• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 510
  • 90
  • 62
  • 51
  • 41
  • 34
  • 13
  • 9
  • 6
  • 6
  • 6
  • 5
  • 5
  • 3
  • 2
  • Tagged with
  • 1041
  • 1041
  • 182
  • 178
  • 178
  • 162
  • 98
  • 82
  • 82
  • 79
  • 73
  • 68
  • 66
  • 64
  • 62
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
501

Analýza dopadů na obyvatelstvo Jihočeského kraje při výpadku prvku kritické infrastruktury - vodní hospodářství / Impact analysis in population in the South Bohemia and failure of critical infrastructure element - water management

BERKOVÁ, Pavla January 2012 (has links)
Sufficient quantity of good quality of drinking water is essential for human society. The existence of life, including life of man is conditioned by water. Water has a large impact on quality of life that we lead. In our conditions it is commonplace that we have unlimited access to drinking water which is provided through the public water supply system. Quality of drinking water in the Czech Republic is strictly monitored and the water from public water supply system has required quality and wholesomeness. The role of society is to ensure that this state will continue in the future. For this reason, water management became a part of critical infrastructure. The main purpose of this thesis is to map the impacts of drinking water supply system interruptions to the population of South Bohemia. This thesis was based on quantitative research and applied the method of secondary analysis of document.
502

Avaliação da utilização de carvão ativado em pó na remoção de microcistina em água para abastecimento público

