Avaliação da qualidade da água do rio Cértima através de ensaios ecotoxicológicos

Mestrado em Engenharia do AmbienteO objectivo geral deste trabalho foi avaliar a qualidade da água da bacia hidrográfica do rio Cértima através de ensaios ecotoxicológicos. Para isso foram seleccionados três locais de amostragem ao longo do rio, com impacto antropogénico diferente: Parada, Ponte do Repolão e Lagoa Seca. Foram consideradas duas campanha de amostragem a fim de avaliar a variabilidade sazonal: Novembro de 2009 e Abril de 2010. A avaliação ecotoxicológica envolveu uma bateria de ensaios com diferentes espécies: a bactéria Vibrio fischeri, a alga Pseudokirchneriella subcapitata, a macrófita Lemna minor e o cladócero Daphnia magna. Paralelamente foi efectuada uma análise físico-química, a qual permitiu identificar problemas de poluição de origem antrópica nos locais Ponte de Repolão e Lagoa Seca. Por outro lado, o local Parada, seleccionado como local de referência apresentou valores típicos de um local com reduzida ou nula pressão antropogénica. Os ensaios ecotoxicológicos revelaram efeitos na taxa de crescimento das espécies L. minor e P. subcapitata no local Parada, no entanto estes efeitos deveram-se claramente à limitação em nutrientes da amostra. No local Ponte do Repolão, foi observada toxicidade elevada para V. fischeri ( EC50 = 44,85) na campanha de Novembro de 2009 e um decréscimo na taxa de crescimento de L. minor (LOEC = 75%) na campanha de Abril de 2010. O local Lagoa Seca apresentou efeitos negativos na taxa de crescimento de P. Subcapitata (LOEC=75%) na campanha de Novembro 2009. O organismo D. magna apresentou estímulos nos locais Lagoa Seca e Ponte do Repolão, em ambas as campanhas, possivelmente devido à presença de partículas nutritivas dissolvidas e algas, abundantes em locais eutrofizados. Dada a natureza essencialmente orgânica da poluição da bacia do rio Cértima, os ensaios ecotoxicológicos efectuados mostraram algumas limitações, já que a elevada carga de nutrientes dos locais Lagoa Seca e Ponte do Repolão podem ter mascarado a possível toxicidade de contaminantes, favorecendo inclusivé o crescimento dos organismos. Por outro lado, a limitação em nutrientes no local tido como referência – Parada, condicionou o crescimento nos ensaios com plantas. Deste modo, a análise ecotoxicológica, em locais sujeitos a poluição orgânica deve ser sempre complementada com uma avaliação físico-química e ecológica das comunidades locais, de modo a obtermos uma visão holística do estado de qualidade da água. ABSTRACT: The main objective of this work was to assess the water quality of the Cértima River (Central Portugal) with ecotoxicological assays. For this purpose three sampling sites were selected on the river basin that were known to be under different human pressures: Parada, Ponte do Repolão and Lagoa Seca. To evaluate the influence of seasonal variation there were two sampling periods: November 2009 and Abril 2010. Several species were used in the ecotoxicological analysis, such as the bacteria Vibrio fischeri, the algae Pseudokirchneriella subcapitata, the macrophyta Lemna minor and the cladoceran Daphnia magna. Physico-chemical parameters were also analysed showing that the Cértima watershed pointed some pollution problems including eutrophication on sites Ponte do Repolão and Lagoa Seca. The site Parada, selected as a reference site, showed concentrations of the physical and chemical parameters typical of a site with almost none human pressures. The ecotoxicological analysis showed negative effects on the growth rate of L. minor and P. subcapitata on the site Parada, but this was clearly due to nutrients limitation. The site Ponte do Repolão showed high toxicity for V. fischeri (EC50 = 44,85) in November 2009 and a decrease on the growth rate of L. minor (LOEC = 75%) in April 2010. Lagoa Seca showed a decrease of the growth rate of P. subcapitata (LOEC = 75%) in November 2009. D. magna had an increase of growth rate on Ponte do Repolão and Lagoa Seca possibly due to the presence of dissolved nutritive particles and algae, abundant in eutrophized sites. Being the pollution essentially organic, the ecotoxicological assays showed some limitations. The high load of nutrients on the sites Lagoa Seca and Ponte do Repolão may have masked the toxicity of contaminants and inclusive favoured the growth of organisms. On the other hand the nutrient limitations on the site considered to be a reference – Parada, conditioned the growth in the plant assays. Thus, the ecotoxicological analysis on sites with organic pollution should always be complemented with a physico-chemical and ecological analysis of the local communities so that it is possible to obtain an holistic overview of the water quality status

