This work represents a study on the biological oxidation of molybdenite, MoS2. The principal objective of this study was to investigate the possibility of the biological oxidation of molybdenite, to determine the physical and chemical conditions under which the oxidative process occurs, and to develop a strain of bacteria or alter the activity of the microorganisms by acclimatization to increase their activity on sulfide minerals, in particular molybdenite. Minerals used in this study were pyrite (FeS2), chalcopyrite (CuFeS2), molybdenite concentrate, and molybdenite ore. The microorganisms used in this investigation were autotrophic bacteria obtained from the leaching streams of Bingham Canyon, Utah. The apparatus consisted of sixty-four airlift percolators containing Ottawa sand (SiO2) as a dispersing medium for the finely divided sulfide minerals. The studies were perfomed by inoculating the solutions in the percolators with active cultures and comparing the amount of soluble molybdenum and other desired components produced with the amount found in a controlled sample. The effect of the following ions in the nutrient requirements: phosphate, ferrous iron, cupric copper, and aluminum on the molybdenite oxidative process were studied. The result of mixing pyrite and chalcopyrite with molybdenite concentrate for oxidation was also determined. The effect of the molybdate ion and phosphate ion concentrations were determined on the biological oxidation of pyrite. Studies were performed on the biological oxidation of molybdenite ore and molybdenite ore mixed with pyrite to determine the percentage molybdenum solublized, also the relative oxidation states or the solublized molybdenum. The effect of repeated bacterial transfer and molybdenite ore particle size was determined upon the biological oxidation. There were no components found in the Bingham Canyon streams that would precipitate the molybdate ion. Although these results were obtained from a synthetic media under laboratory conditions, they have provided conclusive evidence that it is possible to oxidize molybdenite by the aid of soil microorganisms.

This research study's the use of biological sulfate reduction technologies for the treatment of Sasol Secunda's coal-mine drainage (CMD) using Fischer-Tropsch Reaction Water (FTRW) as a cost-efficient carbon source. The research aims to develop a prototype dynamic model that describes this co-treatment of FTRW and CMD in both a continuously stirred tank reactor (CSTR) biological sulfate reduction (BSR) system and a BSR gas-lift (BSR-GL) integrated system. The BSR-GL system recovers elemental sulfur (S0 ) from the H2S produced and stripped from the BSR unit. Furthermore, this study aims to use the prototype model for a quantitative comparison of the CSTR-BSR and BSR-GL systems. Two bench-scale 5-litre CSTR-BSR and a 20-litre BSR-GL system were operated, under varying feed COD concentrations and hydraulic retention times (HRTs), to generate datasets for use in verification and a rudimentary validation of the prototype model. The BSR-GL integrated system includes 1) a 1-litre H2S gas reactive absorption (ABS) unit utilising an aqueous ferric solution for the recovery of elemental sulfur (S0 ) from sulfide and 2) ferrous biological oxidation reactor to regenerate ferric from the ferrous for re-supply to the ABS unit. The datasets generated in the experimental study allowed for the identification, mathematical modelling and reaction verification of 32 components that interact as reactants and products in 23 reactions observed in the two BSR systems. The prototype model is presented in a mass and charge balanced Gujer matrix that includes, i) 5 SRB mediated processes, ii) 2 liquid-gas mass transfer processes, iii) 3 processes describing the ABS and Fe2+ bio-oxidation units, iv) 4 processes describing sulfide and elemental sulfur oxidation and v) the S0 and poly-sulfide aqueous equilibrium and vi) 9 processes describing death regeneration and BPO hydrolysis. This prototype model was implemented in the DHI WEST® software for initial stage simulation trials. The experimental datasets allowed for the first-stage estimation of the best-fit reaction rate equations and the calibration of the kinetic parameters related to the 23 reactions, using MATLAB® curve fitting toolbox. A pre-processor that describe the pH and equilibrium chemistry of the components of the artificially prepared FTRW+CMD feed mixture batches under varying total concentrations have also been developed in this research. This was done to generated influent file to the DHI WEST® simulations that incorporated the dynamics related to the FTRW+CMD feed mixtures. The sulfate utilisation rate (gSO4 -2 .l-1 .d-1 ) of the GL-BSR and CSTR-BSR systems were compared to determine which system had the best sulfate removal. The results were found to be as follows; a. On comparison it was found that the sulfate substrate utilisation rate for the CSTR_BSR system is 39.28% of that of the BSR-GL_N2 system, where both systems were fed at feed mixture of COD of 2500mgCOD/l, where the COD:SO4 2- was 0.7, b. For the same systems fed a feed mixture of COD at 5000mgCOD/l (COD:SO4 2- = 0.7), the sulfate substrate utilisation rate for the CSTR_BSR system was found to be 17.86% less than that of the BSR_GLN2 system. c. Finally, it was also found that the substrate utilisation rate for the CSTR_BSR system was 30.06% less than that of the BSR_GLN2 system at Se of 4gCOD/l, for both systems fed substrate at 5000mgCOD/l. Thus, it can be concluded that the sulfate substrate utilisation rate for the BSR-GL system is higher than that of the CSTR_BSR system, for systems fed COD feed mixtures at 2.5 or 5gCOD/l where both systems have the same effluent substrate concentrations. However, the difference in the comparative substrate utilisation rate is less at higher feed substrate concentrations. This is the influence of substrate inhibition on the active SRB biomass, which increases with higher effluent substrate concentrations. Finally, this research found that the use of gas-lift reactor technologies is superior to CSTR technologies in the treatment of coal-mine drainage utilising biological sulfate reduction (BSR). The CSTR-BSR system, fed sulfate between 1.6 to 14gSO4 2- /l, produced effluent with high dissolved H2S concentrations, on average 285mgS/l and maximum at >600mgS/l. Releasing this effluent to the environment would be hazardous to aquatic and human health and corrosive to infrastructure. As such, the effluent from the CSTR-BSR system requires further treatment to stabilise the water for any use. The BSR-GL technology allows for the conversion of the H2S produced during BSR reactions to form elemental sulfur, which is a resource recovered from this process, thus complying to the circular economy aim of this study.

