Processos de inertização e valorização de cinzas volantes : incineração de resíduos sólidos urbanos

Tese de doutoramento em Engenharia Química (Reactores Químicos) apresentada à Fac. de Ciências e Tecnologia de CoimbraNo presente estudo foi considerado um subproduto do processo industrial de incineração de resíduos sólidos urbanos (RSU), designado por resíduo de controlo de poluição (RCP) atmosférica, ou de um modo mais generalista por "cinzas volantes". O trabalho decorreu em colaboração com a unidade de incineração da área de Lisboa, a qual forneceu as amostras de resíduo. Os principais objectivos centraram-se na análise dos processos de tratamento dos RCP por estabilização química e através de tratamentos de solidificação/estabilização (S/S), tendo em vista o melhoramento do processo industrial. Uma outra vertente constituiu na avaliação da possibilidade de valorização deste tipo de resíduos na produção de materiais cerâmicos, designadamente em agregados leves. Foi realizada uma extensa caracterização física e química dos RCP, uma vez que este é um resíduo relativamente recente em Portugal, e não havia sido caracterizado anteriormente. Analisaram-se os teores elementares totais, as quantidades potencialmente lixiviáveis, tendo sido realizado um estudo aprofundado do comportamento de lixiviação das espécies químicas mais relevantes (Pb, Cd, Zn, Cr, Ni, Cu, K, Na, Ca, Cl- e SO42-). Os métodos S/S imobilizam eficazmente os metais pesados, sendo no entanto, os sais solúveis susceptíveis de serem libertados em quantidades significativas. Podem ser usadas formulações alternativas ao tratamento actualmente utilizado na indústria, as quais podem consistir na redução da quantidade de cimento, na utilização de cinzas volantes de carvão e outros tipos de cimento, bem como o uso de aditivos (fosfatos ou silicatos), sendo facilmente garantida a eficácia em relação aos metais, mas não em relação aos sais solúveis. Foram utilizados modelos matemáticos capazes de identificar os processos de libertação das substâncias poluentes dos sólidos resultantes do tratamento S/S, tendo sido determinados coeficientes de difusão efectivos, factores de retenção física e retenção química. Relativamente à valorização dos resíduos, foi concluído que é tecnicamente possível incorporar os RCP em agregados leves

Urban wastewater as a source of reclaimed water for irrigation: barriers and future possibilities

Water resources are under pressure worldwide, resulting in scarcity and deterioration of freshwater quality. According to European directives, we could reduce the pressure on water resources in urban areas by increasing the reuse of treated wastewater, reducing the impact on water bodies, and promoting water recycling through multiple uses of urban wastewater. Besides the need to address water supply challenges, wastewater treatment systems show environmental stewardship and innovative practices. Using reclaimed water for agricultural irrigation is gaining interest because of the drought conditions experienced in Europe over the past few years. Furthermore, using treated wastewater for agricultural irrigation may help to restore nutrients (N and P) to natural biogeochemical cycles. This review highlights the importance of water reuse, current legislation, and existing technologies to implement in wastewater treatment systems to meet the minimum requirements to produce reclaimed water to reuse in agricultural irrigation.info:eu-repo/semantics/publishedVersio

No evidence for short‐term evolutionary response to a warming environment in Drosophila

Adaptive evolution is key in mediating responses to global warming and may sometimes be the only solution for species to survive.Such evolution will expectedly lead to changes in the populations’ thermal reaction norm and improve their ability to cope with stressful conditions. Conversely, evolutionary constraints might limit the adaptive response. Here, we test these expectations by performing a real-time evolution experiment in historically differentiated Drosophila subobscura populations. We address the phenotypic change after nine generations of evolution in a daily fluctuating environment with average constant temperature, or in a warming environment with increasing average and amplitude temperature across generations. Our results showed that (1) evolution under a global warming scenario does not lead to a noticeable change in the thermal response; (2) historical background appears to be affecting responses under the warming environment, particularly at higher temperatures; and (3) thermal reaction norms are trait dependent: although lifelong exposure to low temperature decreases fecundity and productivity but not viability,high temperature causes negative transgenerational effects on productivity and viability, even with high fecundity. These findings in such an emblematic organism for thermal adaptation studies raise concerns about the short-term effciency of adaptive responses to the current rising temperatures.info:eu-repo/semantics/acceptedVersio

High developmental temperature leads to low reproduction despite adult temperature

