Chromium is used in many processing applications, which has led to the formation of chromium(VI) waste. Cr(VI) is an unstable, mobile carcinogen, which is interchangeable with Cr(III) under certain environmental conditions. Management of this waste, however, is often not considered. Mine under investigation is an example of such historic mismanagement. During the second World War, Cr(VI) waste was transferred to the study site from areas where leather products were made for the war effort. This waste was not managed appropriately in the past and with time Cr(VI) leached into the groundwater and possibly surface water resources. As these water resources are used for domestic and agricultural water supply, this may have serious effects on the human and environmental health in the area. Some of the major Cr(VI) effects on human and animal health include malignant tumours, skin irritation, respiratory and reproductive system damage. Lung cancer is of concern when Cr(VI) is inhaled and stomach tumours occur when this chemical pollutant is ingested. The effects of Cr(VI) on plants include the disruption of shoot and root elongation, and if it accumulates enough within the plant can cause ingested health problems for humans and animals. Water quality guidelines state that the Target Water Quality Range for Cr(VI) in drinking water should not exceed 0.05 mg/L. Prolonged exposure of values higher than this target value has adverse health effects and may result in cancer. The study site has a scarcity in water sources and therefore requires good quality water resources. This study aims to identify and use biomarkers to assist in the hydrological characterization of the mine. Available mitigation options can be implemented once it is known how the water in the area moves and distributes Cr(VI) pollution. A biomarker is an indicator of a biological state, which in turn can be used to assist in characterizing the chemical conditions of the sub-surface. Bacteria can aid as environmental biomarkers as they are sensitive and specific to the environmental conditions in which they flourish. In this way they give a good indication of the environmental condition and any possible pollution. Due to the fact that ground- and surface water are integrated resources, it is likely that if one is impacted by pollution, it will indirectly impact the other one. Therefore, the biomarkers identified can be used to characterize water pollutants that are present in ground- and some surface water resources. A description of the study site is provided, wherein the climate, elevation, geology, land use, geohydrology, hydrochemistry and surface water are documented. These factors help to identify and clarify the sources and pathways that water and the pollution would follow. Ten water samples, from surface and groundwater, were obtained in two separate sampling opportunities. The first analysis of the water samples included the determination of the chemical constituents. Two of these constituents analyzed were the total Cr and individual Cr(VI) levels. Six water samples had excessively high Cr values (exceeding the Water Quality Target Range of drinking water and water agricultural use). These values ranged from 0.1 – 3.9 mg/L. The 6 samples with excessive Cr(VI) values were used for the microbial analyses. The microbial analyses consisted of DAPI (4’,6-diamidino-2-phenylindole ) staining, for cell enumeration, and molecular analyses. The molecular analyses included polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and sequencing applications concluded in the laboratory. Fifteen bands, representing different organisms, were removed from the DGGE polyacrylamide gel and processed for sequencing. The organisms that were present in the sample were uncultured Cyanobacterium, Sediminibacterium salmoneum, uncultured Bacteroidetes bacterium, uncultured betaproteobacterium, uncultured actinobacterium, uncultured Rhodocyclaceae, uncultured Chloroflexi bacterium and uncultured delta-proteobacterium. According to literature most of these organisms may adapt the ability to either reduce Cr(VI) or resist any effect of Cr(VI) in the environment. Two of the bands were highly unidentified organisms, which means that these organisms have not yet been cultured or identified in any sense. The reason for this is that most microorganisms have not yet been documented. This also makes it difficult to identify the exact bacterial strain present within the samples. The deoxyribonucleic acid (DNA) sequences of the different organisms were very different from each other, when compared by a dendrogram. This means that there was a diverse community present within the samples. Electrical conductivity profiles were conducted in the monitoring boreholes to identify possible fracture positions. The total chromium and chromium(VI) levels were documented