Groundwater is an important source of fresh water on earth. A source that is also affected by climate change. Climate change is expected to influence both the groundwater quality and the groundwater level, where elevated levels of iron and manganese in the groundwater are to be expected. In Sweden guideline values are set for iron and manganese in drinking water, which means that waterworks that use groundwater as raw water must treat the water when the guidline values are exceeded. A common treatment step to remove iron and manganese is abiotic oxidation with a chemical oxidant. A relatively new method is biological oxidation where microorganisms oxidize the metals. Biological oxidation has proven to be a faster process than chemical oxidation and better adapted to variations in raw water quality. In this work the possibility of biological oxidation of iron and manganese at smaller groundwater plants with day-to-day production breaks has been studied. The study also concern how seasonal variations in raw water quality might affect the oxidation ability of the microorganisms. During the study a pilot filter for biological oxidation was constructed where the efficiency of the filter and the raw water quality was measured during a one-year test. After a short start-up time for iron oxidation the pilot filter reduced iron in the raw water up to 92 % and after a longer start-up time for manganese oxidation the pilot filter reduced manganese from the raw water up to 97 % during the rest of the test period. The results show that biological oxidation is possible at smaller groundwater plants despite production breaks. The results also show that biological oxidation is not affected by the vaiations i raw water quality that was measured during the test period. Furthermore, the results show that biological oxidation is equally efficient as the chemical oxidation, at the investigated groundwater plant, in terms of removing iron and even more efficient in terms of removing manganese. In addition the biological oxidation do not require pH adjustment or addition of any chemicals. The results indicate that biological oxidation of iron and manganese is a more favorable alternative to chemical oxidation in smaller groundwater plants on the impact of climate change on raw water quality.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2018-04-26T23:32:00Z No. of bitstreams: 1 Aline_Pauli_2018.pdf: 5534766 bytes, checksum: 389503e1e5a4307c462f405e73451ed5 (MD5) / Made available in DSpace on 2018-04-26T23:32:00Z (GMT). No. of bitstreams: 1 Aline_Pauli_2018.pdf: 5534766 bytes, checksum: 389503e1e5a4307c462f405e73451ed5 (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work aims to remove efficiently organic and inorganic pollutants from a municipal sanitary landfill leachate effluent (SLLE) through of the integrated purification treatment application, composed by the electrocoagulation (ECP) and biological oxidation processes (BOP), looking for the drastic drop on the toxicity. In the first treatment phase, an ECP-based reactor was constructed consisting in a series of 6 aluminum electrode, providing an effective area of 350 cm2 and a useful volume of 1,0 L. In the framework of the response surface methodology (RSM), a 3³ complete factorial experimental design (CFED) at three levels of the three ECP important parameters: initial pH, electric current density (ECD) and electrolysis time (ET) was regarded. A set of responses related to the ECP treatment, such as, the reduction of color, turbidity, COD and iron concentration, was interpreted within the RSM. Additionally, the Analysis of Variance (ANOVA was applied to assess the quality of the second-order polynomial mathematical models that were adjusted to the CFED data. Keeping fixed the best ECP condition (pH and ECD) for the pollutant removals, a set of kinetic tests was carried out regarding a wide range of ET values. The toxicity of ECP treated samples was assessed by the application of bioassays based on the mortality level of the brine shrimp (Artemia salina) and the germination of Lactuca sativa seeds. The toxicity level was assessed by a statistical estimation of the median lethal concentration (LC50) through the application of bioassays with Artemia salina and Lactuca sativa. The biodegradability index by applying the Zahn Wellens test was also assessed. Keeping fixed the ECP condition for which was obtained the lowest toxicity and the highest biodegradability index, the second phase of treatment by BOP was performed. In this regard, a biological reactor with a useful volume of 3.5 L was adjusted to operate keeping fixed the condition of pH 