Um dos principais impactos causados pela indústria é a poluição hídrica por meio da eliminação de compostos metálicos em efluentes, gerando acúmulo destes na cadeia alimentar e causando efeitos toxicológicos na biota aquática e na saúde da população. O cádmio e o níquel são exemplos desses tipos de contaminantes, geralmente presentes na mineração de cobre e zinco. Novas tecnologias têm buscado reduzir a concentração destes metais em efluentes de uma forma mais sustentável. Entre elas, a adsorção utiliza adsorventes que apresentam em sua superfície sítios com cargas que podem ser ativadas, sendo capazes de reter íons em solução, como os cátions metálicos. Entre os biossorventes, micro-organismos como as bactérias podem apresentar características para recuperação dos metais, gerando assim o interesse por tecnologias sustentáveis que possam aproveitar rejeitos industriais. Essa técnica utiliza a interação entre os grupos funcionais presentes nos biossorventes com os íons metálicos. Para este estudo, como pH, concentração de adsorventes e metais, tempo de contato e condições de tratamento de biossorventes foram avaliados por meio da utilização de bacterianos presentes no solo de uma região com histórico de contaminações industriais. Foi utilizado sistema em batelada por meio de erlenmeyers com soluções monoelementares de cádmio (II) e níquel (II). Com os resultados obtidos foi concluído que dentre os parâmetros mencionados, o que mais influenciou na biossorção foi o pH; a concentração de biomassa que apresentou maior captação metálica foi a de 0,1g.L-1; o adsorvente que apresentou a maior captação metálica de Cd2+ e Ni2+ foi a biomassa autoclavada, com captação metálica (qe) 294 mg.g-1 para Cd2+ e 46 mg.g-1 para Ni2+. / One of the main impacts caused by the industry is the water pollution by means of the elimination of metallic compounds in effluents, generating accumulation of these in the food chain and causing toxicological effects in the aquatic biota and the health of the population. Cadmium and nickel are examples of these types of contaminants, usually present in copper and zinc mining. New technologies have sought to reduce the concentration of these metals in effluents in a more sustainable way. Among them, the adsorption uses adsorbents that have on their surface sites with charges that can be activated, being able to retain ions in solution, such as metallic cations. Among biosorbents, microorganisms such as bacteria may have characteristics for metal recovery, thus generating interest in sustainable technologies that can take advantage of industrial waste. This technique uses the interaction between the functional groups present in the biosorbents with the metallic ions. For this study, parameters such as pH, concentration of adsorbents and metals, contact time and biosorbent treatment conditions were evaluated through the use of bacterial consortium present in the soil of a region with a history of industrial contamination. A batch system was used with erlenmeyers with monoelement solutions of cadmium (II) and nickel (II). With the results obtained it was concluded that among the mentioned parameters, what influenced biosorption most was the pH; the concentration of biomass that presented the greatest metallic uptake was that of 0.1g.L-1; the adsorbent that presented the highest Cd2+ and Ni2+ metal uptake was the autoclaved biomass, with metal uptake (qe) of the values obtained in the Langmuir isotherms around 294 mg.g-1 for Cd2+ and 46 mg.g-1 for Ni2+.

[pt] A busca por tecnologias alternativas e de baixo custo operacional para a remoção de metais em efluentes tem direcionado a atenção para a biossorção. Recentemente vários materiais de origem biológica, como bactérias e resíduos agro-industriais têm sido utilizados para a remoção de íons metálicos de efluentes industriais. A biossorção de metais pesados por espécies biológicas envolve vários mecanismos que, em geral, dependem das espécies biológicas utilizadas e do processamento da biomassa. O cobalto e o manganês são amplamente utilizados em muitas aplicações industriais, e consequentemente, estão presentes nos efluentes provenientes de vários processos industriais, como por exemplo na mineração e produção de ligas. O objetivo deste trabalho foi investigar a eficiência do Rhodococcus opacus, que apresenta vários grupamentos fenólicos e carboxílicos (capazes de interagir com íons metálicos em solução), como adsorvente para a remoção de Co(II) e Mn(II) de soluções aquosas, visando futuras aplicações para o tratamento de efluentes. A caracterização física da superfície do R. opacus foi realizada com MEV, potencial zeta e análises de FTIR. A biomassa, R. opacus, foi previamente tratada com 0,1 mol.L(-1) NaOH e usada em todos os experimentos de biossorção. Todos os testes de biossorção foram realizados em batelada e os parâmetros avaliados foram: pH, concentração da biomassa e do metal, tempo de contato e temperatura. Os melhores valores de pH para a biossorção de Co(II) e Mn(II) foram 7,0 e 5,0, respectivamente. Para