Sampling method for the determination of methane emissions from landfill surfaces.

The first aim of this work is the definition and the study of a suitable sampling method for the measurement of landfill gas (LFG) emissions from landfill surfaces, since, up to now, there are no codified nor universally accepted sampling methods for this specific task. The studied sampling method is based on the use of a static hood. The research work involves a preliminary theoretical study for the hood design, experimental tests for the definition of the optimal sampling procedures, and simulations of the hood fluid-dynamics for the system validation. The second aim of this study is the investigation of the correlations between LFG emissions and meteorological conditions, whose identification would be very useful in terms of effective landfill management and pollution control. This involved a wide literature study for the selection of those parameters that seem to have an influence on LFG emission, and the collection of a great number of experimental data on a target site, which led to the conclusion that atmospheric pressure and soil humidity are the parameters that mostly affect LFG emissions.

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.

Electronic noses for environmental monitoring applications.

Electronic nose applications in environmental monitoring are nowadays of great interest, because of the instruments' proven capability of recognizing and discriminating between a variety of different gases and odors using just a small number of sensors. Such applications in the environmental field include analysis of parameters relating to environmental quality, process control, and verification of efficiency of odor control systems. This article reviews the findings of recent scientific studies in this field, with particular focus on the abovementioned applications. In general, these studies prove that electronic noses are mostly suitable for the different applications reported, especially if the instruments are specifically developed and fine-tuned. As a general rule, literature studies also discuss the critical aspects connected with the different possible uses, as well as research regarding the development of effective solutions. However, currently the main limit to the diffusion of electronic noses as environmental monitoring tools is their complexity and the lack of specific regulation for their standardization, as their use entails a large number of degrees of freedom, regarding for instance the training and the data processing procedures.

Ammonia diffusion through Nalophan™ bags.

The aim of the work is to verify the diffusion rate of ammonia through the Nalophan™ film that constitutes the sampling bag, considering storage times ranging from 1 to 26 h. The ammonia decay over time was evaluated using gas-chromatography for the quantification of ammonia concentration inside the bag. The research assesses the roles of both of ammonia and water concentration gradients at the polymeric film interface on the diffusion process. The results show that both the ammonia concentration gradient and, in a less pronounced way, the water concentration gradient are the main 'engines' of ammonia diffusion. Double bags seem to represent a simple solution for preventing ammonia losses during storage. Another interesting result concerns the role of the bag surface on the ammonia diffusion rate: the higher the surface/volume (S/V) ratio, the higher the ammonia diffusion rate through the polymeric film.

The need for electronic noses for environmental odour exposure assessment.

This paper focuses on the opportunities for using electronic noses for odour exposure assessment purposes, especially in cases where dispersion modelling is not applicable. Such cases include, for instance, those sources where a detailed characterisation and quantification of the odour emissions for every hour of the simulation time domain is particularly difficult, due to the nature of the source or to the variability of the emissions over time. In such situations, it is useful to determine odour exposure directly at receptors instead. This paper critically discusses the state of the art of electronic nose technology as far as its application to the determination of odour exposure at receptors is concerned. One example of electronic nose application to the monitoring of odours from an Italian municipal solid waste (MSW) landfill is reported, in order to discuss the instrument's potential and limits. The monitoring results are represented by the number of measures that are classified in a specific olfactory class; this information allows the odour exposure at each monitoring site in terms of odour detection frequency to be determined. Besides a quantification of the odour episodes, electronic noses allowed the identification of the landfill gas as the monitored landfill major odour source.

Odor sampling: techniques and strategies for the estimation of odor emission rates from different source types.

Sampling is one of the main issues pertaining to odor characterization and measurement. The aim of sampling is to obtain representative information on the typical characteristics of an odor source by means of the collection of a suitable volume fraction of the effluent. The most important information about an emission source for odor impact assessment is the so-called Odor Emission Rate (OER), which represents the quantity of odor emitted per unit of time, and is expressed in odor units per second (ou∙s-1). This paper reviews the different odor sampling strategies adopted depending on source type. The review includes an overview of odor sampling regulations and a detailed discussion of the equipment to be used as well as the mathematical considerations to be applied to obtain the OER in relation to the sampled source typology.

Development of an electronic nose for environmental odour monitoring.

Exhaustive odour impact assessment should involve the evaluation of the impact of odours directly on citizens. For this purpose it might be useful to have an instrument capable of continuously monitoring ambient air quality, detecting the presence of odours and also recognizing their provenance. This paper discusses the laboratory and field tests conducted in order to evaluate the performance of a new electronic nose, specifically developed for monitoring environmental odours. The laboratory tests proved the instrument was able to discriminate between the different pure substances being tested, and to estimate the odour concentrations giving correlation indexes (R2) of 0.99 and errors below 15%. Finally, the experimental monitoring tests conducted in the field, allowed us to verify the effectiveness of this electronic nose for the continuous detection of odours in ambient air, proving its stability to variable atmospheric conditions and its capability to detect odour peaks.

