1,721,054 research outputs found
Effect of pre-oxidation on the porosity development in a heavy oil fly ash by CO2 activation
No full textThe effect of pre-oxidation on the porosity evolution in heavy-oil fly ash subjected to activation with CO2 has been investigated. After preliminary acid leaching, used to reduce the mineral matter content, the leached fly ash has been oxidised in air at 250 °C for 36 h. Pyrolysis was conducted on the unoxidised and oxidised leached fly ash at 900 °C for 2 h and the resultant chars were activated with CO2 at 900 °C for different times. The activated samples have been characterised as regards the surface area and the pore volume. The pre-oxidation enhances the porosity development mainly in terms of mesoporosity leading to obtain activated products with higher surface area (about 270 m2/g at a 40% burn-off)
DATA ON LEGIONELLA PREVALENCE AND WATER QUALITY IN SHOWERS OF RETIREMENT HOMES AND GROUP HOMES IN THE PROVINCE OF ROME, LAZIO REGION, ITALY
Get PDFThe data presented in this article are related to the research paper
titled "Prevalence of Legionella in retirement homes and group
homes water distribution systems "(DeFilippis,2018) [3]. Most of
the cases of Legionella infection are sporadic and occurin
community-dwellers. Hot water and biofilm samples from the
shower heads of 26 retirement homes and 9 group homes hosting
closed communities were collected, in order to evaluate the pre-
valence of Legionella and generic water quality parameters
(Heterotrophic Plate Counts at 22 °C and 37 °C). Samples were
tested by culture method for the presence of Legionella. Con-
firmation and identification were carried out through Latextest
and PCR. Further data about buildings’ number of floors and rooms
were collected, and put in relation to the presence of Legionella
through constructing contingency tables and performing exact
fisher's or Chi-squaretests. Cold (< 30 °C) water samples are
analyzed apart
Heterogeneous catalysts for hydrothermal liquefaction of lignocellulosic biomass. A review
No full textThe biomass conversion into more valuable fuels represents one of the most viable routes for the exploitation of this material. Hydrothermal liquefaction is currently considered one of the most efficient processes to convert wet biomass into a bio-crude, which however requires expensive upgrading treatments to be used as biofuel. The use of catalysts able to directly improve bio-crude yield and quality during the reaction is of fundamental importance to increase the overall process efficiency. Homogeneous alkaline catalysts are the most studied, but they are not recoverable at the end of the process and so cannot be reused. The use of heterogeneous catalysts allows to overcome this issue making the recovery and reuse possible, maintaining anyway high activity and selectivity in the bio-crude production. The aim of this review is to critically summarize the effect of heterogenous catalyst addition on the hydrothermal liquefaction of lignocellulosic biomass, looking specifically at the improvement in bio-crude yield and quality. On the basis of literature data about the effect of heterogeneous catalyst addition on bio-crude yield and quality in the hydrothermal liquefaction of lignocellulosic biomass, a common catalytic action was identified allowing to group the several catalysts into four classes (alkaline metal oxides, transition metals, lanthanides oxides and zeolites). The hydrodeoxygenation activity of the catalysts, their effect on bio-crude yield and quality and the operating conditions used are highlighted. The highest bio-crude yields are reported using transition metals and lanthanide oxides which are able to guarantee, at the same time, a high-quality bio-crude
Hydrothermal Liquefaction of Biomass using Waste Material as Catalyst: Effect on the Bio-crude Yield and Quality
No full textHydrothermal liquefaction (HTL) is one of the most promising technologies to produce valuable compounds from
biomass and waste. The use of water as solvent makes this process extremely convenient for high moisture
feedstock and also environmentally sustainable. However, the obtained product, the bio-crude, is not ready to
the end use, its oxygen content is quite high making the oil physically and chemically instable and thus difficult
to handle and store. The use of heterogeneous catalysts and hydrogen producers can improve the product
quality during the hydrothermal process being also easy to be separated and recirculated. In this work the use
of reduced red mud acting as hydrogen producer is tested in the hydrothermal process of oak wood. Red mud
is composed mainly by Fe2O3 that was reduced with the char produced by HTL and by a simulated syngas
which is obtained from char gasification. The reduced red mud was mixed with the biomass and fed into the
HTL batch reactor with variable red mud biomass ratio. The reduction temperature was optimized in order to
obtain zero valent Fe able to produce hydrogen reacting with water in HTL conditions. The tests were conducted
at 330 °C with a reaction time of 10 min. The obtained bio-crude was characterized with elemental analysis. The
results in terms of oil yield and quality were compared with those obtained with pure iron powder showing that
red mud can be used successfully as hydrogen producer in HTL process and recycled after its reduction with
char or syngas. The use of red mud leads to an increase of the oil yield of 20% with respect to the blank test
and looking at the oil composition the hydrogenation effect is evident, the amount of hydrogen increases while
the amount of oxygen decreases
LEGIONELLA DETECTION IN HOT WATER DISTRIBUTION SYSTEM OF CLOSED COMMUNITY AND TOURIST ACCOMMODATION FACILITIES IN THE LAZIO REGION, ITALY: RISK ASSESSMENT AND PREVENTION
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Valutazione dell'efficacia del sistema di trattamento mediante lampade UV su vari impianti del consorzio di bonifica tevere agro-romano
No full textOBIETTIVI: Scopo di questo lavoro è stato valutare l’efficacia del trattamento
mediante raggi ultravioletti in tre impianti di depurazione del Consorzio
di Bonifica Tevere e Agro Romano che utilizzano tale sistema di disinfezione
per il recupero di acque a prevalente scopo irriguo.
METODI: I campioni di acqua prelevati da un rubinetto in acciaio posto sopra
i moduli, dove sono posizionate le lampade UV, sono stati raccolti in contenitori
idonei e trasportati refrigerati in laboratorio. I prelievi sono stati eseguiti
sia prima che dopo la messa in funzione delle lampade (tempo di disinfezione
>30 minuti). Nei campioni prima del trattamento, sono stati rilevati i valori
della trasmittanza e dei solidi sospesi totali, fondamentali per questo tipo di
disinfezione. Le analisi batteriologiche eseguite su tutti i campioni raccolti
sono state condotte ricercando i batteri indicatori di contaminazione fecale
(coliformi totali, fecali, enterococchi) e carica batterica totale.
RISULTATI: I valori relativi alla trasmittanza (media 66,5%) ed ai solidi
sospesi totali (media 34,2mg/L) sono sempre risultati superiori a quelli
ritenuti ottimali per questo tipo di impianti. Le acque raccolte prima della
disinfezione, hanno mostrato un elevato grado di inquinamento di origine
fecale con concentrazioni medie pari a 6,3x104UFC/100ml per i Coliformi
totali, 2,1x104UFC/100ml per i Coliformi fecali, 1,0x104UFC/100ml per gli
Enterococchi e 8,3x104UFC/ml per la Carica batterica totale, mentre nelle
acque trattate sono risultate più basse: 5,1x102UFC/100ml per i Coliformi
totali, 6,9x102UFC/100ml per i Coliformi fecali 3,4x102UFC/100ml per gli
Enterococchi e 3,6x103UFC/ml per la Carica batterica totale.
CONCLUSIONI: Analizzando i risultati si osserva una riduzione della contaminazione
microbica nelle acque dopo il trattamento di disinfezione, ma
non sufficiente a renderle idonee per il loro riutilizzo. Pertanto, in presenza
di un elevato carico organico, un pre-trattamento con filtri a sabbia, prima
della disinfezione mediante UV, ridurrebbe le impurità organiche aumentando
la trasmittanza favorendo così l’attività battericida delle lampade
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