Laboratory experiments were carried out to evaluate the effectiveness of antibacterial substances and antibiotics against Thiobacillus ferrooxidans, the organisms responsible for bacterial mediated acidic mine drainage. Twenty two antibiotics (obtained from Lilly and Co.) and two antibacterial substances were added to: bacterial culture ATCC 19859 grown in 9K medium. Appropriate controls were maintained. Inhibition of iron oxidizing bacteria was recorded in terms of changes in Eh of the medium treated with the compound. Seven antibiotics (A38533A:, A38533B, 197506, 13780, 171541, chloramphenicol and cephalexin) and the two antibacterial substances [N-serve(nitrapyrin) and Dicyandiamide] effectively inhibited the oxidation of Fe²⁻ ions in the medium. The kinetics of Fe²⁻ oxidation with the addition of antibiotics and the antibacterial substances was studied. N-serve [2-chloro-6-(trichloromethyl) pyridine], used as a nitrification inhibitor in agriculture, was highly effective at concentrations greater than 0.1 ml/l. Iron oxidation levels were reduced to levels close to that in uninoculated controls (abiotic oxidation). The use of N-serve to inhibit acid mine drainage (AMD) causing bacteria seems to be both economical and environmentally safe. / Master of Science

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Tekstil Mühendisliği Anabilim Dalı, 2008. / Kaynakça var.

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Química / Made available in DSpace on 2012-10-22T09:38:49Z (GMT). No. of bitstreams: 1 229168.pdf: 1272934 bytes, checksum: 85fcc78e6a05f4e4fb32a527d86427e4 (MD5) / O tratamento de águas residuárias contendo compostos nitrogenados e sulforosos é, particularmente, difícil de ser realizado. Muitas vezes, os limites imposto pela legislação ambiental não são atingidos e resíduos, com qualidade inferior aos padrões necessários, são dispostos no meio ambiente. Para reverter este cenário, é necessário o desenvolvimento de tecnologias que busquem aproveitar as interações entre os ciclos do nitrogênio e do enxofre, minimizando os custos do tratamento. Neste sentido, este trabalho foi concebido de forma a promover a eliminação biológica do nitrogênio via a integração dos ciclos do nitrogênio e do enxofre, pela ação das bactérias oxidadoras de amônio e das desnitrificantes autotróficas, como Thiobacillus denitrificans, sob aeração intermitente. Para isto, foram realizados experimentos com uma cultura pura de T. denitrificans e com uma cultura mista de bactérias oxidadoras de amônio e de enxofre. Os experimentos com a cultura pura foram realizados para verificar a influência de suplementos alimentares (Extrato de Levedura e Glicose) na cinética de desnitrificação autotrófica e, após, a influência da relação tiossulfato / nitrato sobre o balanço de enxofre. Observou-se que, neste conjunto de resultados, a presença do extrato de levedura possibilitou um aumento de 9 vezes na cinética de desnitrificação, sem alterar o metabolismo de oxidação de tiossulfato, doador de elétrons. Já, a presença de glicose inibiu a oxidação do tiossulfato, além de não se obter valores tão significativos de velocidade de crescimento. Nos experimentos realizados em diferentes relações S2O3 / NO3 observou-se que, quando o sistema está sob limitação de aceptor de elétrons, ocorre a oxidação parcial do tiossulfato com concomitante acúmulo de intermediários. Nos experimentos com cultura mista, realizados em um reator tipo SBR e alimentado com tiossulfato e amônio, observou-se a eliminação de nitrogênio pelo processo de desnitrificação autotrófica, ocorrendo concomitantemente com o processo de nitrificação parcial, formação do nitrito, se atingido eficiências de remoção acima de 70%. A flexibilidade de T. denitrificans em mudar o seu aceptor final de elétrons (nitrito para o oxigênio) possibilitou a formação do sulfato em todas as condições ensaiadas. A presença deste microrganismo, na biomassa do reator, foi confirmada pelo uso da técnica de biologia molecular FISH. Com estes resultados, a aplicação da fisiologia de T. denitrificans foi ampliada, obteve-se a eliminação biológica do nitrogênio, concomitantemente com a integração dos ciclos do nitrogênio e enxofre, em um único reator.

