Engenharia Agrícola
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11733
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Resultados da Pesquisa
Item Potencial energético e alternativas para o aproveitamento do biogás e lodo de reatores UASB: estudo de caso Estação de tratamento de efluentes Laboreaux (Itabira)(Engenharia Sanitaria e Ambiental, 2016-04) Rosa, André Pereira; Lobato, Lívia Cristina da Silva; Borges, Jorge Martins; Melo, Gilberto Caldeira Bandeira de; Chernicharo, Carlos Augusto de LemosEste trabalho estuda o potencial de aproveitamento energético dos subprodutos biogás e lodo gerados na estação de tratamento de efluentes (ETE) Laboreaux em Itabira (MG), composta de reatores UASB, filtros biológicos percoladores e unidade de desaguamento do lodo por filtro prensa. Os subprodutos biogás e lodo foram caracterizados em termos quantitativos (produção) e qualitativos (composição e poder calorífico) durante 12 meses de monitoramento. Foram estudados dois cenários de aproveitamento energético dos subprodutos: (i) uso prioritário do biogás para a secagem térmica do lodo e o excedente de biogás para geração de eletricidade em motor de combustão interna; e (ii) uso prioritário do biogás visando à geração de eletricidade e ao aproveitamento do calor dos gases de exaustão para a secagem térmica de lodo. Para a análise desses cenários, utilizou-se o software CHEMCAD(r) a fim de determinar as condições de queima do biogás em câmara de combustão e em motor de combustão interna, assim como na determinação dos balanços de massa e energia. O estudo analisou o potencial de aproveitamento dos subprodutos do tratamento como fonte de energia renovável para uso na própria ETE e para fornecimento a terceiros. No cenário 1, a geração de eletricidade é menor (atendendo 22,2% da demanda de energia da ETE), mas a secagem térmica possibilita maior redução no volume final de lodo a ser disposto ou a eliminação completa de disposição final se o lodo seco final (com 10% de umidade) for utilizado como combustível por terceiros. No cenário 2, a geração de eletricidade é capaz de suprir 57,6% da demanda de energia da ETE, todavia o calor contido nos gases de exaustão não é suficiente para a secagem de todo o lodo desaguado, configurando uma menor redução na quantidade de lodo a ser disposto (13,5 ou 24,9% de redução em massa, conforme a alternativa de remoção de umidade selecionada).Item Critérios para Escolha de Distribuições de Probabilidades em Estudos de Eventos Extremos de Precipitação(Revista Brasileira de Meteorologia, 2018-10) Pruski, Fernando Falco; Santos, Gérson Rodrigues dos; Almeida, Laura Thebit de; Cecílio, Roberto Avelino; Abreu, Marcel Carvalho; Zanetti, Sidney SaraEste estudo objetivou estabelecer um critério sobre qual teste de aderência deve ser preferido na escolha de funções de distribuição de probabilidades (fdp). Para tal, foram ajustadas as fdp: Gumbel (GUM), Generalizada de valores extremos (GEV) e Log-normal a 2 parâmetros (LN2), através dos métodos dos momentos, momentos-L e máxima verossimilhança, em séries de precipitação diária máxima anual de 11 estações localizadas na bacia hidrográfica do rio Sapucaí. A aderência dessas fdp aos dados foi feita pelos testes de Kolmogorov-Smirnov (KS), Qui-quadrado (χ2), Filliben (Fi) e Anderson-Darling (AD). Verificaram-se quais testes de aderência são mais rigorosos na seleção de distribuições de probabilidade e, ainda, os testes de aderência que convergem os resultados para a escolha da fdp com melhor desempenho na análise de incerteza e/ou nas estatísticas de ajuste. Os testes de aderência mais rigorosos no aceite da aderência da fdp aos dados são os testes de Fi e AD. O teste de Fi é o que mais converge para a escolha da fdp com melhor desempenho na análise de incerteza e nas estatísticas de ajuste, seguido pelo teste de χ2, portanto devem ser preferidos. As fdp GUM e GEV se destacaram em representar os dados de precipitação máxima anual.Item Water seasonality in granting permits and impact of irrigation in the Dourados River basin, MS, Brazil(Revista Brasileira de Engenharia Agrícola e Ambiental, 2017-07) Pereira, Silvio B.; Ramos, Diovany