Thesis (PhD (Chemical Engineering))--Cape Peninsula University of Technology, 2019 / Simultaneous nitrification and aerobic denitrification (SNaD) is a preferred method for single stage total nitrogen (TN) removal, which was recently proposed to improve wastewater treatment plant design. However, SNaD processes are prone to inhibition by toxicant loading with free cyanide (CN-) possessing the highest inhibitory effect on such processes, rendering these processes ineffective. Despite the best efforts of regulators to limit toxicant disposal into municipal wastewater sewage systems (MWSSs), free cyanide (CN-) still enters MWSSs through various pathways; hence, it has been suggested that CN- resistant or tolerant microorganisms be utilized for processes such as SNaD. To mitigate toxicant loading, organisms in SNaD have been observed to adopt a multiphase growth strategy to sequentially degrade CN- during primary growth and subsequently degrade TN during the secondary growth phase. However, CN- degrading microorganisms are not widely used for SNaD in MWSSs due to the inadequate application of suitable microorganisms (Chromobacterium violaceum, Pseudomonas aeruginosa, Thiobacillus denitrificans, Rhodospirillum palustris, Klebsiella pneumoniae, and Alcaligenes faecalis) commonly used in single-stage SNaD. The use of CN- degrading or resistant microorganisms for SNaD is a cost-effective method compared to the use of other methods of CN- removal prior to TN removal, as they involve multi-stage systems (as currently observed in MWSSs). The use of CN- degrading microorganisms, particularly when used as a consortium, presents a promising and sustainable resolution to mitigate inhibitory effects of CN- in SNaD. However, SNaD is known to be completely inhibited by CN- thus it is imperative to also study some thermodynamic parameters of SNaD under high CN- conditions to see the feasibility of the process. The Gibbs free energy is significant to understand the feasibility of SNaD, it is also vital to study Gibbs free energy to determine whether or not the biological reaction is plausible. The relationship between the rate of nitrification and Gibbs free energy was also investigated. The attained results showed that up to 37.55 mg CN-/L did not have an effect on SNaD. The consortia degraded CN- and achieved SNaD, with degradation efficiency of 92.9 and 97.7% while the degradation rate of 0.0234 and 0.139 mg/L/hr for ammonium-nitrogen (NH4-N) and CN- respectively. Moreover, all the free Gibbs energy was describing the individual processes were found to be negative, with the lowest Gibbs free energy being -756.4 and -1830.9 Kcal/mol for nitritation and nitratation in the first 48 h of the biological, reaction respectively. Additionally, a linear relationship between the rate of NH4-N and nitrite-nitrogen (NO2-N) degradation with their respective Gibbs free energy was observed. Linear model was also used to predict the relationship between NH4-N, NO2-N degradation and Gibbs free energy. These results obtained showed a good correlation between the models and the experimental data with correlation efficiency being 0.94 and 0.93 for nitritation, and nitratation, respectively. From the results found it can be deduced that SNaD is plausible under high cyanide conditions when cyanide degrading or tolerant microorganisms are employed. This can be a sustainable solution to SNaD inhibition by CN- compounds during wastewater treatment. Furthermore, a single strain was purified from the consortium and identified as Acinetobacter courvalinii. This bacterial strain was found to be able to perform sequential CN- degradation, and SNaD; an ability associated with multiphase growth strategy of the microorganism when provided with multiple nitrogenous sources, i.e. CN- and TN. The effect of CN- on nitrification and aerobic denitrification including enzyme