O presente trabalho teve como objetivo desenvolver um protótipo para a produção hidrometalúrgica de sulfato ferroso heptahidratado (FeSO4.7H2O – melanterita). A matéria prima foi um concentrado de pirita obtido a partir de rejeitos do beneficiamento de carvão mineral. Construiu-se, em escala piloto, uma planta de lixiviação com 300 kg de um concentrado com 73,2% de pirita. Nesta unidade, realizou-se uma etapa de lixiviação com água, em circuito fechado, sob condições aeróbias, com o intuito de se obter um extrato aquoso rico em íons férrico e sulfato. A seguir, procederam-se mudanças no sistema de forma a estabelecer uma condição anaeróbia ao meio, transformando os íons férricos em ferrosos. O lixiviado, rico em Fe2+, foi precipitado na forma de sulfato ferroso heptahidratado pela adição de etanol. Esse precipitado foi submetido a uma etapa de recristalização, obtendo-se cristais de melanterita de maior pureza. Ambos os produtos foram caracterizado por análise química elementar e difração de raios X. Os cristais de melanterita recristalizados apresentaram alta pureza, com qualidade para uso químico e farmacêutico. Assim, desenvolveu-se uma nova rota para produção de sulfato ferroso tendo como matéria-prima um concentrado de pirita da mineração de carvão (usualmente o sulfato ferroso é produzido como coproduto da produção de ilmenita e aço). A tecnologia apresenta uma elevada conversão do ferro lixiviado em melanterita e os insumos necessários são pirita, água e álcool etílico. A proposta abre uma nova possibilidade de uso dos rejeitos de carvão e a possibilidade de comercialização de outro produto na cadeia produtiva de carvão mineral. / The aim of this work was to develop a prototype for hydrometallurgical production of ferrous sulfate heptahydrate crystals (FeSO4.7H2O – melanterite). The raw material was a pyrite concentrate obtained from a coal tailing. The leaching system was assembled in pilot scale with 300 kg of a concentrate with 73.2% pyrite. Initially, it was carried out a leaching step in aerobic conditions with the purpose to obtain an aqueous solution rich in ferric ions and sulfate. Next, modifications were proceeded to establish an anaerobic condition in the reactor, converting the ferric to ferrous ions. Ethanol was added to the leaching solution to provide the precipitation of the Fe2+ and sulfate as ferrous sulfate heptahydrate. The ferrous sulfate precipitate was recrystallized, allowing producing melanterite crystals of higher purity. The crystals were characterized in terms of chemical and mineralogical composition. The process allowed producing crystals with a high purity attending chemical and pharmaceutical purposes. Thus, it was developed a process to produce ferrous sulfate from coal wastes (usually, ferrous sulfate crystals are produced as a co product from titanium dioxide and steel production). The technology presents a high conversion factor of soluble Fe2+ to melanterite and the necessary incomes are pyrite, water, and ethylic alcohol. The hydrometallurgical technique applied in this study allowed production of a commercial grade product from coal mining waste material.