D.; Arai, Fabiane K.; Santos, Felipe A. dos; Carnevali, Thiago de O.The objective of this study was to evaluate water seasonality in the process of granting permits and the impact of irrigation in the Dourados River basin. For that, the hydrological behavior of the basin was analyzed. The minimal streamflows (Q7,10 and Q95), irrigation withdrawal flow (Qr) and the percent variation of the grant flows relative to monthly seasonal period in relation to the monthly withdrawal flow were obtained. The results allowed to verify that using criteria based on the monthly streamflow allows for better management of water use, because it allows for greater utilization of this resource in times with high water availability and imposes a realistic restriction during critical periods. The average annual water withdrawal for irrigation in the basin during the studied period was on the order of 2.99 m3 s-1, and the withdrawal flow in the month of highest demand (August) was 5.95 m3 s-1.Item Water footprint of the Sobradinho hydropower plant, Northeastern Brazil(Revista Ambiente & Água, 2018) Pereira, Silvio Bueno; Vieira, Nayara Paula Andrade; Bueno, Eduardo de Oliveira; Mello, Carlos Rogério deHydroelectricity is responsible for the greatest fraction of the electric energy generated in Brazil. The water footprint of hydropower plants (WFP) is an important indicator of the sustainable and efficient use of water resources. In this context, WFP of the Sobradinho Hydropower Plant was determined for the period from 2003 to 2012, taking into account the reservoir’s historical variation for the flooded area. To accomplish this, monthly series of electric energy production, flooded area, evaporation and evapotranspiration rates were used. Average gross and net evaporation were 2,031 and 1,577 mm year-1, respectively. The average power generation of this facility in the analyzed period was 462 MW, and the flooded area of its reservoir presented an average value of 3,054 km². Based on the monthly data, the gross and net water footprints were, respectively, 417 and 325 m³ GJ-1. Based on these results, it can be concluded that the changes in the reservoir’s area exert direct and important influence on the WFP estimates of the Sobradinho hydropower plant. The WFP estimates in this study were different from other studies that adopted a constant value of 4,214 km² for this reservoir’s area, which is taken based on the normal water level of the plant operation.Item Use of PVC pipes to determine bulk density for irrigation management(Revista Ciência Agronômica, 2019-01) Pereira, Silvio Bueno; Oliveira, Rubens Alves de; Assis, Igor Rodrigues de; Oliveira, Reginaldo Miranda; Matsinhe, Daniel ZefaniasIrrigation has a great importance in the production of food, and it is responsible for consuming a large part of the water used by human activities. This makes the rational management of water use fundamental for sustainable food production. For this purpose, the determination of bulk density is important and needs to be obtained with the simplest, least onerous methods possible, while maintaining precision and accuracy. Therefore, the objective of this work was to evaluate the use of PVC pipes of different dimensions to determine bulk density. For comparison purposes, the volumetric ring, paraffin clod, beaker and excavation methods were also used. Deformed and undisturbed soil samples of different granulometries were collected at the depths of 0.025-0.075, 0.050-0.100, 0.075-0.125 and 0.100-0.150 m. The PVC pipes had diameters of 0.040, 0.050, 0.060 and 0.075 m and heights of 0.10, 0.15, 0.20 and 0.25 m. The bulk density results for each PVC pipe dimension were compared with those of the traditional methods by the unpaired t-test at 5% significance. For soils with a clayey or very clayey texture, the 0.040 m diameter and 0.15 m high PVC pipe presented the best results, with values closer to those of the standard method. For soils with a medium and sandy texture, the best results were found when a PVC pipe with a diameter of 0.060 m and a height of 0.15 m was used.Item Crescimento inicial do pinhão-manso submetido a