and compared. Other chemical factors were analysed and those of high value, such as chloride, nitrate and chromium measurements, were used for statistical analyses and comparison with the biomarkers present in the sample. A positive correlation was found between the sample sites and the organisms present within each. It was noted that different communities have different metabolic activities related to susceptibility and will therefore differ under specific environmental conditions. The microorganisms that were present in the 6 water samples all have the ability to either resist or reduce Cr(VI). This means that in Cr(VI) polluted areas they are more likely to flourish than organisms that do not possess this ability. Such susceptible, non-resistant organisms would otherwise occur naturally in a non-polluted environment. From the obtained results it was noted that microorganisms could aid as biomarkers when determining the environmental condition (with respect to Cr(VI) pollution). The bacteria analysed in the samples all indicate a level of chromium pollution, and aided in the determination of pollution sources. These biomarkers can therefore be used to determine the location of other chromium deposits not yet located. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

Made available in DSpace on 2016-01-26T18:55:39Z (GMT). No. of bitstreams: 1 Soraia.pdf: 476391 bytes, checksum: 291042d1569afa2b16dd7b6c72516724 (MD5) Previous issue date: 2013-10-18 / Chromium (Cr) is a relatively common element and occupies the 21st position in the index most commonly occurring elements in the earth´s crust, occurring in nature in various combinations with other substances, may be in the form of ions with valence 0 + 2, +3 or +6. The Cr +3 (III) is considered an essential element for human and animal metabolism in small quantities, inert and stable in the environment, while the +6 Cr (VI) is very unstable, toxic and carcinogenic to a wide variety of occupational and contaminant organisms and water and food. It is estimated that tens of thousands of people are exposed to chromium VI worldwide, leading to toxic effects by inducing free radicals by the reduction of chromium in the presence of cellular reductants and interaction between free radicals and membrane proteins and intracellular modifying the processes of absorption and secretion of various substances. Some live microorganisms, called probiotics, showed antioxidant activity and scavenging of free radicals, which can minimize or prevent the toxic effect of contaminants, for their beneficial effect on human and animal health. The term probiotic is of Greek origin and means "for life" being defined as "live microorganisms administered in adequate amounts, confer health benefits to the host", besides acting in the prevention of cancer in the modulation of allergic reactions in improving health and blood lipid levels. Thus, the aim of this study was to evaluate different doses of potassium dichromate, with or without probiotic on the parameters: nutritional performance and glycemic, lipid, renal and hepatic profiles in Wistar rats. / O crômio (Cr) é um elemento relativamente comum e ocupa a 21a posição no índice de elementos que ocorrem mais comumente na crosta terrestre, ocorrendo na natureza em várias combinações com outras substâncias, podendo apresentar-se na forma de íons com valência 0, +2, +3 ou +6. O Cr +3 (III) é considerado um elemento essencial para o metabolismo humano e animal em pequenas quantidades, inerte e não instável no ambiente, enquanto que o Cr +6 (VI) é muito instável, tóxico e carcinogênico para uma grande variedade de organismos e ocupacionalm e contaminante da água e alimentos. Estima-se que dezenas de milhares de pessoas estão expostas ao crômio VI em todo o mundo, provocando efeitos tóxicos através da indução de radicais livres pela redução do crômio, na presença de redutores celulares e a interação dos radicais livres com as proteínas da membrana e intracelulares, modificando os processos de reabsorção e secreção de diferentes substâncias. Alguns microorganismos vivos, denominados de probióticos, mostraram atividade antioxidante e captadora de radicais livres, o que pode minimizar ou impedir o efeito tóxico de contaminantes, pelo seu efeito benéfico sobre a saúde humana. O termo probiótico é de origem grega e significa "para a vida" sendo definidos como "microrganismos vivos, administrados em quantidades adequadas, que conferem benefícios a saúde do hospedeiro", além de atuar na prevenção de câncer, na modulação de reações alérgicas, na melhoria da saúde e nos níveis sanguíneos de lipídeos. Dessa forma, o objetivo do presente trabalho foi o de avaliar diferentes doses de dicromato de potássio, com ou sem probiótico, sobre os parâmetros: desempenho nutricional e perfis glicêmico, lipídico, renal e hepático em ratos Wistar.