ambos os metais estudados, a capacidade de biossorção específica foi maior em soluções contendo baixas concentrações de metais. Para os dois metais, o processo de biossorção foi melhor descrito pelo modelo de Langmuir e pelo modelo cinético de pseudo segunda ordem. Os parâmetros termodinâmicos como DeltaG, DeltaS e DeltaH foram calculados e os processos de biossorção para a remoção do Co(II) e do Mn(II) a partir de soluções aquosas foram consideradas reações endotérmicas e exotérmicas, respectivamente. Este trabalho mostra que o R. opacus pode ser aplicado para a remoção de íons de Co(II) e Mn(II) de soluções aquosas. Após 180 minutos de contato da biomassa com as soluções contendo Co(II) e Mn(II), 84 por cento e 97 por cento dos íons metálicos presentes em solução foram removidos. / [en] The search for alternative technologies and low operating cost for removal of heavy metals from effluent has directing attention to biosorption. Recently, various biological materials, such as bacteria and agro‐waste, have been used for removal of metallic ions from industrial effluents. Biosorption of heavy metals by biological species involves several mechanisms that, in general, depending on the type of specie used and biomass processing procedure. Cobalt and manganese are widely used in many industrial applications, consequently they are present in effluent derived from various industrial processes, for example: mining, alloy production. The objective of this work is to investigate the efficiency of Rhodococcus opacus, which presents various phenolic and carboxylic groups (able to interact with metal ions in solution), as an adsorbent for the removal of Co(II) and Mn(II) from aqueous solutions, aiming future applications for the treatment of effluents. Surface physical characterization of R. opacus was carried by MEV, zeta potential and FTIR analysis. The biomass, R. opacus, was previously treated with 0.1 mol.L(-1) NaOH solution and used in all biosorption experiments. All the biosorption tests were carried out in batch and the parameters evaluated were: pH, concentration of biomass and metal, contact time and temperature. The best pH value for biosorption of Co(II) and Mn(II) were 7.0 and 5.0 respectively. For both metal studied, the specific biosorption capacity was higher in solutions containing low metals concentrations. For both metals, the biosorption process was better described by the Langmuir and pseudo-second-order kinetic models. The thermodynamics parameters, such as DeltaG, DeltaS and DeltaH were calculated and the biosorption process for Co(II) and Mn(II) removal from the aqueous solutions were considered endothermic and exothermic reactions, respectively. This work shown the R. opacus can be applied for removal Co(II) and Mn(II) ions from aqueous solutions. After 180 min contact of biomass with solutions containing Co(II) and Mn(II), 84 per cent and 97 per cent of the metallic ion present in the solutions were removed.

[pt] Neste trabalho foi avaliado o potencial do microrganismo Streptomyces lunalinharesii como biossorvente para a remoção de Zn(II), Cu(II) e Cd(II) de soluções aquosas pelo processo de biossorção/bioflotação, através de ensaios experimentais em batelada. Os parâmetros operacionais investigados na etapa de biossorção foram: pH da solução, concentração inicial de biomassa, velocidade de agitação, concentração inicial do metal, tempo de contato e a temperatura. Os dados de equilíbrio de adsorção foram avaliados empregando os modelos de isoterma de adsorção de Langmuir e Freundlich. A cinética da sorção para os íons metálicos foram modeladas usando o modelo cinético de ordem zero, primeira e segunda ordem e os modelos de pseudo primeira e pseudo segunda ordem. A separação da biomassa foi realizada mediante a técnica de flotação por ar dissolvido, avaliando a influência da pressão de saturação, concentração de coagulante e taxa de reciclo na eficiência de remoção da biomassa carregada com os íons metálicos. As características da superfície do microrganismo e os possíveis mecanismos de interação envolvidos na sorção dos íons metálicos pela biomassa foram avaliadas com base em medições de potencial zeta, análise por espectrometria no infravermelho e análise de imagens obtidas por microscopia eletrônica de varredura (MEV/EDS). O valor inicial do pH da solução afetou a sorção dos metais, os valores de pH adequados na etapa de biossorção e na bioflotação foram de 6,0 para Zn(II) e 5,0 para Cu(II) e Cd(II). As concentrações iniciais de biomassa utilizadas nos ensaios foram de 3 g.L-1 para Zn(II) e Cu(II), e 2 g.L-1 para Cd(II), apresentando remoções de 57,5%, 35% e 63%, respectivamente. A velocidade de agitação empregada de 120 rpm apresentou as melhores remoções, 60% para Zn(II), 41% para Cu(II), e 62% para Cd(II). Os dados correspondentes à capacidade de captação do S. lunalinharessi em função da concentração dos íons metálicos foram testadas e o modelo de isoterma de Langmuir se ajustou bem para os íons Zn(II) e Cd(II), e o modelo de Freundlich para os