1,402 research outputs found

    Evaluation of solid waste stratified mixtures as constructed wetland fillers under different operation modes

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    Based on the strategy that all processes can and should be modified to contribute to a circular economy, this work evaluates the recovery of waste solids as filler material in Constructed Wetlands (CWs) used for wastewater treatment. Five sets of lab-scale CWs were assembled with mixtures of five waste solids and operated to evaluate the removal of chemical oxygen demand (COD) and nutrients from urban and industrial-types of wastewater. The adaptation and growth of the macrophyte Phragmites australis in the mixed-filler CWs was also monitored. Although all evaluated waste solids showed to be acceptable substrates for macrophyte development and wastewater treatment, CWs assembled with mixtures of limestone waste and coal slag showed the best plant growth indicators and wastewater treatment efficiencies. The CWs assembled with mixtures of limestone waste and clay brick fragments or cork granulates showed to be suitable alternatives. With exception for CWs filled with mixtures of limestone and snail shells, pollutant removal efficiencies up to 95%, 86% and 83% were obtained respectively for COD, total phosphorous and total nitrogen, depending on the type of wastewater and mode of operation. Removal efficiencies were not significantly affected by increased hydraulic rate. The CWs can be operated to a hydraulic loading rate of 0.056 m/d, which corresponds to a retention time of 1.5 days. The valorisation of solid waste as a filler can contribute to CWs closely participating in the creation of circular flows for the reuse of waste solids.The work was partially supported by COMPETE2020 under the grant POCI-01-0145-FEDER-23314. The authors acknowledge the support of the Lab.IPT staff, particularly, Alcino Serras, Isabel Silva and Pedro Costa, the research fellows Ana Alves and Nuno Graça. The authors also acknowledge the contribution of Carlos Ferreira, from IPT’s maintenance services, and Fátima Paiva, from IPT’s language centre.info:eu-repo/semantics/publishedVersio

    When Politicians Talk About Politics: Identifying Political Tweets of Brazilian Congressmen

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    Since June 2013, when Brazil faced the largest and most significant mass protests in a generation, a political crisis is in course. In midst of this crisis, Brazilian politicians use social media to communicate with the electorate in order to retain or to grow their political capital. The problem is that many controversial topics are in course and deputies may prefer to avoid such themes in their messages. To characterize this behavior, we propose a method to accurately identify political and non-political tweets independently of the deputy who posted it and of the time it was posted. Moreover, we collected tweets of all congressmen who were active on Twitter and worked in the Brazilian parliament from October 2013 to October 2017. To evaluate our method, we used word clouds and a topic model to identify the main political and non-political latent topics in parliamentarian tweets. Both results indicate that our proposal is able to accurately distinguish political from non-political tweets. Moreover, our analyses revealed a striking fact: more than half of the messages posted by Brazilian deputies are non-political.Comment: 4 pages, 7 figures, 2 table

    Spin-0 bosons near rotating stars

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    In this work we study the effects of rotating stars on the behavior of bosons close to their surfaces. For this task, metrics determined by the rotation of these stars will be taken into account. We will consider the Klein-Gordon equation in the Hartle-Thorne metric and in the one proposed by Berti et al. by considering some kinds of stars. Pions and Higgs bosons will be investigated as examples. By solving the equations, the main effect that may be observed is a rotational phase, δR\delta_R, that depends on the angular momentum of the star, JJ, in the wave function of the boson. Corrections of higher orders in JJ are also investigated

    Sustainable Production of Reclaimed Water by Constructed Wetlands for Combined Irrigation and Microalgae Cultivation Applications

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    Considering the increasing pressure on freshwater resources due to the constant increase in water consumption and insufficient wastewater control and treatment, recovering waste water is a path to overcoming water scarcity. The present work describes the potential of reusing treated wastewater (reclaimed water) for irrigation and production of microalgae biomass in an integrated way, through experimental evaluation of plant and microalgae growth, and creation of an application model. First, two parallel experiments were conducted to evaluate the use of reclaimed water produced by a constructed wetland filled with a mix of solid waste: the irrigation of a set of small pots filled with soil and planted with Tagetes patula L., and the cultivation of microalgae Chlorella sp.and a mixed microalgae population with predominant species of the genus Scenedesmus sp. in shaken flasks and tubular bubble column photobioreactors. Results indicated no negative effects of using the reclaimed water on the irrigated plants and in the cultivated microalgae. The growth indicators of plants irrigated with reclaimed water were not significantly different from plants irrigated with fertilized water. The growth indicators of the microalgae cultivated with reclaimed water are within the range of published data. Second, to apply the results to a case study, the seasonal variability of irrigation needs in an academic campus was used to propose a conceptual model for wastewater recovery. The simulation results of the model point to a positive combination of using reclaimed water for the irrigation of green spaces and microalgae production, supported by a water storage strategy. Water abstraction for irrigation purposes can be reduced by 89%, and 2074 kg dry weight microalgae biomass can be produced annually. Besides the need for future work to optimize the model and to add economical evaluation criteria, the model shows the potential to be applied to non-academic communities in the perspective of smarter and greener cities.The authors acknowledge the support from the Smart Cities Research Center(Ci2), from the Laboratory of Bioenergy and Applied Biotechnology (Biotec.IPT), and from the staff of the Lab.IPT. The work of Carolina Masseno, an exchange student from Universidade Federal Fluminense, Brasil, and the help of Orlando Fonseca is also acknowledged.N/Ainfo:eu-repo/semantics/publishedVersio

