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Bioleaching of zinc and aluminium from industrial waste sludges by means of Thiobacillus ferrooxidans
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Biosorption of heavy metals by Sphaerotilus natans: an equilibrium study at different pH and biomass concentrations
No full textComparison between Puff and Lagrangian Particle Dispersion Models at a Complex and Coastal Site
No full textA comparison between a puff atmospheric dispersion model (hereafter: PuM) and a Lagrangian particle model (hereafter: LPM) was conducted for a real case of emissions from an industrial plant, in the context of a complex and coastal site. The PuM’s approach is well-known and widely adopted worldwide, thanks to the authoritative suggestions by the US-EPA for regulatory use as, according to the definitions included in its guidelines, an “alternative” to “preferred” models; LPMs are more advanced models and have gained reliability over the last two decades. Therefore, it is of interest to provide insights into the decision to adopt or recommend, in the field of atmospheric impact assessment, a more advanced, but more knowledge- and resource-intensive, modeling tool, rather than an established albeit less accurate one. An inter-comparison of the two approaches is proposed based on the use of various statistical and comparative parameters with the goal of studying their differences in reproducing maps of ground-level ambient concentration statistics for assessment purposes (annual means, hourly peaks). The models were tested under a year-long simulation. The dispersion from both a point and a volume source, belonging to an existing industrial plant, was analyzed separately. The inter-comparison was performed through the analysis of 2D ground concentration maps, scatterplots, and three classical indices from the 2D maps of annual concentration statistics. To correlate the differences among models with site characteristics, the statistics were analyzed not only globally, but also according to distance from the source, the elevation, and the land-use classification. The analysis shows that around-its-axis plume dispersion in LPM is lower than in PuM over all the land-use types except water surfaces, in agreement with the theoretical basis provided by the models. Because of its more advanced theoretical formulation, e.g., in the interaction of the plume with the complex terrain and the three-dimensional wind field, an LPM used as a comparison term allowed us to highlight the weaknesses of a more traditional approach, such as PuM, in reproducing effects such as plume up-sloping, deflection, channeling, confinement, and wind shear diffusion
Kinetics and Isotherms of Mercury Biosorption by Dry Biomass of Arthrospira (Spirulina) platensis
No full textInorganic mercury was effectively removed from water solutions by means of dry biomass of Arthrospira (Spirulina) platensis as biosorbent. The results obtained at defined pH and biomass concentration as well as variable Hg concentrations were used to estimate biosorption kinetics and isotherm parameters. Biosorption kinetics was best described by the pseudo-first-order model of Lagergren that allowed estimating an average specific rate constant as high as 0.044 min−1, while the Dubinin and Radushkevich model was the best fitting isotherm. Hg biosorption seemed to occur via physisorption. Considering the wide dissemination of A. platensis and its easy cultivation, these results point to its biomass as a low-cost biosorbent to treat Hg-contaminated waters
Efficient removal of tetracycline, ciprofloxacin, and amoxicillin by novel magnetic chitosan/microalgae biocomposites
No full textTwo new highly-efficient and eco-friendly biosorbents comprised of magnetite, chitosan and Chlorella vulgaris (MCC) or Arthrospira platensis (MCA) were prepared in such a way to be easily separated and reused for removing different classes of antibiotics such as tetracycline (TC), ciprofloxacin (CIP) and amoxicillin (AMX) from wastewater. They were characterized using SEM, FTIR and TGA. Biosorption experiments were performed to investigate the impact of pH, biosorbent dosage, initial antibiotic concentration, contact time, and concentration of background electrolytes (NaCl, KCl and CaCl2) on adsorption. Both biocomposites showed outstanding per formance in antibiotics removal. Equilibrium data were modelled using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherms, among which the first one gave the best fit, with maximum TC, CIP and AMX adsorption capacities of 834.0, 394.9, and 150.8 mg/g for MCA and of 831.1, 374.2, and 140.2 mg/g for MCC, respectively. To follow the adsorption time-evolution, the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models were tested, the second of which proved to be the best-fitting one. Thermodynamic parameters revealed that adsorption was spontaneous and endothermic. Both biosorbents were re generated through microwave-assisted treatment and reused repeatedly for up to four cycles, losing TC, CIP and AMX adsorption capacities at equilibrium by no >7, 4 and 9 %, respectively. This study suggests that both biocomposites may be effective and sustainable alternatives to commercial adsorbents for removing antibiotics from wastewater
Microalgae growth in winery wastewater under dark conditions
No full textWine-making process leads to large amounts of wastewater. Winery wastewaters (WWW) are produced from different activities of wine production: washing, transferring and storage operations. Tank cleaning and filtration equipment are responsible for the release of the largest amount of wastewater, whose polluting power is mainly due to both the large volumes produced and the high organic load. Because of the latter problem, biological WWW treatments are particularly appropriate. Microalgae, often used to treat civil and different industrial wastewaters, are unicellular organisms that can be grown either in autotrophic or heterotrophic mode using various organic and inorganic carbon sources. Their importance is related to their high growth rate, use to produce different biofuels, use in human or animal nutrition, and extraction of chemicals and pharmaceuticals. Purposes of this work were to reduce WWW environmental impact and to find a cheap growth medium able to reduce the microalgae production costs. In this study, three different wastewaters were used, namely WWW from first (1W) and second (2W) washing tanks, and WWW from filtration apparatus (3W). They were 20:80 (v/v) diluted with Bold Basal medium and treated batchwise with a co-culture of Arthrospira platensis and Chlorella vulgaris. Microalgae were grown under dark conditions in 0.5-L flasks with continuous air supply for 15 days. Biomass concentration was quantified daily by measurements of cell dry weight and optical density at 625 nm and expressed in grams of microalgae per liter (g/L). Chemical Oxygen Demand (COD) and total polyphenols content (by the Folin-Ciocalteu method) of WWWs were quantified daily, in order to evaluate the degradation capability of the co-culture. At the end of cultures, the lipid content of microalgal biomass was also quantified. Biomass grown in the presence of WWW reached final concentrations three times higher than the control. In general, COD was reduced by more than 90 % after 15 days, polyphenols concentration was reduced by 40, 90 and 100 % in 1W, 2W and 3W, respectively, while lipid content of biomass grown in 1W and 3W increased from 7 to 11 and 15 %, respectively. In conclusion, the results of this study demonstrate that microalgae can grow efficiently under dark conditions in media enriched with WWW, hence reducing its environmental impact
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
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