expression, activity and protein functionality of Acinetobacter courvalinii was investigated. It was found that CN- concentration of up to 5.8 mg CN-/L did not affect the growth of Acinetobacter courvalinii. In cultures whereby the A. courvalinii isolate was used, degradation rates of CN- and NH4-N were found to be 2.2 mg CN-/L/h and 0.40 mg NH4-N/L/h, respectively. Moreover, the effect of CN- on NH4-N, nitrate-nitrogen (NO3-N) and NO2-N oxidizing enzymes was investigated, with findings indicating CN- did not affect the expression and activity of ammonia monooxygenase (AMO), but affected the activity of nitrate reductase (NaR) and nitrite reductase (NiR). Nevertheless, a slow decrease in NO2-N was observed after the addition of CN- thus confirming the activity of NaR and the activation of the denitrification pathway by the CN-. Moreover, five models’ (Monod, Moser, Rate law, Haldane, and Andrew’s model) ability to predict SNaD under CN- conditions, indicated that only Rate law, Haldane and Andrew’s models, were suited to predict both SNaD and CN- degradation. Due to low degradation rates of NH4-N and CN-, optimization of SNaD was essential. Therefore, response surface methodology was used to optimize the SNaD under CN- conditions. The physiological parameters that were considered for optimization were temperature and pH; with the result showing that the optimum for pH and temperature was 6.5 and 36.5oC respectively, with NH4-N and CN- degradation efficiency of 50 and 80.2%, respectively. Furthermore, the degradation kinetics of NH4-N and CN- were also studied under the optimum conditions in batch culture reactors, and the results showed that up to 70.6% and 97.3% of NH4-N and CN- were simultaneously degraded with degradation rates of 0.66 and 0.41 mg/L/h, respectively. The predictive ability of RSM was further compared with cybernetic models, and cybernetic models were found to better predict SNaD under CN- conditions. These results exhibited a promising solution in the management of inhibition effected of CN- towards SNaD at an industrial scale.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-08-18T17:45:44Z No. of bitstreams: 1 2010 - Isabel Matos de Fraga.pdf: 5201934 bytes, checksum: 6bbaeba09901aea4cbaa9f69dbb0402e (MD5) / Made available in DSpace on 2017-08-18T17:45:44Z (GMT). No. of bitstreams: 1 2010 - Isabel Matos de Fraga.pdf: 5201934 bytes, checksum: 6bbaeba09901aea4cbaa9f69dbb0402e (MD5) Previous issue date: 2010-12-08 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. / The researches on recycling of industrial wastes has been stepped up around the world to enhance the quality of the recycled product and provide greater efficiency of the productive system. The recycling of plastic materials has also grown in recent years, with Brazil improving its market position. In this way, this work aimed the development of composite materials using as a matrix, the low density polyethylene recycled (PEBDrec), chemical treated with oxidizing agents and, as fillers, E-cat and waste of scale. The PEBDrec was treated with oxidizing agent in order to cause modifications over its chemical structure and to improve compatibility with the residues of scale and E-cat. Were produced composites of PEBDrec treated with hydrogen peroxide (H2O2) and scale; PEBDrec treated with hydrogen peroxide and E-cat; PEBDrec treated with potassium permanganate (KmnO4) and scale and PEBDrec treated with potassium permanganate and E-cat. Were also obtained composites of PEBDrec untreated and mixed with scale or E-cat, to evaluate the action of the oxidizing agent in the compatibility between fillers that were used and the polymer matrix. The results obtained by the analysis of FTIR, XDR, TGA, SEM and mechanicals tests presented that the composites of PEBDrec treated with oxidizing agents showed a good interaction between the dispersed phase and the polymer