33 research outputs found

    The Impacts of Payments for Watershed Services in Ecuador: Emerging Lessons from Pimampiro and Cuenca

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    The project set out to engage stakeholders in the evaluation of this emerging "market" for watershed services and its social impact. The study consists of two documents that are separate but also complement each other. The first document, called Markets or Metaphors? A Sustainable Livelihoods Approach to the Management of Environmental Services: two Cases from Ecuador, written by Dr Joseph Vogel, is at the centre of the research. This document presents the results of the development of a methodology and its application in the field. It also includes an economic and legal analysis that demonstrates the importance of understanding and including social and cultural implications when developing a market for watershed service

    Model d'Avaluació del Risc sobre la Salut. Aplicació als residents a les rodalies de la incineradora de Montcada i Reixac.

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    Durant els últims anys l'oposició de la població cap a certes activitats industrials ha augmentat considerablement, a causa de que cada dia existeix una major consciència de la població dels impactes produïts per les emissions de contaminants sobre la salut. Entre les activitats que han portat un important rebuig per la societat trobem la incineració de residus sòlids urbans, degut principalment a les seves emissions de policlorodibenzo-p-dioxines (PCDDs) i policlorodibenzofurans (PCDFs), així com de metalls pesants.L'elevada toxicitat d'aquests compostos és la que ens va portar a proposar com a objectiu del present estudi: el desenvolupament d'un model d'avaluació del risc de les emissions de dioxines i furans (per als 17 congèneres tòxics) i metalls pesants d'una planta incineradora de residus sòlids urbans.Per tal de poder assolir aquest objectiu el present estudi ha estat dividit en tres parts: 1) el desenvolupament d'un model multi-compartamental, 2) l'avaluació de l'impacte medi ambiental de les emissions de dioxines i furans i de metalls pesants a les rodalies de la planta incineradora de residus urbans de Montcada i Reixac, mitjançant una monitorització de l'àrea d'estudi, i 3) l'anàlisi de risc degut a les emissions de la planta i als nivells ambientals a l'àrea.Desenvolupament d'un model multi-compartamentalPer tal d'assolir l'objectiu de la primera part, el primer que s'ha portat a terme ha estat un estudi de la dispersió dels contaminants des de la seva sortida per xemeneia per als 17 congèneres tòxics de PCDD/Fs i per a metalls pesants. El següent pas ha estat el desenvolupament d'un model multimedia simple (aire - sòl - vegetació), que descriu el transport i transformacions de PCDD/Fs i metalls pesants als diferents medis. En el model sòl-aire s'han considerat 4 vies d'exposició dels contaminants: deposició particulada seca i humida, deposició de gasos i exposició via arrels, a més a més de les pèrdues per lixiviació, degradació, arrossegament per aigües superficials, volatilització i erosió. Per al model aire-vegetals s'han considerat les mateixes vies d'exposició. D'aquesta manera s'han determinat els nivells de contaminants en sòl i vegetació deguts a les emissions de la planta. Durant el desenvolupament d'aquest model s'ha buscat l'equilibri entre un model el qual pugui predir amb una exactitud raonable la bioacumulació de compostos químics en sòls i plantes, i un model que no requereixi una extensiva caracterització i un gran número de dades físico-químiques.Monitorització de l'àreaLa segona part de l'estudi ha estat l'avaluació de l'impacte ambiental de les emissions de dioxines i furans i de metalls pesants a les rodalies de la planta incineradora de residus urbans de Montcada i Reixac. Per tal de poder assolir aquest objectiu, s'ha portat a terme la monitorització de l'àrea d'estudi, on s'han determinat els nivells de dioxines, furans i metalls pesants en 24 mostres de sòls i vegetació durant tres anys consecutius (1996, 1997, 1998). D'aquesta manera s'ha realitzat una avaluació espacial i temporal dels nivells de contaminants. Per altra banda, al 1999 la planta d'incineració de Montcada i Reixac va portar a terme unes millores medi ambientals en la seva instal·lació. D'aquesta manera les emissions de dioxines i furans i metalls pesants entre d'altres es van veure reduïdes considerablement. Per aquesta raó, al 2000 es va a tornar a portar a terme una altra monitorització de les emissions de la planta, per tal de determinar de quina manera la disminució en les emissions afectaria els nivells medi ambientals. Anàlisi de riscFinalment, s'ha quantificat el risc per la població degut a les emissions de PCDD/Fs i metalls pesants. El risc avalua la probabilitat de que un efecte advers sobre la salut pugui ocorre després de l'exposició a una dosi determinada d'una substància definida. L'avaluació del risc realitzada ha estat la deguda a l'exposició a contaminants com a combinació de les cinc vies següents: inhalació de partícules, inhalació d'aire, ingesta de sòls i vegetals conreats a l'àrea d'estudi, i absorció dèrmica. Els individus d'una població poden ser descrits per un número de diferents escenaris d'exposició, ja que poden ocorre diferents nivells de risc dins d'una població. Així, per tal d'avaluar la variabilitat i la incertesa del risc s'ha portat a terme una anàlisi de Monte Carlo