    Reporting Model for Decision Support Based on the SAF-T Standard

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    The purpose of this paper is to summarize the results and conclusions obtained during an investigation aiming to reveal the usefulness and added value of the SAF-T when used to support decision making and the internal management of organizations. The research addresses the SAF-T standard as a source of knowledge for decision support and intelligent auditing. The research contextualizes the contribution of the SAF-T based model as a scalable way to make intelligent audits, implement new business processes and manage electronic control. The information quality of this report and digital model is also stressed. Upon automatic reporting based on SAF-T data one can draw financial conclusions and decide changes on a firm´s commercial scope. This article also highlights the advantages of decision making based on the proposed model and report. A set of hints and suggestions for further re-search work on this topic is also provided

    Bioenergy routes for valorizing constructed wetland vegetation: An overview

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    Valorizing constructed wetlands vegetation into biofuels can be a way to contribute to mitigating the increasing energy demand, avoiding the use of arable land, freshwater, and fertilizers consumption, while simultaneously treating wastewater with eco-friendly technology. This work shortly overviews the main genera of wetland plants and the main routes of vegetal biomass conversion into biofuels including biochemical and thermochemical processes, and through a cross-search, in the Scopus database, the research intensity in bioenergy application for each genus was assessed. A total of 283 genera of wetland plants were identified and classified into five groups, from very common to very rare genera. The very common group includes 10 genera and contributes to 62% of the literature hits, while the 147 genera classified as very rare contribute to only 3% of the hits. Concerning the bioenergy applications, four genera stand out from the remaining. The plants of the genus Sorghum are the most referred to in bioenergy applications, followed by the genera Brassica, Miscanthus, and Saccharum. Miscanthus is a less common wetland plant, while the other genera are rarely applied in constructed wetlands. The relevance of bioenergy routes depends on the plants' group. For common wetland plants, the most relevant applications are biogas production, followed by bio-ethanol production, and pyrolysis processing. As a recommendation for future research works the genera with high energy potential should be evaluated as wetland vegetation, and it is recommended that the goal to recover wetland vegetation for bioenergy applications be viewed as an integral step of the design and implementation of constructed wetlands facilities.info:eu-repo/semantics/publishedVersio

    Screening of Solid Waste as Filler Material for Constructed Wetlands

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    The reuse of solid waste can contribute to reducing Earth’s resource depletion, directly through use in the original production processes or by valorisation in alternative applications. In the present work, ten solid wastes were evaluated as candidates for filling material in constructed wetlands (CWs). For that purpose, physical characterization, leaching and adsorptiontests were conducted. Limestone fragments and brick fragments resulting from construction activities, coal slags resulting from power plants, snail shells resulting from the food and catering industry, and cork granulates resulting from the cork industry have potential for use as CW fillers. These five materials have adequate physical properties and some capacity to adsorb phosphorous and organic compounds from wastewater. On the other hand, crushed eggshells resulting from egg farms, dealcoholized grape pomaces resulting from alcohol distilleries, olive seeds waste from olive-oil mills, and pine bark fragments and wood pellets resulting from forestry cleaning activities, wood mills and pulp mills did not demonstrate sufficient potential to be used as CW fillers, either because they have very low adsorption capacities or leach compounds in contact with water, or because they have less adequate physical properties. None of the tested solid wastes showed the ability to adsorb nitrogen compounds. Although the five selected materials do not present a special capability for adsorption of nitrogen, phosphorous and organic compounds, they can all be valued as CW fillers, representing a way to reduce the amount of solid waste sent to landfills.This work was supported by Program FEDER, ref. POCI-01-0145-FEDER-023314, project VALORBIO. The authors acknowledge the collaboration of the Lab.IPT staff and the assistance of students of chemical and environmental technology courses held at Instituto Politécnico de Tomar. Special thanks to Alcino Serras, Ana Alves, Isabel Silva, Joel Nunes and Nuno Graça.info:eu-repo/semantics/publishedVersio

