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Desalination of water by reverse osmosis using gravitational potential energy and wind energy

Fadigas, Eliane Aparecida Faria Amaral; DIAS, J. R.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
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This paper proposes ail alternative configuration to conventional reverse osmosis (RO) desalination systems by incorporating the use of gravitational potential energy. The proposal suggests a model that can be viewed as the energy station of a RO desalination plant. Conventionally, RO plants use a high-pressure pump, powered by electricity or fossil fuel. The function of the pump is to send a flux of saline water to a group of semi-permeable membrane modules, capable of ""filtering"" the dissolved salts. In this proposed model, we intend to achieve a flux at the inlet of the membrane modules with a pressure high enough for the desalination process, without using, either electricity or fossil fuels. To do this we divised a hybrid system that uses both gravitational potential energy and wind energy. The technical viability of the alternative was theoretically proven by deductions based on physics and mathematics.

Técnicas analíticas para autópsia de membranas de osmose reversa.; Analytical techniques for the autopsy of reverse osmosis membranes.

Costa, Thiago Ranzani da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/11/2011 PT
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Sistemas de membranas filtrantes, principalmente os de osmose reversa, estão sendo cada vez mais utilizados em diversos seguimentos de empresas (farmacêutica, tratamento de água, alimentícia e química), devido à diminuição do preço dos elementos filtrantes e da alta qualidade do produto obtido. Apesar do preço dos elementos de osmose reversa terem caído nos últimos tempos, a substituição destes continua sendo o fator mais dispendioso de um sistema de osmose reversa. A autópsia de membranas é uma técnica utilizada para investigar a causa que levou à colmatação de um elemento, contribuindo no melhoramento do pré-tratamento da água de alimentação e consequentemente aumentando a vida útil dos elementos. O presente trabalho teve como objetivo incrementar a técnica de autópsia de membranas de osmose reversa através da análise da volatilização dos principais compostos inorgânicos presentes nestas membranas, modificação na metodologia de quantificação de açúcares e proteínas, comparação de diferentes técnicas de remoção do material depositado sobre as membranas e análise da distribuição de biofilmes sobre elementos colmatados de osmose reversa. A análise dos resultados mostrou que dentre os inorgânicos...

Avaliação de filtros lentos de areia como pré-tratamento para o controle de biofouling em plantas de osmose reversa aplicadas na dessalinização de água do mar.; Evaluation of slow sand filters as pretreatment for controlling biofouling in seawater reverse osmosis.

Oliveira, Fernando Freitas de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/02/2013 PT
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O presente trabalho avaliou o desempenho de um sistema de pré-tratamento para água do mar constituído por um filtro lento de areia, com uma etapa prévia de filtração por um filtro de discos. O sistema demonstrou eficiência na remoção de fatores causadores de fouling em membranas de osmose reversa, removendo aproximadamente 97% dos sólidos suspensos totais presentes na água bruta, e gerando um filtrado com turbidez entre 0.1 e 0.2 UNT. As concentrações de microrganismos e AOC, principais fatores causadores da formação de biofouling, foram ambas reduzidas em cerca de 90%. Em sistemas de dessalinização de água do mar por osmose reversa, o pré-tratamento da água de alimentação constitui a principal estratégia no controle da formação do biofouling, que é gerado pelo estabelecimento de biofilmes sobre a superfície da membrana. A formação de biofouling gera impacto no desempenho do processo de osmose reversa e nos custos de operação.; This study evaluated the performance of a pretreatment system for seawater comprising of a slow sand filter, with a preliminary stage of filtration by disc filtration system. The system proved to be efficient in removing factors causing fouling in reverse osmosis membranes removing around 97% of the total suspended solids present in the raw water...

Dialysis water treated by reverse osmosis decreases the levels of C-reactive protein in uremic patients

Thomé, Fernando Saldanha; Senger, M.; Garcez, C.; Garcez, J.; Chemello, Clarice; Manfro, Roberto Ceratti
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
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Atherosclerosis is a major complication of chronic renal failure. Microinflammation is involved in atherogenesis and is associated with uremia and dialysis. The role of dialysate water contamination in inducing inflammation has been debated. Our aim was to study inflammatory markers in patients on chronic dialysis, before and 3 to 6 months after switching the water purification system from deionization to reverse osmosis. Patients had demographic, clinical and nutritional information collected and blood drawn for determination of albumin, ferritin, C-reactive protein (CRP), interleukin- 6, and tumor necrosis factor-α in both situations. Acceptable levels of water purity were less than 200 colony-forming units of bacteria and less than 1 ng/ml of endotoxin. Sixteen patients died. They had higher median CRP (26.6 vs 11.2 mg/dl, P = 0.007) and lower median albumin levels (3.1 vs 3.9 g/l, P < 0.05) compared to the 31 survivors. Eight patients were excluded because of obvious inflammatory conditions. From the 23 remaining patients (mean age ± SD: 51.3 ± 13.9 years), 18 had a decrease in CRP after the water treatment system was changed. Overall, median CRP was lower with reverse osmosis than with deionization (13.2 vs 4.5 mg/l, P = 0.022...