Made available in DSpace on 2014-06-11T19:29:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-01Bitstream added on 2014-06-13T20:59:06Z : No. of bitstreams: 1 solcia_rb_me_araiq.pdf: 1432643 bytes, checksum: 92164fbf9e408534eafc69bd3af54fbe (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foram realizados ensaios para o estudo da viabilidade da conversão de lavadores químicos (tecnologia química muito utilizada para a remoção de H2S) em biofiltros percoladores para a remoção de H2S. Foi investigado o efeito inibitório da concentração de sulfato no meio de recirculação de nutrientes, o efeito do pH, da vazão de recirculação de nutrientes, da concentração de alimentação de H2S na corrente gasosa e do tempo de residência na eficiência de remoção de H2S em dois biofiltros percoladores, um recheado com espuma de poro aberto de poliuretano e o outro com anéis de Pall de polipropileno. Durante a etapa de imobilização dos micro-organismos foi observado, experimentalmente, que o anel de Pall de polipropileno não é um bom suporte para a imobilização de Thiobacillus denitrificans e, portanto, no caso da conversão de um lavador químico constituído por um leito de recheio de anéis de Pall em um biofiltro percolador, seria apropriada a substituição deste suporte por espuma de poro aberto de poliuretano, por exemplo, que demonstrou ser um bom suporte para a formação do biofilme. Durante o estudo do efeito do pH observou-se que o aumento de pH aumenta a porcentagem de remoção de H2S, sendo que nas condições utilizadas, o intervalo de pH ótimo ficou entre 7,6 – 8,5. O efeito inibitório da concentração de sulfato foi observado a partir de 16,5 g L-1 no biofiltro de espuma de poro aberto de poliuretano e de 13,0 g L-1 no biofiltro de anéis de Pall de polipropileno. Os efeitos da vazão de recirculação de nutrientes e do tempo de residência do gás foram mais evidentes no biofitro de anéis de Pall comparado a espuma de poro aberto, devido, provavelmente, às características do suporte. No biofiltro de espuma de poro aberto, a diminuição do tempo de residência afetou a... / In this work experiments were carried out in order to study the viability of conversion of chemical scrubbers (current technology) to biotrickling filter for removing H2S. Many parameters were investigated, such as, the inhibitory effect of sulfate concentration in the nutrient recirculation, the effect of the pH, the flow rate of recirculating nutrient, the inlet H2S concentration and the gas stream residence time in the H2S removal capacity in two biotrickling filter. One of them was packaged with open pore polyurethane foam and other with polypropylene Pall rings. During and after the immobilization stage it was observed, experimentally, that polypropylene Pall rings is not a good support for immobilizing Thiobacillus denitrificans. Thus, in the case of a chemical packaged scrubber conversion using such support in a biotrickling filter, it would be appropriate to replace it by open pore polyurethane foam, for instance, which demonstrated to be a better support to the biofilm to establish. It was shown that increasing the pH an increase in the H2S removal was detected. In this experimental work conditions, the optimum pH range was from 7.6 to 8.5. The inhibitory effect of the sulfate concentration was observed from 16.5 g L-1 in the open pore polyurethane foam biofilter and 13.0 g L-1 in the polypropylene Pall rings biofilter. The effects of the flow rate of the recirculating nutrient and the gas residence time were more evident in the Pall ring biofilter when compared with the open pore foam, probably due to the support characteristics. In the open pore foam biofilter, decreasing the residence time the H2S removal percentage was affected only for less than 9 s, whereas in the Pall rings biofilter, before 33 s. In both biofilters as lower the residence time, lower the H2S removal percentage. In the open pore polyurethane foam... (Complete abstract click electronic access below)

