1,579 research outputs found
Part 1: EIA and landforms
No full textA landform can be considered as a geomorphologic asset. It can be regarded as such not only on the basis of scenic, social, economic and cultural value, but also on the basis of other criteria related to the more general scientific concept of an asset. The methods for recognizing and evaluating geomorphologic assets on a scientific basis can be subdivided into two phases: 1) geomorphologic survey and mapping, and 2) selection from the geomorphologic maps of those landforms that may be considered as assets. Here, evaluations of geomorphologic assets in three different areas are presented. -from Author
Past and present of electrochemical treatment of organic pollutants
No full textOxidative electrochemical technologies offer an alternative solution to many environmental problems in the process industry, because electrons provide a versatile, efficient, cost-effective, easily automatable, and clean reagent. In electro-oxidation, organic pollutants can be removed by different methods:
(i) Direct electrolysis: the pollutants (R) are oxidized after adsorption on the anode surface without the involvement of any substance other than electrons:
Rads → Pads + ze-
(ii) Oxidation via intermediates of oxygen evolution: organic compounds are oxidised near the anode surface (M) at high potentials in the region of water discharge due to the participation of intermediates of oxygen evolution:
M + H2O → M(•OH) + H+ + e-
R + M(•OH) → M + CO2 + H2O
Anodes with high oxygen evolution overpotential, such as SnO2, PbO2 or boron-doped diamond (BDD) are ideal electrodes for the complete oxidation of organics to CO2 in wastewater treatment.
(iii) Indirect electrolysis mediated by oxidizing agents generated anodically: organic pollutants are removed through the mediation of some electroactive species generated at the anode surface, which act as intermediaries for electrons shuttling between the electrode and the organic compounds. The main oxidizing chemicals electrogenerated anodically are active chlorine and persulfates, that are produced by the oxidation of chloride and sulphates ions commonly present in wastewaters:
2Cl- → Cl2 + 2e-
2SO42- → S2O82- + 2H+ + 2e-
(iv) Electro-Fenton processes: the pollutants are removed by the •OH produced in the bulk of the solution using the electrogenerated Fenton's reagent where H2O2 is supplied in situ from the two-electron reduction of O2 on cathodes such as gas diffusion electrodes (GDE), reticulated vitreous carbon (RVC) or graphite-felt, and Fe2+ is continually regenerated from Fe3+ reduction:
Fe2+ + H2O2 → Fe3+ + OH- + •OH
O2 + 2H+ + 2e- → H2O2
Fe3+ + e- → Fe2+
(v) Coupled anodic and cathodic Processes: using an undivided cell, the contaminants are treated by H2O2 generated on the cathode and oxidizing agents or •OH generated at the anode.
Process selection depends on the nature of the electrode material, experimental conditions, and electrolyte composition. This lecture focuses on recent progress in the most promising electrochemical tools for the treatment of wastewater contaminated by organic pollutants
Electro-Fenton, solar photoelectro-Fenton and UVA photoelectro-Fenton: Degradation of Erythrosine B dye solution
No full textThe treatment of Erythrosine B, selected as a model compound, has been comparatively studied by electrochemical advanced oxidation processes (EAOPs) such as electro-Fenton, UVA photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Experiments are performed in a one-compartment cell with a BDD anode, and a commercial carbon felt cathode at pH = 3, treating a volume of 0.3 L in each test. The irradiation plays a crucial role in the increasing of hydroxyl radical production and in the recover of iron catalyst. A faster colour and COD removal degradation are achieved under the light application. UVA photoelectro-Fenton and solar photoelectro-Fenton processes allow degrading COD entirely in 90 min, while a conventional electro-Fenton does not reach 90% COD removal after 2 h. Energy consumptions are a substantial factor in process selection. Photo electro-Fenton with a UVA-100 W lamp has one of the best removal performance, but it becomes not suitable for application due to high energy demand, up to 515.6 kWh m−3, and the UVA system requires the main fraction of this energy. Possible alternatives are proposed to contain costs: the first is the reduction of UVA lamp power to 25 W, maintaining a high-performance removal with an Ec decreasing to 187.9 kWh m−3. Nevertheless, the lowest and competitive energy demands is obtained working with a solar photoelectro-Fenton system, where energy consumption are only related to the electrochemical process (20.9 kWh m−3), and removal is complete
Balanced scorecard rafforza il risanamento aziendale. Controllo strategico del piano di risanamento. Affidabilità più alta per advisor ed attestatore
No full textLa Balanced Scorecard è uno strumento di controllo strategico che può essere di validissimo aiuto nella predisposizione del piano di risanamento di impresa. Grazie all’individuazione dei fattori critici di successo e ai correlati indicatori di performance aziendali, questo strumento garantisce l’affidabilità del piano e sorveglia la sua tenuta nel tempo. In caso di crisi, le due principali figure professionali su cui ci si affida per realizzare il piano industriale di risanamento sono il consulente (per la sua elaborazione) e l’attestatore (per garantirne l’autenticità). Con l’ausilio della Balanced Scorecard questi soggetti disporranno di una quantità e varietà di informazioni tali da poter aiutare l’impresa con più efficacia nella ricerca del ritorno al valore. Lo stesso attestatore potrà valutare con maggior successo il rispetto dei princìpi di attendibilità e affidabilità del piano, dato che con la Balanced Scorecard non saranno solo le informazioni di natura strettamente economica, finanziaria e patrimoniale a favorire la verifica della complessiva fattibilità del piano, ma anche un sistema di indicatori di performance che monitorizza nel tempo l’andamento generale dell’azienda e la coerenza del sistema di controllo direzionale con le strategie attuate dai managers. Grazie all’applicazione della Balanced Scorecard nello sviluppo di un piano di risanamento, vedrà la luce un rinnovato percorso logico: dalla definizione delle variabili chiave, al ritorno alla creazione di valore; dalla costruzione del sistema di reporting aziendale, al monitoraggio del piano di risanamento. Il libro ha l’obiettivo di suggerire un nuovo metodo di lavoro, in grado di irrobustire la definizione e l’implementazione della strategia aziendale, nei contesti di crisi e non solo, facilitando nel loro lavoro sia l’advisor che l’attestatore, considerando anche i recenti princìpi di attestazione del piano di risanamento