íons Cu(II). As capacidades máximas de captação obtidas com o modelo de Langmuir para Zn(II), Cu(II) e Cd(II) foram: 13,6; 11,53 e 24,87 mg.g-1, respectivamente. Os ensaios da cinética de biossorção mostraram que o processo é muito rápido nos primeiros 5min de contato entre a biomassa e as soluções metálicas, remoções superiores a 90% foram atingidas em 100 min para Zn(II) e Cd(II), e 50 min para Cu(II). A cinética de sorção para os íons Zn(II), Cu(II) e Cd(II) se ajustaram bem ao modelo de pseudo segunda ordem. O processo de remoção dos íons Zn(II), Cu(II) e Cd(II) foi afetado negativamente pelo incremento de temperatura, sugerindo que o processo seja exotérmico. Os valores de energia de ativação obtidos foram de: 40,11; 59,27 e 55,51 kJ.mol-1, respectivamente. Os espectros obtidos por IV-FT sugerem que os grupos funcionais carboxila, amina, amida, fosfato e hidroxila presentes na parede celular da biomassa S. lunalinharesii são os possíveis responsáveis pela biossorção dos íons metálicos. Na bioflotação empregando a técnica de flotação por ar dissolvido (FAD), verificou-se a necessidade de adição de um coagulante para uma melhor eficiência do processo de flotação. Foram obtidos resultados de remoção da biomassa carregada com os íons Zn(II), Cu(II) e Cd(II) de 94%, 95,5% e 92,1%, respectivamente. Os resultados apresentados correspondem a uma real remoção pelo processo integrado de biossorção e bioflotação de 9,1 mg.L-1 de Zn(II), 8,6 mg.L-1 de Cu(II) e 8,4 mg.L-1 de Cd(II), partindo de uma pressão de saturação de 5 kgf.cm-2, concentração de coagulante de 45 mg.L-1 e taxa de reciclo de 50%. / [en] This study evaluated the potential of the microorganism Streptomyces lunalinharesii as biosorbent for removal of Zn(II), Cu(II) and Cd(II) from aqueous solutions by biosorption/bioflotation process through experimental batch. Operating parameters investigated in the stage of biosorption was solution pH, initial concentration of biomass, agitation speed, initial metal concentration, contact time and temperature. The adsorption equilibrium data were evaluated using Langmuir and Freundlich adsorption isotherm models. The kinetics sorption for metal ions were modeled using the kinetic model of zero order, first and second order models and the pseudo first and pseudo second order. The biomass separation was performed using the dissolved air flotation technique, evaluating the influence of saturation pressure, coagulant concentration and recycle ratio on removal efficiency of biomass loaded with metal ions. The surface characteristics of the microorganism and the possible interaction mechanisms involved in sorption of metal ions by biomass were evaluated based on measurements of zeta potential, analysis by infrared spectroscopy and analysis of images obtained by scanning electron microscopy (SEM/EDS). The initial value of the solution pH affected the sorption of metals, pH values appropriated in the stage of biosorption and bioflotation were 6,0 for Zn(II) and 5,0 for Cu(II) and Cd(II). The initial concentrations of biomass used in the trials were 3 g.L-1 for Zn(II) and Cu(II), and 2 g.L-1 for Cd(II), with removals of 57,5%, 35% and 63%, respectively. The agitation speed of 120rpm employed showed the best removals, 60% for Zn(II), 41% for Cu(II), and 62% for Cd(II). The data corresponding to the uptake capacity of S. lunalinharesii depending on the concentration of metal ions were tested and the Langmuir isotherm model fits well for the ions Zn(II) and Cd(II) and the Freundlich model for Cu(II). The maximum uptake capacities obtained with the Langmuir model for Zn(II), Cu(II) and Cd(II) were: 13,6; 11,53; and 24,87 mg.g-1, respectively. The tests on the biosorption kinetics showed that the process is very fast in the first 5 min of contact between biomass and metal solutions, removals above 90% were achieved for 100 min Zn(II) and Cd(II), and 50 min for Cu(II). Sorption kinetics for the ions Zn(II), Cu(II) and Cd(II) have adjusted well to the pseudo second order model. The process of removal of ions Zn(II), Cu(II) and Cd(II) was negatively affected by increasing temperature, suggesting that the process is exothermic. The values of activation energy obtained were: 40,11; 59,27 and 55,51 kJ.mol-1, respectively. The spectra obtained by IR-FT suggest that the functional groups are carboxyl, amine, amide, phosphate and hydroxyl present in cell wall biomass S. lunalinharesii are potentially responsible for biosorption of metal ions. In bioflotation employing the dissolved air flotation (DAF) technique, there is a need of adding a coagulant for improved efficiency of the flotation process. Were obtained results for biomass removal loaded with ions Zn(II), Cu(II) and Cd(II) of 94%; 95,5% and 92,1% respectively. The results presented correspond to an actual removal by biosorption and bioflotation process integrated of 9,1 mg.L-1 of Zn(II), 8,6 mg.L-1 of Cu(II) and 8,4 mg.L-1 Cd(II), starting from a saturation pressure of 5 kgf.cm-2, coagulant concentration of 45 mg.L-1 and recycle ratio of 50%.