Made available in DSpace on 2016-01-26T18:55:40Z (GMT). No. of bitstreams: 1 Reinaldo Camacho Bezerra.pdf: 607647 bytes, checksum: 1745657e41ebeb1e290325ce90721b08 (MD5) Previous issue date: 2014-03-21 / This work aims to evaluate the alterations, depending on the dose of potassium dichromate (0, 12, 24 and 36 mg.km-¹), in liver tissue after supplementation with probiotic at dosages 0 or 0.2% in 90 male rats. Oral ingestion done for 90 days of increasing amounts of potassium dichromate produced clinical signs of toxicity compared to histopathological analysis (p&#706;0.05), and seric enzymatic activities (p&#706;0.05), markers of hepatic function. The inclusion of probiotics to the diet reduced the effects on the studied parameters, indicating that it can be used to detoxify and/or prevent the action of the mineral, however other studies should be conducted to determine the most appropriate microorganisms and their dosages to minimize and/or to prevent the action of these xenobiotics in humans and animals. / O objetivo do presente trabalho foi o de avaliar as alterações dependentes da dose de dicromato de potássio (0, 12, 24 e 36 mg.kg-1) no tecido hepático, após suplementação com probiótico em dosagens 0 ou 0,2%, em 90 ratos machos. A ingestão oral por 90 dias de doses crescentes de dicromato de potássio produziu sinais clínicos de toxicidade frente a análise histopatológica (p<0,05) e atividades séricas enzimáticas (p<0,05), dos marcadores de função hepática. A inclusão do probiótico na dieta reduziu os efeitos nos parâmetros estudados, indicando que ele pode ser utilizado para desintoxicar e/ou impedir a ação desse mineral, porém outros estudos deverão ser realizados para determinar os microorganismos mais apropriados e suas dosagens, para minimizar e/ou impedir a ação desses xenobióticos nos homens e animais.

Made available in DSpace on 2016-07-18T17:53:12Z (GMT). No. of bitstreams: 1 Soraia.pdf: 476391 bytes, checksum: 291042d1569afa2b16dd7b6c72516724 (MD5) Previous issue date: 2013-10-18 / Chromium (Cr) is a relatively common element and occupies the 21st position in the index most commonly occurring elements in the earth´s crust, occurring in nature in various combinations with other substances, may be in the form of ions with valence 0 + 2, +3 or +6. The Cr +3 (III) is considered an essential element for human and animal metabolism in small quantities, inert and stable in the environment, while the +6 Cr (VI) is very unstable, toxic and carcinogenic to a wide variety of occupational and contaminant organisms and water and food. It is estimated that tens of thousands of people are exposed to chromium VI worldwide, leading to toxic effects by inducing free radicals by the reduction of chromium in the presence of cellular reductants and interaction between free radicals and membrane proteins and intracellular modifying the processes of absorption and secretion of various substances. Some live microorganisms, called probiotics, showed antioxidant activity and scavenging of free radicals, which can minimize or prevent the toxic effect of contaminants, for their beneficial effect on human and animal health. The term probiotic is of Greek origin and means "for life" being defined as "live microorganisms administered in adequate amounts, confer health benefits to the host", besides acting in the prevention of cancer in the modulation of allergic reactions in improving health and blood lipid levels. Thus, the aim of this study was to evaluate different doses of potassium dichromate, with or without probiotic on the parameters: nutritional performance and glycemic, lipid, renal and hepatic profiles in Wistar rats. / O crômio (Cr) é um elemento relativamente comum e ocupa a 21a posição no índice de elementos que ocorrem mais comumente na crosta terrestre, ocorrendo na natureza em várias combinações com outras substâncias, podendo apresentar-se na forma de íons com valência 0, +2, +3 ou +6. O Cr +3 (III) é considerado um elemento essencial para o metabolismo humano e animal em pequenas quantidades, inerte e não instável no ambiente, enquanto que o Cr +6 (VI) é muito instável, tóxico e carcinogênico para uma grande variedade de organismos e ocupacionalm e contaminante da água e alimentos. Estima-se que dezenas de milhares de pessoas estão expostas ao crômio VI em todo o mundo, provocando efeitos tóxicos através da indução de radicais livres pela redução do crômio, na presença de redutores celulares e a interação dos radicais livres com as proteínas da membrana e intracelulares, modificando os processos de reabsorção e secreção de diferentes substâncias. Alguns microorganismos vivos, denominados de probióticos, mostraram atividade antioxidante e captadora de radicais livres, o que pode minimizar ou impedir o efeito tóxico de contaminantes, pelo seu efeito benéfico sobre a saúde humana. O termo probiótico é de origem grega e significa "para a vida" sendo definidos como "microrganismos vivos, administrados em quantidades adequadas, que conferem benefícios a saúde do hospedeiro", além de atuar na prevenção de câncer, na modulação de reações alérgicas, na melhoria da saúde e nos níveis sanguíneos de lipídeos. Dessa forma, o objetivo do presente trabalho foi o de avaliar diferentes doses de dicromato de potássio, com ou sem probiótico, sobre os parâmetros: desempenho nutricional e perfis glicêmico, lipídico, renal e hepático em ratos Wistar.