Müller, Carla Cristine January 2008 (has links)
A eutrofização acelerada dos mananciais superficiais, devido aos despejos de águas residuárias não tratadas, vem comprometendo a qualidade das águas utilizadas no abastecimento público. Como conseqüência desse processo, inúmeros registros de florações de cianobactérias são relatados em todo o mundo. Esses microrganismos são potenciais produtores de toxinas, as quais, presentes na água bruta que abastece uma Estação de Tratamento de Água (ETA), precisam ser removidas. As toxinas podem ter efeitos adversos à saúde, podendo causar danos hepatotóxicos, neurotóxicos e dermatotóxicos. A maioria das ETAs brasileiras tratam a água através do processo convencional de tratamento, compreendendo as etapas de coagulação, floculação, sedimentação, filtração e cloração. Esse tratamento é considerado eficiente para remover células de microrganismos, incluindo as cianobactérias. No entanto, suas toxinas não são afetadas, permanecendo na água tratada. Em função disso, alternativas de tratamento devem ser incorporadas ao tratamento convencional, visando remover a hepatotoxina microcistina a concentrações menores ou iguais a 1 μg.L-1, pois esse é o valor máximo permitido (VMP) pela Portaria nº 518/2004, do Ministério da Saúde, a qual define as diretrizes relativas ao controle e vigilância da qualidade da água para consumo humano. Nesse contexto, o objetivo do trabalho foi avaliar a eficiência do carvão ativado pulverizado (CAP), na remoção da cianotoxina microcistina presente na água utilizada para abastecimento público. Cinco amostras de CAP, produzidas a partir de madeira, osso, antracito e coco, foram caracterizadas e, para cada uma, determinadas as Isotermas de Freundlich. As Isotermas mostraram que os CAPs produzidos a partir da madeira apresentaram maior capacidade de remover microcistina. Os residuais de microcistina obtidos nestes ensaios foram ajustados ao modelo de decaimento logarítmico. Assim, para cada CAP, foi estabelecida uma equação geral do processo adsortivo, com a qual foi possível estabelecer dosagens de CAP, variando a concentração de microcistina inicial, para atingir uma concentração residual de 1 μg.L-1. A aplicabilidade da equação foi testada para uma amostra de CAP, em água natural, utilizando o coagulante policloreto de alumínio e concentrações iniciais de microcistina de 1, 10 e 100 μg.L-1. Os resultados mostraram que as dosagens de CAP calculadas foram suficientes para atingir o residual desejado. Além disso, através de ensaios de adsorção, em equipamento de jarros, foram simuladas as etapas de coagulação (utilizando coagulantes sulfato de alumínio e cloreto férrico), floculação, sedimentação e filtração do tratamento convencional para água natural acrescida de 100 μg.L-1 de microcistina. A aplicação do CAP foi realizada em dois pontos do tratamento (1) entrada da água bruta e (2) antes da aplicação do coagulante. A aplicação na entrada da água bruta possibilitou remoção da toxina abaixo do VMP, correspondendo à redução de, aproximadamente, 99% da concentração inicial de toxina. Já no ponto de aplicação antes do coagulante, não foi atingido o VMP. A partir dos estudos aqui realizados, concluiu-se que a melhor maneira de escolher o CAP para remoção de microcistina é a realização de ensaios específicos, como a Isoterma de Freundlich. Para uma remoção eficiente da toxina, o tratamento convencional mostra-se eficaz, desde que a etapa de adsorção seja incorporada ao tratamento. / The accelerated surface waters eutrophication, due to non treated residual waters discharges, has been harming the water quality utilized in the public supply. As a consequence of this process, countless records of cyanobacterias’ bloom are reported all over the world. These microorganisms potentially producers of toxins, which, when presented in the raw water that supplies the Water Treatment Plant (WTP), needs to be removed. The toxins can have harmfull effects to the health causing hepatotoxic, neurotoxic and dermatotoxic damage. Most of the Brazilian WTPs treat the water through the conventional water treatment process, covering the stages of coagulation, flocculation, sedimentation, filtering and chlorination. This treatment is considered efficient to remove microorganisms’ cells, including cyanobacterias. However its toxins are not affected, remaining in the treated water. Due to this fact, alternative treatment must be incorporated to the conventional one, trying to remove the microcystin hepatotoxin to concentrations lower or equal to 1 μg.L-1, the maximum allowed value (MAV) according to the Brazilian Ministry of Health Administrative Ruling 518/2004, which defines the rules related to the control and vigilance of the water quality for human consumption. In this context, the objective of the present work was to evaluate the efficiency of the powdered activated carbon’s (PAC), in the removal of the microcystin cyanotoxin present in the water for public supply. Five samples of PAC, made of wood, bone, antracite and coconut, were characterized and, for each one, were determined Freundlich adsorption isotherm . The isotherm showed that the PACs produced from wood presented the highest capacity of microcystin removal. The residuals of microcystin obtained in these tests were adjusted to the logarithmic decay model. Thus, for each PAC, it was established a general equation of the adsorptive process, in order to establish PAC dosages, varying the initial microcystin concentration, to achieve the residual concentration of 1 μg.L-1. The usage of this equation was tested for one sample of PAC, in natural water, using poly-aluminum chloride as a coagulant and the initial concentrations of microcystins of 1, 10 and 100 μg.L-1. The results showed that the dosage of PAC calculated was enough to achieve the desired residual. Besides this, through adsorptive tests, using jar’s equipments, were simulated the stages of coagulation (using alum sulphate and ferric chloride as coagulants), flocculation, sedimentation and filtering of the conventional treatment for natural water and with 100 μg.L-1 of microcystin added. The application of the PAC was performed in two points of the treatment: (1) entrance of the raw water and; (2) before the application of the coagulant. The application in the entrance of the raw water made possible the removal of the toxin under MAV, corresponding to a reduction of, approximately, 99% of the initial concentration of the toxin. Nevertheless, in the point of application before the coagulant, the MAV was not achieved. According to these studies, it was concluded that the best manner of choosing the PAC for microcystin removal is the realization of specific tests like a Freundlich isotherm. For an efficient removal of the toxin, the conventional treatment is efficient, once the adsorption stage is incorporated to the treatment.
503

Sustainable Drinking Water Treatment: Using Weak Base Anion Exchange Sorbents Embedded With Metal Oxide Nanoparticles to Simultaneously Remove Multiple Oxoanions

