The existence of small-scale gold mining in Nova Scotia between 1868 and 1942 has resulted in many high arsenic (As) tailings areas in the province, some of which are near rural/urban areas and are used for recreational activities such as dirt bike racing and all-terrain vehicle (ATV) riding. Because of the natural association of As with gold ore in the Meguma Terrane, processing of ore has resulted in As-rich mine waste that contains up to 2500 times more As than the Canadian soil quality guideline of 12 mg/kg. These high As concentrations in combination with the recreational use of these sites creates a risk of human exposure. The objective of this work was to investigate the effects of different cover options that might be used to mitigate the risk of human exposure. Four tailings samples were selected to represent the geochemical variability from two tailings areas: Montague gold mines and Goldenville. These samples were characterized and subjected to 29 weeks of column testing, in which each sample was leached with three different input solutions including synthetic rainwater (to simulate uncovered tailings exposed to natural acid rain), synthetic rainwater equilibrated with calcium carbonate (to simulate rainwater percolation through a crushed limestone cover), and a dilute organic acid solution (to simulate a vegetative cover). Results of acid base accounting (ABA) tests indicate that samples have the potential to generate acid in the future (ratio of neutralization potential to acid potential is less than 2), though surface water at the sites is currently circum-neutral. Acidic paste pH values (2.9) from a sample of As-rich hardpan indicate that a small volume of tailings at Montague are currently generating acid. Results of column testing indicate that the cover types simulated by the input solutions had less of an effect on the out-flowing leachate chemistry than did the small volume of secondary As phases in each sample (scorodite, yukonite, hydrous ferric arsenate and hydrous ferric oxides). For the majority of sample types, columns leached with an organic acid solution reported higher leachate As concentrations than were reported from columns leached with either the rainwater or carbonate-rainwater solutions. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2010-10-27 14:26:06.13

Aquifer Storage and Recovery (ASR) involves the injection of water into an aquifer for subsequent recovery from the same well. Whilst ASR provides a competitive alternative to reservoir storage, a lack of precedence of successful schemes and uncertainties with respect to regulatory requirements, and abstracted water quality and quantity have limited its implementation in the UK. The ambition of this research is to improve understanding of these impediments with particular reference to the Sherwood Sandstone aquifer. Drawing on existing project review and risk management approaches, a decision support tool to help scheme designers scope ASR scheme potential and challenges was developed and tested. The tool provides practitioners with a systematic method for early stage evaluation of ASR schemes with testing confirming broad value and alignment with business processes. Limitations on the recovery of recharged water was investigated through a critical literature review on clogging with geochemical, biological, physical and gaseous binding processes identified as the most likely mechanisms to impact an ASR scheme in this aquifer. Water quality changes during storage and the impact of storage period on recovered water quality were investigated in the laboratory using ASR simulating columns, with storage times of 15, 20, 30 and 60 days. Water quality improvements such as biodegradation of disinfection by-products, denitrification and sulphate reduction were observed. However recovered water quality deteriorated with respect to iron, arsenic, manganese, total organic carbon and nickel. These results, together with the review of regulations conducted as part of decision support tool development, suggest that the current interpretation of the Water Framework Directive requirements is overly restrictive and is deterring wider implementation of ASR in the UK. Conclusions focus on the need for a more appropriate approach to regulating ASR schemes, in particular, one which adopts a risk based approach to determining water quality standards.

[pt] A mobilidade dos hidrocarbonetos de petróleo e os processos de remediação aos quais estão sendo submetidos são de fundamental importância para o gerenciamento de áreas contaminadas. A biorremediação é uma tecnologia multidisciplinar, que envolve ciências como a microbiologia, a engenharia, a geologia e a química, baseada na habilidade dos microrganismos de utilizar o contaminante como fonte exclusiva de energia para o funcionamento de seu metabolismo. O estudo de solos residuais tropicais é de valiosa contribuição para a comunidade científica brasileira por serem encontrados poucos trabalhos na literatura a respeito do comportamento de contaminantes orgânicos nestes solos. O objetivo desta dissertação de mestrado foi estudar a mobilidade de um óleo mineral em um solo arenoso inerte e em um solo residual indeformado. Neste último, em se tratando de um solo microbiologicamente ativo, foram também analisadas a biodegradação do contaminante e a influência da temperatura na atividade degradadora e na descida do óleo. Os ensaios com o solo arenoso inerte, representado por esferas de vidro industrializadas, contaram com uma etapa inicial de testes no intuito de desenvolver as metodologias de adensamento, de saturação e de drenagem. A contaminação somente se deu após a delineação do perfil dos ensaios. Com a finalidade de avaliar a mobilidade do contaminante na coluna de solo, após 24 horas foram realizadas as análises por extração e determinação gravimétrica de hidrocarbonetos totais de petróleo (TPH) e a ressonância magnética nuclear (RMN) das amostras de solo de cada segmento. Os resultados obtidos mostraram que o contaminante migrou facilmente através da coluna de solo arenoso. Os ensaios com o solo residual consistiram na contaminação de colunas de solo indeformado pelo mesmo óleo utilizado nos ensaios com o solo inerte, sob duas condições distintas: Sob a ação de refletores e em condições normais de temperatura. Foram realizadas análises químicas (TPH e RMN) e de atividade degradadora microbiana a cada 5cm, a fim de avaliar a influência dos