Browsing by Author "Nunes, L."
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- Environmental impacts on soil and groundwater at airports: origin, contaminants of concern and environmental risksPublication . Nunes, L.; Zhu, Y.-G.; Stigter, T. Y.; Monteiro, José Paulo; Ribau Teixeira, MargaridaEnvironmental impacts of airports are similar to those of many industries, though their operations expand over a very large area. Most international impact assessment studies and environmental management programmes have been giving less focus on the impacts to soil and groundwater than desirable. This may be the result of the large attention given to air and noise pollution, relegating other environmental descriptors to a second role, even when the first are comparatively less relevant. One reason that contributes to such ‘‘biased’’ evaluation is the lack of systematic information about impacts to soil and groundwater from airport activities, something the present study intends to help correct. Results presented here include the review of over seven hundred documents and online databases, with the objective of obtaining the following information to support environmental studies: (i) which operations are responsible for chemical releases?; (ii) where are these releases located?; (iii) which contaminants of concern are released?; (iv) what are the associated environmental risks? Results showed that the main impacts occur as a result of fuel storage, stormwater runoff and drainage systems, fuel hydrant systems, fuel transport and refuelling, atmospheric deposition, rescue and fire fighting training areas, winter operations, electrical substations, storage of chemical products by airport owners or tenants, and maintenance of green areas. A new method for ranking environmental risks of organic substances, based on chemical properties, is proposed and applied. Results show that the contaminants with the highest risks are the perfluorochemicals, benzene, trichloroethylene and CCl4.
- Estimativa do campo de permeabilidades potenciais e dos tensores de macrodispersividade em aquíferos heterogéneos a partir de informação geofísicaPublication . Nunes, L.Neste trabalho é proposta uma metodologia para obtenção dos campos de permeabilidades potenciais e dos tensores de macrodispersividade de formações heterogéneas a partir de informação geofísica. A metodologia baseia-se nas relações conhecidas entre a resistividade eléctrica e a permeabilidade. É atribuído, heuristicamente, significado em termos de permeabilidade aos valores de condutividade eléctrica, e impostos cortes sobre a função de distribuição desta. Os locais amostrados são classificados como pertencendo, ou não, a cada uma das classes cumulativas (obtenção de variáveis indicatrizes). As variáveis são simuladas por técnicas de simulação condicional, ou outras. Os campos de permeabilidade potencial são obtidos por intersecção dos campos das indicatrizes. As distâncias de autocorrelação obtidas para o campo de permeabilidades servem como dados de entrada em modelos de determinação da macrodispersividade. A metodologia foi aplicada ao aquífero cársico do Escarpão, no Algarve central. As imagens obtidas reproduziram as estruturas geológicas identificadas nos trabalhos de campo. As dispersividades longitudinais variaram entre 82,7 e 165,7 m, e as transversais entre -23,5 m (A12) e 0,96 m (A33). Os resultados da aplicação desta metodologia podem ser usados para selecção de locais para sondagens, e/ ou serem incorporados em modelos de transporte.
- Is filter packing important in a small-scale vermifiltration process of urban wastewater?Publication . Lourenco, N.; Nunes, L.Nowadays, natural resources are under increasing stress which fosters wastewater reuse planning and emphasizes on the decentralized wastewater treatment. Vermifiltration has been described as a viable alternative to treat domestic and urban wastewater, but few studies have focused on the impact of different filter packings on vermifiltration performance. This study evaluates the effect of vermicompost and sawdust in a single-stage vermifilter (VF) for urban wastewater treatment. After an acclimation period of 45 days, urban wastewater from a combined sewage collection system was applied continuously for 24 h. Earthworm stock density was of 20 g L-1, HRT of 6 h, HLR of 0.89 m(3) m(-2) day(-1) and OLR of 7.38 g BOD5 day(-1). System performance was assessed by the removal efficiencies of BOD5, COD, TSS, NH4 (+), TN and TP, and fecal coliforms and helminth eggs elimination. Vermicompost (VE) and sawdust (SE) were tested, using an earthworm abundance of 20 g L-1. Treatment efficiencies were 91.3% for BOD5, 87.6% for COD, 98.4% for TSS and 76.5% for NH4 (+) in VE, and 90.5% for BOD5, 79.7% for COD, 98.4% for TSS and 63.4% for NH4 (+) in SE. Earthworms contributed to reduce NH4 (+) and TN removal and to increase NO3 (-) concentration. No treatment was able to eliminate fecal coliforms down to guidelines values for wastewater irrigation as helminth eggs were completely eliminated. Single-stage vermifiltration system using both filter packings is inconsistent and cannot meet EU guideline values for discharge in sensitive water bodies and WHO guidelines for irrigation with treated wastewater.
