Modelli previsionali di dispersione delle emissioni da traffico in ambito urbano

Nel corso dei secoli l'aumento della mobilità è stato comunemente associato al miglioramento della qualità della vita. Per contro, l’emissione di composti in atmosfera da parte dei veicoli a motore comporta la generazione di una pressione negativa sull’ambiente. La stima della dispersione delle emissioni da traffico veicolare risulta complessa in riferimento alle diverse caratteristiche delle aree colpite e dei veicoli utilizzati ma è comunemente perseguita con modelli di calcolo di ampia diffusione. L’impiego di modelli di dispersione in atmosfera risulta di grande utilità per la determinazione delle pressioni sull’ambiente, tuttavia la complessità del fenomeno e le numerose interazioni possibili richiedono una continua innovazione. Il lavoro introduce i più utilizzati strumenti di modellazione della dispersione delle emissioni in atmosfera da traffico veicolare e delle pressioni ambientali ad essi connesse

Modelli previsionali di dispersione delle emissioni da traffico in ambito urbano

Nel corso dei secoli l'aumento della mobilità è stato comunemente associato al miglioramento della qualità della vita. Per contro, l’emissione di composti in atmosfera da parte dei veicoli a motore comporta la generazione di una pressione negativa sull’ambiente. La stima della dispersione delle emissioni da traffico veicolare risulta complessa in riferimento alle diverse caratteristiche delle aree colpite e dei veicoli utilizzati ma è comunemente perseguita con modelli di calcolo di ampia diffusione. L’impiego di modelli di dispersione in atmosfera risulta di grande utilità per la determinazione delle pressioni sull’ambiente, tuttavia la complessità del fenomeno e le numerose interazioni possibili richiedono una continua innovazione. Il lavoro introduce i più utilizzati strumenti di modellazione della dispersione delle emissioni in atmosfera da traffico veicolare e delle pressioni ambientali ad essi connesse

Removal of pharmaceuticals by sonolysis

Emerging contaminants have been detected in the water environment, since they pose a serious threat to human health as well as environmental ecosystems. Among them, pharmaceuticals, cosmetics, pesticides and several industrial compounds are discharged into the environment; conventional water treatments are not able to remove them efficiently, hence new treatment processes have to be investigated and developed in order to properly manage this hazard. For most emerging contaminants their occurrence and ecotoxicological data are still not available, and it is still difficult to foresee their fate in the environment. It must be considered as well that analytical methods for their determination are still going through development, their occurrence being at very low concentrations. According to the proved low efficiency of conventional biological processes for these compounds removal, the adoption of advanced oxidation processes in the tertiary treatment section of existing wastewater treatment plants can significantly contribute to this reduction. The present work deals with ultrasonic based Advanced Oxidation Processes such as sonolysis, and its combination with different processes as photolysis, photocatalysis and Fenton-like reactions to achieve chemical degradation and mineralization of these dangerous compounds

Membrane Technology in Wastewater Treatments

Water shortage is rapidly becoming a global problem, as climate change and increasing urban population are defining more waterstressed areas. This leads, in turn, to a lower water quality since a higher demand arises. Therefore, novel systems are required in order to provide safe water: one option can be wastewater reclamation through the implementation of membrane filtration. Nowadays, membranes are present in wastewater treatment both in biological oxidation as an hybrid system known as Membrane BioReactor (MBR), and in advanced treatment as pure membrane filtration. For instance, new large treatment plants have been installed in the last years, such as in Singapore, Israel and Spain

Control of fouling in MBRs through nanospheres addition

In the last decade, the membrane bioreactor (MBR) industry expanded and nowadays this technology is diffused worldwide for wastewater treatment. Nevertheless, membrane fouling is still a critical issue and most research is focused on this aspect in order to control the fouling phenomenon, such as the definition of foulant agents, which are mainly extracellular polymeric substances. One of the main drawbacks related to fouling in MBRs is the sudden jump of the transmembrane pressure, often attributed to the collapse of the fouling layer, which in turn leads to a reduction of the pores size. A potential solution to this problem can be the addition of particles as to reduce the compressibility of the fouling layer through the engineering of the cake structure. Aim of the present work is to test this hypothesis through the addition of nanospheres of different diameter in a hollow fiber MBR unit at lab scale. The nanospheres are inert and non-compressible, and have been chosen for their capability to form well-structured layers. In order to analyze the MBR filtration performance, a synthetic solution has been prepared, in which a foulant agent (sodium alginate) has been spiked. A filtration model has been provided as to interpret the results and their eventual dependence on diameter and concentration of the nanospheres. Results obtained at constant flux in dead-end mode show that the presence of particles changes cake resistance and leads to the formation of non-compressible fouling. However, the addition of particles leads to better filtration performances, no matter what the diameter or concentration may be. Nevertheless, further research is required with the aim of testing the hypothesis with real wastewater. This study may, therefore, enlarge the choice of membrane fouling reducers by taking into consideration their ability to form more structured fouling. © 2015 Balaban Desalination Publications

