Assessing the inter-annual variability of separation distances around odour sources to protect the residents from odour annoyance.

In recent years, there has been a growing concern about potential impacts on public health and wellbeing due to exposure to environmental odour. Separation distances between odour-emitting sources and residential areas can be calculated using dispersion models, as a means of protecting the neighbourhood from odour annoyance. This study investigates the suitability of using one single year of meteorological input data to calculate reliable direction-dependent separation distances. Accordingly, we assessed and quantified the inter-annual variability of separation distances at two sites with different meteorological conditions, one in Brazil and the other in Austria. A 5-year dataset of hourly meteorological observations was used for each site. Two odour impact criteria set in current regulations were selected to explore their effect on the separation distances. The coefficient of variation was used as a statistical measure to characterise the amount of annual variation. Overall, for all scenarios, the separation distances had a low degree of inter-annual variability (mean coefficient of variation values from 8% to 21%). Reasonable agreements from year to year were therefore observed at the two sites under investigation, showing that one year of meteorological data is a good compromise to achieve reliable accuracy. This finding can provide a more cost-effective solution to calculate separation distances in the vicinity of odour sources.

Carbon biofixation and lipid composition of an acidophilic microalga cultivated on treated wastewater supplied with different CO2 levels.

This study evaluated productivity, CO2 biofixation, and lipid content in biomass of the acidophilic microalga Chlamydomonas acidophila LAFIC-004 cultivated with five different carbon dioxide concentrations. The influence of carbon dioxide concentration on nutrient removal and pH was also investigated. Treated wastewater (secondary effluent) was used as culture medium. Five experimental setups were tested: T-0% - injection of atmospheric air (0.038% CO2), T-5% (5% CO2), T-10% (10% CO2), T-15% (15% CO2) and T-20% (20% CO2). The T-5% and T-10% experiments showed the highest values of productivity and CO2 biofixation, and maximum biomass dry weight was 0.48 ± 0.02 and 0.51 ± 0.03 g L-1, respectively. This acidophilic microalga proved to be suitable for carbon biofixation and removal of nutrients from secondary effluent of wastewater treatment plants with high CO2 concentration. All assays were performed without pH control. This microalga species presented high lipid content. However, fatty acid methyl esters (FAME) are not suitable for biodiesel use.

An analysis of error propagation in AERMOD lateral dispersion using Round Hill II and Uttenweiller experiments in reduced averaging times.

Dispersion modelling was proved by researchers that most part of the models, including the regulatory models recommended by the Environmental Protection Agency of the United States (AERMOD and CALPUFF), do not have the ability to predict under complex situations. This article presents a novel evaluation of the propagation of errors in lateral dispersion coefficient of AERMOD with emphasis on estimate of average times under 10 min. The sources of uncertainty evaluated were parameterizations of lateral dispersion ([Formula: see text]), standard deviation of lateral wind speed ([Formula: see text]) and processing of obstacle effect. The model's performance was tested in two field tracer experiments: Round Hill II and Uttenweiller. The results show that error propagation from the estimate of [Formula: see text] directly affects the determination of [Formula: see text], especially in Round Hill II experiment conditions. After average times are reduced, errors arise in the parameterization of [Formula: see text], even after observation assimilations of [Formula: see text], exposing errors on Lagrangian Time Scale parameterization. The assessment of the model in the presence of obstacles shows that the implementation of a plume rise model enhancement algorithm can improve the performance of the AERMOD model. However, these improvements are small when the obstacles have a complex geometry, such as Uttenweiller.

Preselection test of jury for improvement of olfactometric certification efficiency.

To certificate an olfactometric jury, laboratories usually follow up the panelist screening methodology described in the European Standard EN 13725/2003. The procedure takes a lot of time, labour and money. In laboratory routine of LCQAr - Laboratory of Air Quality Control, of Federal University of Santa Catarina, Brazil, it was found that the efficiency of jury approvals used to be as low as around 30%. In order to improve the efficiency, a quick preselection test was proposed and tried for late certification recommended by EN 13725. The methodology to create the preselection test was based on the conceptions of the standards EN 13725 (CEN, 2003), ASTM 679 (2011) and ASTM 544 (2010). In the trial test, 31 volunteers participated and then screened according to the EN13725 standard. It was verified that the efficiency increased to 46% from about 30% after the introduction of the preselection test. The experiments were conducted at LCQAr, with the contribution of Water Research Centre of University of New South Wales, Australia.

A review of odour impact criteria in selected countries around the world.

Exposure to environmental odour can result in annoyance, health effects and depreciation of property values. Therefore, many jurisdictions classify odour as an atmospheric pollutant and regulate emissions and/or impacts from odour generating activities at a national, state or municipal level. In this work, a critical review of odour regulations in selected jurisdictions of 28 countries is presented. Individual approaches were identified as: comparing ambient air odour concentration and individual chemicals statistics against impact criteria (maximum impact standard); using fixed and variable separation distances (separation distance standard); maximum emission rate for mixtures of odorants and individual chemical species (maximum emission standard); number of complaints received or annoyance level determined via community surveys (maximum annoyance standard); and requiring use of best available technologies (BAT) to minimize odour emissions (technology standard). The comparison of model-predicted odour concentration statistics against odour impact criteria (OIC) is identified as one of the most common tools used by regulators to evaluate the risk of odour impacts in planning stage assessments and is also used to inform assessment of odour impacts of existing facilities. Special emphasis is given to summarizing OIC (concentration percentile and threshold) and the manner in which they are applied. The way short term odour peak to model time-step mean (peak-to-mean) effects is also captured. Furthermore, the fundamentals of odorant properties, dimensions of nuisance odour, odour sampling and analysis methods and dispersion modelling guidance are provided. Common elements of mature and effective odour regulation frameworks are identified and an integrated multi-tool strategy is recommended.