    Label-free multi-step microfluidic device for mechanical characterization of blood cells: Diabetes type II

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    The increasing interest to establish significant correlations between blood cell mechanical measurements and blood diseases, has led to the promotion of microfluidic devices as attractive clinical tools for potential use in diagnosis. A multi-step microfluidic device able to separate red and white blood cells (RBCs and WBCs) from plasma and simultaneously measure blood cells deformability (5 and 20% of hematocrit) is presented in this paper. The device employs passive separation based on the cross-flow filtration principle, introduced at each daughter channel. At the outlets, hyperbolic geometries allow single-cell deformability analysis. The device was tested with blood from five healthy and fifteen diabetic type II voluntary donors. The results have shown that WBCs have lower deformability than RBCs, and no significant differences were observed in WBCs from healthy and pathological blood samples. In contrast, RBCs have shown significant differences, with pathological cells exhibiting lower deformability. Shear rheology has shown that blood from patients with type II diabetes has higher viscosity than blood from healthy donors. This microfluidic device has demonstrated the ability to reduce cell concentration at the outlets down to 1%, an ideal cell concentration for assessing the blood cells deformability, under healthy and pathological conditions. The results provide new insights and quantitative information about the hemodynamics of in vitro type II diabetes mellitus RBCs. Thus, such device can be a promising complement in clinical diagnosis and biological research as part of an integrated blood-on-a-chip system.This work was supported by Projects NORTE-01-0145-FEDER- 028178, NORTE-01-0145-FEDER-029394, NORTE-01-0145-FEDER- 030171 funded by COMPETE2020, NORTE2020, PORTUGAL2020, and FEDER. This work was also supported by Fundação para a Ciência e a Tecnologia (FCT) under the strategic grants UIDB/04077/2020 and UIDB/00532/2020. D. Pinho and V. Faustino acknowledge the Ph.D. scholarships SFRH/BD/89077/2012 and SFRH/BD/99696/2014, respectively, both provided by FCT. Susana Catarino thanks FCT for her contract funding provided through 2020.00215.CEECIND. F. T. Pinho is thankful to FCT for financial support through projects LA/P/0045/2020 of the Associate Laboratory in Chemical Engineering (ALiCE) and projects UIDB/00532/2020 and UIDP/00532/2020 of Centro de Estudos de Fenómenos de Transporte.info:eu-repo/semantics/publishedVersio

    Absence of self-organized criticality in a random-neighbor version of the OFC stick-slip model

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    We report some numerical simulations to investigate the existence of a self-organized critical (SOC) state in a random-neighbor version of the OFC model for a range of parameters corresponding to a non-conservative case. In contrast to a recent work, we do not find any evidence of SOC. We use a more realistic distribution of energy among sites to perform some analytical calculations that agree with our numerical conclusions.Comment: 7 pages, 4 figures, submitted to Physica

    Volatile sulphur compounds in wines related to yeast metabolism and nitrogen composition of grape musts

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    The influence of nitrogen compounds in grape musts on the content of sulphur compounds of wines was studied. Different vinifications were performed with the addition of methionine (20 mg l−1) and/or cysteine (40 mg l−1) to grape musts before alcoholic fermentation. Six grape musts, with different nitrogen composition, from cultivars of the ‘Vinhos Verdes’ Region, in Portugal, were used. Addition of methionine to grape musts enhanced the content of wines in 3-(methylthio)-1-propanol, acetic acid-3-(methylthio)propyl ester, 3-(methylthio)propionic acid and some unidentified sulphur compounds. Increase of cysteine concentration in musts led to the production of wines with high levels of hydrogen sulphide and cis-2-methyltetrahydrothiophene- 3-OL and also unidentified sulphur compounds; however, the content of 3-(methylthio)propionic acid in the wines decreased considerately with the addition of cysteine to grape musts. This work showed that cultivars from the Vinho Verde Region show different sulphur compound contents. Avesso wines, elaborated from grape musts with low amino acids level, presented the highest total sulphur compounds content. Wines from Azal branco and Alvarinho were characterised by high contents of 4-(methylthio)-1-butanol and 3-(methylthio)propionic acid, respectively. A high content of N-(3-(methylthio) propyl)-acetamide and dimethylsulphone characterise the Loureiro wines. In contrast, Trajadura wines, produced from a must rich in amino acids, presented a low total sulphur compounds content; however, these wines were also characterised by high concentrations of 4-(methylthio)-1-butanol, acetic acid-3-(methylthio)propyl ester and hydrogen sulphide
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