microorganismos do solo no processo de degradação do contaminante ao longo dos 157 dias de monitoramento. Os resultados obtidos indicaram que o óleo é susceptível aos processos de biodegradação pela microbiota nativa, mostrando uma relação direta entre a atividade degradadora dos microrganismos do solo e a queda na concentração de hidrocarbonetos de petróleo. / [en] Petroleum hydrocarbons´ mobility and remediation processes to which they are submitted are of great importance to the management of contaminated areas. The investigation of tropical residual soils is of valuable contribution to the scientific community, not only in Brazil but also across the world, once there is little research work concerning the behavior of organic contaminants in these soils. The main goal of the present thesis was to study the mobility of a mineral oil in sandy and tropical residual silty soils. Since the latter constitutes a microbiologically active soil, both the biodegradation processes of the contaminant and the influence of temperature on its mobility through the porous media and on the degrading activity of the microbial population inhabiting the soil have been evaluated. The experiments regarding the sandy idle soil, represented by perfect industrialized spheres, counted on a initial stage of tests, in order to develop the methodologies most adequate to a situation where the capillary fringe does not represent a considerable portion of the column´s height. The contamination itself only took place after the outline of the whole experiment. With the purpose of analyzing the contaminant´s mobility after 24 hours, every sample of soil from each different section of the column has been chemically and microbiologically analyzed. The results have shown that the mineral oil migrated easily through the porous media. The experiments making use of the tropical residual soil consisted on the contamination of soil columns through their top by the same mineral oil applied to the first experiment. However the experiment took place under two distinct conditions: Under an increase of temperature (represented by the influence of reflectors) and under natural conditions of temperature. The bioremediation of soils contaminated by petroleum hydrocarbons is a multidisciplinary technology which involves sciences such as microbiology, engineering, geology and chemistry, and is based on the ability of microorganisms to utilize contaminants as an exclusive source of energy for the functioning of their metabolisms. Therefore, on the experiments in which the residual soil was the object of investigation, soil samples from the columns´ overture day have been subject to chemical (TPH and MNR) e microbiological (FDA) analysis in order to evaluate the influence of soil microorganisms on the biodegradation processes of the mineral oil throughout the 157 days of experiments. The results have shown that the tropical residual soil studied in the present work is susceptible to the biodegradation processes and is characterized by a direct relationship between the degradative activity and the loss of petroleum hydrocarbons.

[pt] O derramamento no solo de poluentes imiscíveis com a água (NAPLs) devido a vazamentos de tanques de armazenamento ou dutos e acidentes de transporte é de grande interesse, pois o NAPL e/ou seus constituintes podem migrar através da zona vadosa até atingir o lençol freático e contaminar as fontes de água potável. No Brasil, a maioria dos postos de combustível e terminais de armazenamento possui tanques de etanol, gasolina misturada com etanol e óleo diesel. Um eventual derramamento ou vazamento de hidrocarbonetos derivados de petróleo, conhecidos como LNAPL, misturados com etanol tem um maior potencial de contaminação em função do efeito de co- solvência. A motivação deste trabalho é que muitos estudos têm sido realizados com principal interesse na zona saturada e pouco se sabe sobre o comportamento destes contaminantes na zona não saturada (McDowell e Powers, 2003 e Österreicher et al., 2007). Portanto, foram realizados ensaios de coluna com esferas de vidro com o objetivo de simular os vazamentos de hidrocarbonetos líquidos na superfície e comparar a massa de benzeno que fica retida no meio poroso em um vazamento de gasolina pura ou com etanol. Para avaliar estes ensaios em uma dimensão foi utilizado um programa disponível no sítio da Agência de Proteção Ambiental dos Estados Unidos (EPA) chamado Hydrocarbon Spill Screening Model (Weaver et al., 1994) e implementado um modelo para efetuar o balanço de massa e considerar o efeito de co-solvência em função da adição de etanol na gasolina comercial brasileira. Os resultados dos ensaios de laboratório foram comparados com os obtidos através do modelo supracitado e apresentaram uma aproximação satisfatória da previsão do comportamento do contaminante. / [en] The subsurface release of water immiscible pollutants (NAPLs) due to leaks in storage tanks or pipelines and spilling transportation accidents is of great concern, since the NAPL or its constituents may migrate through the vadose zone until reaching the water table and eventually contaminate clean water sources. In Brazil, most of the gas stations store ethanol, pure and gasoline blended ethanol, diesel, among others in tanks. A spill or leak of petroleum hydrocarbons, known as LNAPL (light Nonaqueous phase liquid), combined with ethanol has a major contamination potential associated to cosolvency effects. The motivation of this work is that many studies have been developed with special interest in the saturated zone and little is known about the behavior of these pollutants in the vadose zone (McDowell e Powers, 2003 e Österreicher et al., 2007). Thus, one dimensional column tests were performed in a glass porous media to simulate the spill of hydrocarbons in the subsurface and compare the retained mass of benzene in the porous media after a release of a pure or ethanol blended gasoline. In order to evaluate these 1D tests results, the Hydrocarbon Spill Screening Model - HSSM (Weaver et al., 1994) was used. This program can be found in the Environmental Protection Agency (EPA) website. A model was also implemented to consider the cosolvency effects in function of the ethanol addition in Brazilian`s commercial gasoline. The laboratory`s results were compared with the ones obtained by the model mentioned above and showed a satisfactory approximation for the prediction of the contaminant behavior.