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Optimization of biological sulphate reduction to treat inorganic wastewaters : process control and use of methane as electron donor

This work investigated two different approaches to optimize biological sulphate reduction: to develop a process control strategy to optimize the input of an electron donor and the applicability of a cheap carbon source, i.e., methane. For the design of a control strategy that uses the organic loading rate (OLR) as control input, feast and famine behaviour conditions were applied to a sulphate reducing bioreactor to excite the dynamics of the process. Such feast/famine regimes were shown to induce the accumulation of carbon, and possibly sulphur, storage compounds in the sulphate reducing biomass. This study showed that delays in the response time and a high control gain can be considered as the most critical factors affecting the application of a sulphide control strategy in bioreactors. The delays are caused by the induction of different metabolic pathways in the anaerobic sludge including the accumulation of storage products. Polyhydroxybutyrate (PHB) and sulphate were found to accumulate in the biomass present in the inversed fluidized bed used in this study, and consequently, they were considered to be the main storage compounds used by SRB. On this basis a mathematical model was developed which showed a good fit between experimental and simulated data giving further support to key role of accumulation processes. In order to understand the microbial pathways in the anaerobic oxidation of methane coupled to sulphate reduction (AOM-SR) diverse potential electron donors and acceptors were added to in vitro incubations of an AOM-SR enrichment at high pressure with several co-substrates. The AOM-SR is stimulated by the addition of acetate which has not been reported for any other AOM-SR performing communities. In addition, acetate was formed in the control group probably resulting from the reduction of CO2. These results support the hypothesis that acetate may serve as an intermediate in the AOM-SR process, at least in some groups of anaerobic methanotrophs (ANME) and sulphate reducing bacteriaCe travail a étudié deux approches différentes pour optimiser la réduction biologique des sulfates: la première approche consisté à élaborer une stratégie de contrôle de processus pour optimiser l'ajout d'un donneur d'électrons et la deuxième à vérifier la pertinence de l'utilisation d'une source de carbone bon marché, à savoir, le méthane. Une stratégie de contrôle de l'apport du donneur d'électron en se basant sur le suivi de la charge organique a été mis en place. Des conditions d'abondance et de famine ont été appliquées à un bioréacteur à bactéries sulfato-réductrices (BSR) pour stimuler les dynamiques du processus. Ces conditions d'abondance/famine ont donné lieu à l'accumulation de carbone et également de soufre élémentaire (composants de stockage de biomasse réductrice de sulfate). Cette étude a montré que les retards dans le temps de réponse et un gain de commande élevé peuvent être considérés comme les facteurs les plus critiques affectant l'application d'une stratégie de contrôle de sulfure dans des bioréacteurs à BSR. L'allongement du temps de réponse est expliqué par l'induction de différentes voies métaboliques au sein des communautés microbienne des boues anaérobies, notamment par l'accumulation de sous produits de stockage. Le polyhydroxybutyrate (PHB) et les sulfates ont été retrouvés accumulés par la biomasse présente dans le bioréacteur à lit fluidisé inverse utilisé pour cette étude et donc ils ont été considérés comme les produits majoritaires de stockage par les BSR. Sur cette base, un modèle mathématique a été développé, qui montre un bon compromis entre les données expérimentales et simulées, et confirme donc le rôle clé des processus d'accumulation. Afin de comprendre les voies métaboliques impliquées dans l'oxydation anaérobie du méthane couplé à la réduction des sulfates (AOM-SR), différents donneurs et accepteurs d'électrons ont été ajoutés au cours de test d'incubations in vitro visant à enrichir la communauté microbienne impliqué dans l'AOM-SR à haute pression avec plusieurs co-substrats. L'AOM-SR est stimulée par l'addition de l'acétate ce qui n'a pas été rapporté pour d'autres communautés impliqué dans l'AOM-SR. En outre, l'acétate a été généré dans le test de contrôle résultant probablement de la réduction de CO2. Ces résultats renforcent l'hypothèse que l'acétate peut servir d'intermédiaire dans le processus de l'AOM-SR, au moins pour certains groupes de archées anaérobie méthanotrophe (ANME) et les bactéries sulfato-réductrice