Made available in DSpace on 2016-07-18T17:53:13Z (GMT). No. of bitstreams: 1 Reinaldo Camacho Bezerra.pdf: 607647 bytes, checksum: 1745657e41ebeb1e290325ce90721b08 (MD5) Previous issue date: 2014-03-21 / This work aims to evaluate the alterations, depending on the dose of potassium dichromate (0, 12, 24 and 36 mg.km-¹), in liver tissue after supplementation with probiotic at dosages 0 or 0.2% in 90 male rats. Oral ingestion done for 90 days of increasing amounts of potassium dichromate produced clinical signs of toxicity compared to histopathological analysis (p&#706;0.05), and seric enzymatic activities (p&#706;0.05), markers of hepatic function. The inclusion of probiotics to the diet reduced the effects on the studied parameters, indicating that it can be used to detoxify and/or prevent the action of the mineral, however other studies should be conducted to determine the most appropriate microorganisms and their dosages to minimize and/or to prevent the action of these xenobiotics in humans and animals. / O objetivo do presente trabalho foi o de avaliar as alterações dependentes da dose de dicromato de potássio (0, 12, 24 e 36 mg.kg-1) no tecido hepático, após suplementação com probiótico em dosagens 0 ou 0,2%, em 90 ratos machos. A ingestão oral por 90 dias de doses crescentes de dicromato de potássio produziu sinais clínicos de toxicidade frente a análise histopatológica (p<0,05) e atividades séricas enzimáticas (p<0,05), dos marcadores de função hepática. A inclusão do probiótico na dieta reduziu os efeitos nos parâmetros estudados, indicando que ele pode ser utilizado para desintoxicar e/ou impedir a ação desse mineral, porém outros estudos deverão ser realizados para determinar os microorganismos mais apropriados e suas dosagens, para minimizar e/ou impedir a ação desses xenobióticos nos homens e animais.

This licentiate thesis presents experimental studies concerning two parts of the electrochemical cell in the chlorate process: a cathode and an anode. Newly synthesized MnOx electrodes were investigated for the cathodic reaction, hydrogen evolution reaction (HER) in the chlorate process. In industry addition of toxic and carcinogenic chromium (VI) as sodium dichromate provides high efficiency. Here undesirable addition of sodium dichromate was avoided while high cathodic efficiency was achieved. Cathodic efficiency and selectivity towards HER, achieved by the MnOx electrodes annealed at different temperatures, were measured by means of mass spectrometry (MS).  The second study investigated oxygen evolution in the chlorate process, which is an anodic side reaction. The evolution of oxygen decreases anodic efficiency and also presents a safety risk due to occurrence of HER in the undivided cell. We followed the amount of produced oxygen by two types of the electrode TiRu, similar to that industrially used, and synthesized TiRuSnSb, by means of MS. The produced oxygen amount was compared to the amount produced by Pt. To our best knowledge, this was the first study that successfully disentangles three different sources of oxygen with good time resolution. Oxygen is produced by homogenous hypochlorite decomposition, heterogeneously by different catalysts present in the electrolyte solution and anodically during the electrolysis i.e. electrochemically. Different electrode materials catalyzed hypochlorite decomposition differently and led to a different volume of oxygen produced. / Denna licentiatavhandling redogör för experimentella studier av tvådelar av den elektrokemiska cell som används i kloratprocessen:katoden och anoden. Syntetiserade MnOx elektroder utvärderades för katodreaktionen,vätgasutveckling, i kloratprocessen. Industriellt tillsätts giftigt ochcancerogent