<p>Förorenat dagvatten från Stena Gotthards metallåtervinningsanläggning i Eskilstuna har filtrerats genom kolonner innehållande två olika adsorbenter, torv och furubarksflis. Torv är en organisk jordart som främst används som bränsle och furubarksflis är en biprodukt från skogsindustrin. Båda filtermaterialen är relativt billiga och finns i stora kvantiteter i Sverige. Filtermaterialen har visat sig ha varierande kapacitet att adsorbera metaller i vatten på grund av själva materialet samt vattnets sammansättning. Resultatet från den här studien visar att av de två undersökta filtermaterialen så har furubarksflis störst kapacitet att reducera bly, koppar och zink från det specifika dag vattnet.</p> / <p>Polluted storm water from a metal recycling industry has been filtrated through columns that contained two different adsorbents, peat and pine bark. Peat is an organic soil, mainly used for energy production, and pine bark, a by-product from the forest industry. In Sweden, there are a lot of resources of peat as well as pine bark. Used as filter materials, they are relatively cheep and, like other kinds of filtermaterial used as adsorbents, they have varied capacity to adsorb metals in water. The capacity for the filter materials to adsorb metals depends on the physical structure and chemical contents of the peat and pine bark as well as the water metal composition. Results from this study show that pine bark had the highest adsorption capacity to reduce copper, lead and zinc from the specific storm water.</p>

Förorenat dagvatten från Stena Gotthards metallåtervinningsanläggning i Eskilstuna har filtrerats genom kolonner innehållande två olika adsorbenter, torv och furubarksflis. Torv är en organisk jordart som främst används som bränsle och furubarksflis är en biprodukt från skogsindustrin. Båda filtermaterialen är relativt billiga och finns i stora kvantiteter i Sverige. Filtermaterialen har visat sig ha varierande kapacitet att adsorbera metaller i vatten på grund av själva materialet samt vattnets sammansättning. Resultatet från den här studien visar att av de två undersökta filtermaterialen så har furubarksflis störst kapacitet att reducera bly, koppar och zink från det specifika dag vattnet. / Polluted storm water from a metal recycling industry has been filtrated through columns that contained two different adsorbents, peat and pine bark. Peat is an organic soil, mainly used for energy production, and pine bark, a by-product from the forest industry. In Sweden, there are a lot of resources of peat as well as pine bark. Used as filter materials, they are relatively cheep and, like other kinds of filtermaterial used as adsorbents, they have varied capacity to adsorb metals in water. The capacity for the filter materials to adsorb metals depends on the physical structure and chemical contents of the peat and pine bark as well as the water metal composition. Results from this study show that pine bark had the highest adsorption capacity to reduce copper, lead and zinc from the specific storm water.