[pt] cádmio é um dos maiores agentes contaminantes do meio ambiente devido à sua alta toxicidade, ameaçando às plantas, animais e seres humanos. O uso de biomassas como material sorvente para a remoção do cádmio de efluentes líquidos aparece como uma alternativa promissora às tecnologias existentes. O objetivo desta tese foi determinar a capacidade de adsorção do pó de casca de coco verde (Cocos nucifera) para cádmio num sistema contínuo de biossorção, assim como a dessorção do metal da biomassa, para que esta possa ser utilizada num ciclo de biossorção-dessorção. O equipamento escolhido foi uma coluna de leito fixo. Foram avaliadas a influência da vazão, altura de leito, sentido do fluxo e a eficiência do processo com colunas em série. Os grupos funcionais presentes na superfície da biomassa foram estudados através de análises de espectroscopia no infravermelho. Os experimentos num sistema contínuo com diferentes alturas de leito e concentrações iniciais revelaram que a melhor eficiência do processo foi obtida com maiores alturas de leito (18 cm) e concentrações iniciais baixas (19 mg/l). Obtiveram-se tempos de ruptura de 150 minutos para soluções com vazão de 22 ml/min, obtendo-se uma solução com concentração final de 2,6 mg/l. Uma eficiência de remoção de 46% foi obtida quando se trabalhou com concentrações iniciais de 19 mg/l e o processo torna-se mais eficiente quando é utilizado um sentido de fluxo ascendente.O EDTA mostrou-se como um excelente eluente ao realizar a dessorção dos íons metálicos contidos na biomassa, num processo em batelada. A biomassa foi submetida a quatro ciclos de biossorção-dessorção, apresentando em cada um deles eficiências de dessorção superiores a 70% e uma posterior eficiência de remoção superior a 85% em todos os ciclos. Os grupos funcionais presentes na superfície da biomassa são principalmente grupos carboxila, hidroxila, amina e amida. Os resultados apresentados mostram que o pó de casca de coco verde apresenta as características adequadas para o processo de biossorção de cádmio num processo contínuo utilizando colunas de leito fixo, e que pode ser utilizado como uma alternativa aos processos clássicos de tratamento de efluentes. / [en] Cadmium is one of the greatest actors of environmental pollution due to its high toxicity, threatening plants, animals and humans beings. The use of biomass as a sorbent material for cadmium removal seems to be a promising alternative to existing technologies. The objective of this work was to determine the adsorption capacity of coconut shell powder (Cocos nucifera) for cadmium in a continuous system of biosorption, and also the desorption of the metal from the biomass, so that this material could be used in a new cycle of biosorptiondesorption. A fixed bed column was chosen, as it does not present clogging problems and is easy to operate. The influence of flow rate and its direction, bed height and the efficiency of the process with series columns were evaluated. The functional groups present on the surface of the biomass were studied by infrared spectroscopy analysis.The column experiments with different bed heights and initial concentration revealed that the best efficiency was obtained with higher bed heights (18 cm) and lower initial concentrations (19 mg/l). Breakthrough time of 150 minutes was obtained for solutions with a flow rate of 22 ml/min, generating a solution with final concentration of 2.6 mg/l. A removal efficiency of 46% was obtained when working with initial concentrations of 19 mg/l. The process becomes more efficient when the solution is pumped upward through the columnEDTA was an excellent elutant for desorption of metal ions in the biomass in a batch system. The biomass was subjected to four biosorption-desorption cycles, presenting higher than 70% desorption efficiencies and removal efficiencies of more than 85% in all cases.The functional groups presents on the particle surface of the biomass are mainly carboxyl, hydroxyl, amine and amide groups. The results show that the powder of coconut shell has the appropriate characteristics for biosorption of cadmium in a continuous process using columns of fixed bed, which can be used as an alternative to conventional processes for effluent decontamination.