Clostebol acetate.

The title compound, C(21)H(29)ClO(3) [systematic name (8R,9S,10R,13S,14S,17S)-4-chloro-3-oxoandrost-4-en-17ß-yl acetate], is a 4-chloro derivative of testosterone, used as an anabolic androgenic agent or applied topically in ophthalmological and dermatological treatments. The absolute configurations at positions 8, 9, 10, 13, 14 and 17 were established by refinement of the Flack parameter as R, S, R, S, S, and S, respectively. Rings B and C of the steroid ring system adopt chair conformations, ring A has a half-chair conformation, while ring D is in a C(13) envelope conformation. Ring B and C, and C and D are trans fused. In the crystal, molecules are linked by a weak C-H⋯O interaction.

Olfactometric approach for the evaluation of citizens' exposure to industrial emissions in the city of Terni, Italy.

Since several years odour nuisance is a serious environmental concern in the city of Terni, whose citizens are repeatedly lamenting the presence of malodours. This paper describes the olfactometric approach adopted for assessing the odour impact on the city of Terni, caused by the co-presence of three important industrial poles: the steel industry pole, the chemical pole and a third industrial pole, comprising different activities for the treatment of wastewaters and solid waste. The combination of analyses by dynamic olfactometry and dispersion modelling allowed the evaluation of the citizens' exposure to the industrial odours, resulting in both the quantification of emissions and the assessment of their impact on the territory. The overall odour emissions were estimated to be equal to 218,000 ou(E) s(-1): 51% from the steel industry pole, 29% from the chemical pole and 20% from the other plants, respectively. The simulation of the emission dispersion shows that the odour impact relevant to all three studied industrial poles is considerable, actually investing almost the whole city of Terni. The study results also enabled the identification of the most problematic odour sources, which turned out to be the primary emissions from the furnace for the steel industry pole, Treofan and the wastewater treatment plant for the chemical pole and the municipal wastewater treatment plant and the pulper incinerator as far as the other plants are concerned.

Predicting odour emissions from wastewater treatment plants by means of odour emission factors.

In this study, the results of odour concentration measurements on different wastewater treatment plants are presented and used in order to estimate the odour emission factors relevant to single odour sources. An odour emission factor is a representative value that relates the quantity of odour released to the atmosphere to a specific activity index, which in this case was the plant treatment capacity, resulting in an odour emission factor expressed in odour units per cubic metre of treated sewage. The results show that the major odour source of a wastewater treatment plant is represented by the primary sedimentation (with an OEF equal to 1.9 x 10(5)ou(E) m(-3)). In general, the highest OEFs are observed in correspondence of the first steps of the wastewater depuration cycle (OEF between 1.1 x 10(4)ou(E) m(-3) and 1.9 x 10(5)ou(E) m(-3)) and tend to decrease along the depuration process (OEF between 7.4 x 10(3)ou(E) m(-3) and 4.3 x 10(4)ou(E) m(-3)). In general, the OEFs calculated according to this approach represent a model for a rough prediction of odour emissions independently from the specific characteristics of the different plants.

Continuous monitoring of odours from a composting plant using electronic noses.

The odour impact of a composting plant situated in an urbanized area was evaluated by continuously monitoring the ambient air close to the plant during a period of about 4 days using two electronic noses. One electronic nose was installed in a nearby house, and the other one inside the perimeter of the composting plant in order to compare the response of both instruments. The results of the monitoring are represented by tables that report the olfactory class and the odour concentration value attributed to the analyzed air for each of the 370 measurements carried out during the monitoring period. The electronic nose installed at the house detected the presence of odours coming from the composting plant for about 7.8% of the monitoring total duration. Of the odour detections, 86% (25 of 29 measurements) were classified as belonging to the olfactory class corresponding to the open air storage of the waste screening overflows heaps, which was therefore identified to be the major odour source of the monitored composting plant. In correspondence of the measurements during which the electronic nose inside the house detected the presence of odours from the composting plant, the olfactory classes recognized by both instruments coincide. Moreover, the electronic nose at the house detected the presence of odours from the composting plant at issue in correspondence of each odour perception of the house occupants. The results of the study show the possibility of using an electronic nose for environmental odours monitoring, which enables the classification of the quality of the air and to quantify the olfactory nuisance from an industrial source in terms of duration and odour concentration.