Contribuição ao estudo da concentração de extrato de cafe por osmose inversa; Contribution to the study of the concentration of extract of coffee by reverse osmosis

Maria Beatriz de Abreu Gloria
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em //1982 PT
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A concentração de extrato de café por osmose inversa foi estudada a nlvel de laboratório, visando um melhor conhecimento do comportamentoe da qualidade do extrato de café assim concentrado. Extrato de café, fornecido por indústria de café solúvel a 200Brix, foi utilizado neste processo. Foram estudados os efeitos de pré-tratamento aplicado na matéria prima anterior ao processo de concentração quando se constatou ser de grande importância a filtração do extrato. Ensaios de concentraçãoforam efetuados em regime de recirculação variando-se: tipo de membrana (acetato de celulose e polieteramida), pressão e temperatura de operação. Taxas de concentração e permeação, foram analisadas em cada um dos experimentos realizados. Após cada operação, foram feitos testes de limpeza e higienização da membrana, verificando a eficiência de agente de limpeza e higienização quimicos. Os concentrados e permeados resultantes de cada experimento, com as variáveis acima estabelecidas,foram analisados quanto a Brix, pH, acidez, sólidos solúveis e sólidos totais, cinzas, ferro, potássio, magnésio, cálcio, sódio, cafeína, açúcares totais, viscosidade, cromatografia em fase gasosa dos aromas no espaço livre do recipiente com o extrato de café. O produto final foi submetido a avaliação sensorial com referência a sabor e preferência. A membrana de polieterarnida foi considerada melhor que a de acetato de celulose por possibilitar maior:remoção de água...

Separação de misturas binarias por pervaporação e osmose inversa; Separation of binary mixtures by pervaporation and reverse osmosis

Fabiano Romero Perioto
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/07/2007 PT
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Neste trabalho de tese, foram realizadas a modelagem e a simulação dos processos de separação pervaporação e osmose inversa aplicados a sistemas binários. A premissa empregada foi o desenvolvimento de metodologias de predição das variáveis de processo da pervaporação e osmose inversa independentes de dados experimentais destes processos; os dados necessários para a predição destas variáveis foram propriedades fundamentais dos componentes puros da alimentação. A partir de uma revisão bibliográfica dos modelos existentes para o processo de pervaporação, foi definida uma metodologia de predição das variáveis de processo baseado no modelo solução-difusão. A etapa inicial da metodologia foi o desenvolvimento de um programa de cálculo das composições de sorção na membrana, baseado no modelo UNIQUAC e no método de contribuição de grupos UNIFAC, adaptados ao uso de polímeros. O programa foi validado pela aplicação a sistemas ideais e não-ideais sob o ponto de vista termodinâmico. Os resultados empregando o modelo UNIQUAC apresentaram boaconcordância com os dados experimentais; no caso dos resultados obtidos via UNIFAC para solventes orgânicos obteve-se um bom ajuste dos dados experimentais, mas, no caso da água...

Avaliação do processo de osmose inversa para concentração de suco de laranja e simulação da recuperação do etil butirato através da pervaporação com predição de propriedades; Evaluation of reverse osmosis process for concentrating orange juice and simulation of ethyl butyrate, recovery through pervaporation with prediction of properties

