odour impact on nearby settlements. Odour assessment was done using dynamic olfactometry, mathematical modelling of dispersion and FIDOL factors. The initial assessment was used to elaborate and apply an odour management plan based on biotechnologies which consisted mainly in biological treatments applied to the floor of the pigsties, the slurry transportation channels and the slurry tanks with specific products designed to reduce the Ammonia level, break down her sulphurous compounds in the slurry and increase the quality of the slurry as fertilizer, with the final target of reducing the odour emissions. Results indicate a considerable decrease of odour concentrations in the closest settlements, around the farm and inside pigsties. Further measures must be taken as the concentrations are still over the limit values from most European countries.

Influence of the variability of the odour emission rate on its impact range: a case study of the selected industrial source

Odour concentration measurements in a chosen industrial source were made in this study using the method of dynamic olfactometry. The two different scenarios considered the variation of the odour emission rate as input for the dispersion model were compared for the period 2017 (before installation of the equipment for gas treatment) and 2018 (after implementation of purifying technologies). In this paper the odour impact range was determined by applying model calculations conducted in the Polish reference dispersion model – OPERAT FB software for the grid size 2 x 2 km. The conducted research shows a significant improvement in the odour impact range of chosen industrial source in year 2018 compared to 2017.

Masking agent efficiency on odor removal from WWTP sludge drying process

A study was executed in 2016 to determine the efficiency of two different neutralizers on odor perception from a sludge drying process. One of the products was injected by fogging system at the inlet of the odor control unit while the other was added directly to the washing solution of the last stage of the odor control unit, according to supplier recommendations. Performance evaluations encompassed complementary approaches including both sensorial analyses and analytical measures. Odor analyses were performed via dynamic olfactometry according to European Standard EN 13725 coupled with hedonic tone approach according to VDI 3882. Additional analyses on VOC emissions were conducted using gas chromatography screening. In parallel, several odor panels composed of site operators and plant neighbors carried out observations on the WWTP and its perimeter. The main conclusions of this study illustrates: • Only one test leads to a reduction of the odor concentration at the stack, • Overall, neither of the two masking agents significantly reduce the odor concentration at the stack, • The addition of masking agent seems to increase foul odor persistency, • The local odor panel observed no significant improvement in odor reduction within the environment around the WWTP.

THE EFFECT OF SOLID MANURE INCORPORATION INTO THE SOIL ON THE EMISSION OF GASES AND ODOURS

The aim of the study was to determine the level of emission reduction of selected harmful gases and odours following immediate manure incorporation into soil, using the prototype manure applicator. The research was carried out at the Experimental Station of the National Research Institute of Animal Production, in September 2016. Two experimental fields size 6 x 100 m were located on corn stubble in the distance of 40 m. In field A, the solid manure was incorporated into the soil using the prototype manure applicator. In field B, manure application was made by manure spreader. The prototype manure applicator was designed and made by Industrial Institute of Agricultural Engineering. The concentration of harmful gases (NH3, CO2, CH4, N2O) and odours was measured during the study. Measurements were made in the following periods: immediately after application and 2, 4, 6, 10 and 14 hours after application. The concentration of studied gases was measured immediately after sampling by the photoacoustic spectrometer (Multi Gas Monitor Innova 1312). The odours concentration was determined within 30 hours after air sampling by dynamic olfactometry using the TO 8 olfactometer. The solid manure incorporation reduced NH3 emissions by an average of 66%. For the other studied gases the differences in concentration were too small or this concentration was similar to concentration of these gases in surrounding air. The incorporation of solid manure limited also odour emissions. The level reduction decreased with time and amounted to an average of 25%.