7, temperature of 33 oC and dissolved oxygen of 50%. A relation food/microorganism of one was considered. After that, the residual ammonia in samples was completely removed applying the stripping method (air injection of 50 Lh-1). From the CFED data related to the first treatment phase, the best ECP condition was found by setting the pH at 5, ET at 120 min and ECD at 128.57 Am-2 for which was obtained the maximum removal of 99, 98, 68 e 99% for color, turbidity, COD and iron concentration, respectively. From the kinetic tests, it was possible to verify that the application of the ECP has actually reduced the SLLE toxicity being an ET of 5 min enough to achieve the minimum time required to obtain the lowest toxicity index (LC50 of 43%) that was found in both biotests. The highest biodegradability index was found when an ET value of 45 min. was regarded. The second POB treatment has showed a significant performance on removals of the organic parameters, with values of 95% and 89% for COD and DOC, respectively. Because of achieving an almost 100% removal of the ammoniacal nitrogen, the main result was the substantial improvement on the LC50 value about of 95%, as suggested by the A. salina biotest. Thus, although there were small amounts of pollutants after both treatments (PEC and POB), an almost total toxicity depletion. / Este trabalho, tem como objetivo remover eficientemente os poluentes orgânicos e inorgânicos de efluente de lixiviado proveniente de aterro sanitário municipal mediante a aplicação do tratamento de purificação integrado composto pelos Processos de Eletrocoagulação (PEC) e Oxidação Biológica (POB), visando especificamente a queda da toxicidade e o cumprimento da condição ambientalmente segura para o descarte final em corpos hídricos. Para o PEC, construiu-se um reator com 6 eletrodos de alumínio, tendo uma área efetiva de 350 cm2 e um volume efetivo de efluente de 1,0 L. No contexto da Metodologia de Superfícies de Resposta (MSR), foi proposto um planejamento experimental 3³, variando-se três parâmetros importante do PEC: pH inicial, Densidade de Corrente Elétrica (DCE) e Tempo de Eletrólise (TE). As respostas ao tratamento por PEC (cor, turbidez, DQO e concentração de ferro) foram interpretadas dentro da MSR, verificando pela Análise de variância (ANOVA) a qualidade da representatividade dos modelos matemáticos, polinomiais de segunda ordem, ajustados aos dados. Mantendo fixa a melhor condição de remoção de poluentes pelo PEC quanto ao pH e DCE, experimentos cinéticos foram realizados considerando um amplo intervalo de TE. O nível de toxicidade foi inferido a partir da estimativa estatística da concentração letal mediana (CL50) mediante a aplicação de biotestes utilizando o microcrustáceo Artemia salina e sementes de Lactuca sativa. Avaliou-se o índice de biodegradabilidade, segundo o teste de Zahn Wellens. Na menor toxicidade e o maior índice de biodegradabilidade do lixiviado tratado pelo PEC foi realizada a aplicação da segunda fase de tratamento por POB. Para tanto, foi ajustado o reator biológico, com volume útil de 3,5 L a operar, de forma controlada, na condição de pH 7, temperatura de 33 oC e oxigênio dissolvido de 50%. Utilizou-se uma relação alimento/microrganismo igual a um. Após a realização da integração dos processos, foi feita a remoção de amônia residual do efluente pelo método de arraste (injeção de ar a 50 Lh-1). Da análise do planejamento da primeira fase de tratamento, encontrou-se a melhor condição do PEC no valor de pH igual a 5; TE em 120 min e DCE em 128,57 Am-2 cujo efeito foi a obtenção da máxima remoção de 99, 98, 68 e 99% na cor, turbidez, DQO e concentração de ferro, respectivamente. A partir dos testes cinéticos, foi possível verificar que o PEC reduziu consideravelmente a toxicidade, sendo o TE de 5 minutos a condição de menor toxicidade (CL50 de 43%) que foi encontrada por ambos os biotestes. O índice de biodegradabilidade do efluente de lixiviado tratado teve um aumento de aproximadamente 20% em relação ao efluente bruto para todos os tempos de tratamento por PEC; porém, o maior índice de biodegradabilidade foi encontrado quando houve um TE de 45 minutos. O segundo tratamento por POB apresentou expressiva remoção dos parâmetros orgânicos, sendo obtidas remoções de 95% e 89% para a DQO e o COD, respectivamente. Após a aplicação do processo de arraste de amônia, uma remoção de quase 100% do nitrogênio amoniacal foi alcançada, obtendo uma a CL50 da ordem de 95%, como revelada pelo bioteste com A. salina. Portanto, embora houvesse quantidades pequenas de poluentes após ambos os tratamentos (PEC e POB), atingiu-se a quase total depleção da toxicidade.