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Biomining technologies have been developed to use acidophilic microorganisms and the reactions that they catalyze to extract metals from ores in the mining industry. This biological processing through hydrometallurgy is responsible for the production of a significant portion of the world’s copper and gold supplies. Acidithiobacillus ferrooxidans is one of the better-studied and important chemolithotrophic bacterial species that is a part of the natural consortia found in mines across the world. This acidophile is unique in the array of redox reactions it participates in as it is capable of oxidizing both iron and reduced inorganic sulfur species, enabling dissolution of metal from minerals. As the transition to renewable energy continues and the demand for electronic devices grows, more copper and other valuable metals will need to be extracted from increasingly low-grade ores, such as chalcopyrite. Additionally, there has been a growing interest in further developing this biotechnology for the leaching and the recovery of valuable metals from scrap alloys and electronic waste as these feedstock streams can contain rare metals at concentrations above those found in the earth. However, the challenge in deploying biomining to these applications involves understanding the interactions that can potentially inhibit the extraction of these metals. In this dissertation, we expanded the genetic toolbox for A. ferrooxidans by using a transposition technique for the chromosomal integration of exogenous genes. The ability to permanently modify the genome enables engineering of strains that can be used in industry without the need of maintaining selective pressure for plasmid-based expression. Next, we investigated the potential role of A. ferrooxidans in microbially influenced corrosion. We focused on finding conditions that would enable the corrosion of stainless steel, which is resistant to the medium typically used for the growth of the bacterium. Additionally, the further optimization of the corrosive environment and the introduction of genetically engineered cells led to additional corrosion of a higher-grade stainless steel. Then, we explored how altering the bioavailability of sulfur in different formulations could shift the population phenotypes in A. ferrooxidans. We found that a unified description with a few parameters could describe the wide range of behaviors observed in the presence of iron and sulfur. Thus, using this improved understanding of A. ferrooxidans, we are able to engineer phenotypes of interest to generate robust strains that can modulate leaching conditions.

In the last decades, nitrate pollution has become a major threat to groundwater quality. The consequences include health concerns and environmental impacts. Nitrate contamination is mainly derived from agricultural practices, such as the application of manure as fertilizer. The Osona area (NE Spain) is one of the areas vulnerable to nitrate pollution from agricultural sources. Nitrate is derived from intensive farming activities and the high nitrate content results in a loss of water availability for domestic uses. The most important natural nitrate attenuation process is denitrification. Denitrifying bacteria are generally heterotrophic and use carbon compounds as the electron donor. Nevertheless, a limited number of bacteria are able to carry out chemolithotrophic denitrification, and to utilize inorganic compounds. Several field studies have suggested by means of geochemical and/or isotopic data that denitrification in some aquifers is controlled by pyrite oxidation. However, the feasibility of pyrite-driven denitrification has been questioned several times in laboratory studies. This thesis is concerned with the role of pyrite in denitrification and its potential use as a bioremediation strategy. Earlier studies showed the occurrence of denitrification processes in a small area located in the northern part of the Osona region and suggested that sulfide oxidation had an important role in natural attenuation. Therefore, the first part of this thesis deals with the characterization of the denitrification processes occurring in the Osona aquifer and their spatial and temporal variations. Denitrification processes linked to pyrite oxidation were identified in some zones of the studied area by means of multi-isotopic methods integrated with classical hydrogeological methods. Nitrate removal from groundwater can be accomplished by the enhancement of in situ biological denitrification. One such bioremediation strategy is biostimulation, which involves the addition of suitable electron donors and/or energy sources to stimulate indigenous denitrifying microorganisms. The second part of this thesis is devoted to clarify the role of pyrite as electron donor for denitrification and to