180 resultados para Sewage Purification Heavy metals removal


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The use of organic compounds has been a good option to reduce spending on fertilizers, and gain increased productivity in the cultivation of lettuce. However, given the wide variety of raw materials used in the preparation of organic compounds, studies are needed to evaluate its effects on the release of essential nutrients to plants and on the release of contaminants such as heavy metals. The aim of this study was to evaluate the mineral nutrition and heavy metal contamination of lettuce in soils treated with doses and types of compost. The experiment was conducted in a greenhouse in randomized blocks in factorial scheme 5x4, with five types of organic compounds and four nitrogen levels (0, 35, 70 and 140 kg ha(-1) of N), with four replications. In general, the doses of the compounds were not enough to provide the necessary quantity of nutrients to the lettuce, with the exception of nitrogen. There was no increase in levels of heavy metals in the soil above that allowed by Brazilian legislation. Furthermore, compounds based on manure plus grass, and commercial compound caused increases in Zn concentration in plants at levels above the recommended for consumed.

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The city of Vazante-MG is of great socioeconomic and environmental interest because it is the most important zinc producer district of Brazil. The mineral processing and geochemical processes may determine high concentrations of heavy metals in water intended for human consumption. Thus, the present study aimed to quantify and evaluate the heavy metal genotoxicity of artesian water in the city by Atomic absorption spectrophotometer analysis and testing with the Allium cepa test, respectively. This study reveals a chemical contamination in well water in the city, caused by the presence of heavy metals. Therefore, it can be considered that the high levels of heavy metals found in water samples are correlated with the genotoxic events observed in root cells of A. cepa.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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A reciclagem agrícola do lodo de esgoto tem provocado o acúmulo de metais pesados no solo e na água, podendo atingir níveis tóxicos e causar danos às plantas cultivadas, aos animais e ao homem, por meio da cadeia trófica. Neste intuito foi desenvolvido o presente experimento, em condições de campo, entre 2000 e 2002, onde foram avaliados os efeitos da aplicação de lodo de esgoto por dois anos, sobre a extração de metais de transição (essenciais e não) pelo extrator DTPA em um Latossolo Vermelho distrófico (LVd) de textura média. As concentrações dos elementos metálicos: Mn, Fe, Cd, Ni, Co, Pb e Cr não foram detectados pelo método da absorção atômica na solução obtida com o extrator DTPA. A aplicação de lodo de esgoto causou inicialmente pequena elevação no pH do solo, posteriormente a diminuição do mesmo, e manteve-se próximo ao original. Foi possível concluir que, com a aplicação consecutiva do lodo, os teores extraíveis de Fe e Mn nas amostras de solos aumentaram gradativamente nos dois anos agrícolas, com as doses do lodo de esgoto aplicado, época de amostragens, e foram superiores ao tratamento testemunha. O extrator apresentou capacidade restrita para avaliação da fitodisponibilidade dos metais pesados decorrentes das baixas concentrações nas amostras de solo.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Two patterns of solubilization of metal ions resulting from bioleaching of sewage sludge by sulphur-oxidizing Thiobacillus spp. were established as a function of pH. Chromium and copper ions required a pH of 2-3 to initiate their solubilization, whereas nickel and zinc ions had their solubilization initiated at pH 6-6.5. The patterns obtained were independent of the sludge solids concentrations investigated (10, 17, 25, 32.5 and 40 g l(-1)).

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Sewage sludge may be used as an agricultural fertilizer, but the practice has been criticized because sludge may contain trace elements and pathogens. The aim of this study was to compare the effectiveness of total and pseudototal extractants of Cu, Fe, Mn, and Zn, and to compare the results with the bioavailable concentrations of these elements to maize and sugarcane in a soil that was amended with sewage sludge for 13 consecutive years and in a separate soil that was amended a single time with sewage sludge and composted sewage sludge. The 13-year amendment experiment involved 3 rates of sludge (5, 10, and 20 t ha-1). The one-time amendment experiment involved treatments reflecting 50, 100, and 200 % of values stipulated by current legislation. The metal concentrations extracted by aqua regia (AR) were more similar to those obtained by Environmental Protection Agency (EPA) 3052 than to those obtained by EPA3051, and the strongest correlation was observed between pseudo(total) concentrations extracted by AR and EPA3052 and bioavailable concentrations obtained by Mehlich III. An effect of sewage sludge amendment on the concentrations of heavy metals was only observed in samples from the 13-year experiment. © 2012 Springer Science+Business Media B.V.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The objective of this work was to evaluate Cd, Cr, Ni and Pb total contents in soil and sugar cane after four annual applications of sewage sludge and vinasse to supply all N and all K required by the crop. A field experiment was carried out on clayey Typic Haplustox. It was used a randomized block design with seven treatments and three replications. The treatments consisted in: (i) rate of sewage sludge to supply 100% of the N required by the crop; (ii) rate of sewage sludge to supply 200% of the N required; (iii) rate of vinasse to supply 100% of the K required; (iv) rate of vinasse to supply 200% of the K required; ( v) combination of the treatments ( i) and ( iii); ( vi) combination of the treatments ( ii) e ( iv); (vii) control ( mineral fertilization). The contents of Cd, Cr, Ni and Pb in sewage sludge reached maximum values of 1.58, 41.66, 35.17 and 45.25 mg kg(-1), respectively. These metals were not detected in vinasse. The residues were applied annually for four years. At the end of this period, sewage sludge and vinasse accumulated rates, that get up to 51 t ha(-1) and 762 m(3) ha(-1), respectively, did not cause alteration in Cd, Cr, Ni and Pb total contents in soil, up to 50 cm of depth, and in plant. Sewage sludge and vinasse application to supply N and K for sugar cane did not offer soil pollution risk by heavy metals.

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O uso de resíduos agroindustriais pode acumular metais pesados no solo e na planta. O objetivo deste trabalho foi avaliar os efeitos do lodo de esgoto e/ou vinhaça, aplicados no solo, disponibilizando Cd, Cr, Ni e Pb ao solo e quantificar as respectivas concentrações em plantas de cana-de-açúcar, após três aplicações anuais sucessivas. O experimento foi conduzido em condições de campo, com parcelas experimentais de cinco linhas espaçadas de 1,5 m e 10 m de comprimento. O delineamento experimental adotado foi o de blocos casualizados, com três repetições. Os tratamentos avaliados foram: 1. Lodo de esgoto com 100% de N; 2. Lodo de esgoto com 200% de N; 3. Vinhaça com 100% de K; 4. Vinhaça com 200% de K; 5. Lodo de esgoto+vinhaça com 100% de N e K; 6. Lodo de esgoto+vinhaça com 200% de N e K; 7. Testemunha (fertilização mineral). Os baixos teores de metais pesados (Cd, Cr, Ni e Pb) disponíveis no solo e nas partes das plantas de cana-de-açúcar indicam que o lodo de esgoto e a vinhaça, empregados nas doses mencionadas, não apresentaram, após três aplicações anuais sucessivas, potencial de contaminação do sistema solo-planta.