Optimisation de la réduction biologique de sulfates pour le traitement des eaux usées : contrôle du processus et utilisation du méthane comme donneur d'électrons

Ce travail a étudié deux approches différentes pour optimiser la réduction biologique des sulfates: la première approche consisté à élaborer une stratégie de contrôle de processus pour optimiser l'ajout d'un donneur d'électrons et la deuxième à vérifier la pertinence de l'utilisation d'une source de carbone bon marché, à savoir, le méthane. Une stratégie de contrôle de l'apport du donneur d'électron en se basant sur le suivi de la charge organique a été mis en place. Des conditions d'abondance et de famine ont été appliquées à un bioréacteur à bactéries sulfato-réductrices (BSR) pour stimuler les dynamiques du processus. Ces conditions d'abondance/famine ont donné lieu à l'accumulation de carbone et également de soufre élémentaire (composants de stockage de biomasse réductrice de sulfate). Cette étude a montré que les retards dans le temps de réponse et un gain de commande élevé peuvent être considérés comme les facteurs les plus critiques affectant l'application d'une stratégie de contrôle de sulfure dans des bioréacteurs à BSR. L'allongement du temps de réponse est expliqué par l'induction de différentes voies métaboliques au sein des communautés microbienne des boues anaérobies, notamment par l'accumulation de sous produits de stockage. Le polyhydroxybutyrate (PHB) et les sulfates ont été retrouvés accumulés par la biomasse présente dans le bioréacteur à lit fluidisé inverse utilisé pour cette étude et donc ils ont été considérés comme les produits majoritaires de stockage par les BSR. Sur cette base, un modèle mathématique a été développé, qui montre un bon compromis entre les données expérimentales et simulées, et confirme donc le rôle clé des processus d'accumulation. Afin de comprendre les voies métaboliques impliquées dans l'oxydation anaérobie du méthane couplé à la réduction des sulfates (AOM-SR), différents donneurs et accepteurs d'électrons ont été ajoutés au cours de test d'incubations in vitro visant à enrichir la communauté microbienne impliqué dans l'AOM-SR à haute pression avec plusieurs co-substrats. L'AOM-SR est stimulée par l'addition de l'acétate ce qui n'a pas été rapporté pour d'autres communautés impliqué dans l'AOM-SR. En outre, l'acétate a été généré dans le test de contrôle résultant probablement de la réduction de CO2. Ces résultats renforcent l'hypothèse que l'acétate peut servir d'intermédiaire dans le processus de l'AOM-SR, au moins pour certains groupes de archées anaérobie méthanotrophe (ANME) et les bactéries sulfato-réductricesThis work investigated two different approaches to optimize biological sulphate reduction: to develop a process control strategy to optimize the input of an electron donor and the applicability of a cheap carbon source, i.e., methane. For the design of a control strategy that uses the organic loading rate (OLR) as control input, feast and famine behaviour conditions were applied to a sulphate reducing bioreactor to excite the dynamics of the process. Such feast/famine regimes were shown to induce the accumulation of carbon, and possibly sulphur, storage compounds in the sulphate reducing biomass. This study showed that delays in the response time and a high control gain can be considered as the most critical factors affecting the application of a sulphide control strategy in bioreactors. The delays are caused by the induction of different metabolic pathways in the anaerobic sludge including the accumulation of storage products. Polyhydroxybutyrate (PHB) and sulphate were found to accumulate in the biomass present in the inversed fluidized bed used in this study, and consequently, they were considered to be the main storage compounds used by SRB. On this basis a mathematical model was developed which showed a good fit between experimental and simulated data giving further support to key role of accumulation processes. In order to understand the microbial pathways in the anaerobic oxidation of methane coupled to sulphate reduction (AOM-SR) diverse potential electron donors and acceptors were added to in vitro incubations of an AOM-SR enrichment at high pressure with several co-substrates. The AOM-SR is stimulated by the addition of acetate which has not been reported for any other AOM-SR performing communities. In addition, acetate was formed in the control group probably resulting from the reduction of CO2. These results support the hypothesis that acetate may serve as an intermediate in the AOM-SR process, at least in some groups of anaerobic methanotrophs (ANME) and sulphate reducing bacteri