Wilson Andalecio de Araujo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/08/2007 PT
Relevância na Pesquisa
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Os processos de separação com membranas (PSM) têm sido considerados como alternativa a processos clássicos de separação. Esta é uma área de estudo que apresenta uma forte interdisciplinaridade. Há um crescente interesse nestes processos para diversas aplicações como, por exemplo, tratamento de efluentes industriais, desalinização de águas, purificação e concentração de correntes da indústria alimentícia. A separação, em geral, não envolve mudança de fase, o que significa economia no consumo de energia e operações a temperaturas moderadas. Na tecnologia de separação com membranas, os componentes das misturas líquidas ou gasosas são separados ao permearem de forma seletiva através de uma membrana. As membranas podem ser poliméricas ou cerâmicas. A corrente de alimentação é dividida em duas correntes de saída: a que permeou através da membrana (permeado) e a corrente concentrada retida (“retentate”). Estes processos têm sido aplicados no processamento de bebidas, sucos, e aromas. Neste trabalho, dois PSM foram estudados, a Osmose Inversa (OI) e a Pervaporação (PV). Experimentos em escala piloto foram realizados empregando-se o processo de OI (membrana de poliamida) para a concentração de suco de laranja a 20°Brix. Avaliou-se a retenção de compostos de voláteis (acetaldeído...

Forward osmosis membranes tailored by hydrogel coatings

Monteiro, Maria Inês Gonçalves
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2012 ENG
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Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica; Forward osmosis (FO) is a promising process to substitute reverse osmosis (RO), as a lower cost and more environmentally friendly desalination process. However, FO still presents some drawbacks, in particular the several internal concentration polarization (CP) effects and insufficient salt selectivity. In order to overcome these disadvantages, this study focuses on the use of hydrogel surface-coated FO membranes to minimize internal CP effect in water purification, and also to improve membrane salt rejection. For this, a series of crosslinked poly(ethylene glycol) (PEG)-based hydrogels were synthesized, by the photopolymerization of poly(ethylene glycol) diacrylate (PEGDA) and the monomer (PEG) in the presence of a photoinitiator. The water uptake and salt permeability of the resulting films were controlled by manipulating the composition ratio of PEGDA and the monomer PEG, by varying the water content in the prepolymerization mixture and the UV-exposure time. High water uptake and low salt permeability values were observed for the films prepared with 50wt% of water content(50%PEGDA). The hydrogels were applied using different techniques (pressure...

Use of reverse osmosis membranes for the separation of lemongrass essential oil and supercritical CO2

Sarmento,L.A.V.; Machado,R.A.F.; Bolzan,A.; Spricigo,C.B.; Petrus,J.C.C.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2004 EN
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Although it is still used very little by industry, the process of essential oil extraction from vegetable matrices with supercritical CO2 is regarded as a potentially viable technique. The operation of separating the extract from the solvent is carried out by reducing the pressure in the system. Separation by membranes is an alternative that offers lower energy consumption and easier operation than traditional methods of separation. Combining the processes essential oil extraction with supercritical CO2 and separation by membranes permits the separation of solvent and oil without the need for large variations in extraction conditions. This results in a large energy savings in the case of solvent repressurisation and reuse. In this study, the effectiveness of reverse osmosis membranes in separating lemongrass essential oil from mixtures with supercritical CO2 was tested. The effects of feed oil concentration and transmembrane pressure on CO2 permeate flux and oil retention were studied for three membrane models.

Evaluation of the acerola juice concentrated by reverse osmosis

Gomes,Eliane Rodrigues dos Santos; Mendes,Elisabete Scolin; Pereira,Nehemias Curvelo; Barros,Sueli Teresa Davantel de
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
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The aim of this study was to obtain the acerola juice using separation processes with membranes. The acerola pulp was initially defrosted and treated with 100 ppm of Citrozym Ultra L enzyme at 45ºC for one hour, then ultrafiltrated at 3 bar at 45ºC using 0.1 µm ceramic membrane, and concentrated by reverse osmosis using a spiral membrane of a compound film. The pressures on the reverse osmosis were 20, 30, and 40 bar at environmental temperature, thus, resulting a juice with 9.76, 14.56, and 17.36 ºBrix, respectively. The physicochemical characteristics of the juice were preserved and, studies on evaluation of the public acceptability, showed that 75% of the consumers liked the juice.

Amelioration of smoke taint in wine by reverse osmosis and solid phase adsorption