[pt] Neste estudo foi avaliada a capacidade de adsorção do poluente orgânico tolueno em contato com a cepa Rhodococcus opacus. O tolueno foi selecionando por fazer parte do grupo de compostos BTEX (Benzeno, Tolueno, Etilbenzeno e Xileno), que possui elevada toxicidade, causando impacto ambiental em corpos hídricos, solo e ar, além de possuir características mutagênica e carcinogênica em humanos. A determinação e quantificação do tolueno na solução aquosa foram realizadas em um cromatógrafo a gás, acoplado ao espectrômetro de massas com amostrador automático headspace. A cepa Rhodococcus opacus foi caracterizada por análise de espectrometria no infravermelho e medição de potencial zeta, sendo a última realizada antes e após o contato com o tolueno. Os modelos de isotermas lineares de Langmuir, Freundlich e Temkin foram aplicados aos dados experimentais para descrever o processo de adsorção. Tendo o modelo de Langmuir se adaptado melhor ao processo em análise. As variáveis estudadas para otimizar as condições máximas de adsorção foram: tempo de contato, variação do pH, variação da biomassa. Este estudo mostrou que a cepa bacteriana R. opacus apresentou uma boa capacidade de biossorção, principalmente para concentrações baixas, onde removeu 95,99 porcento e 85,69 porcento das respectivas concentrações de 0,6 e 0,8 mg/L de tolueno, atendendo a resolução do CONAMA 357/2005 para águas salobras de Classe I. / [en] In this study was evaluated the adsorption capacity of the organic pollutant toluene by the Rhodococcus opacus strain. Toluene was chosen by being part of the group of BTEX compounds (benzene, toluene, ethylbenzene and xylene), which has high toxicity, causing environmental impact on water bodies, soil and air, and also are mutagenic and carcinogenic to humans. The determination and quantification of toluene in aqueous solution were performed on a gas chromatograph, coupled with a mass spectrometer with headspace autosampler. The strain Rhodococcus opacus was characterized by infrared spectrometry analysis and zeta potential measurement, the last done before and after the sorption. The isotherm linear models of Langmuir, Freundlich and Temkin were applied to the experimental data to describe the adsorption process. Having the Langmuir model better adapted to process analysed. The variables studied to optimize the maximum adsorption conditions were: contact time, pH variation, biomass variation. This study showed that the bacterial strain R. opacus has good biosorption capabilities, particularly at low concentrations, where it removed 95.99 percent and 85.69 percent of the respective concentrations of 0.6 and 0.8 mg/L of toluene, attending the CONAMA resolution 357/2005 for salt waters of Class I.

No description available.

Equilibrium isotherms and the adsorption kinetics of heavy metals onto chitosan were studied experimentally. Chitosan, a biopolymer produced from crustacean shells, has applications in various areas, particularly in drinking water and wastewater treatment due to its ability to remove metallic ions from solutions. The adsorption capacity of chitosan depends on a number of parameters: deacetylation degree, molecular weight, particle size and crystallinity. The purpose of this work was to study the adsorption of copper, zinc, mercury, and arsenic on chitosan produced from shrimp shells at a laboratory level. The experimental work involved the determination of the adsorption isotherms for each metallic ion in a batch system. The resulting isotherms were fitted using the Langmuir model and the parameters of the equation were determined. Kinetic studies of adsorption for different metallic ions at different concentrations and with different particle sizes were performed in batch and column systems. Simplified models such as pseudo-first-order, pseudo-second-order, and intra-particle diffusion equations were used to determine the rate-controlling step. Some preliminary studies were carried out to address the application of chitosan as an adsorbent in the removal of heavy metals or other metallic ions from natural water and wastewater. The regeneration of chitosan was also studied. The results showed that the adsorption capacity depends strongly on pH and on the species of metallic ions in the solution. The optimum pH value for the metallic cation adsorption was between 4 and 6, whereas for arsenic adsorption it was about 3. When the pH is not controlled, the adsorption capacity is independent of the initial pH with the solution reaching a final pH of about 7. It was also found that the Langmuir equation described very well the experimental adsorption data for each metallic ion. The adsorption capacity for the metals on chitosan follows the sequence Hg>Cu>Zn>As. The study of the adsorption kinetics of these metallic ions shows that the particle size has a significant influence on the metal uptake rate for copper; but that it has only a slight influence on the adsorption rate of zinc and mercury in the range studied. Arsenic adsorption exhibited an interesting behaviour which depends strongly on the pH of the solution; the uptake increased at short adsorption times and then decreased at long times. The analysis of kinetic models showed that the pseudo-second-order adsorption mechanism is predominant, and the overall rate of the metallic ion adsorption process is therefore controlled by adsorption reactions and not by mass transfer for the range of particle sizes examined in this study. With regard to the regeneration of chitosan, it was found that sodium hydroxide is a good agent for zinc and arsenic desorption, whereas ammonium sulphate and sodium chloride were the most suitable for copper and mercury desorption, respectively. The ability of chitosan to remove arsenic from natural water, and copper and zinc from mining waste water was verified. The use of these results for designing purposes is a subject for future work. / QC 20101104