diferentes regimes hídricos em latossolo vermelho distrófico(Ciência Florestal, 2016-04) Pereira, Silvio Bueno; Padilha, Neriane de Souza; Silva, Cesar José da; Silva, João Alfredo Neto da; Heid, Débora Menani; Bottega, Simone Priscila; Scalon, Silvana de Paula QuintãoO objetivo deste trabalho foi avaliar o crescimento inicial e algumas variáveis fisiológicas de pinhão-manso (Jatropha curcas L.) submetido a diferentes regimes hídricos em Latossolo Vermelho distrófico. O experimento foi conduzido em casa de vegetação da Embrapa Agropecuária Oeste, em Dourados-MS. Os tratamentos corresponderam aos regimes hídricos de 20, 40, 60, 80 e 100% da capacidade de retenção de água no solo. O delineamento experimental adotado foi o inteiramente casualizado com cinco regimes hídricos e cinco repetições. As avaliações de altura de plantas, diâmetro de caule e número de folhas foram realizadas em seis épocas, enquanto as variáveis condutância estomática e taxa fotossintética foram determinadas em duas épocas. No término do experimento avaliaram-se área foliar, massa seca de folhas, pecíolos, caules e raízes de todas as plantas de pinhão-manso. Os regimes hídricos de 60 e 80% da capacidade de retenção de água no solo proporcionam as melhores respostas para as variáveis fisiológicas e de crescimento na fase inicial do pinhão-manso. Teores de água disponível em um Latossolo Vermelho distrófico, abaixo de 60% e superiores a 80% da capacidade de retenção de água no solo, induzem sinais de estresse hídrico em plantas jovens de pinhão-manso.Item Calibration and validation of the swat hydrological model for the mucuri river basin(Engenharia Agrícola, 2018-01) Pereira, Silvio B.; Almeida, Rafael A.; Pinto, Daniel B. F.Hydrological models are becoming more and more widespread, mainly due to their capacity to simulate the impact of environmental changes on water resources. In this way, the aim of this study was to calibrate and validate the SWAT model for the soil and climatic conditions of the Mucuri River Basin, located in the Northeast region of the States of Minas Gerais, Brazil. The SWAT-CUP software module SUFI2 was used to analyze the sensitivity, calibration and validation of the model. The calibration was performed in an intermediate fluviometric station and the validation in five other located: three upstream, one downstream and one independent from the calibration point. It was evidenced for the study area that the parameters referring to the basic flow processes were more sensitive. The model obtained a good adjustment with an overestimate tendency of 15%. In general, the SWAT model, using SWAT-CUP was good and adequate in terms of its calibration performance and validation of the flow simulation in the Mucuri River Basin by the determination coefficients, Nash-Suttclife efficiency and percentage of trend.Item Water balance in soil cultivated with forage cactus clones under irrigation(Revista Caatinga, 2017-07) Pereira, Poliana de Caldas; Zolnier, Sérgio; Silva, Thieres George Freire da; Silva, Sérvulo Mercier Siqueira e; Silva, Marcelo José daForage cactus species may belong to different genera (such as Opuntia and Nopalea), which can result in different water dynamics at the biosphere-atmosphere interface. The objective of this study was to analyze the water balance in soil cultivated with forage cactus clones under different conditions of soil water availability in the Brazilian semi-arid. The experiment was conducted in the municipality of Serra Talhada, State of Pernambuco. The crop was subjected to nine treatments arranged in a randomized complete block design with three replications in a factorial arrangement of 3x3. The plots were composed of three water availability conditions, with the application of a water depth of 7.5 mm at intervals of 7, 14, and 28 days, and the subplots consisted of three forage cactus clones (IPA Sertânia, Miúda, and Orelha de Elefante Mexicana). The soil water balance (SWB) method was applied, and the ET/ETo ratio was estimated (ET is the actual crop evapotranspiration, and ETo is the reference evapotranspiration) at intervals of 14 days; the results were represented in nine