1,721,020 research outputs found
Environmental Odour Nuisance Assessment in Urbanized Area: Analysis and Comparison of Different and Integrated Approaches
No full textProlonged exposure to odour emissions causes annoyance which leads to nuisance and consequently to complaints. Different methodologies exist in the literature to evaluate odour impacts, but not all are suitable to assess environmental odour nuisance. Information about their applicability criteria and comparison, is scarce and referred to short time analysis. The research presents and discusses the application of different methods to characterize and assess odour nuisance around an industrial plant localized in a sensitive area. Experimental activities are carried out through a long-time analysis programme. Field inspections and predictive methods are investigated and compared. A modification of the traditional dispersion modelling approach is proposed in order to adapt its application for the prediction of the odour nuisance. The offensiveness and location factors are identified as key parameters in the quantification of the perceived nuisance. The integrated dispersion modelling multi-level approach is highlighted as the most suitable for defining the plant strategies. The paper provides useful information to characterize environmental odour problems and identify appropriate solutions for an effective management of odorous sources, with the aim of reducing complaints, restoring the proper relationship between odorous plants and the surrounding communities and increasing the overall quality of the environment
Environmental odour quantification by ioms: Parametric vs. non-parametric prediction techniques
No full textOdour emissions are a global issue that needs to be controlled to prevent negative impacts. Instrumental odour monitoring systems (IOMS) are an intelligent technology that can be applied to continuously assess annoyance and thus avoid complaints. However, gaps to be improved in terms of accuracy in deciphering information, especially in the implementation of the mathematical model, are still being researched, especially in environmental odour monitoring applications. This research presents and discusses the implementation of traditional and innovative parametric and non-parametric prediction techniques for the elaboration of an effective odour quantification monitoring model (OQMM), with the aim of optimizing the accuracy of the measurements. Artificial neural network (ANN), multivariate adaptive regression splines (MARSpline), partial least square (PLS), multiple linear regression (MLR) and response surface regression (RSR) are implemented and compared for prediction of odour concentrations using an advanced IOMS. Experimental analyses are carried out by using real environmental odour samples collected from a municipal solid waste treatment plant. Results highlight the strengths and weaknesses of the analysed models and their accuracy in terms of environmental odour concentration prediction. The ANN application allows us to obtain the most accurate results among the investigated techniques. This paper provides use-ful information to select the appropriate computational tool to process the signals from sensors, in order to improve the reliability and stability of the measurements and create a robust prediction model
Tecniche di upgrade del biogas a biometano.
No full textIl biogas prodotto dalla digestione anaerobica (AD) a partire da matrici organiche, sia in reattori controllati (digestori) che da discariche controllate, è costituito principalmente da metano, CH4 (50÷70%) e anidride carbonica, CO2 (30÷50%). Il contenuto relativo di CH4 e CO2 nel biogas dipende principalmente dalla natura del substrato e dal pH nella massa in digestione. Oltre a questi due, il biogas contiene, inoltre, quantità minori di altri composti, come l'azoto (0÷3%), il vapore acqueo (5÷10%), l’ossigeno (0÷1%), l’idrogeno solforato (0÷10.000 ppmv), che è prodotto dalla riduzione del solfato contenuto in alcuni rifiuti, l’ammoniaca, proveniente prevalentemente da idrolisi di materiali proteici, gli idrocarburi (0÷200 mg·m-3) e i silossani (0÷41 mg·m-3), ossia composti silico-organici. Oltre al CH4, tutti gli altri gas contenuti nel biogas sono indesiderati e sono considerati inquinanti del biogas stesso; alcuni di questi si ritengono addirittura dannosi al punto da scoraggiare l'utilizzo del biogas nei motori a combustione, come gli idrocarburi alogenati e i silossani, poiché producono acidi alogenati e silice che, a lungo termine, corrodono le superfici metalliche dei motori, ricoprono le candele, abradono le superfici e ostacolano il funzionamento delle valvole. Il contenuto energetico del metano descritto dal potere calorifico inferiore (PCI) è 50,4 MJ·kg-1CH4 o 36 MJ·Nm-3CH4 (in condizioni standard di temperatura e pressione). Tale valore risulta tanto minore quanto maggiore è il contenuto di CO2 o di N2 nel biogas. Per il biogas con contenuto di metano nell'intervallo 60-65%, Il PCI è di circa 20-25 MJ·m-3biogas. H2S e NH3 sono tossici ed estremamente corrosivi, danneggiando l'unità combinata di calore e potenza (CHP) e le parti metalliche attraverso l'emissione di SO2 dalla combustione. A ciò contribuisce anche la presenza di silossani come già accennato. In virtù delle sue proprietà energetiche, oggi sono sempre più proposte ed applicate tecnologie di miglioramento qualitativo delle caratteristiche del biogas allo scopo di poterne attuare lo sfruttamento per alimentazione/integrazione di reti di distribuzione di gas naturali, per autotrazione, per produzione energia elettrica e per teleriscaldamento (Fig. 1.1). Gli impianti di trattamento del biogas finalizzati al miglioramento delle sue potenzialità energetiche sono configurati, normalmente, in due stadi di trattamento: il primo stadio), denominato "biogas cleaning", ha l’obiettivo di rimuovere i composti nocivi e/o tossici (come H2S, Si, composti organici volatili (VOC), silossani, CO e NH3. All’atto pratico tale stadio è praticamente costituito solo dall'unità di rimozione dell’H2S, comunemente basata sull'ossidazione biologica dell'H2S da