evaluate the feasibility of a bioremediation strategy based on pyrite addition to stimulate native denitrifying bacteria. Nitrate consumption in experiments amended with pyrite and inoculated with “Thiobacillus denitrificans” demonstrated that this bacterium is able to reduce nitrate using pyrite as the electron donor. The efficiency in nitrate removal and the nitrate reduction rate depended on the initial nitrate concentration, pH and pyrite grain size. High nitrate removal efficiency was attained in long-term flow-through experiments under laboratory conditions similar to those found in slow-moving, nitrate-contaminated groundwater. In addition, biostimulation experiments performed with sediments and groundwater from the Osona aquifer showed that the addition pyrite stimulated the activity of the indigenous microbial community and enhanced the nitrate removal. Furthermore, the long-term efficiency of the process was demonstrated. Hence, biostimulation with pyrite could be considered to remediate nitrate contamination in groundwater in future water management strategies, although further research is needed, especially at field scale. It is critical for the success of the bioremediation strategy that not only the processes but also the microbial populations and their changes induced by the bioremediation treatment be well understood. The addition of pyrite resulted in an increase in the proportion of denitrifying bacteria and both autotrophic and heterotrophic denitrifiers were stimulated. Bacterial populations closely related to the “Xanthomonadaceae” might probably be the dominant autotrophic denitrifiers that used pyrite as the electron donor in the biostimulated experiments. The N and O isotopic enrichment factors associated with the pyrite‐driven denitrification were computed and used to recalculate the extent of the natural nitrate attenuation in the Osona aquifer. This refinement becomes useful to predict the evolution of the contaminant in the aquifer, and it should be taken into account for potential implementation of induced remediation techniques. The isotopic approach was proved to be an excellent tool to identify and quantify natural denitrification processes in the field, and to monitor the efficacy of bioremediation strategies in the laboratory. In order to improve the long-term performance of potential bioremediation strategies based on pyrite-driven denitrification, it is necessary to know the contribution of attached and free-phase denitrifying bacteria to this process in aquifers. The last part of this thesis addresses the ability of “T. denitrificans” to grow and colonize pyrite surfaces. In the colonization experiments, attachment onto pyrite surface was required for at lest a small number of the cells in order to accomplish pyrite-driven denitrification. Nevertheless, both attached and planktonic cells probably contributed to the overall denitrification. However, the details of the relative roles of the two phases and the specific mechanisms remain to be addressed. / A les darreres dècades, la contaminació de nitrat de l’aigua subterrània ha esdevingut un dels principals problemes que afecten la qualitat dels recursos hídrics subterranis. La presència de nitrat a l’aigua subterrània està relacionada, principalment, amb pràctiques agrícoles, com per exemple, l’ús intensiu de purins com a fertilitzant orgànic. La comarca d’Osona (Catalunya) és una de les àrees declarades vulnerables a la contaminació per nitrat d’origen agrícola. El nitrat procedeix principalment de la intensa activitat agrícola i ramadera. El principal procés d’atenuació natural del nitrat és la desnitrificació. La majoria dels bacteris desnitrificants són heteròtrofs i usen compostos orgànics com a font d’electrons. Tanmateix, també existeixen bacteris desnitrificants autòtrofs que són capaços d’usar compostos inorgànics, com a donants d’electrons. Estudis de camp previs han demostrat a partir de dades geoquímiques i/o isotòpiques que en alguns aqüífers la desnitrificació està controlada per l’oxidació de pirita. Tot i així, hi ha estudis de laboratori que qüestionen la viabilitat de la desnitrificació lligada a l’oxidació de pirita (compost inorgànic donant d’electrons). En aquesta tesi s’estudia el paper de la pirita en la desnitrificació i la seva possible aplicació com a estratègia de bioremediació d’aigües contaminades amb nitrat. Estudis previs demostraren l’ocurrència de processos