Sistema com aeração, decantação e filtragem para a melhoria da qualidade de água em irrigação localizada

A qualidade da água é muito importante para irrigação por gotejamento, pois ela escoa por pequenos bocais dos emissores, podendo ocorrer obstrução devido à deposição dos sólidos em suspensão. Portanto, antes da instalação do projeto, devem-se avaliar parâmetros de qualidade da água, para adotar medidas preventivas, evitando o risco de entupimento do sistema. Este trabalho teve como objetivo avaliar um sistema composto por aeradores com aspersores, sobre leito de pedra, para a precipitação dos íons Fe+2e Mn+2 em tanque de decantação, e um conjunto de filtragem composto por três filtros de areia e um de disco, em sistema de irrigação localizada. O trabalho foi realizado na Fazenda Alvorada, no município de Nova Granada - SP, no período de março a outubro de 2008. Foram realizadas determinações de variáveis físicas e químicas da água, ao longo do sistema de aeração, decantação e filtragem, o qual foi eficiente para a melhoria da qualidade de água, reduzindo os níveis de risco de entupimento de severo para médio e de médio para baixo. Oxigênio dissolvido, condutividade elétrica, pH, Fe+2e Fe+3 não diferenciaram a qualidade de água entre os pontos do sistema de tratamento, porém a turbidez, sólidos dissolvidos, sólidos em suspensão, ferro total e manganês total reduziram-se significativamente pelo uso do sistema proposto, melhorando a qualidade da água.

AC impedance study of Ni, Fe, Cu, Mn doped ceria stabilized zirconia ceramics

Doped zirconia has been used in electronic applications in the cubic crystalline phase. Ceria-stabilized tetragonal zirconia presents high toughness and can also be applied as solid electrolytes. The tetragonal phase of zirconia can be stabilized at room temperature with ceria in a broad range of composition. However, CeO2-ZrO2 has low sinterability. so it is important to investigate the effect of sintering dopants. In this study the effect of iron, copper. manganese and nickel was investigated. The dopants such as iron and copper lowered the sintering temperature from 1600 degreesC down to 1450 degreesC, with a percentage of tetragonal phase retained at room temperature higher than 98% and also with an increase of the electrical conductivity. The electrical conductivity was measured using impedance spectroscopy. The grain boundary contribution was determined and the activation energy associated with the ionic conduction was 1.04 eV. The dopants can also promote a grain boundary cleanliness verified by blocking effect measurement. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Simultaneous and Direct Determination of As, Bi, Pb, Sb, and Se and Co, Cr, Cu, Fe, and Mn in Milk by Electrothermal Atomic Absorption Spectrometry

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

Sistema com aeração, decantação e filtragem para melhoria da qualidade da água para irrigação localizada

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Concentrations of Cu, Fe, Mn, and Zn in tropical soils amended with sewage sludge and composted sewage sludge

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.

Chemical composition of ocean Fe-Mn ores

The monograph includes the study of chemical and mineral compositions of terrestrial and marine manganese ores, methods of their analysis, dependence of manganese crust geochemistry on tectonic position of their formation, problems of manganese genesis and sources of manganese in ocean ores in connection with geohistorical aspects of ocean formation and development. A hypothesis is offered that formation of giant manganese mineral basins on continental margins resulted from a large asteroid fall to the ocean.

Speciations of Mn and Fe in Fe-Mn nodules from the western part of the Clarion-Clipperton ore province

Hydrogenic forms of iron and manganese occurrence were studied in samples of ferromanganese nodules sampled within two polygons during Cruise 28 of R/V Dmitry Mendeleeev (1982) in the western part of the Clarion-Clipperton ore province. Contents of labile exchangeable Fe and Mn, amorphous hydroxides and poorly soluble compounds of Fe and Mn were analyzed. In nodules from DM28-2474 Polygon labile exchangeable Fe and Mn and amorphous hydroxides dominated; in nodules from DM28-2483 Polygon poorly soluble compounds dominated. Analysis of contents of labile forms of Fe and Mn occurrence in different morphological types of nodules distinguished predominantly hydrogenous botryoidal nodules, spheroidal and ellipsoidal intergrowth nodules, and hydrogenic-diagenetic discoid nodules.