Fudge, A.; Ristic, R.; Wollan, D.; Wilkinson, K.
Fonte: Australian Society of Viticulture and Oenology Publicador: Australian Society of Viticulture and Oenology
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
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Background and Aims:  Wines made from grapes harvested from vineyards exposed to bushfire smoke can exhibit objectionable ‘smoky’, ‘cold ash’, ‘medicinal’ and ‘ashy’ aroma and flavour characters. This study evaluated a combined reverse osmosis and solid phase adsorption process as a potential amelioration method for the treatment of smoke-tainted wines. Methods and Results:  Smoke-tainted wines were treated using either pilot or commercial scale reverse osmosis systems and the chemical composition and sensory properties of wine compared before and after treatment. The concentrations of smoke-derived volatile phenols, including marker compounds, guaiacol and 4-methylguaiacol, decreased significantly with treatment. As a consequence, diminished smoke-related sensory attributes enabled treated wines to be readily differentiated from untreated wines. However, the taint was found to slowly return with time, likely because of hydrolysis of glycoconjugate precursors, which were not removed during the treatment process. Conclusions:  Reverse osmosis and solid phase adsorption reduced the concentration of smoked-derived volatile phenols and improved the sensory attributes of smoke-tainted wines. Significance of the Study:  This is the first study to evaluate the amelioration of smoke taint in wine using reverse osmosis and solid phase adsorption.; A.L. Fudge...

Piecewise-linear model for electro-osmosis-surcharge preloading coupled consolidation

Zhou, Y.D.; Wang, B.T.; Deng, A.
Fonte: Editorial Office of Chinese Journal of Geotechnical Engineering Publicador: Editorial Office of Chinese Journal of Geotechnical Engineering
Tipo: Artigo de Revista Científica
Publicado em //2013 ZH
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A numerical model for consolidation of soils treated by electro-osmosis-surcharge preloading coupled process is proposed. The model employs piecewise linear finite difference method to account for the nonlinear variation of physical and electro-chemical properties of soils during consolidation with large deformation. The physical and electro-chemical properties of soils include void ratio, coefficients of compressibility and permeability, electrical potential and resistance. FORTRAN programming package is used to implement the computation of the model and verify the model against analytical exact solutions. It is found that numerical results derived from the model are in good agreement with the analytical solutions in relation to an identical scenario of small-deformation consolidation. A laboratory model test is conducted to further verify the validity of the proposed model in simulating the consolidation process of soils. The results show that the approximations of consolidation settlement obtained by using EC2 are in good agreement with the measurements of the model tests.; Zhou, Ya-dong, Wang, Bao-tian, Deng, An

Selección de alternativas de pretratamiento de ósmosis inversa

Quevedo Díaz, Noelia
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Tese de Doutorado
SPA
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RESUMEN: En el presente trabajo se plantea como primer objetivo la optimización de la línea de tratamiento previa a la ósmosis inversa para reducir el ensuciamiento de las membranas. Para ello, se han considerado dos casos de estudio basados en los resultados de pretratamiento convencional para agua de alimentación a ósmosis inversa obtenidos en dos plantas de demostración. En ambos casos, se prueban diferentes configuraciones de pretratamiento, basadas en un tratamiento físico-químico seguido por una doble etapa de filtración incluyendo ésta filtros bicapa y tricapa presurizados, combinadas con la adicción de diversos coagulantes y floculantes. Para cada una de las configuraciones de pretratamiento estudiadas, los valores de SDI (Índice de Densidad de Sedimentos) y MFI (Índice de Atascamiento Modificado) obtenidos en cada ensayo se evaluaron en gráficos de probabilidad con una distribución normal y manteniendo intervalos de confianza del 95%. Como segundo objetivo del trabajo, se estudió si existe una correspondencia entre los criterios basados en los parámetros SDI y MFI, analizados previamente.; ABSTRACT: The first objective of current work is to establish the best reverse osmosis pretreatment line in order to reduce the membranes fouling. Two case studies have been considered...

Tratamiento integrado y valorización de concentrados salobres de ósmosis inversa; Integrated treatment and valorization of reverse osmosis saline concentrates