January 2016 (has links)
abstract: Ion exchange sorbents embedded with metal oxide nanoparticles can have high affinity and high capacity to simultaneously remove multiple oxygenated anion contaminants from drinking water. This research pursued answering the question, “Can synthesis methods of nano-composite sorbents be improved to increase sustainability and feasibility to remove hexavalent chromium and arsenic simultaneously from groundwater compared to existing sorbents?” Preliminary nano-composite sorbents outperformed existing sorbents in equilibrium tests, but struggled in packed bed applications and at low influent concentrations. The synthesis process was then tailored for weak base anion exchange (WBAX) while comparing titanium dioxide against iron hydroxide nanoparticles (Ti-WBAX and Fe-WBAX, respectively). Increasing metal precursor concentration increased the metal content of the created sorbents, but pollutant removal performance and usable surface area declined due to pore blockage and nanoparticle agglomeration. An acid-post rinse was required for Fe-WBAX to restore chromium removal capacity. Anticipatory life cycle assessment identified critical design constraints to improve environmental and human health performance like minimizing oven heating time, improving pollutant removal capacity, and efficiently reusing metal precursor solution. The life cycle environmental impact of Ti-WBAX was lower than Fe-WBAX as well as a mixed bed of WBAX and granular ferric hydroxide for all studied categories. A separate life cycle assessment found the total number of cancer and non-cancer cases prevented by drinking safer water outweighed those created by manufacture and use of water treatment materials and energy. However, treatment relocated who bore the health risk, concentrated it in a sub-population, and changed the primary manifestation from cancer to non-cancer disease. This tradeoff was partially mitigated by avoiding use of pH control chemicals. When properly synthesized, Fe-WBAX and Ti-WBAX sorbents maintained chromium removal capacity while significantly increasing arsenic removal capacity compared to the parent resin. The hybrid sorbent performance was demonstrated in packed beds using a challenging water matrix and low pollutant influent conditions. Breakthrough curves hint that the hexavalent chromium is removed by anion exchange and the arsenic is removed by metal oxide sorption. Overall, the hybrid nano-sorbent synthesis methods increased sustainability, improved sorbent characteristics, and increased simultaneous removal of chromium and arsenic for drinking water. / Dissertation/Thesis / Doctoral Dissertation Civil and Environmental Engineering 2016
504

Estudo para a remocao de fluoreto em aguas e efluentes

CHARBEL, MARIA Y. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:36:21Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:29Z (GMT). No. of bitstreams: 1 03871.pdf: 2892098 bytes, checksum: 5369857479c6fb9952c9855c38d0ee35 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
505

Estudo e desenvolvimento de metodos analiticos para determinacao da radioatividade natural em aguas

SAMPA, MARIA H. de O. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:29:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:23Z (GMT). No. of bitstreams: 1 00374.pdf: 1851667 bytes, checksum: eb55ab298cfe6ea72073a36c84226d72 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Energia Atomica - IEA
506

Avaliacao do impacto de agrotoxicos em areas de protecao ambiental, pertencentes a bacia hidrografica do rio Ribeira de Iguape, Sao Paulo. Uma contribuicao a analise critica da legislacao sobre o padrao de potabilidade

MARQUES, MARIA N. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:49:22Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:34Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP
507

Adsorption of perfluorinated water contaminants on Agave sisalana activated carbon fibre