krom(IV) som natriumdikromat för hög verkningsgrad. Denna studie uteslöt oönskad tillsats av natriumdikromat samtidigt som hög katodisk effektivitet erhölls. Katodisk effektivitet och selektivitet för vätgasutveckling, med MnOx elektroder,värmebehandlade vid olika temperaturer, uppmättes med masspektrometer. I den andra studien undersöktes syrgasutveckling i kloratprocessen,vilket är en anodisk sidoreaktion. Syrgasutvecklingen minskar den anodiska effektiviteten och utgör en säkerhetsrisk med anledning avden pågående vätgasutvecklingen i den odelade cellen. Vi uppmättemängden producerad syrgas med två olika elektroder TiRu, liknandeden som industriellt används, och syntetiserad TiRuSnSb, med masspektrometer. Den producerade syrgasmängden jämfördes med mängden producerat på Pt. Såvitt vi vet var detta den första studiesom särskiljer på tre olika syrgaskällor med god tidsupplösning. Syrgas produceras homogent av hypokloritsönderfall, heterogent av olika katalysatorer närvarande i elektrolyten och anodiskt vid elektrolys dvs. elektrokemiskt. Olika elektrodmaterial katalyserade hypokloritsönderfall olika och producerade olika volym syrgas. / <p>QC 2021-04-28</p>

Este trabajo tiene como objetivo el desarrollo de la metodología de diseño óptimo de procesos de separación con membranas líquidas selectivas en su aplicación a la separación de mezclas multicomponentes con recuperación selectiva del componente de interés. Para ello se ha investigado la separación selectiva y concentración de cromo(VI) presente inicialmente en un acuífero subterráneo contaminado por acción de la actividad industrial desarrollada a nivel superficial y donde a su vez, coexisten otras especies aniónicas competitivas (sulfato y cloruro mayoritariamente) presentes por las propias características del acuífero y por su localización en una zona litoral. Tras la selección de Alamine 336 (amina terciaria) y NaOH como agentes de extracción y reextracción respectivamente, se caracterizaron experimentalmente las reacciones químicas responsables de la etapa de extracción, así como la cinética del proceso de separación-concentración cuando se emplea la tecnología de pertracción en emulsión (EPT) en contactores de fibra hueca. Finalmente, se desarrolló un modelo matemático multicomponente y se determinaron los parámetros característicos del mismo con el fin de llevar a cabo el diseño óptimo del proceso mediante técnicas de optimización matemática. / This work aims at the development of the methodology for the optimal design of selective liquid membrane processes as efficient alternatives for the separation and selective recovery of raw materials and valuable compounds from multicomponent systems. For this purpose, the proposed methodology has been applied to the remediation of polluted groundwater containing hexavalent chromium as a consequence of effluent leaking from surface deposition of industrial wastes. Furthermore, other competitive anionic species (mainly sulphate and chloride anions) were also present in the groundwaters due to the specific location being close to the shore.After selecting Alamine 336 (tertiary amine) and NaOH as the best extraction and back-extraction agents respectively, a careful experimental design was performed in order to analyse the chemical equilibria involved in the extraction step. Once the emulsion pertraction technology (EPT) was selected as the most suitable separation-concentration process configuration, the experimental kinetic analysis and mathematical modeling of EPT were carried calculating the values of the design parameters. Finally, the proposed multicomponent model was employed to carry out the optimal process design by means of mathematical optimization techniques.