O presente trabalho teve como objetivo desenvolver um protótipo para a produção hidrometalúrgica de sulfato ferroso heptahidratado (FeSO4.7H2O – melanterita). A matéria prima foi um concentrado de pirita obtido a partir de rejeitos do beneficiamento de carvão mineral. Construiu-se, em escala piloto, uma planta de lixiviação com 300 kg de um concentrado com 73,2% de pirita. Nesta unidade, realizou-se uma etapa de lixiviação com água, em circuito fechado, sob condições aeróbias, com o intuito de se obter um extrato aquoso rico em íons férrico e sulfato. A seguir, procederam-se mudanças no sistema de forma a estabelecer uma condição anaeróbia ao meio, transformando os íons férricos em ferrosos. O lixiviado, rico em Fe2+, foi precipitado na forma de sulfato ferroso heptahidratado pela adição de etanol. Esse precipitado foi submetido a uma etapa de recristalização, obtendo-se cristais de melanterita de maior pureza. Ambos os produtos foram caracterizado por análise química elementar e difração de raios X. Os cristais de melanterita recristalizados apresentaram alta pureza, com qualidade para uso químico e farmacêutico. Assim, desenvolveu-se uma nova rota para produção de sulfato ferroso tendo como matéria-prima um concentrado de pirita da mineração de carvão (usualmente o sulfato ferroso é produzido como coproduto da produção de ilmenita e aço). A tecnologia apresenta uma elevada conversão do ferro lixiviado em melanterita e os insumos necessários são pirita, água e álcool etílico. A proposta abre uma nova possibilidade de uso dos rejeitos de carvão e a possibilidade de comercialização de outro produto na cadeia produtiva de carvão mineral. / The aim of this work was to develop a prototype for hydrometallurgical production of ferrous sulfate heptahydrate crystals (FeSO4.7H2O – melanterite). The raw material was a pyrite concentrate obtained from a coal tailing. The leaching system was assembled in pilot scale with 300 kg of a concentrate with 73.2% pyrite. Initially, it was carried out a leaching step in aerobic conditions with the purpose to obtain an aqueous solution rich in ferric ions and sulfate. Next, modifications were proceeded to establish an anaerobic condition in the reactor, converting the ferric to ferrous ions. Ethanol was added to the leaching solution to provide the precipitation of the Fe2+ and sulfate as ferrous sulfate heptahydrate. The ferrous sulfate precipitate was recrystallized, allowing producing melanterite crystals of higher purity. The crystals were characterized in terms of chemical and mineralogical composition. The process allowed producing crystals with a high purity attending chemical and pharmaceutical purposes. Thus, it was developed a process to produce ferrous sulfate from coal wastes (usually, ferrous sulfate crystals are produced as a co product from titanium dioxide and steel production). The technology presents a high conversion factor of soluble Fe2+ to melanterite and the necessary incomes are pyrite, water, and ethylic alcohol. The hydrometallurgical technique applied in this study allowed production of a commercial grade product from coal mining waste material.

In Boden, northern part of Sweden, there is a site called Solgårdarna which has been used for wood impregnation. The activities on the site have led to soil contamination with chrome (Cr), copper (Cu) and arsenic (As), where the arsenic contamination is the most problematic. This master’s thesis has studied the possibility to stabilise As in-situ with iron (Fe). The aim of the thesis was to investigate how well the distribution of Fe in the soil with the help of electrokinetics occurs. The work was divided into 3 parts, where part 1 and part 2 were performed in the laboratory and part 3 was performed in field. Part 1 investigated how Fe can distribute depending on how the electrodes were connected. This was done using quartz sand so visual assessment of the distribution could be done. Part 2 used the results from part 1 for a similar experiment performed on soil from Solgårdarna to see how stabilisation of As in the soil will work. Part 3 was a field test at Solgårdarna where it was tested on a pilot scale. Part 1 of was performed in two sets, 7 days each. It showed that it is possible to spread iron in the sand with the help of this method. The sand experiments achieved a covering area of 27 % respectively 28 % of rust over the entire profile during one week. Measurement with the XRF showed that where the electrode had been located the concentration of Fe increased up to 0.21-0.29 % and the concentration of Fe between the electrodes were 0.04-0.06 %. Part 2 of the experiment was performed in one setup over a 51-day period, after day 35 the experimental setup was changed due to highly fluctuating pH. The results from the experiment with soil showed that the pH is highly affected by how long the electrodes close to the sampling points were anodes or cathodes. During the experiment, a general trend for increasing As concentration in the different locations in the cell were seen. After the experiment the leachable amounts of As decreased down to 0.8-1.7 mg/kg TS compared to the untreated soil, 2.9 mg/kg TS. Part 3 of the experiment represent a 2-month field pilot test period during the autumn. Towards the end of the sampling period there was a general decrease in dissolved As and Fe in the groundwater, during the same time the groundwater level decreased, the redox potential increased and the electrical conductivity decreased. The laboratory experiments with the sand showed a removal rate around 90 % or higher, which is a good result. Those experiments were however performed using a clean inert material which is not comparable with real conditions. The field experiment was done over a short period of time due to time limitations of this thesis, while follow up of the pilot test was done within the scope of a continued research project at LTU. The given results showed a decrease in dissolved arsenic in groundwater which is a positive result. To determine whether the decrease is due to the natural adsorption of As to soil or due to the impact of provided Fe oxides requires longer monitoring of the experiment.

