1,721,019 research outputs found
Sequencing batch reactor performance treating PAH contaminated lagoon sediments
No full textThe applicability of sediment slurry sequencing batch reactors (SBR) to treat Venice lagoon sediments contaminated by polycyclic aromatic hydrocarbons (PAHs) was investigated, carrying out experimental tests. The slurry, obtained mixing tap water and contaminated sediments with 17.1 mg kg-1 TS total PAHs content, was loaded to a 8 l lab-scale completely stirred reactor, operated as a sequencing batch reactor. Oxygen uptake rate exerted by the slurry, measured by means of a DO-stat titrator, was used to monitor the in-reactor biological activity and to select the optimal operating conditions for the sediment slurry SBR. The PAHs removal efficiency was evaluated in different operating conditions, obtained changing the hydraulic retention time (HRT) of the lab-scale reactor and adding an external carbon source to the slurry. HRT values used during the experiments are 98, 70 and 35 days, whereas the carbon source was added in order to evaluate its effect on the biological activity. The results have shown a stable degradation of PAHs, with a removal efficiency close to 55%, not dependent on the addition of carbon source and the tested HRTs
Sustainable Power Production in a Membrane-Less and Mediator-Less Synthetic Wastewater Microbial Fuel Cell
No full textMicrobial fuel cells (MFCs) fed with wastewater are currently considered a feasible strategy for production of renewable electricity. A membrane-less MFC with biological cathode was built from a compact wastewater treatment reactor and fed with synthetic wastewater. When operated with an external resistance of 250 Ohm, the MFC produced a long-term power of about 70 mW/m2 for 10 months. Denaturing Gradient Gel Electrophoresis (DGGE) analysis of the cathode biomass when the MFC was closed on a 2100 Ohm external resistance showed that the sequenced bands were affiliated with Firmicutes, alfa-Proteobacteria, beta-Proteobacteria, gamma-Proteobacteria, and Bacteroidetes groups. When the external resistance was varied between 250 and 2100 Ohm,, minimum sustainable resistance decreased from 900 to 750 Ohm, while maximum sustainable power output decreased from 32 to 28 mW/m2. It is likely that these effects were caused by changes in the microbial ecology of anodic and cathodic biomass attached to the electrodes. Results suggest that cathodic biomass enrichment in electroactive bacteria may improve MFCs power output in a similar fashion to what has been already observed for anodic biomass
Utilizzo di una MFC per la degradazione di sostanza organica e recupero di corrente elettrica. Primi risultati sperimentali.
No full textLe Microbial Fuel Cell (MFC) sono dispositivi in grado di convertire energia chimica in energia elettrica. Il loro sviluppo riveste un notevole interesse nel medio termine, in quanto potrebbero garantire un recupero energetico nell’ambito del processo depurativo di un refluo poiché, teoricamente, ogni substrato organico biodegradabile può essere convertito in elettricità.
I ricercatori dell’ENEA (sede di Bologna) hanno proposto una configurazione impiantistica di MFC concepita sia per la depurazione che per il recupero energetico, la cui fattibilità è stata
verificata nell’ambito di una sperimentazione sviluppata in circa 14 mesi, mediante un impianto sperimentale in scala laboratorio avente una capacità complessiva di circa 60 L. La MFC, alimentata con un refluo sintetico (COD variabile tra 1.5 e 5 g/L) ha prodotto una potenza ed una corrente specifica rispettivamente pari a 70 mW/mq elettrodo e 175 mA/mq elettrodo, ottenendo rendimenti medi di rimozione del COD superiori al 98 %, ed un processo di
nitrificazione pressoché completo. In una seconda fase della sperimentazione, la resistenza esterna applicata è stata variata da 250 a 2100 Ohm, ottenendo sensibili modifiche dei valori ottenuti di potenza sostenibile, riconducibili a tale variazione
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
Analysis of an archaeological linen cloth: The shroud of Arquata
No full textThe linen cloth of the shroud of Arquata, a precious copy of the Shroud of Turin which dates back to 1653, was discovered in 1980 during the restoration works of the St. Francis church in Arquata del Tronto (Ascoli Piceno, Italy). Following the strong earthquake that hit central Italy in August 2016, the church was seriously damaged and it was therefore necessary to secure the shroud in the Cathedral of Ascoli Piceno. A multidisciplinary approach was required in order to evaluate the correct intervention methods that will be performed in the next future: although several investigation techniques were performed on the Arquata shroud, this paper focuses on the combination of two different techniques, optical microscopy and scanning electron microscopy coupled with energy dispersive spectroscopy microanalysis (SEM-EDS). Few samples of fibrils of the linen cloth of the Arquata shroud were analysed, achieving information about their morphology, the surface characteristics, the chemical composition and the possible deterioration phenomena. Light microscopic analyses showed some typical features of the single elementary flax fibre: lumen, dislocations and cross markings (X). SEM-EDS analysis also revealed interesting morphological features of the flax fibrils and the presence of encrustations on their surface, while the microanalysis preformed on the encrustations revealed the presence of calcium, silicon, magnesium, aluminium, sodium, and potassium, due to dust deposits. Moreover, the absence of biological attacks by microorganisms, parasites, moulds or fungi was highlighted. Finally, numerous defects of the surface that could characterise the linen cloth as antique were identified (cross cuts). These results suggested some actions useful for the conservation of the shroud, thus avoiding the use of more invasive methods which could impact the integrity of this precious object of veneration
Treatment of distillery wastewater by a pilot scale anaerobic sequencing bacth reactor
No full textIl comparto della distillazione in Italia rappresenta un’importante realtà economica ed industriale data l’enorme disponibilità di sottoprodotti da trasformare in alcool, provenienti in particolare dal settore vitivinicolo. Le distillerie, qualunque siano le materie prime utilizzate, danno luogo a notevoli quantitativi di reflui inquinanti, ad alta concentrazione di sostanza organica, che necessitano di un trattamento di depurazione a monte dello scarico nei corpi idrici recettori.