Pérez González, Antía
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Tese de Doutorado
SPA
Relevância na Pesquisa
37.56%
RESUMEN: La creciente demanda de agua de consumo es parcialmente satisfecha por las plantas de desalinización que utilizan tecnologías de membranas de forma creciente, destacando entre ellas la ósmosis inversa (OI). El rendimiento de las unidades de OI en la obtención del agua desalada oscila entre 35% y 85% (en función de la salinidad del agua de partida) y como resultado se genera un volumen de concentrados entre 15% y 65% del caudal de agua alimentada, en el que están contenidos los compuestos retenidos. La opción mayoritariamente utilizada en la gestión de estos concentrados es su vertido directo, o tras dilución, al mar o aguas superficiales constituyendo una seria amenaza para los ecosistemas receptores. Sin embargo es conveniente tener en cuenta que los concentrados, también llamados salmueras, son una fuente de compuestos orgánicos e inorgánicos que pueden ser recuperados aplicando la estrategia adecuada. Esta tesis profundiza en la recuperación de materiales a partir de los concentrados generados en procesos de desalinización por OI. Tras realizar una profunda revisión bibliográfica acerca de las tecnologías de tratamiento aplicables a concentrados de OI, se plantea un proceso de recuperación que contempla la obtención de HCl y NaOH como productos finales mediante la aplicación de la tecnología de electrodiálisis con membranas bipolares (EDBM). La aplicación de este proceso a concentrados reales procedentes de procesos de desalinización requiere un acondicionamiento previo de las salmueras. Por ello se estudian diversas opciones de pretratamiento como son el intercambio iónico y la nanofiltración. La tesis contribuye de forma especial al diseño de la separación de iones de distinta valencia (sulfato y cloruro) mediante la tecnología de nanofiltración.; ABSTRACT: The growing demand for fresh water is partially satisfied by desalination plants that increasingly use membrane technologies and among them reverse osmosis (RO) to produce purified water. The performance of RO units varies from 35% to 85% (according to the salinity of the inlet water) and huge volumes of concentrates...

Diseño y construcción de un sistema de recuperación de energía de alta eficiencia para sistemas de desalinización de agua de mar por osmosis inversa

Juan Luis Arias Lara; Jack Stern N.
Fonte: Corporação de Fomento da Produção Publicador: Corporação de Fomento da Produção
Tipo: proyecto
Publicado em 20/06/2000
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El presente proyecto pretende desarrollar la ingeniería y construcción de un sistema prototipo de recuperación de energía asociado a una planta de osmosis inversa, con capacidad para producir 100.000 litros de agua dulce por día, a partir de agua de mar, con la instrumentación debida para la toma de muestras y parámetros, con el objeto de certificar la validez de esta innovación. La tecnología más utilizada en el mundo para la desalinización de agua de mar es la osmosis inversa. el nivel de desarrollo de esta tecnología se encuentra en su punto de madurez, impulsando el perfeccionamiento de varios de sus componentes:*desarrollo de membranas*desarrollo de bombas de alta presión de desplazamiento positivo*materiales e instrumentación*desarrollo de sistemas de recuperación de energía.; Corporación de Fomento de la Producción

Evaluating salinity sources of groundwater and implications for sustainable reverse osmosis desalination in coastal North Carolina, USA

Vengosh, A; Vinson, DS; Schwartz, HG; Dwyer, GS
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica Formato: 981 - 994
Publicado em 01/08/2011
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The natural and pumping-induced controls on groundwater salinization in the coastal aquifers of North Carolina, USA, and the implications for the performance of a reverse osmosis (RO) desalination plant have been investigated. Since installation of the well field in the Yorktown aquifer in Kill Devil Hills of Dare County during the late 1980s, the groundwater level has declined and salinity of groundwater has increased from ∼1,000 to ∼2,500 mg/L. Geochemical and boron isotope analyses suggest that the salinity increase is derived from an upflow of underlying saline groundwater and not from modern seawater intrusion. In the groundwater of four wells supplying the plant, elevated boron and arsenic concentrations were observed (1.3–1.4 mg/L and 8–53 μg/L, respectively). Major ions are effectively rejected by the RO membrane (96–99% removal), while boron and arsenic are not removed as effectively (16–42% and 54–75%, respectively). In coming decades, the expected rise of salinity will be associated with higher boron content in the groundwater and consequently also in the RO-produced water. In contrast, there is no expectation of an increase in the arsenic content of the salinized groundwater due to the lack of increase of arsenic with depth and salinity in Yorktown aquifer groundwater.

Reverse osmosis powered by concentrating solar power (CSP): a case study for Trapani, Sicily

Ahmed, Mahran K. A.; Cardoso, João P.; Mendes, J. Farinha; Casimiro, Sergio
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2015 ENG
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The objective of this paper is to analyse the physical performance of two technologies in a water and electricity co-generation scheme: Concentrated Solar Power (CSP) plant coupled to a Reverse Osmosis (RO) unit for a location in the city of Trapani, in southern Italy. The modelled system is compared with the results of another study [2], in which a Multi-Effect Desalination (MED) is powered by a CSP plant for the same location in Italy, using as reference an existing stand-alone gas powered MED plant located at Trapani [3] (which has operated until very recently). The overall aim is to assess and compare these two cogeneration schemes, using as reference the existing MED plant. This work was conducted using as the main simulation tool: the System Advisor Model (SAM) developed by the US National Renewable Energy Laboratory (NREL); a recent upgrade to SAM made available to this work through Laboratório Nacional de Energia e Geologia I.P. (LNEG); and the Reverse Osmosis System Analysis (ROSA) developed by the Dow Chemical Company. A technical visit to a real commercial RO plant in the south of Portugal (Alvor) was conducted, and the data gathered was used in the validation of the ROSA model. The results for the Trapani case study show that the CSP-RO arrangement has the capability to produce ~50% of the total production of the full scale plant at Trapani...

