C-MADE - Center of Materials and Building Technologies
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C-MADE, Centre of Materials and and Building Technologies, is a research unit in civil engineering and related areas, formed by consortium between the University of Beira Interior (UBI) and the University of Trás-os-Montes and Alto Douro (UTAD) that have complementary resources for research, advanced training, technological development and innovation, within its scientific objectives.
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- Parameterisation effect on the behaviour of a head-dependent hydro chain using a nonlinear modelPublication . Catalão, João Paulo da Silva; Mariano, S.; Mendes, V. M. F.; Ferreira, L. A. F. M.This paper is on the problem of short-term hydro scheduling (STHS), particularly concerning a head-dependent hydro chain. We use a method based on nonlinear programming (NLP), namely quadratic programming, to consider hydroelectric power generation a function of water discharge and of the head. The method has been applied successfully to solve a test case based on a realistic cascaded hydro system with a negligible computational time requirement and is also applied to show that the role played by reservoirs in the hydro chain do not depend only on their relative position. As a new contribution to earlier studies, which presented reservoir operation rules mainly for medium and long-term planning procedures, we show that the physical data defining hydro chain parameters used in the nonlinear model have an effect on the STHS, implying different optimal storage trajectories for the reservoirs accordingly not only with their position in the hydro chain but also with the new parameterisation defining the data for the hydro system. Moreover, considering head dependency in the hydroelectric power generation, usually neglected for hydro plants with a large storage capacity, provides a better short-term management of the conversion of the potential energy available in the reservoirs into electric energy, which represents a major advantage for the hydroelectric utilities in a competitive electricity market.
- Removal of organic matter and nitrogen in an horizontal subsurface flow (HSSF) constructed wetland under transient loadsPublication . Albuquerque, Antonio; Arendacz, M.; Gajewska, M.; Obarska-Pempkowiak, Hanna; Randerson, Peter; Kowalik, P.A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1–8 to weeks 9–14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient load.
- Investigations of nitrogen removal pathways in a biological packed bed reactor using elementary mass balancesPublication . Albuquerque, Antonio; Makinia, Jacek; Pagilla, KrishnaNitrogen cycle involves a complex set of potential biochemical pathways with reactions catalyzed by different microorganisms. Elementary mass balances for COD, DO, NH4-N and alkalinity were conducted and stoichiometric relationships were investigated to explain possible pathways of the nitrogen removal mechanisms in a lab-scale submerged down flow biological packed bed (BPB) reactor. Four sets of experiments were performed by modifying the organic loading and C/N ratio in comparison with steady-state conditions. Approximately 90% of COD and NH4-N removal occurred in two upper sections occupying 1/5 of the reactor height. The elementary mass balances could not explain all the experimental results with respect to nitrogen removal and oxygen consumption by known mechanisms. The mass balance calculations, excluding the possibility of nitrification, were in general in accordance with the observations indicating no or minimal NO3-N production. The theoretical stoichiometric requirements for nitrification reaction were satisfied in 6 experiments and in another 8 experiments nitrification may have occurred, but stoichiometry was not satisfied. Using C/N ratio as the variable, only at C/N ratio = 10, the predictions confirmed the possibility of nitrification in the same 3 (out of 4) assays as observed in practice. The results of this study reveal that the nitrogen transformations occurring in the studied reactor are complex and cannot be explained by simple mechanisms of microbial assimilation and nitrification
- Influence of bed media characteristics on ammonia and nitrate removal in shallow horizontal subsurface flow constructed wetlandsPublication . Albuquerque, Antonio; Oliveira, José; Semitela, Sabrina; Amaral, LeonorTwo bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH4–N m−2 d−1 and 3 g NO3–N m−2 d−1) and removal efficiencies (>62% for ammonia, 90–100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both ammonia and nitrate seems to have involved not only the conventional pathways of nitrification–denitrification. The nitrogen loading rate of both ammonia (0.8–2.4 g NH4–N m−2 d−1) and nitrate (0.6–3.2 g NO3–N m−2 d−1) seem to have influenced the respective removal rates.
