1,721,214 research outputs found
Treatments of asbestos containing wastes
No full textSince the second half of the twentieth century, many studies have indicated inhalation of asbestos fibers as the main cause of deadly diseases including fibrosis and cancer. Consequently, since the beginning of the 80s, many countries started banning production and use of asbestos containing products (ACP), although still present in private and public buildings. Due to some extraordinary catastrophic events and/or the aging of these products, people's health and environmental risk associated with the inhalation of asbestos fibers keeps being high even in those countries where it was banned. For these reasons, many communities are developing plans for an environmental and sanitary safe asbestos removal and management. Asbestos containing wastes (ACW) are usually disposed in controlled landfills, but this practice does not definitively eliminate the problems related with asbestos fiber release and conflicts with the ideas of sustainable land use, recycling, and closing material cycles. Consequently, many scientific papers and patents proposed physical, chemical, and biological treatments aimed to the detoxification of ACW (or the reduction of their health effects) and looking for the adoption of technologies, which allow the reuse of the end-products. By including recent relevant bibliography, this report summarizes the status of the most important and innovative treatments of ACW, providing main operating parameters, advantages, and disadvantages
I TRATTAMENTI BIOLOGICI DELLE ACQUE REFLUE E DEI RIFIUTI: ASPETTI INTRODUTTIVI
No full textNegli ultimi 20 anni, sia nel campo della depurazione delle acque reflue che in quello del trattamento dei rifiuti sono state introdotte numerose ed interessanti novità, che hanno in particolare riguardato i sistemi basati sull’applicazione di processi biologici. Tali nuovi sistemi sono stati messi a punto con l’obiettivo precipuo di superare i problemi o i limiti delle soluzioni convenzionali, permettendo altresì l’adozione di nuovi schemi impiantistici, specificamente mirati al trattamento di flussi influenti caratterizzati dalla presenza di substrati sempre più differenziati. Secondo un meccanismo di causa/effetto, allo sviluppo ed alla diffusione delle suddette novità ha certamente contribuito l’emanazione di nuovi provvedimenti normativi, orientati, in generale, verso il miglioramento delle caratteristiche dei flussi in uscita dagli impianti e il loro proficuo (ri)utilizzo.
Il programma dell’edizione 2018 del BIOMAC prevede una successione di interventi su alcuni dei più noti sistemi innovativi per il trattamento biologico, sia nel campo della depurazione delle acque reflue che in quello del trattamento della frazione organica dei rifiuti solidi (FORSU). Nella fattispecie, relativamente alla depurazione, l’attenzione è soprattutto posta alla disamina dei cosiddetti bioreattori a membrana, meglio noti con l’acronimo MBR (Membrane Bio-Reactor), che, costituiscono, in pratica, una variante del classico sistema a fanghi attivi. Per quanto riguarda, invece, il campo della FORSU, sono in particolare approfonditi gli aspetti inerenti ai sistemi di trattamento anaerobico, facendo riferimento in primis alla digestione anaerobica.
Nella presente relazione introduttiva sono fornite, quindi, alcune informazioni preliminari sia sugli MBR, mettendo in evidenza i vantaggi che offrono in confronto al sistema a fanghi attivi, che ai sistemi di trattamento per via anaerobica della FORSU, sottolineando le caratteristiche e le potenzialità della digestione nonché le sue possibili varianti. L’obiettivo è quello di introdurre i lettori negli specifici argomenti, rinviando i necessari approfondimenti sugli aspetti di maggior dettaglio alla lettura delle relazioni che seguono
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
Enhanced bio-methane production from co-digestion of different organic wastes
No full textThis paper deals with an experimental study aimed at assessing the effect of mixing different organic wastes on the anaerobic digestion process. Livestock manure and organic solid wastes have been taken into account as substrates to verify if their mixing gives rise to higher methane production rates and lower risk of process failure. Bio-methane potential (BMP) tests have been conducted using the following substrates: buffalo manure (BM), poultry manure (PM), organic fraction of the municipal solid waste (OFMSW), greengrocery waste (GW) and two different mixtures composed of BM and OFMSW. Mixing BM with OFMSW resulted in 12% and 30% higher methane volumes after 30 and 15 days from the test start, respectively. Experimental data have been also used to calibrate and validate a mathematical model previously proposed by the authors, showing its capability to reproduce the synergistic effect on methane production promoted by co-digesting BM and OFSMW. © 2012 Taylor and Francis
Modelling the effect of the OLR and OFMSW particle size on the performances of an anaerobic co-digestion reactor
No full textA dynamic mathematical model capable to predict the methane production in an anaerobic completely stirred tank reactor (CSTR), performing the co-digestion of the organic fraction of municipal solid waste (OFMSW) and sewage sludge, is used to assess the effect of the organic loading rate (OLR) and OFMSW particle size on the reactor performances. The model is based on the approach proposed by the IWA Anaerobic Digestion Model no. 1 (ADM1), which has been modified to take into account the peculiarities of a co-digestion process. The main distinctiveness of the proposed model consists in considering two separate influent substrates (i.e. sewage sludge and OFMSW), which are modelled with different biodegradation kinetics. The sewage sludge degradation is modelled according to the ADM1 while a surface based kinetics is used to simulate the OFMSW disintegration process, which depends on particle size distribution (PSD) of the solid waste to be disintegrated. The methane production of a full scale municipal wastewater treatment plant (MWWTP) digester has been evaluated to assess the model capability to estimate the potential energy production under different process conditions. In particular, a sensitivity analysis on two key operational parameters of the CSTR co-digestion process, i.e. OLR and OFMSW particle size, has been carried out. This analysis shows the model suitability to assess the combined effect of such parameters on the digester performances, predicting the process failure occurrence. © 2010 Elsevier Ltd
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