periods of 28 days. There was a difference between SWB components along the cycle and between irrigation conditions (p < 0.05). Nevertheless, ET and rainfall were the most important components in SWB when irrigation was performed. There was no difference in water consumption between forage cactus clones belonging to different genera, resulting in an average of 1.50 mm day-1. The ET/ETo ratio had low magnitude (0.29 ± 0.12), indicating that the ET was more dependent on the water regime than on the atmospheric demand.Item Soil water dynamics and evapotranspiration of forage cactus clones under rainfed conditions(Pesquisa Agropecuária Brasileira, 2015-07) Pereira, Poliana de Caldas; Silva, Thieres George Freire da; Primo, Jorge Torres Araújo; Moura, Magna Soelma Beserra de; Silva, Sérvulo Mercier Siqueira e; Morais, José Edson Florentino de; Souza, Carlos André Alves deThe objective of this work was to evaluate soil water dynamics in areas cultivated with forage cactus clones and to determine how environmental conditions and crop growth affect evapotranspiration. The study was conducted in the municipality of Serra Talhada, in the state of Pernambuco, Brazil. Crop growth was monitored through changes in the cladode area index (CAI) and through the soil cover fraction, calculated at the end of the cycle. Real evapotranspiration (ET) of the three evaluated clones was obtained as the residual term in the soil water balance method. No difference was observed between soil water balance components, even though the evaluated clones were of different genus and had different CAI increments. Accumulated ET was of 1,173 mm during the 499 days of the experiment, resulting in daily average of 2.35 mm. The CAI increases the water consumption of the Orelha de Elefante Mexicana clone. In dry conditions, the water consumption of the Miúda clone responds more slowly to variation in soil water availability. The lower evolution of the CAI of the IPA Sertânia clone, during the rainy season, leads to a higher contribution of the evaporation component in ET. The atmospheric demand controls the ET of clones only when there is higher soil water availability; in this condition, the water consumption of the Miúda clone decreases more rapidly with the increase of atmospheric demand.Item Productive-economic benefit of forage cactus-sorghum intercropping systems irrigated with saline water(Revista Caatinga, 2018-01) Pereira, Poliana de Caldas; Lima, Lucivania Rodrigues; Silva, Thieres George Freire da; Morais, José Edson Florentino de; Assis, Mery Cristina de SáThe objective of this study was to evaluate the productive and economic performance of a forage cactus and sorghum intercropping system in relation to a forage cactus single cropping system under different irrigation blades with saline water. The study was conducted in Serra Talhada, State of Pernambuco, in a randomized block design, consisting of a factorial arrangement with split-plot parcels (5×2) and four replications. The five plots were the irrigation depths based on the reference evapotranspiration (ETo) (0, 8.75, 17.5, 26.25, and 35% ETo) and the two cropping systems were single forage cactus cropping and cactus intercropped with sorghum. The experiment was conducted for one year, with one forage cactus cycle and two cycles of sorghum. Yields were obtained at the end of the cycles. Economic profitability was analyzed by means of net revenue (NR) and the benefit/cost ratio (B/C), with cactus forage sold as forage or as "seed" and sorghum as forage. Net revenue and B/C simulations were carried out over an eight-year useful life span of the irrigation system. Increasing irrigation depth increased the dry matter yield of the intercropping system because of higher sorghum yield. Based on the NR and B/C ratio values, forage cactus and sorghum produced as forage produced higher economic outcomes in the intercropping system and showed a higher profitability from the 2nd year of implementation of the irrigation system. Forage cactus and sorghum intercropping irrigated with saline water is therefore recommended for forage production in the Brazilian semi-arid region.