Phenotypic plasticity can help organisms cope with changing thermal conditions and it may depend on which life-stage the thermal stress is imposed: for instance, exposure to stressful temperatures during development can trigger a positive plastic response in adults. Here, we analyze the thermal plastic response of laboratory populations of Drosophila subobscura, derived from two contrasting latitudes of the European cline. We measured reproductive performance through fecundity characters, after the experimental populations were exposed to five thermal treatments, with different combinations of developmental and adult temperatures (14°C, 18°C, or 26°C). Our questions were whether (1) adult performance is changed with exposure to higher (or lower) temperatures during development; (2) flies raised at lower temperatures outperform those developed at higher ones, supporting the “colder is better” hypothesis; (3) there is a cumulative effect on adult performance of exposing both juveniles and adults to higher (or lower) temperatures; (4) there is evidence for biogeographical effects on adult performance. Our main findings were that (1) higher developmental temperatures led to low reproductive performance regardless of adult temperature, while at lower temperatures reduced performance only occurred when colder conditions were persistent across juvenile and adult stages; (2) flies raised at lower temperatures did not always outperform those developed at other temperatures; (3) there were no harmful cumulative effects after exposing both juveniles and adults to higher temperatures; (4) both latitudinal populations showed similar thermal plasticity patterns. The negative effect of high developmental temperature on reproductive performance, regardless of adult temperature, highlights the developmental stage as very critical and most vulnerable to climate change and associated heat waves.info:eu-repo/semantics/publishedVersio

Beneficial developmental acclimation in reproductive performance under cold but not heat stress

Thermal plasticity can help organisms coping with climate change. In this study, we analyse how laboratory populations of the ectotherm species Drosophila subobscura, originally from two distinct latitudes and evolving for several generations in a stable thermal environment (18 °C), respond plastically to new thermal challenges. We measured adult performance (fecundity traits as a fitness proxy) of the experimental populations when exposed to five thermal regimes, three with the same temperature during development and adulthood (15-15 °C, 18-18 °C, 25-25 °C), and two where flies developed at 18 °C and were exposed, during adulthood, to either 15 °C or 25 °C. Here, we test whether (1) flies undergo stress at the two more extreme temperatures; (2) development at a given temperature enhances adult performance at such temperature (i.e. acclimation), and (3) populations with different biogeographical history show plasticity differences. Our findings show (1) an optimal performance at 18 °C only if flies were subjected to the same temperature as juveniles and adults; (2) the occurrence of developmental acclimation at lower temperatures; (3) detrimental effects of higher developmental temperature on adult performance; and (4) a minor impact of historical background on thermal response. Our study indicates that thermal plasticity during development may have a limited role in helping adults cope with warmer - though not colder - temperatures, with a potential negative impact on population persistence under climate change. It also emphasizes the importance of analysing the impact of temperature on all stages of the life cycle to better characterize the thermal limits.info:eu-repo/semantics/publishedVersio

Parceria nos cuidados à criança nos serviços de pediatria: Perspetiva dos enfermeiros

A prestação de cuidados em âmbito pediátrico implica que o enfermeiro detenha um complexo domínio de capacidades comunicacionais, relacionais e cognitivas, que lhe permitam interagir, de forma profissional, com a presença e participação do acompanhante no cuidado à criança hospitalizada. Inúmeras evidências científicas revelam as dificuldades que os acompanhantes sentem no processo de adaptação e trabalho em parceria com o enfermeiro. No entanto, são poucas ou, quase inexistentes, aquelas que se referem à perspetiva dos enfermeiros e às suas dificuldades neste processo. É com base nesta constatação que emerge o presente trabalho, cujo cerne se vincula à temática da presença e participação do acompanhante nos cuidados à criança hospitalizada, numa abordagem centralizada na opinião dos enfermeiros. Concluiu-se que os enfermeiros reconhecem a importância de envolver os acompanhantes no cuidado à criança hospitalizada, revelando que efetivamente o promovem nos cuidados básicos, contudo não o fazem nos de maior complexidade. Face ao Modelo de Parceria de Cuidados, baseado num processo de negociação, este estudo revelou que os enfermeiros ainda têm alguma dificuldade em incluir os acompanhantes como verdadeiros parceirosThe provision of care in the pediatric context requires to the nurses a complex domain of communicative skills, relational, and educational, that allow them interacting, so full and healthy, with the permanent presence and participation of caregivers of hospitalized children. Several scientific evidence explain the difficulties that caregivers feel in this adaptation process, in particular working in partnership with the nurse. However there are few or almost non-existent those related to the perspective of nurses and their difficulties in this process. Is based on this verification that emerges the present work, which consists in a research connected the theme, family participation in caring for hospitalized children, on a centralized approach in the opinion of nurses. It was concluded that nurses recognize the importance of involving caregivers in the care of hospitalized children and actively promote the involvement of caregivers in basic care, however do not make in care more complex. Face to Partnership Model of care, fully based in a negotiation process, this study shows that nurses still have some difficulty in including accompanying as real partners.info:eu-repo/semantics/publishedVersio