matrix in comparison to composites PEBDrec without chemical treatment, and this compatibility was better for the lowest proportions. But this good interaction resulted in a decrease of thermal stability of composites in relation to the polymer matrix. It was also observed that the oxidizing agent KMnO4 was more effective in increasing the compatibility between the polymer and the E-cat, while the oxidizing agent H2O2 acted more strongly on increasing the compatibility between the polymer and scale. The composites of PEBDrec untreated, compared to the composites of PEBDrec treated with H2O2 and treated with KMnO4 , had a lower water absorption, indicating that chemical treatment was effective to modify the structure of the polymer, inducing the surface to a greater polarity, giving the chemical treated composites of PEBDrec a higher affinity to water. However a material more mechanical resistant was obtained just with the untreated polymer. The incorporation of the charges in the polymer matrix did not change the density of the material composites, indicating that despite of these materials be crystalline, they present low density, being possible to be used in civil construction. / As pesquisas sobre a reciclagem de res?duos industriais v?m sendo intensificadas em todo o mundo a fim de aumentar a qualidade do produto reciclado e propiciar maior efici?ncia do sistema produtivo. O reaproveitamento de materiais pl?sticos tamb?m tem crescido nos ?ltimos anos, com o Brasil melhorando seu posicionamento no mercado. Nesse sentido, essa disserta??o objetivou o desenvolvimento de materiais comp?sitos utilizando como matriz, o polietileno de baixa densidade reciclado (PEBDrec), tratado quimicamente com agentes oxidantes e como cargas, res?duos de Carepa e E-cat. O PEBDrec foi submetido a tratamento com agentes oxidantes com o objetivo de causar modifica??es na sua estrutura qu?mica e, propiciar uma melhoria na compatibilidade com os res?duos de carepa e E-cat. Foram produzidos comp?sitos de PEBDrec tratado com per?xido de hidrog?nio (H2O2) e carepa; PEBDrec tratado com per?xido de hidrog?nio e E-cat; PEBDrec tratado com permanganato de pot?ssio (KMnO4) e carepa e PEBDrec tratado com permanganato de pot?ssio e E-cat. Tamb?m foram obtidos comp?sitos de PEBDrec n?o tratado misturado a carepa ou E-cat, para avaliar a a??o do agente oxidante na compatibilidade entre a matriz polim?rica e as cargas utilizadas. Os resultados obtidos pelas an?lises de FTIR, DRX, TGA, MEV e ensaios mec?nicos mostraram que os comp?sitos de PEBDrec tratado com os agentes oxidantes apresentaram uma boa intera??o entre a fase dispersa e a matriz polim?rica em compara??o aos comp?sitos de PEBDrec sem o tratamento qu?mico, e essa compatibilidade foi melhor para as menores propor??es. Por?m, essa boa intera??o acarretou em uma diminui??o da estabilidade t?rmica dos comp?sitos, em rela??o a matriz polim?rica. Tamb?m foi poss?vel observar que o agente oxidante KMnO4 foi mais eficaz no aumento da compatibilidade entre o pol?mero e o E-cat, enquanto que o agente oxidante H2O2 atuou mais fortemente no aumento da compatibilidade entre o pol?mero e a carepa. Os comp?sitos de PEBDrec n?o tratado, em compara??o aos comp?sitos de PEBDrec tratados com H2O2 e tratados com KMnO4, apresentaram uma menor absor??o de ?gua, indicando que o tratamento qu?mico foi eficaz para modificar a estrutura do pol?mero deixando sua superf?cie com maior polaridade e conferindo aos comp?sitos de PEBDrec tratado quimicamente uma maior afinidade pela ?gua. Por?m um material mais resistente mecanicamente s? foi obtido com o pol?mero n?o tratado. A incorpora??o das cargas na matriz polim?rica praticamente n?o alterou a densidade desses materiais comp?sitos, indicando que apesar de eles serem materiais cristalinos, eles apresentam baixa densidade, sendo poss?vel suas aplica??es no ramo da constru??o civil.