[pt] A pesquisa de novas tecnologias para remover metais tóxicos de efluentes industriais tem focado sua atenção na capacidade de certos materiais biológicos de fixarem e flotarem íons metálicos. O objetivo desta dissertação foi avaliar o potencial do Rhodococcus opacus como biossorvente natural destinado à remoção de cádmio e zinco por bioflotação. As características da superfície do microorganismos foram avaliadas através de medições do potencial zeta, coloração de Gram e análise de micrografias obtidas no microscópio eletrônico de varredura (MEV). No processo de biossorção foi avaliado o pH, a concentração inicial do metal e a cinética do processo. Na bioflotação se avaliou o tempo de flotação, a vazão de ar e as características da espuma. Obtiveram-se porcentagens de remoção de 60% e 83% para cádmio e zinco na etapa de sorção, partindo de concentrações iniciais de 15 e 5 ppm, respectivamente e os valores de pH adequados na sorção e na flotação foram de 7,0 para ambos os metais. Utilizaram-se os modelos de Langmuir e Freundlich para analisar a capacidade de adsorção de cádmio e zinco em R. opacus sendo o modelo de Freundlich o que explicou melhor o processo de sorção de cada metal. A cinética de sorção revelou que o processo segue o modelo de pseudo-segunda ordem. Na bioflotação, encontrou-se que o microorganismo apresenta excelentes características como coletor e espumante, obtendo-se porcentagens de remoção de cádmio de 90% partindo de uma concentração de 15 ppm. Os resultados apresentados mostram que R. opacus apresenta características importantes para a bioflotação de metais pesados, embora tenha uma capacidade moderada de captação, a qual poderia ser melhorada mediante um pré- tratamento da biomassa. / [en] The search for new technologies for the removal of hazardous metals from wastewater has been focused on several features for the biological materials as such: metal binding and flotation abilities. The aim of this work was to evaluate the biosorption and bioflotation abilities of Rhodococcus opacus for cadmium and zinc removal. Pre and post-characterizations for the microorganism features were performed in terms of: type of surface charge according zeta potential value; relative membrane composition by Gram`s stain and electron microscopy scan (EMS). Parameters for biosorption were studied according to: pH, initial metal concentration and time removal; and for bioflotation: flotation speed, air flow-rate and foam formation, were evaluated. The Cd and Zn uptake capacity by Rhodococcus opacus have been also studied using Langmuir and Freundlich models. Preliminary observations confirmed that R. opacus, corresponds to a grampositive microorganism, with an isoelectric point (IEP) of 2.5, indicating the predominance of acidic groups (polysaccharides and carboxylic molecules) on its membrane composition. Analysis by EMS, showed changes on structure conformation and metal up-take by the microorganism. At pH 7.0 and 26°C, Cd and Zn removals of 60 and 83% were observed from initial concentration of 15 and 5 ppm, respectively. Results showed that metal uptake capacity can be expressed by the Freundlich isotherms for both metals. Kinetics studies demonstrated that biosorption process follows a pseudo- second order model. Bioflotation process showed that R. opacus has excellent features as collector and foaming agent. Around 90% removal of cadmium has been achieved used metal loaded biomass. R. opacus showed to have good metal binding and flotation abilities.

[pt] Neste trabalho foi avaliado o potencial do microorganismo R. opacus como biossorvente para a remoção de Pb(II), Cr (III) e Cu(II) de soluções aquosas pelo processo de biossorção/bioflotação, através de ensaios experimentais em batelada. Os parâmetros operacionais investigados na etapa de biossorção foram: o pH da solução, a concentração de biomassa, o tempo de contato e a concentração inicial do metal. Na separação da biomassa carregada mediante a bioflotação por ar disperso se avaliou o tempo de flotação, e as características da espuma. As características da superfície do micro-organismo e os possíveis mecanismos de interação envolvidos na sorção dos metais tóxicos por R. opacus, foram avaliadas com base em medições de potencial zeta, análise por espectrometria no infravermelho e análise de micrografias obtidas no microscópio eletrônico de varredura (MEV). O valor inicial do pH da solução afetou a sorção dos metais, os valores de pH adequados na etapa de sorção e na flotação foram de 5,0 para o Pb(II) e pH igual a 6,0 para o Cr(III) e Cu(II). Os ensaios da cinética de biossorção mostraram que o processo é rápido e em 60 minutos de contato entre a biomassa e a solução de metal foi atingida a máxima captação das espécies metálicas em estudo. Os dados correspondentes à capacidade de captação do R. opacus em função da concentração dos íons metálicos foram bem ajustados ao modelo da isoterma de Langmuir para as três espécies em estudo, onde as capacidades máximas de captação obtidas foram: 94,3; 72,9 e 32,2 mg.g-1 para Pb(II), Cr(III) e Cu(II), respectivamente. A cinética da sorção para o Pb(II), Cr(III) e Cu(II) foram modeladas usando a equação de pseudo segunda ordem. A ordem de afinidade do R. opacus obtida em sistemas individuais foi estabelecida como: Pb(II) >Cr(III)>Cu(II). Essa diferença na afinidade do R. opacus pode ser atribuída às propriedades físico-químicas destes metais, dentre elas peso atômico, raio iônico e eletronegatividade. A capacidade de captação dos íons Pb (II) pela biomassa foi reduzida pela presença de