de desnitrificació a Osona, en una petita àrea situada en el sector nord de la zona d’estudi. Els resultats d’aquests estudis suggereixen que l’oxidació de sulfurs hi juga un paper molt important en l’atenuació natural. A la primera part de la tesi s’exposa la caracterització dels processos de desnitrificació que tenen lloc en l’aqüífer d’Osona, així com de les seves variacions temporals i espacials. S’han usat mètodes multi-isotòpics integrats amb mètodes hidrogeològics clàssics, que han servit per identificar l’existència de processos de desnitrificació lligats a l’oxidació de pirita en algunes zones de l’àrea d’estudi. L’eliminació del nitrat de l’aigua subterrània pot aconseguir-se mitjançant estratègies que incentiven la desnitrificació biològica in situ. Una de les estratègies de bioremediació in situ és la bioestimulació, que consisteix en afegir donants d’electrons o fonts d’energia apropiades per tal d’estimular l’activitat de bacteris desnitrificants existents en el medi. En la segona part de la tesi s’esbrina el paper de la pirita com a potencial donant d’electrons en els procés de desnitrificació i s’avalua la viabilitat d’una estratègia de bioremediació, basada en l’addició de pirita per estimular l’activitat de bacteris desnitrificants autòctons. Experiments amb pirita i inoculats amb “Thiobacillus denitrificans” han demostrat que aquest bacteri és capaç de reduir el nitrat utilitzant la pirita com a donant d’electrons. A més a més, s’ha determinat que l’eficiència i la velocitat de reducció del nitrat depèn de la seva concentració inicial, del pH i de la mida de gra de la pirita. En experiments de flux continu, de llarga durada que simulen el flux d’aigües subterrànies contaminades amb nitrat, s’han aconseguit altes eficiències en l’eliminació del nitrat. A més a més, s’han realitzat experiments de bioestimulación amb pirita usant aigua subterrània i sediments de l’aqüífer d’Osona. Aquests experiments han demostrat que afegint pirita s’aconsegueix d’estimular l’activitat dels bacteris desnitrificants autòctons i, per tant, induir i/o augmentar la desnitrificació. També, s’ha provat l’alta eficiència d’aquest procés a llarg termini. Per tant, l’ús de la pirita podria tenir-se en compte com a estratègia per a l’eliminació de nitrat en properes mesures de gestió dels recursos hídrics. Tanmateix, cal més investigació, i especialment, a escala de camp. Per aconseguir l’èxit amb la bioremediació cal conèixer amb detall els processos i les poblacions microbiològiques que intervenen en els canvis poblacionals associats al tractament de bioremediació. Els resultats dels experiments de bioestimulació han demostrat que els bacteris desnitrificants autòtrofs dominants en el sistema són probablement poblacions relacionades amb Xanthomonadaceae. L’addició de pirita puposa un increment en la proporció de bacteris desnitrificants i produeix l’estimulació tant dels desnitrificants autòtrofs com dels heteròtrofs. A més a més, s’han calculat els factors d’enriquiment isotòpic de N i O associats al procés de desnitrificació per oxidació de pirita. Aquests factors d’enriquiment s’han usat per recalcular el grau d’atenuació natural del nitrat que té lloc en l’aqüífer d’Osona. Aquest recàlcul pot ser d’utilitat a l’hora de predir l’evolució de la contaminació en l’aqüífer i cal tenir-lo en compte a l’hora d’implementar possibles tècniques de remediació induïda. Per tant, la metodologia isotòpica ha demostrat ser una eina excel∙lent per identificar i quantificar processos de desnitrificació natural i per monitoritzar l’eficàcia d’estratègies de bioremediació en el laboratori. Per millorar el rendiment i la durabilitat de potencials estratègies de bioremediació basades en la desnitrificació i oxidació de pirita és necessari conèixer la contribució relativa dels bacteris desnitrificants planctònics i dels bacteris adherits als sediments. Així, a l’última part de la tesi l’interès s’enfoca en l’avaluació de l’habilitat de “T. denitrificans” en colonitzar i créixer sobre la superfície de la pirita. Els resultats experimentals de colonització suggereixen que per aconseguir la desnitrificació amb pirita com a donant d’electrons, cal que una part dels bacteris s’adhereixi a la superfície de la pirita. No obstant, sembla que ambdós bacteris, adherits i planctònics, contribueixen al procés global. Tanmateix, queda pendent d’examinar el paper específic de cada tipus en la desnitrificació.