parte di batteri solfo-ossidanti. Il secondo stadio di trattamento è denominato "upgrading del biogas" e mira ad aumentare il potere calorifico basso del biogas e, quindi, a convertirlo in standard di combustibile più elevato (Sun et al., 2015). Nel processo di “upgrading” la CO2 contenuta nel biogas grezzo viene rimosso o convertito in CH4 mediante reazione con H2 (Kougias et al., 2017). Nel caso in cui il biogas trattato sia purificato fino ad assumere composizione simile a quella del gas naturale, il prodotto finale del gas è chiamato biometano (Kougias et al., 2017). Attualmente, le specifiche della composizione del gas naturale sono fissate dalle normative nazionali e in alcuni paesi è richiesto che il contenuto metano sia maggiore del 95%. Tuttavia, la Commissione Europea ha come obiettivo quello di determinare norme per armonizzare la qualità del gas in tutti gli stati membri (Angelidaki et al., 2018). Oggi sono disponibili numerose tecnologie commerciali per effettuare l’upgrading del biogas e, pertanto, negli ultimi anni è crescente in Europa, soprattutto in quella del nord, il numero di impianti a questo finalizzati (Fig. 1.2). Ciò anche in virtù del fatto che, come si può notare nella Figura 1.3, il biometano produce un quantitativo di GHG, in termini di CO2eq. emessa, nettamente inferiore rispetto i comuni combustibili applicati negli autoveicoli, e, in particolare, meno di 2432 volte la quantità emessa per uso di combustibili fossili. Ciò rende il biometano un combustibile “sostenibile”
Advanced instrumental odour monitoring system for the continuous management and control of environmental odour in complex industrial plants
No full textOdour emissions from complex industrial plants may cause potential impacts on the surrounding areas and, as consequence, complaints with the local residents. The identification of specific odour control plan is therefore needed in the plant management. The current challenge is the definition of Instrumental Odour Monitoring Systems (IOMSs) that allow the continuous odour characterization. No regulation or standardized procedure exist at present. Limited data are available in the literature with reference to the characteristics and operational procedure of this systems for the environmental odours monitoring. The study presents a novel prototype of intelligent and integrated IOMS for the continuous classification and quantification of the odours emitted in ambient air by complex industrial plants, with the scope to control the plants emissions in an objective and continuous manner, thus avoiding odour impact. The architecture and the principal components of the IOMS are highlighted. The operational procedures are presented and discussed.
Results highlights the importance and the flexibility of the proposed IOMS in the odour monitoring. Real-time and accurate information are provided by the system about the source and concentration of the odour emission
Volatile organic compounds (VOCs) control by combining bio-scrubber and ozone pretreatment
No full textVolatile Organic Compounds (VOCs) are toxic for the environment and human health and their tendency to readily volatilize in the atmosphere can lead to problems connected to odours annoyance. Conventional VOCs gaseous emissions treatments entail the application of chemical-physical processes, only promoting the transfer of the contaminants from gas to liquid and/or solid phases. Advanced Oxidation Process (AOPs) and biological processes, conversely, support the oxidation of the organic pollutants, promoting their conversion into harmless and odourless compounds. The integration of booth processes is suggested to increase treatability of VOC. The research presents the application of an innovative treatment system composed by an AOPs pretreatment coupled with a bio-scrubbing unit for the abatement of VOCs, with the aim to increase the removal efficiency. The evaluation of the performance of the proposed system is discussed with reference to the analysis carried out using toluene as model substance. Different operating conditions have been analyzed and investigated to optimize the removal efficiency. The results show that the ozonation applied as pretreatment to the biological process may promote an increase of the pollutant biodegradability along with synergic effects due to the absorption of the ozone derived compounds into the culture growth, resulting in a significant enhancement of removal performances respect to the conventional biotechnologies. A toluene removal efficiency up to 95% were obtained under the investigated conditions
Proactive approach for odour emissions characterization in wastewater treatment plant by H2odour system
No full textThe characterization and quantification of the odour emissions in wastewater treatment plant (WWTP) represents a fundamental step in order to identify potential odour problems and establish the best and most appropriate odour management tools. Now a days odour emissions in WWTP are characterized by the use of sampling techniques which take samples directly from the gaseous phase: i.e. when the emission and consequently the potential problem are already present. The definition of proactive tools for the assessment of potential odour emissions from the emitting sources can prevent the occurrence of potential significant odours events and as consequence complaints. The research presents and describes a novel system, called H2Odour, useful to measure the potential Odour Emission Capacity (OEC) directly from liquids. The system has been designed and developed to standardize the stripping phase of gaseous samples, ensuring the maximization of the odour compounds transfer from the liquid to the gaseous phase. The application on a real full scale WWTP is highlighted. H2Odour represents a novel, proactive device to prevent potential critical situations, allowing a preliminary characterization of the maximum potential odour emissions directly from the liquid phase and through this control activity, leading to a greater environmental and social acceptability of the WWTP
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