Modelli previsionali di dispersione delle emissioni da traffico in ambito urbano

Nel corso dei secoli l'aumento della mobilità è stato comunemente associato al miglioramento della qualità della vita. Per contro, l’emissione di composti in atmosfera da parte dei veicoli a motore comporta la generazione di una pressione negativa sull’ambiente. La stima della dispersione delle emissioni da traffico veicolare risulta complessa in riferimento alle diverse caratteristiche delle aree colpite e dei veicoli utilizzati ma è comunemente perseguita con modelli di calcolo di ampia diffusione. L’impiego di modelli di dispersione in atmosfera risulta di grande utilità per la determinazione delle pressioni sull’ambiente, tuttavia la complessità del fenomeno e le numerose interazioni possibili richiedono una continua innovazione. Il lavoro introduce i più utilizzati strumenti di modellazione della dispersione delle emissioni in atmosfera da traffico veicolare e delle pressioni ambientali ad essi connesse

Dispersion Models to Forecast Traffic-related Emissions in Urban Areas

Down the centuries, a direct link had been developed between increase in mobility and increase in wealth. On the other hand, air emission of greenhouse gases (GHG) due to vehicles equipped with internal combustion engines can be regarded as a negative pressure over the environment. In the coming decades, road transport is likely to remain a significant contributor to air pollution in cities. Many urban trips cover distances of less than 6 km. Since the effectiveness of catalytic converters in the initial minutes of engine operation is small, the average emission per distance driven is very high in urban areas. Also, poorly maintained vehicles that lack exhaust aftertreatment systems are responsible for a major part of pollutant emissions. Therefore in urban areas, where higher concentrations of vehicles can be easily found, air pollution represents a critical issue, being it related with both environment and human health protection: in truth, research in recent decades consistently indicates the adverse effects of outdoor air pollution on human health, and the evidence points to air pollution stemming from transport as an important contributor to these effects. Several institutions (EEA, USEPA, etc.) focused their interest in dispersion models because of their potential effectiveness to forecast atmospheric pollution. Furthermore, air micropollutants such as Polycyclic Aromatic Compounds (PAH) and Metallic Trace Elements (MTE) are traffic-related and although very low concentrations their dispersion is a serious issue. However, dispersion models are usefully implemented to better manage this estimation problem. Nonetheless, policy makers and land managers have to deal with model selection, taking into account that several dispersion models are available, each one of them focused on specific goals (e.g., wind transport of pollutants, land morphology implementation, evaluation of micropollutants transport, etc.); a further aspect to be considered is the model scale: not every model can be usefully implemented in all conditions, e.g. for a careful simulation of the transport of pollutants in a range of 50 – 500 m, it is recommended to select Lagrangian or Eulerian tridimensional models, instead of Gaussian models, which may be preferable to simulate dispersion over longer distances. In addition, emission factors have to be evaluated as well, considering that nowadays vehicles release pollutants in the environment depending on both their engine and technological innovation level. Dispersion models are commonly used in order to define pressures on the environment, although phenomenon complexity and numerous interactions require continuous innovation. The paper aims to explain dispersion models implementation and to introduce the most used models available for both the transport sector and the GHG emissions in order to help land managers to better assess air quality thanks to a deeper comprehension of pollutants dispersion

Sustainable power plants: A support tool for the analysis of alternatives

Shortage of fossil fuels and global oil crisis are leading many national energy authorities to switch from traditional fuels to other renewable ones. On the other hand, in several western countries – due to an increasing environmental awareness – public acceptance of traditional power plants (e.g., coal or fired oil) is steadily decreasing, mostly because of their significant environmental pressures. Decision makers’ activities need to be supported by objective tools, which must be designed to be able to select the best alternative in order to achieve some prefixed goals. Therefore, in the present study, a tool is proposed to support decision makers: it is based on Life Cycle Assessment data from seven different power plants (coal, fired oil, fired gas, nuclear, wind, solar and hydroelectric), to understand what is taken into in terms of material fluxes, and how much it costs in a specific context. Consequently, an Analytic Hierarchy Process has been proposed to select which one might be the best alternative in function of the considered scale and ten environmental criteria. The proposed procedure aims to evaluate different power plants and identify the most environmentally sustainable one in function of plant construction and operation phases