outras espécies metálicas no sistema, apresentando o Cr(III) maior afinidade pelos sítios da biomassa do que os outros íons. Na bioflotação, verificou-se que o micro-organismo apresenta resultados muito promissores como coletor e espumante, obtendo-se percentagens de remoção de Pb(II), Cr(III) e Cu(II) de 94%, 54% e 43% , respectivamente, partindo de uma concentração de 20 mg.l-1. Os resultados apresentados mostram que R. opacus apresenta características adequadas no que tange a biossorção e bioflotação para a remoção de metais pesados. / [en] This work evaluated the potential of the Rhodococcus opacus strain as a biosorbent for the removal of Pb(II), Cr(III) and Cu(II) from aqueous solutions by Biosorption/bioflotation process, through experimental batch tests. The operational parameters investigated in the biosorption´s stage were: pH of the solution, biomass concentration, contact time and initial metal concentration. In the separation of the loaded biomass by bioflotation process for dispersed air were evaluated the flotation time and the foam characteristics. The characteristics of the microorganism surface and the involved interaction mechanisms in the heavy metals sorption by R. opacus, were evaluated based in the potential zeta measurements, infrared spectroscopy and electron microscopy scanning analysis. The solution initial pH value affected metals sorption, the adjusted pH values in the sorption and the flotation stage were 5.0 for the Pb(II) and pH value of 6.0 for the Cr(III) and Cu(II). The experiments of biosorption kinetics showed that the process is relatively fast and in sixty minutes of contact between the biomass and the metal solution were reached the maximum metal uptake capacities. The data pertaining to the uptake capacity of the R. opacus in function of the metal ion concentration fitted to the Langmuir isotherm model for the tree species in study, where the maximum uptake capacities obtained were: 94.3; 72.9 and 32.2 mg.g-1 for Pb (II), Cr(III) and Cu(II), respectively. The kinetics of sorption of Pb(II), Cr(III) and Cu(II) were modeled using a pseudo second order rate equation. The affinity order of R. opacus for the three metals under study has been established as: Pb(II)>Cr(III)>Cu(II). The selectivity of the biomass for the Pb(II) over the other two metals was well exhibited by the results obtained in the biosorption and bioflotation. This difference in the affinity of the R. opacus can be attributed to the physiochemical properties of these metals, amongst them atomic weight, ionic radio and electronegativity. The uptake capacity of ions Pb(II) for the biomass was reduced by the presence of other metallic species in the system, and the results showed that the Cr(III) has greater affinity for the biomass than the others ions. In the bioflotation, it was found that the microorganism presents excellent characteristics as collector and foaming agent, reaching 94%, 54% and 43% removal of lead, chromium and copper, respectively, to 20 mg.l-1 of concentration. The results of this study showed that R. opacus has important features for the heavy metal removal; moreover, the results also showed that R. opacus is especially effective biosorbent for the removal of Pb(II).

Achieving energy neutrality has shifted focus towards aeration systems optimization, due to the high energy consumption of aeration processes in modern advanced wastewater treatment plants. The activated sludge wastewater treatment process is dependent on aeration efficiency which supplies the oxygen needed in the treatment process. The process is a complex heterogeneous mixture of microorganisms, bacteria, particles, colloids, natural organic matter, polymers and cations with varying densities, shapes and sizes. These activated sludge parameters have different impacts on aeration efficiency defined by the OTE, % and alpha. Oxygen transfer efficiency (OTE) is the mass of oxygen transferred into the liquid from the mass of air or oxygen supplied, and is expressed as a percentage (%). OTE is the actual operating efficiency of an aeration system. The alpha Factor (α) is the ratio of standard oxygen transfer efficiency at process conditions (αSOTE) to standard oxygen transfer efficiency of clean water (SOTE). It is also referred to as the ratio of process water volumetric mass transfer coefficient to clean water volumetric mass transfer coefficient. The alpha factor accounts for wastewater contaminants (i.e. soap and detergent) which have an adverse effect on oxygen transfer efficiency. Understanding their different impacts and how different treatment technologies affect aeration efficiency will help to optimize and improve aeration efficiency so as to reduce plant operating costs. A pilot scale study of fine pore diffuser fouling and mitigation, quantified by dynamic wet pressure (DWP), oxygen transfer efficiency and alpha measurement were performed at Blue Plains, Washington DC. In the study a mechanical cleaning method, reverse flexing (RF), was used to treat two diffusers (RF1, RF2) to mitigate fouling, while two diffusers were kept as a control with no reverse flexing. A 45 % increase in DWP of the control diffuser after 17 month of operation was observed, an indication of fouling. RF treated diffusers (RF1 and RF2) did not show any significant increase in DWP, and in comparison to the control diffuser prevented a 35 % increase in DWP. Hence, the RF fouling mitigation technique potentially saved blower energy consumption by reducing the pressure burden on the air blower and the blower energy requirement. However, no significant impact of the RF fouling mitigation treatment technique in preventing a decrease in alpha-fouling (𝝰F) of the fine pore diffusers over time of operation was