- Analysis of constructed wetland performance for irrigation reusePublication . Monte, Helena Marecos do; Albuquerque, AntonioMost of the wastewater treatment systems in small rural communities of the Cova da Beira region (Portugal) consist of constructed wetlands (CW) with horizontal subsurface flow (HSSF). It is believed that those systems allow the compliance of discharge standards as well as the production of final effluents with suitability for reuse. Results obtained in a nine-month campaign in an HSSF bed pointed out that COD and TSS removal were lower than expected. A discrete sampling also showed that removal of TC, FC and HE was not enough to fulfill international irrigation goals. However, the bed had a very good response to variation of incoming nitrogen loads presenting high removal of nitrogen forms. A good correlation between mass load and mass removal rate was observed for BOD5, COD, TN, NH4-N, TP and TSS, which shows a satisfactory response of the bed to the variable incoming loads. The entrance of excessive loads of organic matter and solids contributed for the decrease of the effective volume for pollutant uptake and therefore, may have negatively influenced the treatment capability. Primary treatment should be improved in order to decrease the variation of incoming organic and solid loads and to improve the removal of COD, solids and pathogenic. The final effluent presented good physical–chemical quality to be reused for irrigation, which is the most likely application in the area.
- O ambiente interior e a saúde dos ocupantes de edifícios de habitação – Estudo de caso em Covilhã, PortugalPublication . Abreu, Catarina Fabíola Cardoso; Lanzinha, João; Nepomuceno, MiguelO tema ambiente interior em edifícios surge forçosamente associado à energia e ao conforto. O conceito de qualidade do ambiente interior é um tema bastante complexo e abrangente, que depende de um grande número de factores. Esses factores podem ser agrupados em quatro grandes áreas, a qualidade do ar, a qualidade higrotérmica, a qualidade acústica e a qualidade da iluminação. Este trabalho tem como objectivo avaliar as consequências na saúde dos ocupantes, das condições e das situações de deficiência do ambiente interior dos edifícios de habitação, provocadas pelos materiais de construção de pouca qualidade e pela má implementação de medidas de eficiência energética. Para avaliar melhor estas consequências efectuou-se um estudo de caso, precisamente dois inquéritos destinados a diversos intervenientes, em que se pretendeu avaliar a sensibilidade das pessoas sobre as condições da habitação e os seus efeitos na saúde dos seus ocupantes.
- Potential for reuse of tungsten mining waste-rock in technical-artistic value added productsPublication . Gomes, João Castro; Silva, Abílio P.; Peralbo Cano, Rafael; Durán Suárez, Jorge Alberto; Albuquerque, AntónioMining and quarrying activities in Europe generate approximately 55% of total industrial wastes, according to a recent Eurostat report. Most of these wastes are directly dumped on land or deposited in landfill sites. The first solution may lead to negative environmental impacts on land (removal of vegetation, deforestation, land slope changes and increased risk of erosion), water (pollutant transport through surface runoff, soil infiltration and contamination of water resources), may lead to the contamination of agricultural goods and may impose risks on human health. In Portugal, about 20% of industrial waste produced originates from mines and quarries, particularly from Panasqueira mining, one of the largest tungsten mines in the world. Currently, Panasqueira mining generates almost 100 tonnes of waste-rock, per day. Such waste-rock have accumulated over a number of years into very large heaps and it is desirable to seek new economic solutions that can contribute towards their reuse. In this context, this work discusses the potential for reuse of waste-rock piles of Panasqueira tungsten mine, which may be a case statement to be followed. The proposed solution described in this paper consists in developing innovative polymer-based composite materials, obtained from non-contaminated waste-rock tailings. Such materials must have suitable properties for technical-artistic value added applications, such as conservation, restoration and/or rehabilitation of historic monuments, sculptures, decorative and architectural intervention, or simply as materials for building revetments.