Este trabalho teve como objetivo geral estudar a viabilidade técnica de utilizar bagaço de cana como meio reativo de barreiras reativas permeáveis (BRP) para remoção de sulfato e metais de águas subterrâneas contaminadas. O estudo baseou-se em investigação experimental, por meio de ensaios laboratoriais de coluna, e em modelagem matemática, para a qual utilizaram-se também alguns dados obtidos em um estudo de caso de uma unidade industrial contaminada com sulfato e metais. Neste local contaminado, as características hidrogeológicas e topográficas propiciam a utilização de uma barreira reativa permeável como técnica de remediação. Barreiras reativas permeáveis são uma alternativa para remediação de águas subterrâneas que vem progredindo rapidamente na última década, a partir de ensaios de bancada e coluna em laboratório para implementação em escala real em campo. Três colunas bióticas foram montadas utilizando bagaço de cana como meio reativo e um material de base poroso constituído de areia e cascalho para fornecer adequada condutividade hidráulica, com a proporção de 1:28 em massa seca. Também foi adicionado ao meio reativo um inóculo bacteriano composto por esterco bovino dissolvido. Uma quarta coluna, sem inóculo e contendo um agente biocida, compôs o experimento branco (abiótico). Uma solução sintética foi introduzida nas colunas simulando condições da água subterrânea do estudo de caso, com velocidade de Darcy em torno de 2,0x10-7 m/s composta por sulfato e metais (zinco e níquel) com concentrações de 6.000 mg/L e 15 mg/L, respectivamente. Os resultados das análises da fase líquida das colunas bióticas apresentaram: (i) média da taxa de remoção de sulfato durante todo o tempo do experimento de 49 mg/L/dia; (ii) as concentrações de Zn e Ni diminuíram de 15 mg/L para valores não detectáveis pela técnica analítica utilizada (< 0,01 mg/L); (iii) aumento do pH de 5.5-5.8 para valores entre 6,8-8,0; (iv) redução do valor do potencial de óxido redução (Eh) para valores de até -200mV. Não foram observadas reduções das concentrações de metais e sulfato na fase líquida da coluna abiótica e os valores de pH e Eh permaneceram dentro das faixas iniciais. Análises nas fases sólidas das colunas bióticas por MEV e EDS após o término do experimento identificaram a presença de Ni, Zn, S e Mn, indicando a precipitação desses metais em forma de sulfetos. Estes elementos não foram detectados na fase sólida da coluna abiótica. Assim, pôde-se inferir que toda a remoção de sulfato verificada nas colunas bióticas pode ser atribuída a redução bacteriana de sulfato. A partir das condições experimentais dos ensaios, foi realizada a modelagem e o dimensionamento da BRP. Para a estimativa da cinética de redução de sulfato, aplicou-se a solução analítica de Van Genuchten para transporte de contaminantes com degradação, obtendo-se uma taxa de decaimento de primeira ordem de 0,01 dia-1. A determinação da espessura e tempo de residência da barreira foi realizada considerando que a concentração de sulfato na saída da barreira fosse menor ou igual a 250 mg/L. O resultado do dimensionamento de uma BRP preenchida com bagaço de cana e areia nas proporções de 1:28 em massa seca resultaria em uma BRP de 7,1 m de espessura, com tempo de residência de 950 dias, no local de estudo de caso. Caso fosse utilizado o dobro da proporção de bagaço de cana e areia em massa seca (1:14), a implantação da BRP apresentar-se-ia viável, com espessura aproximada de 4 m. Através destes resultados, pôde ser comprovada a hipótese de que bagaço de cana como substrato e esterco bovino como inóculo compõem um meio reativo viável para a redução de sulfato e precipitação de metais em uma BRP. / This research had as general objective to study the technical feasibility of use sugarcane bagasse as reactive medium of permeable reactive barriers (PRB) for removal of sulfate and metals from contaminated groundwater. The study was based on experimental investigation, through laboratory column tests and by mathematical modeling, for which data of a case study of an industrial unit contaminated with sulfate and metals was used. At this contaminated unit, the hydrogeological and topographical features propitiate the utilization of a permeable reactive barrier as remediation technique. Reactive permeable barriers are an alternative to groundwater remediation that comes progressing quickly in the last decade, from bench and column tests in the laboratory to full-scale implementation in the field. Three biotic columns were assembled using bagasse as a reactive medium and a porous base material consisting of sand and gravel to provide adequate hydraulic conductivity, with the proportion of 1:28 by dry mass. It was also added to the reactive medium a bacterial inoculum consisting of dissolved cow manure. A fourth column, without inoculum, and containing a biocidal agent composed the blank experiment (abiotic). A synthetic solution was introduced in columns simulating groundwater conditions of the case study, with Darcy velocity around 2, 0x10-7 m/s, composed by sulfate and metals (zinc and nickel) with concentrations of 6,000 mg/L and 15 mg/L, respectively. The results of the analyses of the liquid phase of the biotic columns showed: (i) the average of sulfate removal rate during all the time of the experiment of 49 mg/L/day; (ii) the concentrations of Zn and Ni decreased from 15 mg/L to non-detectable values by the used analytical technique (0.01 mg/L); (iii) increase in the pH of 5.5-5.8 for values between 6.8-8.0; (iv) reduction in the value of the oxidation-reduction potential (Eh) for values up to -200mV. The reductions were not observed in concentrations of metals and sulfate in liquid phase of abiotic column and the values of pH and Eh remained within the initial tracks. Analyses on solid phases of biotic columns by SEM and EDS after experiment finalization have identified the presence of Ni, Zn, S and Mn, indicating the precipitation of these metals in the form of sulfides. These elements were not detected in the solid phase of the abiotic column. So, it might be inferred that any reduction in sulfate removal biotic columns can be attributed to bacterial sulfate reduction. Base on the experimental conditions of the tests, it was conducted the modeling and PRB dimensioning. For the sulfate reduction kinetics estimation, the analytical solution of Van Genuchten was applied for contamination degradation and transport, obtaining a first-order decay rate of 0.01 day-1. The determination of the thickness and residence time of the barrier was performed considering the concentration of sulfate in the output of the barrier being less than or equal to 250 mg/L. The result of the dimensioning of the PRB filled with bagasse and sand in 1:28 dry mass ratios would result in a PRB of 7.1 m thick, with 950 days residence time on the site of case study. If the proportion of bagasse and sand were 1:14 by dry mass (twice), the deployment of the PRB would be feasible, with approximate thickness of 4 m. Through these results, it might be concluded that the hypothesis that sugarcane bagasse as a substrate and cow manure as inoculum make up a reactive medium viable for the reduction of sulfate and precipitation of metals in a PRB.