Knowledge Management and Operational Capacity in Water Utilities, a Balance between Human Resources and Digital Maturity—The Case of AGS

Digitalization and knowledge management in the water sector, and their impacts on performance, greatly depend on two factors: human capacity and digital maturity. To understand the link between performance, human capacity, and digital maturity, six AGS water retail utilities were compared with all Portuguese utilities using Portuguese benchmark data (2011–2019). AGS utilities achieved better results, including in compound performance indicators, which are assumed to be surrogates for digital maturity. These compound indicators were also found to correlate positively with better performance. In fact, AGS utilities show levels of non-revenue water (NRW) (<25%) below the national median (30–40%), with network replacement values similar to the national median (<0.5%). These results seem to imply that higher digital maturity can offset relatively low network replacement levels and guarantee NRW levels below the national average. Furthermore, regarding personnel aging index and digital maturity—two internally developed indicators—there was an increase in the digital maturity and aging of the staff, which, again, raises questions about long-term sustainability. The growing performance and the slight increase in digital maturity can be attributed to group-wide capacity building and digitalization programs that bring together staff from all AGS utilities in year-long activities

Two-stage anaerobic digestion system treating different seasonal fruit pulp wastes: impact on biogas and hydrogen production and total energy recovery potential

Anaerobic digestion has been shown to be an effective treatment for high organic matter wastes, while producing clean energy. However, anaerobic digesters in some companies must support variations of substrate composition due to the seasonality of feedstocks. In this study, a two-stage anaerobic digestion system was operated treating three different fruit pulp wastes in a sequential operation. The effect of substrate shifts and operational conditions on acidogenesis, biogas production/composition and overall system performance was assessed. Substrate shifts did not cause long-term instability issues. No evident association was found between operational condition changes on the profile of fermentation products and acidification degrees (53.7%-76.4%) in the acidogenic stage. However, substrate composition affected the gas production in the acidogenic stage, whereas it had no effect on the gas production in the methanogenic stage. The initial substrate composition affected the percentage of hydrogen (H-2) (0-34%) in the biogas produced in the first stage. Consistently high methane (CH4) yields (0.30-0.37 L-CH4 g(-1) CODdegraded) were obtained in the methanogenic stage. The biogas produced in the second stage (0.5-2.1 L-CH4 L-1 d(-1)) was rich in CH4 (75.9-80.6%) regardless of the operational conditions tested. The CH4 produced could be used to generate energy up to 79.5 kJ L-reactor(-1) d(-1) while the H-2 production in the acidogenic reactor, when treating fruit pulp waste with high content of sugars, could further increase this energy by up to 22.4% (H-2 content between 25 and 30%). This process has shown to be robust in treating seasonal wastes from a fruit juice industry, supporting full scale application

Automated biological sulphate reduction: a review on mathematical models, monitoring and bioprocess control