- Life-cycle assessment of decentralized solutions for wastewater treatment in small communitiesPublication . Lourenço, Nelson; Nunes, L.This study benchmarks vermifiltration (VF) as secondary wastewater treatment in three natured-based decentralized treatment plants using life-cycle assessment. The comparison is justified by the comparatively easier and cheaper operation of VF when compared to more traditional technologies, including small rate infiltration (SRI), constructed wetlands (CW), and activated sludge (AS). Standard life cycle assessment was used and applied to three case-studies located in southern Europe. Material intensity during construction was highest for VF, but impacts during operation were lower, compensating those of the other phases. Impacts during the construction phase far outweigh those of operation and dismantling for facilities using constructed wetlands and activated sludge, when the number of served inhabitants is small, and due to lack of economies of scale. VF used as secondary treatment showed to contribute to reduce the environmental impacts, mainly in constructed wetlands and activated sludge. The replacement of CW by VF seems to bring important environmental benefits in most impact categories, in particular in the construction phase. The replacement by VF in facilities with SRI seems to result in the improvement of some of the impact categories, in particular in the operation phase. As for dismantling, no conclusive results were obtained.
- OPTEXPLOR – new application for water resources management for private water supply utilitiesPublication . Nunes, L.; Monteiro, José Paulo; Stigter, T. Y.; Ribau Teixeira, Margarida; Nascimento, João; Ribeiro, L.; Lucas, HelenaThis article presents the steps made for the development of a new water management system (WMS) for a private water utility in the south of Portugal, and its main results. The WMS is composed of a set of models representing the water resources, surface and groundwater, water quality models, economic models, and water allocation optimization models. The system was developed at the request of the regional water utility (Águas do Algarve, S.A.), which is responsible for distributing water to the entire Algarve region (most touristic area in Portugal, with about ten million tourists per year, and a local population of about four hundred thousand). Results clearly show that independently of the amount of water available, inter-annual exploration is always the best solution, if possible. When water scarcity is high, as in consecutive dry years, the water utility will need to call municipalities to use their systems to complement supply. The level of supply deficit is higher, in any case, for annual exploration management, and so are exploration costs. These results clearly show that water resources management needs careful inter-annual planning, even for a private water supply utility with very limited control over water exploration by other competing users.
- Optimization of a vermifiltration process for treating urban wastewaterPublication . Lourenço, Nelson; Nunes, L.Optimization of a vermifiltration process was made for hydraulic retention time (HRT), hydraulic loading rate (HLR) and recirculation ratio (R), organic loading rate (OLR), earthworm abundance and reactor type on organic matter removal from urban wastewater using a small-scale vermifiltration process comprising single stage, and four-stage vermifilter (VF) systems. All reactor modules were made of PVC with a total volume of 25 L using vermicompost as the filtering material and quartz sand and gravel as the inert filter. System performance was assessed by the removal efficiencies of BOD5, tCOD, sCOD, pCOD, TSS and NH4+. In the earthworm study, four abundances were evaluated: 10 g L-1 (W10), 20 g L-1 (W20), 30 g L-1 (W30) and 40 g L-1 (W40). In the four-stage VF the earthworm abundance evaluated was 20 g L-1. W20 proved to be the optimal treatment condition with efficiencies for BOD5, tCOD, pCOD, TSS and NH4+ of 97.5%, 74.3%, 91.1%, 98.2% and 88.1%, for a pCOD/tCOD ratio of 0.20. The four-stage sequential VF promoted a decrease of BOD5 (98.5%), tCOD (74.3%), pCOD (86.7%), TSS (96.6%), and NH4+ (99.1%). Results indicate that sequential VF systems can significantly improve treatment efficiencies when compared to single stage VF. (C) 2016 Elsevier B.V. All rights reserved.
- Optimization of an estuarine monitoring program: selecting the best spatial distributionPublication . Caeiro, S.; Nunes, L.; Goovaerts, Pierre; Ribeiro, Luís; Painho, M.; Costa, Maria H.Monitoring estuarine programs are fundamental to evaluate the status and trends of pollution abatement actions, fulfillment of environmental quality standards and compliance with permit conditions. Their sampling designs should provide statistically unbiased estimates of the status and trends with quantitative confidence limits on both spatial and temporal scales. Variance reduction techniques have proved to be good methodologies for choosing better spatial and temporal designs. The aim of this work is to select a subset of monitoring sampling stations based on locations from an extensive estuarine sediment campaign. In this campaign 153 sites were sampled in the Sado estuary (southern Portugal). In each location three sediment parameters were determined with the objective of defining spatially homogenous environmental areas. The new monitoring program is based on fewer and on the most representative monitoring stations inside each homogeneous environmental area for their future contaminant assessment. Simulated annealing was used to iteratively improve on the mean square error of estimation, by removing one station at a time and estimating it by indicator kriging using the remaining stations in the sub-set, within a controlled non-exhaustive looping scheme. Different sub-set cardinalities were tested in order to determine the optimal cost-benefit relationship between the number of stations and monitoring costs. The model results indicate 60 station design to be optimal, but 17 additional stations with expertise criteria of proximity to point sources and characterization of all homogenous areas were added.