Separation of the chromium(III) present in a tanning wastewater by means of precipitation, reverse osmosis and adsorption

Hintermeyer,B. H.; Lacour,N. A.; Perez Padilla,A.; Tavani,E. L.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
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The separation of the chromium(III) dissolved in a tanning wastewater was studied by means of precipitation with calcium carbonate, reverse osmosis with polyamide membrane and adsorption on activated carbon. All tests were carried out at laboratory scale with a wastewater obtained from a unique typical tannage process. In a first stage, the original effluent was treated by sieving and ultrafiltration to perform a partial removal of fats and denaturalized proteins. The separation of chromium(III) by precipitation, reverse osmosis and adsorption was performed with the tanning wastewater so treated. The precipitation efficiency was determined by taking into account the chromium(III) content of the supernatant with the reaction time and with the alkali amount added. The polyamide membrane behavior used was established by the permeate flux and by the rejection of each species. The adsorption valuation involved the determination of the adsorbed amounts of chromium(III), sodium, chloride and sulfate. Under optimum conditions established for each process, the following results were obtained: a supernatant with less than 3.0 mg L-1 of chromium(III) by precipitation, a permeate with less than 2.0 mg L-1 of chromium(III) by reverse osmosis and an equilibrium solution with less than 6.0 mg L-1 of chromium(III) by adsorption. To conclude...

Nitrate-nitrogen removal with small-scale reverse osmosis, electrodialysis and ion-exchange units in rural areas

Schoeman,J J
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2009 EN
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The nitrate-nitrogen concentration in water supplied to clinics in Limpopo Province is too high to be fit for human consumption (35 to 75 mg/ℓ NO3-N). Therefore, small-scale technologies (reverse osmosis, ion-exchange and electrodialysis) were evaluated for nitrate-nitrogen removal to make the water potable (< 10 mg/ℓ NO3-N). It was found that the reverse osmosis process should function well for nitrate-nitrogen removal. Nitrate-nitrogen could be reduced from a concentration of 35 to 43 mg/ℓ in 1 case to a concentration of between 1.4 and 5.5 mg/ℓ in the treated water. In another case it could be reduced from 54 to 72 mg/ℓ to 12 to 17 mg/ℓ in the treated water. The water was also effectively desalinated. The ion-exchange process could also reduce the nitrate-nitrogen concentration to less than 10 mg/ℓ in the treated water. However, the water could not be efficiently desalinated and the process should function better when the level of total dissolved solids in the feed is not very high. The electrodialysis process should also function well for nitrate-nitrogen and salinity removal. However, the electrodialysis process is more complicated to operate. The reverse osmosis and ion-exchange processes are therefore suggested for nitrate-nitrogen removal at clinics. Capital costs for small-scale reverse osmosis and ion-exchange units are estimated at ZAR7 000 and ZAR10 000...

Performance of tubular reverse osmosis for the desalination/concentration of a municipal solid waste leachate

Schoeman,JJ; Strachan,LJ
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2009 EN
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Municipal solid waste leachate (MSWL) has the potential to pollute the water environment and to affect biological treatment processes adversely if not properly handled. Reverse osmosis (RO) has the ability to remove both organics and inorganics effectively from effluents. Therefore, RO was evaluated for the treatment of MSWL. It was found that both cellulose acetate and polyamide RO membranes should function effectively for the treatment of the leachate and that it should be possible to control membrane fouling with chemical cleaning. The polyamide membranes, however, performed somewhat better than the cellulose acetate membranes for the treatment of the leachate. The quality of the treated leachate with the exception of ammonia-nitrogen and COD should comply with the quality requirements for discharge into the water environment. Biological treatment processes are effective in complete removal (to only traceable levels) of ammonia-nitrogen and biodegradable COD. The quality of the treated effluent further complies with the quality requirements (chloride and heavy metals) for discharge into the municipal biological treatment system. The capital and operational cost of a 250 m³/d tubular reverse osmosis (TRO) plant is estimated at R1.95 m. and R11.45/m³...