Imwer, Serge Mapan January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Magister Technologiae: Chemical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2014 / An awareness campaign on the harmful effects of Perfluorinated compounds (PFCs), especially Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonate (PFOS) has been conducted to inform the general public about the impact of these organic compounds on hu-mans and biota. These compounds have been shown to be potential carcinogens, as indi-cated by the United States Environmental Protection Agency (USEPA) and the Organization for Economic Co-operation and Development . A major concern about these chemicals is that they have been widely used in consumer products and have been detected in food and drinking water. They have been determined to be resistant to biological degradation, owing to their unique chemical and physical properties (fluorine atoms that have substituted hydrogen atoms in their chemical structure). Owing to their characteristics of being highly soluble in water, they cannot be removed from water using ordinary purification processes. Studies have been conducted to evaluate the removal of PFOA and PFOS from water using different methods. Among these methods, it has been proved that adsorption is a suitable method with the best adsorbent identified as activated carbon (AC). AC can be found in many forms, including as a fibre. The use of AC for the removal of PCFs can be augmented with sonica-tion and electro-chemical methods for rapid absorption of these compounds. The aim of this study was to remove these contaminants using a microporous AC fibre (ACF) made from an indigenous plant, Agave sisalana, which is widely available across sub-Saharan Africa, by using electro-physico-chemical methods. ACF has the following advantages when compared with granulated and/or powdered AC: it has a slightly larger reactive surface area; small quantities can be used; it is easily handled; it retains its shape under stress, thus does not require additional filtration to remove particulate residue; and can be regenerated easily. The manufacturing process of the ACF was done in several steps: 1) harvesting of the A. sisalana leaves, stripping them to obtain wet fibre by scrapping using traditional meth-ods, 2) chemical activation using NaOH, KOH, ZnCl2 and H3PO4, employing a spraying method instead of soaking, which was followed by drying, and 3) carbonisation in a furnace at the required temperature. The use of activation reagents involved the determination of an appropriate concentration, with optimum concentrations determined as 0.54M, 0.625M, 1.59M and 0.73M for NaOH, KOH, ZnCl2 and H3PO4, respectively. Apart from the fibre acti-vation, temperature and activation time were also important parameters that were optimised. A response surface methodology was used to design a set of experiments that provided the optimum temperature and activation time. From the input variables, the Expert design soft- ware generated experimental runs (n = 13) for each fibre activation reagent used with a tem-perature range of 450°C to 933°C being assessed for carbonisation time of between 17 to 208 minutes. ACF activated with KOH (0.54 M) and characterised by micropores with the highest surface area achieved being 1285.8 m2/g in comparison with Granular activated car-bon (Ounas et al., 2009) with an average surface area range of 1000 to 1100 m2/g. This sur-face area was measured using Dubinin-Astakhov isotherm with CO2 at 273 K. The physical characteristics of the ACF were analysed using a Scanning Electron Microscope to ascertain the integrity of the fibres. PFOA and PFOS were analysed using a solid phase extraction (SPE) method fol-lowed by analysis using a liquid chromatography/tandem mass spectrometer (SPE-LC/MS/MS). The water sample volume used for extraction was 60 mL. The instrument used was an HPLC - Ultimate 3000 Dionex HPLC system and MS model - Amazon SL Ion Trap, with the following MS/MS operational conditions and ion mode: MS Interface → ESI; dry temp → 350C; nebulising pressure → 60 psi; dry gas flow → 10 L/min; ionisation mode → negative; capillary voltage → +4500V; end plate offset → −500V, while the separation col-umn was a Waters Sunfire C18, 5 μm, 4.6 × 150 mm column (supplier: Waters, Dublin, Ire-land), with an operational temperature of 30C. Initially, adsorption studies (n = 48) using sonication (20 kHz) in batch systems indi-cated efficient removal of PFOA and PFOS within 120 min, with numerous samples (n = 14) achieving complete removal for both PFOA and PFOS. The minimum removal rates ob-served were 65.55% for PFOA and 95.92% for PFOS. From the ACF samples in which high-est removal rates were achieved, a number (n = 3) of the ACF samples were selected for surface characterisation. Based on the sonication in the previous experiments, an electro-physico-chemical adsorption regime was designed, to facilitate the rapid adsorption of PFOS and PFOA from contaminated drinking water in an electrolytic cell. In these experiments, si-multaneous sonication and electrolysis were used. A comparison was made between ACF produced in this study and the commercial activated carbon. The result revealed that adsorp-tion of PFOA and PFOS on ACF was a monolayer adsorption type phenomenon and had the best fit using a Freundlich isotherm compared with the Langmuir isotherm. Adsorption of PFOA and PFOS on the commercial AC presented a multilayer adsorption type of isotherm fit with the Langmuir isotherm having the best fit compared with the Freundlich isotherm.
508

Avaliação do desempenho operacional de um sistema de ultrafiltração para tratamento de água utilizando um coagulante inorgânico e um derivado de tanino