The chemical contamination of natural waters is a global problem with a worldwide impact. Considering the relevance of this problem, this thesis is intended, on one hand, to develop different separation/preconcentration techniques based on membranes ability to permeate anions for the transport of toxic oxyanions of chromium(VI) and arsenic contained in aqueous matrices. In particular, we have investigated supported liquid membranes and polymer inclusion membranes, both of which contain the commercial quaternary ammonium salt Aliquat 336 as a carrier, as well as commercial anion exchange membranes. On the other hand, we have focused on the development of chemical sensors to facilitate the monitoring of several metals from different aqueous matrices. Thus, a selective optical sensor for Cr(VI) based on polymeric membranes containing Aliquat 336 as an ionophore has been designed. Additionally, mercury-based screen-printed electrodes have been evaluated for for cadmium, lead, copper and zinc detection. / La contaminació química de les aigües naturals és un problema global amb repercussió a nivell mundial. Donada la rellevància que té aquesta problemàtica, en la present tesi s’han desenvolupat d’una banda tècniques de separació/preconcentració basades en diferents sistemes de membrana en què el mecanisme de transport proposat és un bescanvi aniònic per als oxoanions tòxics de crom(VI) i arsènic presents en matrius aquoses. Concretament, s’ha treballat amb membranes líquides suportades que contenien el portador comercial Aliquat 336, membranes d’inclusió polimèriques amb el mateix portador i membranes de bescanvi aniònic comercials. D’altra banda, s’ha treballat en el desenvolupament de diferents sensors químics per monitoritzar diversos metalls presents en matrius aquoses. Així, s’ha dissenyat un sistema de sensor òptic selectiu a Cr(VI) basat en membranes polimèriques utilitzant també el portador Aliquat 336 i s’ha desenvolupat un sistema de monitorització per plom, coure, cadmi i zinc basat en microelèctrodes serigrafiats modificats amb mercuri.

This study took place in Malawi, south eastern Africa. Metal contamination of water and soil is a threat to the environment and human health and is a serious concern in many countries including Malawi. Blantyre is the city of commerce where most of the industry is located along the banks of the main rivers. Some of the industries produce wastewater, which due to poor access to wastewater treatment plants, is discharged without treatment into the environment. A match factory in Blantyre uses chromium as a colouring agent for match heads and very high concentrations of chromium(VI) have been measured downstream the factory with concentrations up to 56 mg/l, which is much higher than the WHO guidelines of 0.05 mg/l.  Chromium(VI) mainly occurs as chromate CrO42- and dichromate Cr2O72- ions. They are both toxic and carcinogenic and can cause mutations and chromosomal aberrations.   The aim of the study was to evaluate the efficiency of Granular Ferric Hydroxide (GFH) in adsorbing and removing chromium from an aqueous phase. Wastewater was collected from the match factory and by optimizing relevant parameters the removal efficiency was maximized. The parameters optimized were pH, dosage and contact time and the effect of initial concentration. After respective experiment, all samples were analysed for chromium using microwave plasma atomic emission spectroscopy (MP-AES).   The optimum pH was chosen to 8.0, the dosage to 17.4 g GFH/l and the contact time to 2 hours for a 95% removal of total chromium in undiluted wastewater. The removal efficiency of the GFH was 2.84 mg Cr/g GFH. To implement wastewater purification with GFH a number of practical issues have to be taken into consideration. Above all, a sufficient stirring method has to be devised as the removal efficiency is much affected by improper stirring. / Denna studie genomfördes i Malawi, sydöstra Afrika. Metallföroreningar i vatten och mark är ett stort problem i många länder, inklusive Malawi. Landets centrum för industri och handel ligger i Blantyre där de flesta av industrierna ligger längs med floderna. En del industrier genererar utsläppsvatten och på grund av dålig tillgång till vattenreningsteknik och vattenreningsanläggningar släpps mycket av det förorenade vattnet obehandlat ut i naturen. En tändsticksfabrik i Blantyre använder kromsalter för att färga tändstickshuvudena röda och höga koncentrationer av sexvärt krom har uppmätts nedströms fabriken. De uppmätta koncentrationerna var upp till 56 mg/l vilket är betydligt högre än WHO:s riktvärde på 0,05 mg/l. Sexvärt krom förekommer som kromat CrO42- och dikromat Cr2O72- joner vilka båda är mycket toxiska och cancerframkallande och därmed ett hot mot miljö och människor. Syftet med studien var att undersöka om granulära järnoxider (GFH) kunde användas som en adsorbent för att rena utsläppsvatten från kromater. Utsläppsvatten hämtades från tändsticksfabriken och genom att optimera relevanta parametrar kunde GFHns adsorbtionseffektivitet maximeras. Parametrarna som optimerades var pH, dos, kontakttid och initialkoncentration. Efter respektive experiment mättes kromkoncentrationen med mikrovågsplasma atomemissionsspektroskopi (MP-AES) Det optimala pH-värdet valdes till 8.0, dosen till 17.4 g GFH/l med en kontakttid på 2 timmar för en 95.3% reningsgrad på outspätt utsläppsvatten. Adsorptionseffektiviteten på GFHn var 2.84 mg Cr/g GFH. För att implementera vattenrening med GFH behöver flera praktiska aspekter tas med i beaktning. Framförallt är det viktigt med en bra omrörning för att GFHn ska kunna adsorbera effektivt.