The ability of Nakivubo wetland (which has performed tertiary water treatment for Kampala city for the past 40 years) to respond to pollution and to protect the water quality of Inner Murchison Bay of Lake Victoria was investigated. The aim of this study was to assess the capacity of Nakivubo wetland to remove nitrogen from the wastewater after its recent encroachment and modification, in order to optimize biological nitrogen removal processes using constructed wetland technology. Field studies were performed to assess the hydraulic loading, stability and water quality of this wetland. The distribution and activity of ammonium-oxidizing bacteria (AOB) in Nakivubo channel and wetland were also investigated, and the significance of the different matrices in biological nitrogen transformations within the two systems elucidated. Studies to optimize nutrient removal processes were carried out at pilot scale level both in container experiments and in the field using substrate-free constructed wetlands (CWs) planted with Cyperus papyrus and Miscanthidium violaceum which were adapted to the local ecological conditions. Results showed that Nakivubo wetland performs tertiary treatment for a large volume of wastewater from Kampala city, which is characterised by large quantities of nutrients, organic matter and to a lesser extent metals. Mass pollutant loads showed that wastewater effluent from a sewage treatment plant constituted a larger proportion of nitrogen and phosphorus and biochemical oxygen demand (BOD) discharged into the wetland. The upper section of Nakivubo wetland exhibited high removal efficiencies for BOD, whereas little or no ammonium-nitrogen and metals except Lead were removed by wetland. Studies further showed that nitrifying bacteria existed in the wetland but their activity was limited by oxygen depletion due to the high BOD in the wastewater and heterotrophic bacteria from the sewage treatment plant. Distributional studies indicated the presence of more AOB in surface sediments than the water column of the lower section of Nakivubo channel, an indication that nitrifiers settled with particulate matter prior to discharge into the wetland, and thus did not represent seeding of the wetland. The significant reductions in concentrations of BOD compared to ammonium and total nitrogen in the channel and wetland wastewater confirmed this finding. Whereas suspended nitrifiers upstream of Nakivubo channel equally influenced total nitrogen balance as those in surface sediments, epiphytic nitrification was more important than that of sediment/peat compartments in the wetland, and thus highlighted the detrimental impacts of wetland modification on the water quality Inner Murchison Bay and Lake Victoria as a whole. Performance assessment of pilot-scale container experiments and field-based CWs indicated highly promising treatment efficiencies, notably in papyrus-based treatments. Plant biomass productivity, nutrient storage, and overall system treatment performance were higher in papyrusbased constructed wetlands, and resulted in effluent that met national discharge limits. Thus, papyrus-based CWs were found to be operationally efficient in removing pollutants from domestic wastewater. / QC 20101028

The objectives of this project were to evaluate the efficacies of electrolyzed oxidizing (EO) and ozonated waters as antimicrobial agents for enhancing the microbiological safety of fresh strawberries (Fragaria x ananassa). The influence of sodium chloride (NaCl) concentrations used for preparing EO water was evaluated on their bactericidal activities against naturally occurring aerobic mesophiles on strawberries with a contact time of 5, 10, or 15 min. EO water and ozonated water containing about 1.90 ppm ozone were evaluated and compared with sodium hypochlorite (NaOCl) solution on their capabilities to inactivate and control the growth of Listeria monocytogenes and Escherichia coli O157:H7 inoculated onto strawberries stored at 4 ± 1 °C for up to 15 d, respectively. Post-treatment neutralization of fruit surfaces by washing was also investigated. More than 2 log₁₀ CFU/g reduction of mesophilic aerobic bacteria was achieved in samples washed for 10 or 15 min in EO water prepared from 0.10% (w/v) NaCl solution. Bactericidal activity of treatment solutions against L. monocytogenes and E. coli O157:H7 was not affected by post-treatment neutralization, and their effectiveness against both pathogens in whole fruit tissues did not significantly increase with increasing exposure time. The EO water had an equivalent antibacterial effect as