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No. of bitstreams: 1 ferreira_tm_me_rcla.pdf: 2453303 bytes, checksum: 1fb9668aac7a92d7731e47a007d17c32 (MD5) Previous issue date: 2018-09-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / No processo industrial da produção sucroalcooleira um dos efluentes gerados é a vinhaça, que se destaca pelo grande volume com que é produzida e pelo alto potencial fertilizante, característica que possibilita seu aproveitamento em atividades agrícolas, no entanto, a vinhaça também possui alto poder poluente. Neste contexto, o uso da vinhaça na fertilização de cana-de-açúcar, embora seja uma prática aceita, deve ser realizado de forma controlada, sendo regulamentado no Estado de São Paulo pela Companhia Ambiental do Estado de São Paulo – CETESB através da Norma Técnica P4.231. Devido a composição da vinhaça ser muito variável não há como estabelecer doses fixas, assim, atualmente as dosagens de aplicação no solo são calculadas em função das necessidades da planta em relação ao potássio, sendo consideradas a capacidade de troca catiônica do solo e as concentrações de potássio no solo e na vinhaça. Todavia, além da oscilação composicional da vinhaça, seus efeitos sobre cada tipo de solo também são muito diversos, podendo modificar parâmetros hidráulicos do solo e, consequentemente, alterar a velocidade de percolação da água e dos contaminantes presentes na solução. Diante desta problemática, para avaliar o uso da dosagem calculada pela Norma P4.231 da CETESB, foram realizados ensaios laboratoriais de percolação a carga constante, em colunas com amostras de solo arenoso da Formação Rio Claro previamente infiltradas com as doses de 0 (testemunho), 55 (equivalente a dose máxima permitida pela CETESB), 80, 400 e 800 m3/ha. A aplicação destas doses permitiu a avaliação de seus efeitos nos parâmetros hidráulicos do solo estudado e a possível geração de diferentes graus de contaminação nos efluentes percolados, implicando um potencial risco para a água subterrânea e superficial. Os resultados obtidos indicam que com a aplicação das doses de 55 e 80 m3/ha houve um aumento na capacidade de retenção do solo, fator este positivo tanto para o aspecto fertilidade do solo quanto ao ambiental. Entretanto, com a aplicação de doses elevadas como as de 400 e 800 m3/ha observa-se uma queda progressiva na capacidade de retenção do solo, que implica em perdas por lixiviação e consequente aumento nas concentrações de sólidos totais dissolvidos, cloreto, fluoreto, acetato, carbono orgânico total, alumínio, ferro, manganês e zinco, que em algumas amostras apresentaram concentrações superiores aos valores de referência ambiental e de potabilidade adotados podendo, portanto, gerar riscos à qualidade do solo e da água subterrânea tornando-a imprópria para consumo humano. Quanto à condutividade hidráulica saturada, os valores obtidos para a coluna com 55 m3/ha foram muito similares aos obtidos na coluna sem aplicação de vinhaça, indicando que para o solo estudado esta dosagem não trouxe nenhuma alteração significativa, porém, com o aumento das dosagens houve redução gradual destes valores. Com base nos resultados obtidos para a configuração dos testes laboratoriais realizados, pode-se afirmar que, a aplicação de vinhaça na dose máxima estabelecida pela norma P4.231 CETESB (2015) não apresentou riscos à qualidade do solo estudado e da água subterrânea. / In the industrial production process of sugar and a lcohol, one of the effluents generated is vinasse, which stands out for the larg e volume produced and for the high fertilizing potential, allowing its use in agr icultural activities, however, the vinasse also has high pollution power. In this context, the use of vinasse in the fertilization of sugarcane, although it is an accepted practice, mus t be carried out in a controlled manner, being regulated in the State of São Paulo b y the Companhia Ambiental do Estado de São Paulo (CETESB) through Technical Stan dard P4. 231. Due to the composition of the vinasse being very variable, it is not possible to establish fixed doses, so, currently the dosages of application in the soil are calculated according to the needs of the plant in relation to potassium ion , considering the cation exchange capacity of the soil and the concentrations of pota ssium in soil and vinasse. In addition to the compositional oscillation of vinasse, its effects on each type of soil is also very diverse, being able to modify hydraulic p arameters of the soil and, consequently, to change the rate of percolation of the water and the contaminants present in the solution. In order to evaluate the u se of the dosage calculated by CETESB Standard P4.231, constant load percolation t ests were carried out in columns with samples of a sandy soil from the Rio C laro Formation previously infiltrated with the doses of 0 (control), 55 (equi valent to the maximum dose allowed by CETESB), 80, 400 and 800 m 3 /ha. The application of these doses allowed the evaluation of its effects on the hydraulic paramete rs of the studied soil and the possible generation of different degrees of contami nation in the percolated effluents implying a potential risk for groundwater and surfa ce water. The results indicated that for the doses of 55 and 80 m 3 /ha there was an increase in the retention capacity of soil, which is positive about the aspect of soil fe rtility as well as the environmental aspect. However the application of high doses such as 400 and 800 m 3 /ha, there is a progressive decrease in the soil retention capacity , which implies losses due to leaching and consequent increase