>Magister Scientiae - MSc / Over the past 5 years, South Africa has been experiencing a severe drought. This has caused industrial and agricultural processes, to compete for a limited supply of water. Since the economy relies mostly on agricultural activities, water consumption by industrial processes is taking its toll. One of these processes is the introduction of wet flue gas desulphurization (FGD) treatment at Eskom coal fired power stations. This dissertation explores the possibility of using membrane technology as a means of water recovery after the coal combustion flue gas has been treated with wet FGD. A lab-scale permeance testing system was specially built and modified to have complete thermal control of the environment inside the system. The permeance testing system produced a gas, similar to that of a wet FGD treated flue gas, which was then tested. A tubular lab-scale membrane module was designed and produced for the permeance testing system. The permeance figures of both Nitrogen gas and water vapour were determined for the membrane used in module production. These figures coincided with figures provided by the supplier, which warranted successful permeance testing. After success of the lab-scale testing, the data was used to design and develop a pilot-scale membrane module. This module was designed to meet pre-determined requirements as set forth by the project team. Producing lab-scale membrane modules helped identify and address possible problems in pilot-scale module design. This lead to the successful design and construction of a pilot-scale membrane module that could be used to recover the water that is needed to run the wet FGD process.

Here the nature of gas phase processes and their implications for flow and transport were examined using a pilot-scale, 2-dimensional, laboratory tank instrumented for direct, in situ trapped gas measurements. Experimental conditions mimicked an unconfined, homogeneous sand aquifer with horizontal flow. Key areas of investigation included i) trapped gas dissolution following a water table fluctuation; and ii) gas phase dynamics within a hydrocarbon plume experiencing dissolved gas production via biodegradation. In the first experiment, dissolution occurred as a diffuse, wedge-shaped front propagating down-gradient in the tank over time, with enhanced dissolution at depth. Front advancement at the deepest monitoring point was 4.1 - 5.7x faster. This dynamic, depth-dependent pattern was mainly attributed to increased dissolved gas solubility. An estimated 12% increase in quasi-saturated hydraulic conductivity (Kqs) also contributed to greater dissolution at depth. Overall, the dissolution front near the water table advanced 1 m down-gradient in 344 days, suggesting that gas trapped shallowly will likely persist for significant periods of time. The utility of total dissolved gas pressure sensors for simple in-well measurements to detect trapped gas and monitor its dissolution were also demonstrated. During the second experiment, biodegradation occurred under variable redox conditions, ranging from denitrification to methanogenesis. Significant in situ increases in trapped gas were observed within the tank over 330 days. Maximum gas saturations never exceeded 27% of pore volume even during continued dissolved gas production, indicating ebullition upon reaching a gas phase mobilization threshold. Consequently, associated reductions in Kqs were restricted to a factor of 2 or less, but still appeared to alter the groundwater flow field. While trapped gas increases within the biodegradation plume were expected, declines in gas saturations were also observed. Thus, the overall pattern of trapped gas growth exhibited high spatial and temporal variability. Influencing factors included changes in hydrocarbon inputs and microbial controls on redox zonation, in addition to ebullition and changes in groundwater flow; emphasizing that gas phase growth in contaminant plumes will be highly complex and dynamic in the natural systems. Given the impacts on hydraulic conductivity, and the fate and transport of volatile compounds, an improved understanding of quasi-saturated conditions will be beneficial for various groundwater applications, from recharge and paleoclimate studies to site characterizations and remediation strategies. / Dissertation / Doctor of Philosophy (PhD)

No description available.