Slow and population specific evolutionary response to a warming environment

Adaptation to increasingly warmer environments may be critical to avoid extinction. Whether and how these adaptive responses can arise is under debate. Though several studies have tackled evolutionary responses under different thermal selective regimes, very few have specifically addressed the underlying patterns of thermal adaptation under scenarios of progressive warming conditions. Also, considering how much past history affects such evolutionary response is critical. Here, we report a long-term experimental evolution study addressing the adaptive response of Drosophila subobscura populations with distinct biogeographical history to two thermal regimes. Our results showed clear differences between the historically differentiated populations, with adaptation to the warming conditions only evident in the low latitude populations. Furthermore, this adaptation was only detected after more than 30 generations of thermal evolution. Our findings show some evolutionary potential of Drosophila populations to respond to a warming environment, but the response was slow and population specific, emphasizing limitations to the ability of ectotherms to adapt to rapid thermal shifts.info:eu-repo/semantics/publishedVersio

Rapid sintering of weathered municipal solid waste incinerator bottom ash and rice husk for lightweight aggregate manufacturing and product properties

This study assessed the technical feasibility of formulating lightweight aggregates (LWA) from municipal solid waste incinerator bottom ash (IBA) and residual biomass. Weathered IBA (WIBA) particles larger than 8 mm contain a mixture of calcium-rich compounds and other silicates mainly composed of glass and synthetic and natural ceramics, with low contents of heavy metals and soluble salts. Unfired LWA were formulated with the particle size fraction of WIBA larger than 8mm and rice husk (RH) used as the bloating agent. Rapid sintering of the unfired spherical pellets at 1,100°C for 5min produced some cohesive sintered LWA, whose porosity, apparent particle density, water absorption, and compressive strength directly correlated with the percentage of RH added. The fired LWA formulated with 5wt% of RH showed the highest bloating index (115%) and porosity (53%) and the lowest apparent particle density (0.61Mgm−3) and compressive strength (1.4MPa). The addition of more than 5wt% of RH increased the internal temperature of the sintered aggregates and decreased the viscosity of the molten glassy materials, resulting in the collapse of the inner structure. Consequently the porosity decreased and the apparent density of the particles increased, thereby shrinking the volume of the fired LWA. According to the standard leaching test (EN 12457-4), both the unfired precursor and the sintered aggregates showed concentrations of heavy metals and metalloids in the leachates that were well below the safety limits established for their reuse as secondary material

Editorial: Coping With Climate Change: A Genomic Perspective on Thermal Adaptation

info:eu-repo/semantics/publishedVersio

Electrochemical reduction of hematite-based ceramics in alkaline medium: challenges in electrode design

Electrochemical reduction of low-conductive hematite-based ceramics represents a novel approach for iron recovery and waste valorisation. The process itself allows a flexible switching between hydrogen generation and iron reduction, important for the intermittent renewable-energy-powered electrolytic process. The present study focuses on the direct electrochemical reduction of aluminium-containing hematite in strong alkaline media. Within this scope, the reduction mechanisms of porous and dense cathodes, with 60%, 37% and 3% of open porosity, were investigated using different types of electrodes configuration: nickel-foil and Ag-modified nickel-foil supported configuration (cathodes facing or against the counter electrode), and nickel-mesh supported configuration. The efficiency of the iron reduction was compared for different electrode concepts. The results highlight the importance of electrolyte access to the interface between the metallic current collector and ceramic cathode for attaining reasonable electroreduction currents. Both excessively porous and dense ceramic cathodes are hardly suitable for such reduction process, showing a necessity to find a compromise between mechanical strength of the electrode and its open porosity, essential for the electrolyte access.publishe