in the concentrati ons of total dissolved solids, chloride, fluoride, acetate, total organic carbon, aluminum, iron, manganese and zinc, which in some samples presented concentrations high er than the values of potability and environmental reference adopted, what could gen erate risks to soil and groundwater quality. Regarding the saturated hydraulic conductivity, the values obtained for the column with 55 m 3 /ha dosage were very similar to those obtained in the control column, indicating that this dosage did not bring any significant change, but with the increase of the dosages there was grad ual reduction in those values. Based on the results obtained for the configuration of the laboratory tests carried out, it can be stated that the application of vinasse at the maximum dose established by standard P4.231 CETESB (2015) did not present risks to the quality of the studied soil and groundwater. / CAPES: 33004137036P9.

Este trabalho teve como objetivo geral estudar a viabilidade técnica de utilizar bagaço de cana como meio reativo de barreiras reativas permeáveis (BRP) para remoção de sulfato e metais de águas subterrâneas contaminadas. O estudo baseou-se em investigação experimental, por meio de ensaios laboratoriais de coluna, e em modelagem matemática, para a qual utilizaram-se também alguns dados obtidos em um estudo de caso de uma unidade industrial contaminada com sulfato e metais. Neste local contaminado, as características hidrogeológicas e topográficas propiciam a utilização de uma barreira reativa permeável como técnica de remediação. Barreiras reativas permeáveis são uma alternativa para remediação de águas subterrâneas que vem progredindo rapidamente na última década, a partir de ensaios de bancada e coluna em laboratório para implementação em escala real em campo. Três colunas bióticas foram montadas utilizando bagaço de cana como meio reativo e um material de base poroso constituído de areia e cascalho para fornecer adequada condutividade hidráulica, com a proporção de 1:28 em massa seca. Também foi adicionado ao meio reativo um inóculo bacteriano composto por esterco bovino dissolvido. Uma quarta coluna, sem inóculo e contendo um agente biocida, compôs o experimento branco (abiótico). Uma solução sintética foi introduzida nas colunas simulando condições da água subterrânea do estudo de caso, com velocidade de Darcy em torno de 2,0x10-7 m/s composta por sulfato e metais (zinco e níquel) com concentrações de 6.000 mg/L e 15 mg/L, respectivamente. Os resultados das análises da fase líquida das colunas bióticas apresentaram: (i) média da taxa de remoção de sulfato durante todo o tempo do experimento de 49 mg/L/dia; (ii) as concentrações de Zn e Ni diminuíram de 15 mg/L para valores não detectáveis pela técnica analítica utilizada (< 0,01 mg/L); (iii) aumento do pH de 5.5-5.8 para valores entre 6,8-8,0; (iv) redução do valor do potencial de óxido redução (Eh) para valores de até -200mV. Não foram observadas reduções das concentrações de metais e sulfato na fase líquida da coluna abiótica e os valores de pH e Eh permaneceram dentro das faixas iniciais. Análises nas fases sólidas das colunas bióticas por MEV e EDS após o término do experimento identificaram a presença de Ni, Zn, S e Mn, indicando a precipitação desses metais em forma de sulfetos. Estes elementos não foram detectados na fase sólida da coluna abiótica. Assim, pôde-se inferir que toda a remoção de sulfato verificada nas colunas bióticas pode ser atribuída a redução bacteriana de sulfato. A partir das condições experimentais dos ensaios, foi realizada a modelagem e o dimensionamento da BRP. Para a estimativa da cinética de redução de sulfato, aplicou-se a solução analítica de Van Genuchten para transporte de contaminantes com degradação, obtendo-se uma taxa de decaimento de primeira ordem de 0,01 dia-1. A determinação da espessura e tempo de residência da barreira foi realizada considerando que a concentração de sulfato na saída da barreira fosse menor ou igual a 250 mg/L. O resultado do dimensionamento de uma BRP preenchida com bagaço de cana e areia nas proporções de 1:28 em massa seca resultaria em uma BRP de 7,1 m de espessura, com tempo de residência de 950 dias, no local de estudo de caso. Caso fosse utilizado o dobro da proporção de bagaço de cana e areia em massa seca (1:14), a implantação da BRP apresentar-se-ia viável, com espessura aproximada de 4 m. Através destes resultados, pôde ser comprovada a hipótese de que bagaço de cana como substrato e esterco bovino como inóculo compõem um meio reativo viável para a redução de sulfato e precipitação de metais em uma BRP. / This research had as general objective to study the technical feasibility of use sugarcane bagasse as reactive medium of permeable reactive barriers (PRB) for removal of sulfate and metals from contaminated groundwater. The study was based on experimental investigation, through laboratory column tests and by mathematical modeling, for which data of a case study of an industrial unit contaminated with sulfate and metals was used. At this contaminated unit, the hydrogeological and topographical features propitiate the utilization of a permeable reactive barrier as remediation technique. Reactive permeable barriers are an alternative to groundwater remediation that comes progressing quickly in the last decade, from bench and column tests in the laboratory to full-scale implementation in the field. Three biotic columns were assembled using bagasse as a reactive medium and a porous base material consisting of sand and gravel to provide adequate hydraulic conductivity, with the proportion of 1:28 by dry