    Joint Environmental and Economical Analysis of Wastewater Treatment Plants Control Strategies : a Benchmark Scenario Analysis

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    In this paper, a joint environmental and economic analysis of different Wastewater Treatment Plant (WWTP) control strategies is carried out. The assessment is based on the application of the Life Cycle Assessment (LCA) as a method to evaluate the environmental impact and the Benchmark Simulation Model No. 1 (BSM1). The BSM1 is taken as the benchmark scenario used to implement the control strategies. The Effluent Quality Index (EQI) and the Overall Cost Index (OCI) are two indicators provided by BSM1 and used to evaluate the plant's performance from the efluent quality and the economic points of view, respectively. This work conducts a combined analysis and assessment of ten different control strategies defined to operate a wastewater treatment plant. This analysis includes the usual economic and performance indexes provided by BSM1 joined with the LCA analysis that determines the environmental impact linked to each one of the considered control strategies. It is shown how to get an overall evaluation of the environmental effects by using a normalized graphical representation that can be easily used to compare control strategies from the environmental impact point of view. The use of only the BSM1 indexes provides an assessment that leads to a clustering of control strategies according to the cost/quality tradeoff they show. Therefore, regarding the cost/quality tradeoff, all strategies in the same group are almost equal and do not provide an indication on how to proceed in order to select the appropriate one. It is therefore shown how the fact of adding a new, complementary, evaluation (LCA based) allows either to reinforce a decision that could be taken solely on the basis of the EQI/OCI tradeoff or to select one control strategy among the others

    Anaerobic digestion process control using a data-driven internal model control method

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    Anaerobic digestion processes offer the possibility for wastewater treatment while obtaining a benefit through the obtained biogas. This paper aims to continue the effort to adopt data-driven control methods in the case of anaerobic digestion processes. The paper proposes a data-based Internal Model Control approach applied to an anaerobic digestion process. The paper deals extensively with the issue of choosing the reference model and proposing an engineering approach to this issue. The paper also addresses the issue of verifying robust stability, a very important aspect considering the uncertainties that characterize bioprocesses in general. The approach proposed in the paper is validated through a numerical simulation using the Anaerobic Digestion Model No. 1. During the validation of the proposed control solution, the main operating conditions were analyzed, such as the setpoint tracking performance, the rejection of disturbance generated by variations in the influent concentration, and the effect of the measurement noise on the controlled variable

    Design of feedback control strategies in a plant-wide wastewater treatment plant for simultaneous evaluation of economics, energy usage, and removal of nutrients

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    Simultaneous removal of nitrogen and phosphorous is a recommended practice while treating wastewater. In the present study, control strategies based on proportional-integral (PI), model predictive control (MPC), and fuzzy logic are developed and implemented on a plant-wide wastewater treatment plant. Four combinations of control frameworks are developed in order to reduce the operational cost and improve the effluent quality. As a working platform, a Benchmark simulation model (BSM2-P) is used. A default control framework with PI controllers is used to control nitrate and dissolved oxygen (DO) by manipulating the internal recycle and oxygen mass trans-fer coefficient (KLa). Hierarchical control topology is proposed in which a lower-level control framework with PI controllers is implemented to DO in the sixth reactor by regulating the KLa of the fifth, sixth, and seventh reactors, and fuzzy and MPC are used at the supervisory level. This supervisory level considers the ammonia in the last aerobic reactor as a feedback signal to alter the DO set-points. PI-fuzzy showed improved effluent quality by 21.1%, total phosphorus removal rate by 33.3% with an increase of operational cost, and a slight increase in the production rates of greenhouse gases. In all the control design frameworks, a trade-off is observed between operational cost and effluent quality

    Nitrous oxide reduction in wastewater treatment plants by the regulation of the internal recirculation flow rate with a fuzzy controller