In the sulphate-reducing process, bioprocess control can be used to regulate the competition between microbial groups, to optimize the input of the electron donor and/or to maximize or minimize the production of sulphide. As shown in this review, modelling and monitoring are important tools in the development and application of a bioprocess control strategy. Pre-eminent literature on modelling, monitoring and control of sulphate-reducing processes is reviewed. This paper firstly reviews existing mathematical models for sulphate reduction, focusing on models for biofilms, microbial competition, inhibition and bioreactor dynamics. Secondly, a summary of process monitoring strategies is presented. Special attention is given to in situ sensors for sulphate, sulphide and electron donor concentrations as well as for biomass activity and composition. Finally, the state of the art of the bioprocess control strategies in biological sulphate reduction processes is overviewed

Assessment of river water quality using an integrated physicochemical, biological and ecotoxicological approach

In order to maintain and improve the water quality in European rivers, the Water Framework Directive (WFD) requires an integrated approach for assessing water quality in a river basin. Although the WFD aims at a holistic understanding of ecosystem functioning, it does not explicitly establish cause-effect relationships between stressors and changes in aquatic communities. To overcome this limitation, the present study combines the typical WFD physicochemical and biological approaches with an ecotoxicological approach. The main goal was to assess river water quality through an integrated manner, while identifying potential risk situations for aquatic communities in the Certima river basin (Portugal). To achieve this goal, surface water samples and macroinvertebrate specimens were collected under contrasting hydrological conditions (autumn and spring seasons) at three river sites exposed to distinct pollution levels defined according to the WFD (low, moderate and highly polluted). Physicochemical water quality status was defined according to the Portuguese classification for multipurpose surface waters, whereas biological water quality was assessed in accordance with the South Invertebrate Portuguese Index. Ecotoxicological assays included four standard species, a bacterial species (Vibrio fischeri), a unicellular algae (Pseudokirchneriella subcapitata), a macrophyte (Lemna minor) and a crustacean (Daphnia magna), which were exposed to different river water concentrations. The study sites represented a clear and pronounced gradient of pollution, from the unpolluted reference site to the sites under moderate to high anthropogenic pressure. In the latter sites, clear signs of organic pollution were found, such as low dissolved oxygen concentrations, high nutrient loads and prevalence of highly tolerant macroinvertebrate species. Despite the evident signs of pollution, no clear evidence of toxicity was observed in test species, suggesting that ecotoxicological assays using standard laboratory species and methodologies might not be suitable for assessing the effects of organic pollution. Nevertheless, the integrated methodology presented in this study provided important additional information on the Certima's water quality status. Its wider use could contribute to a more comprehensive assessment of the effects of anthropogenic pollution on the status and functioning of aquatic ecosystems under the WFD and, thereby, improve the scientific foundations for the sustainable future management of surface water resources

Performance of a two-stage anaerobic digestion system treating fruit pulp waste: the impact of substrate shift and operational conditions

Food and beverage industry wastes present high amounts of organic matter, which may cause water quality degradation if not treated. Two-stage anaerobic digestion is a promising and efficient solution for the treatment of this type of wastes whilst producing bioenergy. The composition of fruit pulp waste varies throughout the different harvesting seasons, which may impact the process performance. In this study, a two-stage anaerobic digestion system was operated to assess the effect of substrate shift from peach to apple pulp wastes (obtained from a fruit juice company) on the microbial community activity and performance. During acidogenesis, the sugar conversion was higher than 95% for all operational conditions tested, obtaining a degree of acidification up to 89%. Principal Component Analysis was used to evaluate the relationship between the initial fermentation state of the residues in each operational condition and the obtained effluent. Methanogenic activity resulted in high organic carbon consumption (89%) and high methane productivities, achieving a maximum of 4.33 L/L.d for peach waste influent. Overall, the results showed that the microbial community activity was not affected by the substrate shift, converting the sugars into biogas rich in methane (>70% CH). Microbial analysis showed that the communities present in the acidogenic and methanogenic reactors were highly enriched in bacteria and archaea, respectively. The observed stability of the process, also demonstrated in pilot scale, confirmed the robustness of the process and thus, was suitable for implementation in companies producing seasonally different fruit wastes in a continuous operation