(Table 1, page 126) Concentration of elements in Fe and Mn rich pisoliths (nodules) from Lake Storsjoen, South Norway

A detailed description of the ores of Lake Storsjoen was given by Vogt J. H. L., 1915 who pointed out that the ores may be divided into two principal types; first, iron ore with 2% or less of manganese (ex: Ertemalm), and, second, ores with manganese contents of up to 30% (ex: Korinter). The iron-rich ore sometimes occurs as a conglomerate embedded in manganese-rich ores, clearly demonstrating that two distinctly different precipitates are involved. In the iron-rich ore, a concentric structure is common of which light brown layers of loose, almost dusty material alternate with hard and brittle black layers, the thickness of each being 0.5 mm or less. The analyses presented in this paper seem to demonstrate that the composition of the sedimentary ores of Lake Storsjden could result from fluctuations in the composition of ground waters feeding the lake.

A purple acid phosphatase from sweet potato contains an antiferromagnetically coupled binuclear Fe-Mn center

A purple acid phosphatase from sweet potato is the first reported example of a protein containing an enzymatically active binuclear Fe-Mn center. Multifield saturation magnetization data over a temperature range of 2 to 200 K indicates that this center is strongly antiferromagnetically coupled. Metal ion analysis shows an excess of iron over manganese. Low temperature EPR spectra reveal only resonances characteristic of high spin Fe(III) centers (Fe(III)-apo and Fe(III)-Zn(II)) and adventitious Cu(II) centers. There were no resonances from either Mn(II) or binuclear Fe-Mn centers. Together with a comparison of spectral properties and sequence homologies between known purple acid phosphatases, the enzymatic and spectroscopic data strongly indicate the presence of catalytic Fe(III)-Mn(II) centers in the active site of the sweet potato enzyme. Because of the strong antiferromagnetism it is likely that the metal ions in the sweet potato enzyme are linked via a mu -oxo bridge, in contrast to other known purple acid phosphatases in which a mu -hydroxo bridge is present. Differences in metal ion composition and bridging may affect substrate specificities leading to the biological function of different purple acid phosphatases.

Precipitation hardening of Cu-Fe-Cr alloys - Part I - Mechanical and electrical properties

This research is part of a project whose scope was to investigate the engineering properties of new non-commercial alloy formulations based on the Cu rich corner of the Cu-Fe-Cr ternary system with the primary aim of exploring the development of a new cost-effective high-strength, high-conductivity copper alloy. The literature indicated that Cu rich Cu-Cr and Cu-Fe alloys have been thoroughly investigated. A number of commercial alloys have been developed and these are used for a variety of applications requiring combinations of high-strength, high-conductivity and resistance to softening. Little evidence was found in the literature that the Cu rich corner of the Cu-Fe-Cr system had previously been investigated for the purpose of developing high-strength, high-conductivity copper alloys resistant to softening. The aim of these present investigations was to explore the possibility that new alloys could be developed that combined the properties of both sets of alloys, ie large precipitation hardening response combined with the ability to stabilise cold worked microstructures to high temperatures while at the same maintain high electrical conductivity. To assess the feasibility of this goal the following alloys were chosen for investigation: Cu-0.7wt%Cr-0.3wt%Fe, Cu-0.7wt%Cr-0.8wt%Fe, Cu-0.7wt%Cr-2.0wt%Fe. This paper reports on the mechanical property investigation which indicated that the Cu-0.7wt%Cr-0.3wt%Fe, and Cu-0.7wt%Cr-2.0wt%Fe alloys were worthy of further investigation. (C) 2001 Kluwer Academic Publishers.