1,720,995 research outputs found
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
Particle-based biofilm reactors for the bioremediation of infiltration water contaminated by aromatic sulfonates
No full textDevelopment of particle-based biofilms for degradation of xenobiotic organic compounds
No full textThe aim of the experiments performed in this work was to develop a biofilm airlift suspension (BAS) process for the degradation of a mixture of organic sulfonates contained in the infiltration water from a contaminated site. To achieve this goal, active biomass growing on the contaminating xenobiotic organics as the sole source of carbon was obtained by enriching a mixed microbial culture sampled from an activated sludge treatment plant. After kinetic characterisation, the enriched culture was inoculated in the BAS reactor, where it colonised carrier particles and formed stable and uniform biofilms. In spite of the slow growth and degradation kinetics (mu(max) = 0.014h(-1)), due to high biomass concentration (up to 12gvs L-1) a high rate process was performed in the BAS reactor, achieving a degradation capacity of 8.7kg(COD)m(-3) d(-1), with an overall degradation efficiency of 70% based on COD measurements. (c) 2005 Elsevier Ltd. All rights reserved
High-rate degradation of aromatic sulfonates in a biofilm airlift suspension reactor
No full textA wastewater containing aromatic sulfonates was treated in a laboratory-scale biofilm airlift suspension (BAS) reactor. The general objective of the experiments was to assess the performance of a particle-based biofilm reactor in the biodegradation of refractory organic compounds under varying operating conditions. To this end, the reactor was inoculated with a mixed culture of biomass, adapted to grow on the leachate as the sole source of carbon, which colonized carrier particles in the reactor and formed stable and uniform biofilms. Depending on their degradation kinetics (characterized in independent experiments) and the fraction of specific degraders in the biofilms, aromatic sulfonates attain different degradation efficiencies in the BAS reactor, with more compex molecules (e.g., trisusbtituted naphthalene sulfonates and some bisubstituted naphthalene sulfonates) showing the lowest degradation efficiencies. The BAS reactor achieved high biomass concentration (12 g L-1) and an overall degradation efficiency of 67% based on COD measurements for loading rates up to 0.45 kg(COD) kg(vs)(-1) day(-1), corresponding to a specific degradation rate of 0.3 kg(COD) kgvs(-1) day(-1). For higher loading rates, the hydraulic retention time of leachate in the reactor proved to be insufficient for complete degradation of aromatic sulfonate with slow degradation kinetics, resulting in a decrease of overall degradation efficiency. The fast degradation rate of most aromatic sulfonates is attributed to the long biomass retention time and reactor biomass concentration, resulting in high concentrations of degraders for specific compounds
Conventional and fast pyrolysis of automobile shredder residues (ASR)
No full textThis work aims at comparing performance and product yields in conventional pyrolysis and fast pyrolysis of automotive shredded residues. In both processes, carbon conversion to gaseous and liquid products was more than 80%. Gas production was maximised in conventional pyrolysis (about 35% by weight of the initial ASR weight), while fast pyrolysis led to an oil yield higher than 55%. Higher heating values (HHV) of both conventional pyrolysis gas and fast pyrolysis oil increased from 8.8 to 25.07 MJ/Nm(3) and from 28.8 and 36.27 MJ/kg with increasing pyrolysis temperature. (C) 2004 Elsevier Ltd. All rights reserved
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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