compare with NaOCl in eliminating L. monocytogenes and E. coli O157:H7 on whole strawberry tissues. Fruit surfaces washing with distilled water resulted in 1.90 and 1.27 log₁₀ CFU/ml of rinse fluid reduction of L. monocytogenes and E. coli O157:H7, respectively, whereas ≥ 2.60 log₁₀ CFU/ml of rinse fluid reduction of L. monocytogenes and up to 2.35 and 3.12 log reduction of E. coli O157:H7 were observed on fruit surfaces washed with EO water and NaOCl solution, respectively. However, EO water and NaOCl solution treatments did not exhibit a higher microbicidal activity than water treatment during refrigeration storage. The ozone treatment on inoculated strawberries was not remarkably effective in removing and eliminating pathogens on the whole fruit tissues, but the populations of L. monocytogenes and E. coli O157:H7 were significantly decreased after ozone treatment regardless of the exposure time. The number of L. monocytogenes and E. coli O157:H7 on fruit surfaces was decreased by 2.17 and 2.02 log₁₀ CFU/ml of rinse fluid, respectively, after washing with ozonated water for 10 min. / Graduation date: 2008

Nanoenergetic composite materials have been synthesized by a sol-gel chemical process where the addition of a weak base molecule induces the gelation of a hydrated metal salt solution. A proposed proton scavenging mechanism, where a weak base molecule extracts a proton from the coordination sphere of the hydrated iron (III) complex in the gelation process to form iron (III) oxide/hydroxide, FeIIIxOyHz, has been confirmed for the weak base propylene oxide (PO), a 1,2 epoxide, as well as for the weak bases tetrahydrofuran (THF), a 1,4 epoxide, and pyridine, a heterocyclic nitrogen-containing compound. THF follows a similar mechanism as PO; the epoxide extracts a proton from the coordination sphere of the hydrated iron complex forming a protonated epoxide which then undergoes irreversible ring-opening after reaction with a nucleophile in solution. Pyridine also extracts a proton from the hydrated metal complex, however, the stable six-membered molecule has low associated ring strain and does not endure ring-opening. Fe2O3/Al energetic systems were synthesized from the epoxides PO, trimethylene oxide (TMO) and 3,3 dimethyl oxetane (DMO). Surface area analysis of the synthesized matrices shows a direct correlation between the surface area of the iron (III) oxide matrix and the quantified exothermic heat of reaction of the nano-scaled aluminum-containing energetic material due to the magnitude of the interfacial surface area contact between the iron (III) oxide matrix and the aluminum particles. The Fe2O3(PO)/Al systems possess the highest heat of reaction values due to the oxide interfacial surface area available for contact with the aluminum particles. Also, reactions containing nano-scale aluminum react differently than those containing micron-scale aluminum. RuO2/Al energetic systems behave differently dependent on the atmosphere the sample is heated. Heating the RuO2/Al samples in an inert atmosphere results in the complete reduction of the ruthenium oxide matrix to Ru(0) before reaction with the aluminum particles, resulting in the exothermic formation of RuxAly intermetallics, with the stoichiometry dependent on the initial Ru:Al concentration. However, heating the samples in an oxygen-rich atmosphere results in an exothermic reaction between RuO2 and Al.

A facile method for the direct conversion of oximes into carbonyl compounds by treatment with manganese triacetate is described. Manganese triacetate can be used for an effective and mild oxidizing agent for the regeneration of carbonyl compounds in good yield. Many functional groups are tolerated under reaction conditions.

No description available.

Vast amounts of carbon are stored forest soils, a product of decaying organic matter. Increased CO2 in the atmosphere is predicted to lead to increasing global temperatures, and more extreme moisture regimes. Such increases in mean temperature could accelerate the rate of organic matter decay in soils and lead to additional release of CO2 into the atmosphere, thus exacerbating climate change. However, due to its impact on plant metabolism, high atmospheric CO2 concentrations may also lead to greater condensed tannins (CT) and reduced nitrogen (N) content in leaf litter. This reduction in litter quality has the potential to slow decay of organic matter in soil and therefore offset the accelerated decay resulting from a warmer climate. My research aimed to quantify the effects of climate and litter chemistry, specifically CT and