Vascular networks are required to support the formation and function of three-dimensional tissues. Biodegradable scaffolds are being considered in order to promote vascularization where natural regeneration of lost or destroyed vascular networks fails. Particularly; composite materials are expected to fulfill the complex demands of a patient's body to support wound healing. Microbial biopolyesters are being regarded as such second and third generation biomaterials. Methylobacterium extorquens is one of several microorganisms that should be considered for the production of advanced polyhydroxyalkanoates (PHAs). M. extorquens displays a distinct advantage in that it is able to utilize methanol as an inexpensive substrate for growth and biopolyester production. The design of functionalized PHAs, which would be made of both saturated short-chain-length (scl, C [less than or equal to] 5) and unsaturated medium-chain-length (mcl, 6 [less than or equal to] C [less than or equal to] 14) monomeric units, aimed at combining desirable material properties of inert scl/mcl-PHAs with those of functionalized mcl-PHAs. By independently inserting the phaC1 or the phaC2 gene from Pseudomonas fluorescens GK13, recombinant M. extorquens strains were obtained which were capable of producing PHAs containing C-C double bonds. A fermentation process was developed to obtain gram quantities of biopolyesters employing the recombinant M. extorquens ATCC 55366 strain which harbored the phaC2 gene of P. fluorescens GK13, the better one of the two strains at incorporating unsaturated monomeric units. The PHAs produced were found in a blend of scl-PHAs and functionalized scl/mcl-PHAs (4 [less than or equal to] C [less than or equal to] 6), which were the products of the native and of the recombinant PHA synthase, respectively. Thermo-mechanical analysis confirmed that the functionalized scl/mcl-PHAs exhibited the desirable material properties expected. This project contributed to current research on polyhydroxyalkanoates at different levels. The terminal double bonds of the functionalized scl/mcl-PHAs are amenable to chemical modifications and could be transformed into reactive functional groups for covalently linking other biomacromolecules. It is anticipated that these biopolyesters will be utilized as tissue engineering materials in the future, due to their functionality and thermo-mechanical properties.

O processo de nitrificação e desnitrificação simultâneas (NDS) permite alcançar a remoção combinada de matérias carbonácea e nitrogenada em uma única unidade. O reator de leito estruturado, com biomassa imobilizada e recirculação interna, apresenta características positivas para que estes processos envolvidos ocorram, tais como propiciar a formação de biofilme e evitar a colmatação do leito. Esta configuração tem sido estudada com êxito em reatores em escala de bancada para tratamento de esgoto. Nesta pesquisa foi utilizado um reator de leito estruturado em escala piloto com a finalidade de avaliar sua implantação, eficiência e estabilidade tratando esgoto doméstico em condições reais para futura aplicação em pequenas comunidades, condomínios residenciais entre outros como sistema descentralizado. O reator foi construído em fibra de vidro, de formato cilíndrico, com diâmetro interno de aproximadamente 0,80 m e 2,0 m de altura. O volume total foi de aproximadamente 0,905 m3 e o volume útil de 0,642 m3. A operação foi realizada sob condições de aeração contínua e intermitente e os tempos de detenção hidráulica (TDH) testados foram de 48, 36 e 24 horas. A remoção de DQO manteve-se acima de 90% com TDH de 48 e 36 horas. A melhor eficiência de remoção de nitrogênio total foi de 72,4 ± 6,4%, sob TDH de 48 horas e a aeração intermitente, com 2 horas de aeração e 1 hora não aerada. A concentração de oxigênio dissolvido (OD) média de 2,8 ± 0,5 mg.L-1 na fase aerada e temperatura média de 24,7 ± 1,0 °C. Nesse mesmo período, a eficiência média de remoção de DQO foi de 94 ± 4 %. Apesar das dificuldades apresentadas no controle da aeração, as eficiências das remoções obtidas indicaram que o reator de leito estruturado e aeração intermitente (LEAI) se apresenta como uma alternativa promissora em escala plena, requerendo ajustes para construção e incremento da estabilidade da NDS. / The simultaneous nitrification and denitrification (SND) process allow achieving a combined nitrogen and carbon removal in a single unit. The structured-bed reactor, with immobilized biomass and internal recirculation, presents positive characteristics for occurrence of these involved processes, such as providing biofilm formation and prevent clogging. This configuration have been study successfully in a bench scale for sewage treatment. In this research was used a structured-bed reactor in a pilot scale in order to evaluate its implantation, efficiency and stability treating sewage in real conditions to future application in small communities, residential condominium among others, as decentralized treatment. The reactor was constructed with cylindrical glass fiber modules, with internal diameter of 0.8 m and 2.0 m height. The total volume was about 0.905 m3 and 0.642 m3 working volume. It was worked under continuous and intermittent aeration conditions and the tested hydraulic retention times (HRT) were 48, 36 e 24 hours. The maximum total nitrogen removal was 72.4 ± 6.4% ; the HRT was 48 hours with intermittent aeration, in which 2 hours in aeration and 1-hour nonaeration. An average dissolved oxygen (DO) concentration of 2.8 ± 0.5 mg.L-1 in the aerated time and an average temperature of 24.7 ± 1.0°C. In the same period, the average COD removal was 94 ± 4%. Despite of the difficulties presented in aeration control, the obtained removals indicated the structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA) can be a promising alternative in full scale, demanding adjustments to improve the reactor construction and the SND stability.