Bidone Filho, Jacques Lara January 2016 (has links)
Novas tecnologias para o tratamento de água potável vêm sendo empregadas na medida em que a utilização de sais de alumínio tem apresentado correlação com doenças de envelhecimento mental nos seres humanos. Os coagulantes orgânicos de origem vegetal podem substituir de forma satisfatória estes sais no tratamento convencional de água potável. A utilização de processos combinados utilizando membranas de ultrafiltração com coagulação é uma alternativa aos métodos convencionais de potabilização. Com este cenário, o presente trabalho tem como objetivo comparar o desempenho operacional de uma planta piloto de ultrafiltração com membranas submersas para produção de água potável a partir do Lago Guaíba, utilizando o coagulante convencional poli (cloreto de alumínio) (PAC) e um coagulante orgânico oriundo da casca da Acácia Negra (Acacia maernsii) Tanfloc SG, com a análise da morfologia, massa molar de corte e permeabilidade hidráulica da membrana e com análises da água bruta e filtrada. As membranas de fibra oca de Poliéter Sulfona (PES) com massa molar de corte de 50 kDa, permearam sob pressão fixa de -500 mbar, com ação de borbulhamento em testes de 140 horas para avaliação da performance e testes de 10 horas para avaliação da qualidade de permeado. Os resultados indicaram semelhança no desempenho operacional dos dois coagulantes quanto à redução da permeância hidráulica relativa, e a qualidade do permeado indicou que mesmo com a ausência de flocos no tanque de alimentação, não houve passagem significativa de coagulante para o permeado. Os parâmetros de potabilidade indicaram o enquadramento da água produzida nos padrões organolépticos na atual Portaria 2914/2011 do Ministério da Saúde. / New technologies to water treatment have been applied as the aluminum salts commonly used have shown correlations with mental diseases in human beings. The organic coagulants from natural sources can satisfactorily replace those inorganic salts in drinking water treatment. The hybrid processes join ultrafiltration membranes with coagulation are alternatives to the standard potabilization. The present study compares the operational behavior of a submersed ultrafiltration (UF) pilot plant producing drinking water from Guaíba Lake, using poli (aluminum chloride) (PAC) and an organic coagulant extracted from Acacia maernsii Tanfloc SG. The membrane and the permeate were investigated. The polyether sulfone hollow fiber membranes filtered with a -500 mbar constant vacuum and air bubbles through 140 hours for performance test and for 10 hour for permeate quality verification. The results showed similarity of the relative hydraulic permeability of the two coagulants, and even with the absence of visible flocs in the membrane tank, there were no significant coagulant carryover through the membrane. The analytical data pointed that the water produced with both coagulants had concentration bellow the Brazilian organoleptic standards, according to the Portaria 2914/2011 of the Health Ministry.
509

Concentração de flúor no biofilme dental de indivíduos expostos a diferentes fontes de flúor de base comunitária / Dental biofilm fluoride concentration of subjects exposed to different community-based fluoride sources

Mua, Bruna January 2013 (has links)
O objetivo deste estudo foi comparar a concentração de flúor do biofilme dental de indivíduos residenteste em áreas com água fluoretada (AF) ou sal fluoretado (SF) e determinar o efeito do dentifrício fluoretado na concentração de flúor [F] do biofilme dental destes indivíduos. Dezesseis indivíduos resendentes em Montevidéu (SF) e dezesseis indivíduos residentes em Porto Alegre (AF) participaram deste estudo randomizado, cruzado e duplo-cego. Profilaxia dental e raspagem supragengivel foram realizaras antes de cada fase experimental. Durante as fases experimentais (14 dias/cada), os indivíduos escovaram os dentes, 2x/dia, com dentifrício fluoretado (DF) ou dentifrício não-fluoretado (DNF). As amostras de biofilme dental foram coletadas 8 horas após a última escovação. As análises de [F] no biofilme dental foram realizadas com um íon epecífico e as leituras foram convertidas em μgF¯/g de biofilme. Equações de estimativas generalizadas foram aplicadas para analisar a variância de medidas repetidas e as diferenças em cada desfecho. Uma maior [F] no biofilme foi observada na área com SF(2.69±0.10 IC 2.48–2.89) em comparação a área com AF (2.44±0.06 IC 2.32-2.57) quando do uso regular de DNF (p = 0.047). Entretanto, não houve diferença significativa na [F] no biofilme entre as áreas com SF (2.60±0.12 IC 2.37-2.83) e AF (2.81±0.10 CI 2.62-3.01) quando do uso de FD (p = 0.153). Adicionalmente, não foi observada diferença siginifcativa na [F] do biofilme quando DF e DNF foram usados nas áreas com SF (p = 0.294) e AF (p = 0.320). A maior [F] no biofilme observada na área com SF, sob uso regular DNF, pode não ter significância clínica, uma vez que ela desapareceu quando o DF foi usado. / The aim of this study was to compare the fluoride concentration in dental biofilm of subjects living in fluoridated- salt (FS) or water (FW) areas and to determine the effect of fluoride dentifrice on the fluoride concentration [F] in dental biofilm of these subjects. Sixteen individuals residing in Montevideo (FS) and sixteen individuals living in Porto Alegre (FW) participated in this randomized, double-blind, crossover study. Dental prophylaxis and scaling were performed prior to each experimental phase. During the experimental phases (14d/each) subjects brushed their teeth, 2x/day, with fluoridated dentifrice (FD) or non-fluoridated fluoride (NFD). Dental biofilm samples were collected 8 hours after the last toothbrushing. Analyses were performed with a fluoride ion-specific electrode and the reading was transformed into μgF¯/g biofilm. Generalized estimating equations were used to analyze the variance for repeated measures and the differences in each outcome. Higher biofilm [F] was found in FS (2.69±0.10 CI 2.48–2.89) compared to FW (2.44±0.06 CI 2.32-2.57) areas under regular use of NFD (p = 0.047). However, no significant differences were found on dental biofilm [F] between FW (2.60±0.12 CI 2.37-2.83) and FS (2.81±0.10 CI 2.62-3.01) areas under FD use (p = 0.153). Furthermore, no significant difference was observed in the biofilm [F] when FD or NFD were used in the FS (p = 0.294) and FW (p = 0.320) areas. The higher dental biofilm [F] was found in FS areas under NFD use may not have clinical significance once it disappeared when FD was used.
510