mass. It was also added to the reactive medium a bacterial inoculum consisting of dissolved cow manure. A fourth column, without inoculum, and containing a biocidal agent composed the blank experiment (abiotic). A synthetic solution was introduced in columns simulating groundwater conditions of the case study, with Darcy velocity around 2, 0x10-7 m/s, composed by sulfate and metals (zinc and nickel) with concentrations of 6,000 mg/L and 15 mg/L, respectively. The results of the analyses of the liquid phase of the biotic columns showed: (i) the average of sulfate removal rate during all the time of the experiment of 49 mg/L/day; (ii) the concentrations of Zn and Ni decreased from 15 mg/L to non-detectable values by the used analytical technique (0.01 mg/L); (iii) increase in the pH of 5.5-5.8 for values between 6.8-8.0; (iv) reduction in the value of the oxidation-reduction potential (Eh) for values up to -200mV. The reductions were not observed in concentrations of metals and sulfate in liquid phase of abiotic column and the values of pH and Eh remained within the initial tracks. Analyses on solid phases of biotic columns by SEM and EDS after experiment finalization have identified the presence of Ni, Zn, S and Mn, indicating the precipitation of these metals in the form of sulfides. These elements were not detected in the solid phase of the abiotic column. So, it might be inferred that any reduction in sulfate removal biotic columns can be attributed to bacterial sulfate reduction. Base on the experimental conditions of the tests, it was conducted the modeling and PRB dimensioning. For the sulfate reduction kinetics estimation, the analytical solution of Van Genuchten was applied for contamination degradation and transport, obtaining a first-order decay rate of 0.01 day-1. The determination of the thickness and residence time of the barrier was performed considering the concentration of sulfate in the output of the barrier being less than or equal to 250 mg/L. The result of the dimensioning of the PRB filled with bagasse and sand in 1:28 dry mass ratios would result in a PRB of 7.1 m thick, with 950 days residence time on the site of case study. If the proportion of bagasse and sand were 1:14 by dry mass (twice), the deployment of the PRB would be feasible, with approximate thickness of 4 m. Through these results, it might be concluded that the hypothesis that sugarcane bagasse as a substrate and cow manure as inoculum make up a reactive medium viable for the reduction of sulfate and precipitation of metals in a PRB.

The soil strata is often subjected to various kinds of vibrations such as that caused by earthquakes, water waves, traffic loads, wind power plants, construction related equipments, pile driving and vibratory machines. The strains induced in a soil mass due to the vibrations generated by these different sources often lie in a range of 0.0001% - 0.1%. The estimation of the shear modulus (G) and damping (D) of soils in this strain range becomes an important aspect for performing the analysis and design of various geotechnical structures subjected to different kinds of vibrations. Strain amplitude, effective confining stress, void ratio/relative density, number of vibration cycles and cyclic strain history are some of the key parameters that influence the modulus and damping characteristics of sands. Although, the effects of strain amplitude, confining pressure and relative density have been studied quite extensively in literature, only limited studies seem to have been reported in literature to examine the effects of the cyclic strain history and the vibration cycles on these dynamic properties. The objective of this thesis is to study the effects of the cyclic strain history and the number of vibration cycles on the shear modulus and damping ratio of dry sands in a strain range of 0.0001% to 0.1%. A number of resonant column tests have been performed on dry sand specimens to examine the effect of the cyclic shear strain history, by including both increasing and decreasing strain paths, on the shear modulus and damping ratio for different combinations of relative densities (Dr) and confining pressures (σ3); an increasing strain path intends to simulate a situation when a vibratory machine is just started before reaching a steady state of vibration, and on the other hand, the decreasing strain path matches a condition when the machine is shut down after running continuously in a steady state for some time. The specimen has been subjected to a series of cycles of increasing and decreasing shear strain paths approximately in a shear strain range of 0.0006% - 0.1%. For chosen values of relative density and confining pressure, two different series of tests beginning with either (i) an increasing strain path or (ii) a decreasing strain path, were performed. In addition, the influence of the numbers of the vibration cycles which are used to measure the resonant frequency of the specimen, referred to as the cycle constant, on the values of shear modulus has also been analyzed. Irrespective of the strain path adopted to commence the test or the cycle constant used to perform a resonant column test, for a given strain amplitude, the shear modulus along the increasing strain path has been found to be always greater than the corresponding modulus value along the decreasing strain path. For the series of tests which were commenced with the increasing strain path, the shear modulus corresponding to the first increasing strain path becomes always the highest as compared to the subsequent strain paths. For a given strain cycle, irrespective of relative