O processo de nitrificação e desnitrificação simultâneas (NDS) permite alcançar a remoção combinada de matérias carbonácea e nitrogenada em uma única unidade. O reator de leito estruturado, com biomassa imobilizada e recirculação interna, apresenta características positivas para que estes processos envolvidos ocorram, tais como propiciar a formação de biofilme e evitar a colmatação do leito. Esta configuração tem sido estudada com êxito em reatores em escala de bancada para tratamento de esgoto. Nesta pesquisa foi utilizado um reator de leito estruturado em escala piloto com a finalidade de avaliar sua implantação, eficiência e estabilidade tratando esgoto doméstico em condições reais para futura aplicação em pequenas comunidades, condomínios residenciais entre outros como sistema descentralizado. O reator foi construído em fibra de vidro, de formato cilíndrico, com diâmetro interno de aproximadamente 0,80 m e 2,0 m de altura. O volume total foi de aproximadamente 0,905 m3 e o volume útil de 0,642 m3. A operação foi realizada sob condições de aeração contínua e intermitente e os tempos de detenção hidráulica (TDH) testados foram de 48, 36 e 24 horas. A remoção de DQO manteve-se acima de 90% com TDH de 48 e 36 horas. A melhor eficiência de remoção de nitrogênio total foi de 72,4 ± 6,4%, sob TDH de 48 horas e a aeração intermitente, com 2 horas de aeração e 1 hora não aerada. A concentração de oxigênio dissolvido (OD) média de 2,8 ± 0,5 mg.L-1 na fase aerada e temperatura média de 24,7 ± 1,0 °C. Nesse mesmo período, a eficiência média de remoção de DQO foi de 94 ± 4 %. Apesar das dificuldades apresentadas no controle da aeração, as eficiências das remoções obtidas indicaram que o reator de leito estruturado e aeração intermitente (LEAI) se apresenta como uma alternativa promissora em escala plena, requerendo ajustes para construção e incremento da estabilidade da NDS. / The simultaneous nitrification and denitrification (SND) process allow achieving a combined nitrogen and carbon removal in a single unit. The structured-bed reactor, with immobilized biomass and internal recirculation, presents positive characteristics for occurrence of these involved processes, such as providing biofilm formation and prevent clogging. This configuration have been study successfully in a bench scale for sewage treatment. In this research was used a structured-bed reactor in a pilot scale in order to evaluate its implantation, efficiency and stability treating sewage in real conditions to future application in small communities, residential condominium among others, as decentralized treatment. The reactor was constructed with cylindrical glass fiber modules, with internal diameter of 0.8 m and 2.0 m height. The total volume was about 0.905 m3 and 0.642 m3 working volume. It was worked under continuous and intermittent aeration conditions and the tested hydraulic retention times (HRT) were 48, 36 e 24 hours. The maximum total nitrogen removal was 72.4 ± 6.4% ; the HRT was 48 hours with intermittent aeration, in which 2 hours in aeration and 1-hour nonaeration. An average dissolved oxygen (DO) concentration of 2.8 ± 0.5 mg.L-1 in the aerated time and an average temperature of 24.7 ± 1.0°C. In the same period, the average COD removal was 94 ± 4%. Despite of the difficulties presented in aeration control, the obtained removals indicated the structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA) can be a promising alternative in full scale, demanding adjustments to improve the reactor construction and the SND stability.