N, on litter decay, N mineralization and associated microbes in the field. Strings of litterbags were laid on the forest floor along climate transects of mature Douglas-fir stands of coastal British Columbia rain-shadow forests. In-situ climate was monitored alongside carbon and nitrogen loss over 3.58 years of decay along three transects located at different latitudes, each transect spanning the coastal Western Hemlock and Douglas-fir biogeoclimatic zones. Microbial communities in the decaying litter and in forest soils were also analyzed using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Microbial biogeography at field sites was partially influenced by climate, soil characteristics and spatial distance, but did not improve best fit decay models using climate and litter chemistry variables. Litter with greater initial CT and smaller N concentration slowed down early decay (0 - 0.58 yr) and net N mineralization. Warmer temperatures accelerated later decay (0.58 - 3.58 yr) and net N mineralization. Water-soluble CT were rapidly lost during decay, while other forms of CT were likely responsible for slower decay. The composition of fungal communities on decaying litter was affected by initial concentrations of CT and N. On a yearly basis, the slower decay of litter with high CT and reduced N content can offset accelerated rates of decay associated with warmer temperatures. Concurrent shifts in microbial communities and net N mineralization suggest potential benefits to trees. / Graduate / 2017-12-19

Submitted by (edna.saturno@ufrpe.br) on 2017-02-22T13:18:21Z No. of bitstreams: 1 Talita da Silva Esposito.pdf: 1198598 bytes, checksum: 814b0f7dce6420e7e8723706bb578b48 (MD5) / Made available in DSpace on 2017-02-22T13:18:21Z (GMT). No. of bitstreams: 1 Talita da Silva Esposito.pdf: 1198598 bytes, checksum: 814b0f7dce6420e7e8723706bb578b48 (MD5) Previous issue date: 2006-02-06 / Alkaline proteases are commercially important group of enzymes and have a large variety of applications, mainly in the detergent and food industries. The proteases currently uses in the market are serine proteases produced by Bacillus strains, principally. Fish viscera have wide biotechnological potential as a source of digestive proteases. Biotechnology provides a means for transforming such materials usually discarded into valuable produts such as enzymes. The objective of this research was to test if alkaline proteases from fish viscera could be used as an additive in commercially available detergent formulations. Viscera from Colossoma macropomum, the most important native fish for Brazilian aquaculture, and Cyprinus carpio, the second exotic fish in importance for Brazilian aquaculture, were extracted and used as a source of enzyme for this research. The crude extract obtained upon the homogenization of the viscera was submitted to a partial purification with ethanol. The protein content,proteolytic activity of the fractions thus obtained was assessed. The fraction presenting the highest proteolytic activity was further studied (30-70% of ethanol) resulting in 74.9% and 142.4% of protein recovery for tambaqui and carpa, respectively. This fraction was assayed at different temperatures and pH aiming to estimate the conditions for higher proteolysis. Temperarture and pH stability experiments were also carried out. Different commercial lyavailable detergents, surfactants and hydrogen peroxide were used to test the compatibility of these proteases with detergent formulations. The results reveal that these alkaline proteases extracted from C. macropomum show desirable characteristics for its use in laundry industry such as: retention of 73% and 63% of its initial activity in the presence of Surf® and 5% H202, respectively, after 1 hour of incubation at 40ºC. In addition to that it was observed a slight increase of the proteolytic activity in the presence of non-ionic (Tween 20 and Tween 80) and ionic surfactants (Saponin and Sodium cholate). On the other hand, the proteases extracted from the intestine of C. carpio were compatible with the surfactants and oxidants tested butdid not present the same property in the presence of commercially available detergents. / As proteases alcalinas são as enzimas de maior importância comercial devido a sua vasta aplicabilidade, sendo empregadas principalmente nas indústrias de detergentes e de alimentos. Atualmente, a maior parte das proteases utilizadas no mercado é produzida por bactérias do gênero Bacillus, no entanto, elas podem ser amplamente encontradas em um dos principais resíduos da indústria pesqueira, as