- Overview of greenhouse horticulture in Portugal: technology and environmentPublication . Costa, J. M.; Reis, Mário; Palha, M. G.; Passarinho, J. A.; Carvalho, S. M. P.; Almeida, D.; Nunes, L.; Ferreira, M. E.Total greenhouse production area in Portugal is about 3,000 ha with a tendency for expansion, and tomato is the most important greenhouse crop. Protected cultivation in Portugal modernized in recent decades but remains heterogeneous in terms of technology, yields and management. The sector organizational structure and technological trajectory is characterized by increased greenhouse area per grower and higher volume/covered area ratio, and soilless cultivation has expanded. Therefore, less expensive alternatives may arise as the common solution for the sector. Most of the greenhouse area (about 75%) corresponds to single and multiple plastic tunnels with semi automatic or automatic climate control. The use of glasshouses with fully controlled environment remains minor, due to the high costs of equipment, energy consumption, and limited expertise and technical support for local conditions. Greenhouse horticulture has an undesirable environmental impact which must be properly monitored and minimized, while guaranteeing its socio-economic benefits. In addition, there is more strict environmental EU legislation and stakeholders are more informed which puts pressure on the greenhouse industry in order to use more efficiently resources and minimize its environmental impact. However, the Portuguese sector still lacks relevant quantitative information and standards on performance indicators, e.g. resource use efficiency (e.g. water, energy) and related economic/environmental performance. A SWOT analysis is presented for the most important greenhouse production areas in Portugal and guidelines are suggested for more competitive and environmental sustainable greenhouse production.
- Performance indicators matrix as a methodology for energy management in municipal water servicesPublication . Ribau Teixeira, Margarida; Mendes, Paula; Murta, Eurico; Nunes, L.Holistic management of water and energy resources is critical for municipalities facing increasing energy prices and stringent regulatory requirements. Management for energy efficiency in water supply and wastewater collection systems demands evaluation of how energy is consumed and how efficiently such energy is spent. The present work proposes a performance indicators matrix that allows the evaluation and monitoring of energy consumption, energy costs and CO2 emissions, leading to the identification of opportunities for performance improvement for continuous and sustainable development in municipalities. The methodology for the development of the indicators performance matrix was based the application of the activities from integrated management systems the integrated management energy (ISO 50001), quality (ISO 9001) and environment (ISO 14001) systems. A set of criteria and performance indicators adapted from international guidelines and literature indicators, which complement energy efficiency measure by municipalities, were chosen by consensus between experts and stakeholders. Indicators were classified according to their strategic objective in four categories: environmental (E), technical (T), social (S) and governance (G). The indicator matrix was tested in a case study, namely the municipality of Louie in Portugal. Results showed that experts and stakeholders attribute more importance to indicators from the strategic objectives Environmental protection and Promote efficient use of water resource (34.3%), meaning that most of the chosen indicators are directly related with energy efficiency. Results of meta-evaluation of the tool showed optimal performance for most of the indicators. (C) 2016 Elsevier Ltd. All rights reserved.
- Permeability fields estimation by conditional simulations of geophysical dataPublication . Nunes, L.; Ribeiro, LuísA new method for the determination of permeability fields in highly heterogeneous aquifers is proposed. It stems from the known relations between soil electric resistivity and permeability. Several cut-offs are made to electric resistivity probability distribution. These cut-offs are heuristic estimates about what classes of values of one variable should relate to what classes of values of the other. The outcome of this process is a set of cumulative indicator variables. These variables are then simulated. The permeability fields are obtained by the intersection of the indicator variables. These permeability fields may be used in the development of conceptual models; autocorrelation distances (integer scales) obtained on the permeability fields may used as input to macrodispersivity models. The method was applied to the Karst aquifer of the Escarpão, in central Algarve, Portugal. The images obtained fitted well the geologic structures identified by field works. The results of this method may be useful for the selection of new drilling spots, as input to flow and solute transport models, for the a priori determination of macrodispersivity parameters, and of the fractal behaviour of permeability distribution. This approach may be a very useful tool for aquifer parameterisation when the available information is scarce.