Os sistemas combinados anaeróbio/aeróbio para tratamento de esgotos sanitários têm sido considerados alternativas viáveis do ponto de vista técnico-econômico em relação aos sistemas tradicionais. Este trabalho apresenta os resultados obtidos com uma nova configuração de reator, composto por uma unidade central - um reator anaeróbio de manta de lodo (UASB) modificado de 286 L, associado a um reator radial aerado de leito fixo (RRLF) de 215 L, disposto de maneira a circundar a zona de separação sólido/líquido/gás do reator UASB. A principal modificação no reator UASB foi, portanto, a incorporação, junto à sua parede externa, do RRLF. A alimentação do RRLF com o efluente do UASB dá-se através de aberturas laterais na parede do UASB, o que permitiu eliminar as calhas de coleta e sistemas de alimentação do segundo reator. Esse sistema foi alimentado com esgoto sanitário obtido da rede coletora de esgotos do campus da USP de São Carlos. Esperava-se obter remoção considerável de matéria orgânica solúvel e particulada, bem como a remoção parcial de nitrogênio. Foram obtidas eficiências médias de remoção de matéria orgânica (expressa como demanda química de oxigênio - DQO) e de sólidos suspensos voláteis (SSV), de 80% e 89%, respectivamente. Em condições de operação estável, os valores de DQO e SSV no efluente atingiram 110 mg/L e 16 mg/L, respectivamente. Observou-se, também, que o sistema apresentou grande estabilidade operacional, tendo a taxa de carregamento orgânico volumétrica atingido valores da ordem de 4,0 Kg DQO.m-3d-1. Nessas condições, o sistema atingiu eficiências de remoção de DQO e SSV da ordem de 90%. O sistema misto ensaiado mostrou ser uma configuração promissora, pois promoveu a remoção eficiente de matéria orgânica e de sólidos suspensos. Considera-se, no entanto, a necessidade de se introduzirem modificações no projeto RRLF que permitam o estabelecimento dos processos de nitrificação e desnitrificação nesse reator, uma vez que foi obtida baixa eficiência de nitrificação e, conseqüentemente, a remoção de nitrogênio foi prejudicada. / Integrated anaerobic/aerobic systems have been considered feasible alternatives concerning technical and economic aspects for treating domestic wastewaters. This paper presents the results obtained from the operation of this new reactor configuration, made up of a central unit - an upflow anaerobic sludge blanket reactor (UASB), with a working volume of 286 L, associated to a radial-flow aerobic immobilized-biomass (RAIB), with a working volume of 215 L. The RAIB reactor circles the solid/liquid/gas separation zone. The main modification in the UASB reactor concerns this association with the RAIB. The UASB effluent was distributed through openings along its side walls to the RAIB, allowing the elimination of collecting channels and feeding devices from the latter reactor. The objective of this work was to promote organic matter (raw and soluble) and nitrogen removal from domestic sewage. Organic matter (as COD) and volatile suspended solids removal achieved efficiencies of 80% and 89%, respectively. Under stable operational conditions, the system effluent presented COD and volatile suspended solids values of 110 mg/L and 16 mg/L, respectively. Efficiencies of 90% for COD and volatile suspended solids removal were achieved with a organic loading rate of 4,0 Kg COD.m-3.d-1. This integrated system has shown to be a valid configuration, efficiently removing organic matter and suspended solids from the domestic wastewater. However, contrarily to expectations based on the previous studies with RAIB, nitrification was poor. Therefore, modifications to the RAIB design must be considered for the establishment of nitrogen removing processes.