vísceras. Portanto, uma forma de otimizar o aproveitamento do pescado e, conseqüentemente, reduzir o desperdício é reaproveitar esses subprodutos. Neste trabalho testou-se a aplicabilidade das proteases de vísceras de peixes como aditivo de detergentes em pó comerciais. Para extração das enzimas foram utilizadas vísceras de Colossoma macropomum e de Cyprinus carpio, principal peixe nativo e segundo peixe exótico da aqüicultura continental nacional, respectivamente. A partir deste material obteve-se o extrato bruto, que passou por uma semi-purificação fracional com etanol. As frações obtidas deste procedimento tiveram sua atividade enzimática e quantidade de proteínas determinadas para escolha da fração a ser trabalhada. A fração saturada com 30- 70% de etanol apresentou maior atividade específica tanto no tambaqui quanto na carpa, com rendimentos de 74,9% e 142,4%, respectivamente. Nesta fração verificou-se em que temperatura e pH as proteases apresentavam maior atividade, além da sua estabilidade em relação a esses parâmetros. Para testar a compatibilidade com detergentes comerciais, foram utilizados quatro detergentes comerciais, cinco agentes surfactantes e peróxido de hidrogênio em diferentes concentrações. Os resultados obtidos sugerem que as proteases alcalinas encontradas nas vísceras de tambaqui apresentam características ideais para utilização na indústria de detergentes em pó, como: retenção de até 73% da sua atividade na presença de Surf® e de 63% na presença de 5% de H2O2 após 1 hora de incubação a 40ºC. Além disso, a atividade da enzima foi estimulada na presença de surfactantes não-iônicos (Tween 20 e Tween 80) e iônicos (Saponin e Colato de sódio). As proteases obtidas a partir do intestino da carpa, no entanto, só foram estáveis na presença dos diferentes surfactantes e a 5% de H2O2, perdendo estabilidade quando adicionadas aos detergentes comerciais.

O presente estudo teve como objetivo avaliar a comunidade envolvida na desnitrificação autotrófica pela oxidação de sulfetos, aplicada ao pós-tratamento de efluentes anaeróbios. O enriquecimento da comunidade bacteriana e da comunidade desnitrificante autotrófica foi realizado a partir de amostras da biomassa coletadas de três reatores verticais de leito fixo operados em condições distintas, sendo, redução autotrófica de nitrato, redução autotrófica de nitrito e redução autotrófica de nitrato com excesso de sulfeto. Após a determinação da melhor condição de enriquecimento, a cultura foi purificada, identificada por meio de ferramentas da biologia molecular e caracterizada quanto às melhores condições de crescimento. O enriquecimento foi bem sucedido com a biomassa dos três reatores. No entanto, a condição de redução de nitrato com relação \'N\'/\'S\' igual a 0,8 foi a que apresentou maior concentração de microrganismos desnitrificantes autotróficos. A bactéria isolada foi identificada como Pseudomonas stutzeri. A velocidade específica máxima de crescimento da cultura (\'mü\'máx) foi de 0,037/h, com tempo de duplicação de 18,7 horas. O rendimento celular (Y) do composto nitrogenado foi de 0,15 gSSV.g/\'N\' e a velocidade de desnitrificação foi de aproximadamente 0,24 g\'N\'/gSSV.h. Os dados obtidos indicaram a viabilidade da aplicação da espécie isolada no processo de desnitrificação autotrófica utilizando sulfeto como doador de elétrons. / The aim of this study was to evaluate the community involved on autotrophic denitrification by sulfide oxidation applied to the post-treatment of anaerobic effluents. The enrichment of the bacterial community and autotrophic denitrifier community was accessed in three immobilized bed reactors operated at the conditions of autotrophic reduction of nitrate, autotrophic reduction of nitrite and autotrophic reduction of nitrate under excess of sulfide. Following the determination of the best enrichment conditions, the culture was purified, identified by molecular biology tools and the best growth conditions were characterized. Enriched cultures were obtained for the three operational conditions, but the best condition for the growth of autotrophic denitrifiers microorganisms was at \'N\'/\'S\' ratio of 0,8. The isolated microorganism was identified as Pseudomonas stutzeri. The maximum specific growth rate (\'mü\'máx) was 0.037/h, with a doubling time of 18.7 hours. The growth yield (Y) of nitrogen compound was 0.15 gSSV/g\'N\' and the specific rate of nitrogen utilization was approximately 0.24 g\'N\'/gSSV.h. The results indicated the viability of application of this microorganism for autotrophic denitrification using sulfide as electron donor.