1,720,994 research outputs found
Enhancing volatile fatty acid production in batch test reactors by modulating microbial communities with potassium permanganate
Full text linkThe shift from conventional wastewater treatment plants to biorefineries is one of the most environmentally and
economically sustainable pathways for extracting valuable compounds from waste. Besides chemical-physical
processes, microorganisms within sewage sludge utilize organic and inorganic pollutants in the wastewater as
nutrients, leading to effective water purification. However, the remaining solid sludge residue, typically destined
for specific landfills or incineration, could undergo microbial fermentation to produce volatile fatty acids (VFA),
metabolic precursors for biopolymers. Increasing attention has been directed towards optimizing operational
parameters to enhance VFA production during sewage sludge fermentation. This study examined the impact of
potassium permanganate (PP) on microbial communities during the sewage sludge’s acidogenic fermentation.
The results highlighted the positive effect of PP treatment, which increased COD production and VFA yield up to
1263.5 mg/L and 664.2 mg COD/L, respectively. The presence of PP significantly enhances VFA yield promoting
bacteria positively linked to VFA production
Modulation of sewage sludge microbiota for enhancing the transition from wastewater treatment plants into biorefineries in the circular economy era
Full text linkTransitioning traditional wastewater treatment plants into biorefineries offers an environmentally and economically sustainable solution. Indeed, valuable compounds can still be extracted from waste. Utilizing sewage sludge (SS) with its microbial component, materials such as volatile fatty acids (VFAs) and polyhydroxyalkanoates (PHAs) within specially designed WWTP reactors can be obtained. VFAs serve as precursors to PHAs, which provide an eco-friendly alternative to petroleum-based plastics. Understanding the impact of various operating conditions on microbial components is crucial for driving microbial metabolism toward the biosynthesis of these molecules. This innovative study, part of the European project “Achieving wider uptake of water-smart solutions”, focused on evaluating the effects of two operating conditions—the headspace volume in the fermenter and the organic loading rate (ORL) in the selective-sequence batch reactor (S-SBR)—on VFA and PHA production. The wastewater from the Palermo University campus was used to inoculate a pilot plant to simulate a real urban WWTP. Our approach is based on comparing the microbial community before and after the incubation process through metagenomic DNA extraction and 16S rDNA sequencing and on quantifying PHA and VFA yields by gas chromatography analysis. This analysis revealed that 40% of headspace volume in a 225L fermenter and an ORL of 1.3 g COD L−1d−1 in S-SBR maximized VFA and PHA production. The metataxonomic analysis showed significant changes in the SS microbiota structure, promoting the growth of bacteria like Proteobacteria, Firmicutes, and Actinobacteria while reducing Verrucomicrobia. These findings enhance our understanding of bacterial modulation under various operational conditions and highlight the potential for exploiting the resources in SS within a circular economy framework
CFD Analysis on the Effect of Baffles Geometry on Sedimentation Efficiency
No full textSedimentation tanks represent one of the most important components of any water and wastewater treatment plants. The lack of knowledge of hydraulics in sedimentation tank leads to unnecessary capital and operating costs as well as water pollution in the form of excessive sludge. The focus of this study is to apply Computational Fluid Dynamics (CFD) to study and to improve the sedimentation efficiency through the optimization of the hydrodynamics inside the disinfection tank. In the present analysis, Large Eddy Simulation (LES) is used to simulate three-dimensional turbulent flow and scalar tracer transport in different settlers using a structured finite-volume discretization. The results show how the baffles’ geometry influences the retention time distribution of the tank, varying the sedimentation efficiency
INCIDENZA SULL’ANALISI DI RISCHIO DELLE MODALITÁ DI MISURA DEI SOIL GAS: IL CASO DI UN S.I.N. SICILIANO
No full textIl monitoraggio delle matrici aeriformi sta assumendo importanza crescente nell’ambito dei procedimenti di bonifica di siti contaminati, con riferimento sia all’esecuzione delle analisi di rischio, sia alla conseguente progettazione degli interventi di risanamento. L’utilizzo di misure dirette di campo si rivela di notevole interesse per la verifica di quelle indirette, ottenute con gli algoritmi implementati nei modelli matematici utilizzati per l’analisi di rischio. Obiettivo del lavoro presentato nella nota è stato quello di valutare l’influenza di misure dirette di soil gas e di flussi emissivi sull’analisi di rischio sanitaria. Come caso studio, si è considerato un S.I.N. nel territorio siciliano. I risultati ottenuti hanno permesso di evidenziare una generale sovrastima dei valori delle concentrazioni dell’aria ambiente e dei conseguenti rischi sanitari, ottenuti mediante i modelli di trasferimento dei gas, che possono così condurre a scenari troppo cautelativi e poco verosimili
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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