density of sand, the difference between the values of G associated with the increasing and decreasing strain paths becomes always the maximum corresponding to a certain shear strain level. The maximum reduction in the shear modulus, due to the cyclic variation of the shear strain, was noted to be approximately one fourth of the maximum shear modulus (G0). This reduction in the shear modulus, on account of the cyclic variation of the shear strain, increases generally with decrease in the values of both relative density and confining pressure. The damping ratio for a given shear strain for the increasing strain path was noted to be lower than the corresponding value for the decreasing strain path except for the first increasing strain path. For a particular strain level, the series of tests started with the decreasing strain path resulted in a lower value of shear modulus for all the cyclic strain paths as compared to the tests which were commenced with the increasing strain path. The modulus reduction curve for the first increasing strain path was noted to be more or less the same irrespective of the value of the chosen cycle constant. For the subsequent strain paths, an increment in the cycle constant value caused a reduction in the shear modulus at a particular shear strain level. In order to match a situation when the machine is running continuously in a steady state of vibration, resonant column tests were conducted in a torsional mode by inducing a large number of the vibration cycles with the shear strain amplitude in a range of 0.0005%-0.05%. Corresponding to a given input voltage of the drive mechanism, the specimens were subjected to a number of vibration cycles ranging from 1,000 to 50,000. The values of shear modulus and damping ratio, before and after the application of vibration cycles, were determined for several input voltages ranging from 0.001 V (minimum) to 0.3 V (maximum). The tests were carried out for different combinations of relative densities and confining pressures. For the chosen relative densities, hardly any influence of vibration cycles on the values of G and D were noted for the strain amplitude below the threshold strain level (0.0024% - 0.0044%). Beyond the threshold strain level, an induction of the vibration cycles leads to a continuous increment in the shear strain which eventually causes (i) a decrease in the shear modulus, and (ii) an increase in the damping ratio. This effect was found to become especially more significant for lower values of relative densities as well as confining pressures. The percentage changes in the values of (i) shear strain, (ii) shear modulus, and (iii) damping ratios after the introduction of vibration cycles were noted to increase with an increment in the number of vibration cycles. However, for a given increment of the vibration cycles, the changes in the values of shear modulus and damping ratio were generally noted to subside with an increase in the number of the vibration cycles. At various strain levels, the magnitude of the shear modulus was observed to increase continuously with an increase in the values of both relative density and confining pressure. For the shear strain greater than the threshold strain (0.0024% - 0.0044%), a reduction in the damping ratio values was also noted with an increase in the magnitudes of the confining pressure. On the other hand, the influence of relative density on the damping ratio was found to be relatively negligible. The shear modulus reduction curves from the present tests' data were found to compare reasonably well with the empirical curves proposed in the literature, especially for low values of the confining pressure. A deviation of the present modulus reduction curves from the empirical curves was observed generally at large shearing strains. However, the damping values obtained from the present study were noted to be lower than the values predicted by the existing empirical correlations, particularly for low values of the confining pressure. An attempt has also been made to improve the accuracy of the measurement of the arrival times of both primary (P) waves and shear (S) waves while conducting bender/extender element tests. For this purpose, a series of laboratory tests were performed on dry sand at different frequencies, varying between 1 kHz and 10 kHz, for medium dense and very dense sands with different values of the confining pressures. While determining the times of arrival of both P and S waves, two corrections have been proposed to incorporate (i) the presence of an initial offset in the input signal, and (ii) the time lag due to an existence of peripheral electronics between the input and received signals when the source and receiver elements are kept in direct contact with each other. The absolute magnitude of the resultant of these two corrections was found to reduce with an increase in the frequency of the input signal. The determination of the P-wave arrival time does not pose much difficulty. It has been noted that it becomes equally accurate to measure the arrival times of the S-wave provided the proposed corrections are incorporated. The maximum shear modulus values measured from the resonant column tests and the bender element tests by incorporating these two corrections were found to compare reasonably well with each other. The thesis brings out the effects of the cyclic strain history and the vibration cycles on the shear modulus and damping ratio of dry sand. The results obtained are expected to be useful while doing the analysis and design of geotechnical structures subjected to different kinds of vibrations.