Biological and electrochemical oxidation of naphthalenesulfonates
No full textA biofilm airlift suspension (BAS) reactor and an undivided flow cell equipped with a boron-doped diamond (BDD) anode and a stainless-steel cathode were used to investigate the effects of varying operating conditions on process performance in the biological and electrochemical oxidation of a mixture of naphthalenesulfonates contained in the infiltration water of a contaminated industrial site. The experiments were aimed at evaluating the feasibility of process integration and the criteria for optimization (i.e. how to maximize degradation efficiency with minimum energy consumption) in combined biological and electrochemical oxidation of scarcely biodegradable compounds. Because of high reactor biomass concentration and long biomass retention time, the BAS reactor achieved a high degradation capacity (up to 6.8 kg COD m(-3) d(-1)). On the other hand, owing to the recalcitrant character of some of the aromatic sulfonates in the leachate, the overall degradation efficiency did not exceed 70% based on COD measurements. All naphthalene-mono- and -disulfonates (except naphthalene-1,5-disulfonate) were completely degraded in the BAS reactor, whereas more complex molecules (e.g. naphthalenetrisulfonates) were more recalcitrant to biological oxidation. These compounds were completely mineralized by electrochemical oxidation using a boron-doped diamond anode. The energy consumption and the time required for the complete mineralization of the infiltration water decreased from 80 kWh m(-3) and 4 h to 61 kWh m(-3) and 3 h for the oxidation of raw and biologically pretreated leachate, respectively. (c) 2005 Society of Chemical Industry
Geomorphology and environmental impact assessment: a methodologic approach
No full textTwo different paths to define geomorphologic environmental impact assessment are outlined. The first considers the relationships between a project and landforms or raw materials, the second the relationships between a project and geomorphologic processes. The term "impact' (I) refers to the relationships among a project, landforms and geomorphologic raw materials, and can be expressed as: I = Ga × F × Ha where: Ga=geomorphologic asset, F=fragility, Ha=human activity related to a project. The term risk (R) refers to the relationships between a project and geomorphologic processes, and covers the expected numbers of lives lost and persons injured, damage to property and the disruption of economic activity by a natural phenomenon. Risk can be expressed as: R=E × V × H, where: E=element at risk, V=vulnerability (ie the degree of loss that a set of elements at risk might suffer if a natural phenomenon of given magnitude recurs at given intervals), H=natural hazard (ie a potentially damaging phenomenon, often expressed as the probability of occurrence in a given area within a specific period). There are four methods of assessing hazards: direct measurements; mechanical models and calculations; overlaying thematic maps of potential causal factors; the statistical approach to effects, including recurrence. -from Author
Rischio geomorfologico e turismo
No full textRiguardo agli studi intorno ai complessi rapporti tra uomo e ambiente geomorfologico è utile porre l’attenzione a un campo di ricerca relativamente recente, che riguarda le relazioni tra pericolosità geomorfologiche e fruizione turistica. Ormai, sempre più spesso, tutti noi veniamo informati in modo più o meno scientifico, più o meno rigoroso, di eventi naturali di instabilità geomorfologica che, interagendo in modo per lo più improvviso con attività che potremmo definire ludiche, provocano situazioni più o meno gravi di rischio per coloro che, per motivi ricreativi, si trovano ad interagire con i processi dinamici dell’ambiente geomorfologico. La grande attrazione che da sempre esercitano le forme del rilievo, tanto maggiore quanto più sono spettacolari, rappresenta molto spesso “la base dell’offerta turistica di una regione” (Reynard e al., 2003). Accanto agli indubbi effetti positivi legati agli aspetti economici e ai vantaggi sociali che derivano dalla possibilità di conoscere regioni diverse, differenti culture e vivere, anche se per un periodo limitato, dimensioni fisiche ed emotive lontane dalla quotidianità, esistono, sempre più urgenti, problemi di impatto sulle risorse paesaggisIl conseguente aumento del carico turistico in aree caratterizzate da una spiccata dinamicità geomorfologia (vette montuose, gole torrentizie, pareti in roccia, ecc.) e le variazioni climatiche in atto portano da un lato ad una maggiore vulnerabilità dell’elemento umano, sia per l’alto numero di fruitori sia per una non sempre adeguata preparazione individuale, e dall’altro ad un incremento della pericolosità, legato alla rapida risposta dei processi geomorfologici sia ai cambiamenti globali, che alle conseguenze delle attività antropiche. La risultante crescita delle possibili situazioni di rischio, in cui possono venire coinvolti fruitori ed escursionisti, richiede dunque, prima di tutto, la conoscenza delle dinamiche geomorfologiche proprie di un determinato ambiente, della tipologia di risposta dei processi alle variazioni climatiche e meteorologiche ad esse associate ed infine, ma non meno importante, delle possibili interazioni dei fenomeni naturali con le diverse attività turistico-ricreative tiche e di rischio, come già accennato, per i frequentatori
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