Pragmatic evaluation of odour emissions from a rendering plant in southern Brazil.

In the food industry and linked activities, environmental impacts relate mainly to the generation of liquid and gaseous effluents. Rendering plants, which process animal by-products, are strongly associated with malodorous emissions. Thus, effective odour-control technologies are required to minimise odour annoyance in nearby communities and thereby public complaints. In this paper, the effectiveness of a biofilter for the treatment of odours from a meat-rendering plant located in southern Brazil was evaluated based on German guideline VDI 3477:2004-11. Samples were collected upstream and downstream of the gas treatment system using a pragmatic approach in order to minimise the cost of such a study. Odour concentration was determined according to European standard EN 13725:2003. The results showed an OER of 8.82 × 108 ouE h-1 and odour removal efficiency lower than the established benchmark set by SEMA Resolution 054/2006, taken as reference for being the only Brazilian regulation to establish quantitative odour emission criteria. Enhancement of the biofiltration system and/or association with other odour abatement technologies are required to increase odour removal, limit impacts and comply with regulatory requirements. The paper also includes a discussion on the current odour regulation in Brazil.

Photocatalytic oxidation of H2S in the gas phase over TiO2-coated glass fiber filter.

To promote the photocatalytic oxidation (PCO) of hydrogen sulfide (H2S) in the gas phase, TiO2-coated glass fiber filters were packed in an annular photoreactor. Glass fibers coated with TiO2 thin films were characterized structurally and morphologically by field emission gun scanning electron microscopy (FEG-SEM), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Flow rate and H2S inlet concentration were evaluated to determine the performance of the reactor. Removal efficiencies up to 99% were achieved for flow rate of 25 L h(-1) (residence time of 121 s) and H2S inlet concentration from 12 to 14 ppmv. The long-term experiment presented H2S removal of 89% for 16 h. After 28 h of continuous use, H2S degradation was observed at 64%, which suggests that the photocatalyst was losing activity due to deactivation. Moreover, the kinetics of the PCO of H2S according to the Langmuir-Hinshelwood (L-H) approach along with the mass balance of a plug-flow reactor was modeled. The reaction constant (k) was calculated at approximately 10.5 µmol m(-3) s(-1) and the adsorption constant (K) of approximately 5263 m(-3) mol with linearity (R2) of 0.98.

Gestão de odores: fundamentos do Nariz Eletrônico / Odor management: fundamentals of Electronic Nose

Narizes Eletrônicos têm sido desenvolvidos para detecção automática e classificação de odores, vapores e gases. São instrumentos capazes de medir a concentração ou intensidade odorante de modo similar a um olfatômetro, mas sem as limitações inerentes ao uso de painéis humanos, o que é altamente desejável. Um Nariz Eletrônico é geralmente composto por um sistema de sensores químicos e um sistema eletrônico associado à inteligência artificial para reconhecimento. Têm sido aplicados em muitas áreas, tais como análise de alimentos, controles ambientais e diagnósticos médicos. Do ponto de vista ambiental, sistemas de Narizes Eletrônicos vêm sendo usados para monitorar a qualidade do ar, detectar fontes e quantificar emissões odorantes. Este artigo pretende apresentar os fundamentos dos Narizes Eletrônicos.

Electronic noses have been developed for automatic detection and classification of odors, vapors and gases. They are instruments capable to identify odors as the human nose does, and measure the odor concentration or intensity according to similar metrics as an olfactometer, but without the inherent limitations of human panels. An Electronic Nose is generally composed of a matrix of chemical sensors and computer based system for odor recognition and classification. It has been applied in many areas, such as food quality analysis, explosives detection, environmental monitoring and medical diagnosis. In the ambient environment, systems of Electronic Noses have been used to monitor the quality of air and to detect and quantify odor sources and emissions. This article intends to present the fundamentals and main characteristics of Electronic Noses.

Dispersion of odorous gases in the atmosphere - Part I: Modeling approaches to the phenomenon.

The study of odor dispersion, particularly its modeling, is an important decision tool for estimating the impact of human activities on the environment and its populations. In this sense, software to model the dispersion of odorous gases was developed and is presented. It is based on the theory established by Högström on the odor dispersion of puff emissions. This theory is applied to Gaussian models and takes the frequency of values for odor intensity over any time period into account. Such a model is able to consider the instantaneous characteristics of odor perception by human beings. Nine approaches that explore several solutions within the Gaussian domain for the atmospheric dispersion problem are proposed in software named ODODIS (ODOr DISpersion Software). This software was developed to test the different solutions. Four of these solutions are based on the punctual (or point source) emission or classic equation; two are based on the instantaneous punctual emission equation; and the other three, on the prolonged punctual emission equation (puff models). Measuring units used for the input data may be g s(-1) or OU (Odor Units). The software developed here satisfies the need to obtain instantaneous data of either a passive or an odorous gas at a specific point of an area. The simulation time varies depending on the purpose of the analysis. Mean concentration values may be obtained by integrating the instantaneous results generated by the model.