Remoção de carbono orgânico dissolvido de águas de abastecimento por adsorção em carvão ativado granular / Dissolved organic carbon removal from source water by granular activated carbon

Teixeira, Marina Bergamaschi January 2014 (has links)
A crescente contaminação dos sistemas de água doce com milhares de compostos químicos naturais e industriais é um dos principais problemas ambientais enfrentados pela humanidade. Embora a maioria destes compostos esteja presente em baixas concentrações, muitos deles podem causar efeitos danosos à saúde. Adicionalmente ao aumento da poluição, com a descarga de fertilizantes, pesticidas, fármacos, detergentes, derivados de petróleo, entre outros, grande parte das instalações para tratamento de água no Brasil opera com sistema convencional, não atuando de forma eficiente na remoção desses microcontaminates. Carvão ativado em pó (CAP) e granular (CAG) tem sido utilizados em muitos países para remoção de microcontaminantes e substâncias que causam gosto e odor na água. No Brasil já foram desenvolvidas diversas pesquisas com o emprego de CAP para remoção de gosto e odor e alguns contaminantes específicos de águas de abastecimento. Neste trabalho foi testado um CAG produzido a partir de cascas de coco para remoção por adsorção de microcontaminates orgânicos de águas de abastecimento. A água utilizada nos experimentos foi coletada no ponto de captação da Estação de Tratamento de Água (ETA) Lomba do Sabão. Para a caracterização da capacidade adsortiva do carvão foram realizados seis ensaios de isotermas de adsorção e quatro ensaios em colunas de leito fixo, projetada com base na norma ASTM D 3922. Os microcontaminantes orgânicos foram quantificados pela concentração de carbono orgânico dissolvido (COD), medido em analisador de carbono orgânico e por absorbância em espectofotômetro em comprimento de onda de 254nm. Os resultados indicam que o carvão utilizado tem baixa capacidade de adsorver a mistura de microcontaminantes presentes na água de abastecimento, quantificados como COD. Isto se deve, provavelmente, a falta de afinidade entre muitos destes compostos e o carvão. / Pollution growth in water bodies brought by daily discharge of thousands of chemicals from anthropogenic sources is one of the main environmental issues confronting humankind. Although most of these chemicals are present in very low concentrations, they can still be hazardous.to health. Additionally to the increasing levels of pollution brought by discharges of fertilizers, pesticides, prescription drugs and pharmaceuticals, detergents, and petroleum derivatives, among others, the standard processes that are used in drinking water treatment plants in Brazil are not effective to remove these micropollutants. Powdered (PAC) and granular (GAC) activated carbon have been used in many countries to remove micropollutants and taste and odor-causing substances from water. In Brazil, research has been made using PAC to remove taste and odor substances and specific micropollutants from water. In this research, GAC produced from coconut shells was used to test the removal of organic micropollutants present in source water by adsorption. Water used in this research was collected at the intake of Lomba do Sabão drinking water treatment plant in Porto Alegre. In order to assess the GAC adsorption capacity, six isotherm (batch) and four column (continuous flow) assays were performed according to ASTM D 3922 standard. Organic micropollutants were quantified by the concentration of dissolved organic carbon (DOC) and by ultraviolet absorption at 254 nm wavelength. The results suggest that the tested GAC have limited capability in adsorb the complex mixture of micropollutants that are present in source water, as measured by DOC. This is probably caused by lack of affinity between many micropollutants present in the mixture and the carbon.

Page generated in 0.0759 seconds