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    Altres ajuts: acords transformatius de la UABThe reduction of greenhouse gas emissions due to anthropogenic causes is one of the world's main challenges to face climate change. Wastewater treatment plants are necessary to improve the quality of wastewater before it is discharged into the receiving environment, but they have the disadvantage of generating nitrous oxide emissions during the biological treatment, which is a potent greenhouse gas. Avoiding partial nitrification by increasing dissolved oxygen is one of the ways to reduce these emissions. However, this article proposes to face a reduction of nitrous oxide emissions by reducing oxygen to minimum levels causing heterotrophic microorganisms to reduce nitrous oxide to dinitrogen. To achieve this objective, the present work proposes a regulation of the internal recirculation flow rate of the biological treatment by means of a fuzzy controller. This regulation is added to a usual control strategy in wastewater treatment plants, which achieves satisfactory results with respect to water quality and operational costs but that generates high nitrous oxide emissions. The Benchmark Simulation Model no. 2 Gas is used as working scenario, which includes the two main nitrous oxide emission pathways: heterotrophic denitrification and ammonia oxidizing bacteria denitrification. The proposed internal recirculation manipulation is shown to achieve nitrous oxide reductions of 26.70 and 30.83 % in different time periods with a slight effluent quality improvement and an operational cost reduction

    COVID-19 Infection among Nursing Students in Spain: The Risk Perception, Perceived Risk Factors, Coping Style, Preventive Knowledge of the Disease and Sense of Coherence as Psychological Predictor Variables: A Cross Sectional Survey

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    The exploration of patterns of health beliefs about COVID-19 among nursing students may be beneficial to identify behaviors, attitudes and knowledge about contagion risk. We sought to analyze the variables of risk perception, perceived risk factors, coping style, sense of coherence and knowledge of preventive measures as possible predictors of having suffered from COVID-19. Participants were nursing students from 13 universities in Spain. Sociodemographic and health variables were collected. To test the independent variables, the Perception Risk Coping Knowledge (PRCK-COVID-19) scale was created and validated because there was no specific survey for young people adapted to the pandemic situation of COVID-19. It was validated with adequate psychometric properties. A total of 1562 students (87.5% female, mean age 21.5 ± 5.7 years) responded. The high perception of the risk of contagion, the high level of knowledge and a coping style focused on the situation were notable. Significant differences by gender were found in the coping styles, problem-focused, avoidance and knowledge scales, with women scoring higher in all categories. The multiple regression analysis was significant (F = 3.68; p < 0.001). The predictor variables were the coping styles subscale search for support and the intrinsic and extrinsic perceived risk factors. Our model predicts that nursing students with a social support-based coping style are at a higher risk of becoming infected with COVID-19, based on their own health belief model.Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Acknowledgments: We are grateful to all participating institutions and students

    Design of the EBE-ST questionnaire among nursing students: mnulticenter study from eight universities in Spain

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    Background: Twenty years after the degree in nursing was introduced in Spain, the subject of evidence-based nursing is still unstructured and unestablished in most faculties. Moreover, there are hardly any rigorous studies at a national level that evaluate the current state of this competence in our faculties. Understanding the starting point is essential for the curricular design to ensure that evidence-based practice is implemented among future professionals. Aim: To design and validate an evidence-based nursing competency questionnaire for fourth-year nursing students. Methods: A specific questionnaire was developed and validated (EBE-ST). A cross-sectional survey design with psychometric validation of an instrument. Participants were 304 senior year nursing students from eight universities in Spain (2020). Results: The EBE-ST questionnaire is composed of 33 items that determine eight factors. It presents adequate reliability and validity (alpha = 0.882), measuring knowledge, attitudes and the practical application of evidence-based practice. Conclusions: We have created an instrument with good psychometric properties to measure evidence-based practice competence among senior nursing students. The heterogeneity of knowledge regarding evidence-based nursing in our country suggests that further reflection is warranted on the incorporation of this topic during undergraduate training. We have designed and validated an evidence-based nursing competency questionnaire specific to nursing student

    A hotspot for posttranslational modifications on the androgen receptor dimer interface drives pathology and anti-androgen resistance

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    Mutations of the androgen receptor (AR) associated with prostate cancer and androgen insensitivity syndrome may profoundly influence its structure, protein interaction network, and binding to chromatin, resulting in altered transcription signatures and drug responses. Current structural information fails to explain the effect of pathological mutations on AR structure-function relationship. Here, we have thoroughly studied the effects of selected mutations that span the complete dimer interface of AR ligand-binding domain (AR-LBD) using x-ray crystallography in combination with in vitro, in silico, and cell-based assays. We show that these variants alter AR-dependent transcription and responses to anti-androgens by inducing a previously undescribed allosteric switch in the AR-LBD that increases exposure of a major methylation target, Arg761. We also corroborate the relevance of residues Arg761 and Tyr764 for AR dimerization and function. Together, our results reveal allosteric coupling of AR dimerization and posttranslational modifications as a disease mechanism with implications for precision medicine
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