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais / This work was to study the influence of the magnetic field on the reduction of hexavalent chromium, removal of COD and total chromium, addition of cell growth in batch (batch reactor), using a mixed culture from located in a tanning city of Franca-SP (AMCOA). The influence of static magnetic field generated by a device that produces an electric current through a conductor, producing a magnetic field around the conductor, like a magnet. This equipment produces a magnetic field pulsed square wave of constant intensity and frequency. In the first step of adjusting the mixed cultures of chromium VI obtained a promising response. Thereafter, a preliminary test was performed to analyze the behavior of the influence of the magnetic field in the reduction of chromium VI and diameter of the reactor, obtaining 71% reduction of chromium VI with a larger diameter, without the presence of magnetic field has seen a reduction of 53%, with an initial concentration of 100 mg/l of chromium and a time of 4 hours of process. In other stages of the project, performing the tests with different frequencies of the magnetic field (1,2,5 and 10 Hz) and doing an analysis related to cell death of micro-organisms, showed that for frequencies of 10 Hz, there was cell death presents some cultures, which was confirmed in a lower frequency. The results were satisfactory when used in a magnetic field frequency of 5 Hz, maximal reduction of chromium VI reducing the time about 4 hours of processing, better removal of COD and total chromium using a volume of 500 ml and concentration of 100 mg/l initial chromium. Checking the influence of different frequency magnetic field, the initial effluent volumes (300 and 1000 ml) and initial concentration of chromium VI (50, 150 and 200 mg/l). The higher the initial concentration the lower the chromium reduction of chromium VI, larger volumes and a reduction of chromium VI and removal of COD and total chromium is not as significant as the use of smaller volumes. / Neste trabalho foi realizado o estudo da influência do campo magnético sobre a redução de cromo hexavalente, remoção de cromo total e DQO, além do crescimento celular em modo descontínuo (reator batelada), utilizando-se de uma cultura mista proveniente do curtume AMCOA localizado na cidade de Franca-SP. Foi avaliada a influência de campo eletromagnético estático gerado por um equipamento que produz uma corrente elétrica, passando por um condutor, produzindo um campo magnético ao redor do condutor, como se fosse um ímã. Este equipamento produz um campo magnético pulsante com onda quadrática de intensidade e frequência constantes. Na primeira etapa de adaptação das culturas mistas ao cromo VI obteve-se uma resposta promissora. Posteriormente, foi realizado um teste preliminar para analisar o comportamento da influência do campo magnético na redução de cromo VI e diâmetro de reator, obtendo 71% de redução de cromo VI com um maior diâmetro, sem a presença de campo magnético obteve uma redução de 53%, com uma concentração inicial de 100 mg/L de cromo e com um tempo de 4 horas de processo. Nas outras etapas do projeto, realizando os testes com diferentes frequências de campo magnético (1, 2, 5 e 10 Hz) e fazendo uma análise relacionada à morte celular dos micro-organismos, mostrou-se que para frequências de 10 Hz, havia morte celular de algumas culturas presentes, o que não foi verificado em uma frequência menor. Os resultados foram satisfatórios quando se utiliza uma frequência de campo magnético de 5 Hz, com máxima redução de cromo VI reduzindo o tempo em torno de 4 horas de processo, com melhor remoção de cromo total e DQO, utilizando um volume de 500 mL e concentração de 100 mg/L de cromo inicial. Verificando a influência de diferentes frequências de campo magnético, volumes iniciais de efluente (300 e 1000 mL) e concentrações iniciais de cromo VI (50, 150 e 200 mg/L). Quanto maior a concentração inicial de cromo menor foi a redução de cromo VI, e em volumes de efluentes maiores a redução de cromo VI e remoção de cromo total e DQO não foram tão significativas quanto em se aplicar volumes menores. / Mestre em Engenharia Química