- Effect of particle size distribution and calcium aluminate cement on the rheological behaviour of all-alumina refractory castablesPublication . Silva, Abílio P.; Segadães, A M; Pinto, Deesy G.; Oliveira, Luiz A.; Devezas, TessalenoPrevious works based on statistical design of experiments (DoE) defined a model all-alumina self-flow refractory castable (SFRC) with optimized particle size distribution for simultaneous high flowability index (FI) and superior post-sintering performance. This work compares the SFRC rheological behaviour and setting time with those of alternative all-alumina castables with different Andreasen aggregate particle size distribution modulus, and of the equivalent castables containing calcium aluminate cement. The model castable showed Bingham behaviour with low yield stress, viscosity and thixotropy, guaranteeing easier casting and less wear in the casting and/or projection equipment. However, as the coarse particle fraction increases, the castable flow tends to be non-linear and changes from Bingham to Herschel–Bulkley. The cement containing castables quickly loose flowability despite the applied shear. This work confirmed previous conclusions based on FI measurements and demonstrates the adequacy of the use of FI values in the calculation of FI response surface by DoE.
- Carbon Fiber Epoxy Composites for Both Strengthening and Health Monitoring of StructuresPublication . Salvado, Rita; Lopes, Catarina; Szojda, Leszek; Araújo, Pedro; Górski, Marcin; Velez, Fernando J.; Castro-Gomes, João; Krzywon, RafalThis paper presents a study of the electrical and mechanical behavior of several continuous carbon fibers epoxy composites for both strengthening and monitoring of structures. In these composites, the arrangement of fibers was deliberately diversified to test and understand the ability of the composites for self-sensing low strains. Composites with different arrangements of fibers and textile weaves, mainly unidirectional continuous carbon reinforced composites, were tested at the dynamometer. A two-probe method was considered to measure the relative electrical resistance of these composites during loading. The measured relative electrical resistance includes volume and contact electrical resistances. For all tested specimens, it increases with an increase in tensile strain, at low strain values. This is explained by the improved alignment of fibers and resulting reduction of the number of possible contacts between fibers during loading, increasing as a consequence the contact electrical resistance of the composite. Laboratory tests on strengthening of structural elements were also performed, making hand-made composites by the “wet process”, which is commonly used in civil engineering for the strengthening of all types of structures in-situ. Results show that the woven epoxy composite, used for strengthening of concrete elements is also able to sense low deformations, below 1%. Moreover, results clearly show that this textile sensor also improves the mechanical work of the strengthened structural elements, increasing their bearing capacity. Finally, the set of obtained results supports the concept of a textile fabric capable of both structural upgrade and self-monitoring of structures, especially large structures of difficult access and needing constant, sometimes very expensive, health monitoring.
- Quantificação de mercúrio em amostras de pó doméstico recolhidas na cidade da Covilhã (Portugal) - Resultados preliminares do projeto 6x60x6Publication . Neves, Sara M.; Pastorinho, Manuel Ramiro Dias; Barata, Luis Taborda; Patto, Maria Da Assunção Vaz; Monteiro, Marisa Rodrigues; Nepomuceno, Miguel; Lanzinha, João; Sousa, Ana Catarina AlmeidaA avaliação da qualidade do ambiente interior, particularmente do ambiente doméstico, por ser aquele em que o ser humano passa a maior parte do seu tempo, reveste-se de particular importância. Esta qualidade é modulada por um conjunto de fatores entre os quais se encontram os contaminantes ambientais com potencial tóxico, que têm vindo a ser quantificados de forma consistente no pó doméstico, uma matriz com grande capacidade integradora. Este trabalho, que utiliza o mercúrio como caso de estudo, integra-se no âmbito de um projeto pioneiro e multidisciplinar, em que se pretende estudar por um período de sessenta dias, seis habitações particulares localizadas na cidade da Covilhã, para compreender de que forma as características do imóvel e os hábitos dos habitantes podem influenciar a qualidade do ambiente interior e consequentemente a saúde dos residentes. Os níveis de mercúrio total nas amostras de pó doméstico variaram entre 138,7 ppb e 1075,5 ppb, com um só dos imóveis a transcender o valor máximo permissível estabelecido pela Portaria Nº1450/2007. Estabelece-se uma comparação com os valores registados para outros estudos similares e traça-se um plano de ação para o pleno desenvolvimento do estudo.