La digestione anaerobica dei reflui di distilleria è ampiamente applicata in scala reale come sistema di depurazione poiché consente di ottenere una notevole riduzione della sostanza organica con la produzione di biogas (ad elevato contenuto di metano) utilizzabile come fonte di energia.
Attualmente, la ricerca scientifica nel campo della digestione anaerobica dei reflui di distilleria è orientata allo sviluppo di sistemi di depurazione caratterizzati da bassi tempi di ritenzione idraulica ed elevate età del fango. Tra questi sistemi, particolare interesse riveste l’ASBR (Anaerobic Sequencing Batch Reactor), nel quale il processo depurativo è articolato in una successione di cicli caratterizzati dalle seguenti fasi: carico dell’influente, reazione in ambiente anerobico e scarico dell’effluente. Il principale vantaggio dell’ASBR, rispetto ai sistemi tradizionali, consiste in un maggior controllo e flessibilità dell’intero processo biologico.
La Sezione Gestione Risorse Idriche dell’ENEA di Bologna ha curato la progettazione e realizzazione di un impianto ASBR in scala pilota (180 l) allo scopo di verificare l’efficienza di depurazione su reflui di distilleria con caratteristiche fisico-chimiche differenti fra loro.
Sono stati testati 4 tipologie di reflui (borlanda, due reflui misti e melasso) alimentati in modo da operare con un fattore di carico organico volumetrico pari a circa 5 kg COD/(m3 giorno).
L’efficienza di rimozione della sostanza organica (in termini di COD) è stata superiore al 70% (e nel caso della borlanda oltre il 90%).
La produzione di biogas è risultata variabile con la tipologia di refluo, presentando un fattore di produzione compreso tra 1 e 3 litri di biogas /litro di reattore.
Complessivamente si è avuta una produzione di gas metano pari a 340 l/(kg COD rimosso) valore prossimo a quello teorico di 350.
A differenza dei tradizionali sistemi CSTR, gli ASBR non necessitano, tra l’altro, di una fase di sedimentazione, rappresentando quindi una valida alternativa per il trattamento anaerobico dei reflui di distilleria
The Geochemical and microbiological monitoring of the sediments of "Sacca di Goro" Costal lagoon (Po river Delta)
No full text“Sacca di Goro” is a coastal lagoon, south of the Po River Delta, and it is one of the most important aquacultural systems in Italy. That area has a strong environmental value for its large biodiversity and it is inserted in SCI (Site of Community Importance) and SPAs (Special Protection Areas) areas. This paper reports the data of geochemical and microbiological characterization and monitoring of sediments carried out in the 2003, 2004 , 2005 and 2006 years.
All samples were collected from the surface sediment (20 cm) on the entire extension of the lagoon. Sediments were analysed after oven drying at 50°C for 48 hrs, except microbiological parameters. The major elements (expressed in percentage of oxide) and the trace elements (expressed in ppm) were carried out by X ray Fluorescence. The granulometric classification was carried out according to Shepard diagram in order to estimate the granulometric variations in the time. Carbon and nitrogen elemental measurements were performed by aqueous acidification procedure to remove carbonate [1]. Samples were then analysed by a Carlo Erba CHNS-O 1108 elemental analyser configured for C and N analysis. Polycyclic aromatic hydrocarbons (PAHs), were determinated by an Agilent GC (6890N)/MS (5973) after extraction, clean up and chromatographic separation according to EPA methods (3500B, 3540C 3600C 8000B). The microbial analyses were performed within 18-24 hrs and include: total coliforms, faecal coliforms, faecal streptococci by MPN methods [2, 3], Salmonellae by the enrichment and selective media [2]; spores of solfate reducing bacteria [4].
The heavy metal concentration in the sediments of “Sacca di Goro” is similar to the Po river alluvional plain sediments near the city of Ferrara (“background level”). The range of the quality of “Sacca di Goro” sediments is from poor to medium – good as a grain size function of that kind of sediments [5].
Total Organic Carbon ranged from 0.14 to 1.40 % (dry weight). PAHs concentration ranged from 89 to 326 mg/Kg (dry weight). The values of total and faecalis coliform ranged from 1 to 49 and from 1 to 33 MPN (g), respectively. The content of faecalis streptococci was generally low ranging from 1 to 33 MPN (g) except two samples (1400 and 8800 MPN (g)). Spores of solfate reducing bacteria were not present. Salmonellae was present only from the samples collected in the year 2005. Moreover near the coastal arrows and the lagoon mouth an increase in the coarse grain fraction is observed and the sediments quality improve.
The research individualities Sacca areas with low quality sediments located in internal areas near the shore. These areas are not fit to aquaculture system. The work shows moreover the good quality of the sediments present in coastal arrows and in the zones near the lagoon mouth. Litologically sediments features are not variable during the experimental time and the work shows the correlations between the tessiturally-structural characteristics of the sediments and the kind of pollution. The sediments in the lagoon area extending from the shore nearly 1 Km on shore, show an high percentage of fine grain fraction with an increased heavy metal content, exceeding the values of the Italian laws
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
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