observed. This was because either the RF treatment method maintained wide pore openings after cleaning over time, or a dominant effect of other wastewater characteristics such as the surfactant concentration or particulate COD could have interfered with OTE. Further studies on the impact of wastewater characteristics (i.e., surfactants and particulate COD) and operating conditions on OTE and alpha were carried out in another series of pilot and batch scale tests. In this study, the influence of different wastewater matrices (treatment phases) on oxygen transfer efficiency (OTE) and alpha using full-scale studies at the Blue Plains Treatment Plant was investigated. A strong relationship between the wastewater matrices with oxygen transfer characteristics was established, and as expected increased alphas were observed for the cleanest wastewater matrices (i.e., with highest effluent quality). There was a 46 % increase in alpha as the total COD and surfactant concentrations decreased from 303 to 24 mgCOD/L and 12 to 0.3 mg/L measured as sodium dodecyl sulphate (SDS) in the nitrification/denitrification effluent with respect to the raw influent. The alpha improvement with respect to the decrease in COD and surfactant concentration suggested the impact of one or more of the wastewater characteristics on OTE and alpha. Batch testing conducted to characterize the mechanistic impact of the wastewater contaminants present in the different wastewater matrices found that the major contaminants influencing OTE and alpha were surfactants and particulate/colloidal material. The volumetric mass transfer coefficient (kLa) measurements from the test also identified surfactant and colloidal COD as the major wastewater contaminants present in the influent and chemically enhanced primary treatment (CEPT) effluent wastewaters impacting OTE and alpha. Soluble COD was observed to potentially improve OTE and alpha due to its contribution in enhancing the oxygen uptake rate (OUR). Although the indirect positive impact of OUR on alpha observed in this study contradicts some other studies, it shows the need for further investigation of OUR impacts on oxygen transfer. Importantly, the mechanistic characterization and quantitative correlation between wastewater contaminants and aeration efficiency found in this study will help to minimize overdesign with respect to aeration system specification, energy wastage, and hence the cost of operation. This study therefore shows new tools as well as the identification of critical factors impacting OTE and alpha in addition to diffuser fouling. Gas transfer depression caused by surfactants when they accumulate at the gas-liquid interface during the activated sludge wastewater treatment process reduces oxygen mass transfer rates, OTE and alpha which increases energy cost. In order to address the adverse effect of surfactants on OTE and alpha, another study was designed to evaluate 4 different wastewater secondary treatment strategies/technologies that enhances surfactant removal through enhanced biosorption and biodegradation, and to also determine their effect on oxygen transfer and alpha. A series of pilot and batch scale tests were conducted to compare and correlate surfactant removal efficiency and alpha for a) conventional high-rate activated sludge (HRAS), b) optimized HRAS with contactor-stabilization technology (HRAS-CS), c) optimized HRAS bioaugmented (Bioaug) with nitrification sludge (Nit S) and d) optimized bioaugmented HRAS with an anaerobic selector phase technology (An-S) reactor system configuration. The treatment technologies showed surfactant percentage removals of 37, 45, 61 and 87 %, and alphas of 0.37 ±0.01, 0.42 ±0.02, 0.44 ±0.01 and 0.60 ±0.02 for conventional HRAS, HRAS-CS, Bioaug and the An-S reactor system configuration, respectively. The optimized bioaugmented anaerobic selector phase technology showed the highest increased surfactant removal (135 %) through enhanced surfactant biosorption and biodegradation under anaerobic conditions, which also complemented the highest increased alpha (62 %) achieved when compared to the conventional HRAS. This study showed that the optimized bioaugmented anaerobic selector phase reactor system configuration is a promising technology or strategy to minimize the surfactant effects on alpha during the secondary aeration treatment stage / Ph. D. / In the activated sludge process, the energy requirement for aeration which also includes nitrogen removal is a major operating expense for utilities, and it has limited the ability of most water and wastewater reclamation facilities to achieve energy neutrality. Aeration has therefore become one of the most energy and capital intensive aspects of wastewater treatment. There are still knowledge gaps and mechanistic understanding of the impact of wastewater characteristics and treatment processes on aeration efficiency, which past and current studies are yet to provide. Aeration efficiency is defined by oxygen transfer efficiency and alpha (an indicator of wastewater contaminant effect on aeration efficiency). This study provided an insight into important wastewater characteristics, treatment processes and operational parameters contributing to aeration cost. An understanding of the impacts of wastewater characteristics and how different treatment technologies affect aeration efficiency as discussed in this study will help design engineers and operators to optimize and improve aeration efficiency, so as to reduce plant operating costs. The first study objective on fine bubble diffuser fouling dynamics and physical treatment method quantified by dynamic wet pressure (DWP), oxygen transfer efficiency and alpha measurement was carried out in a pilot reactor. DWP quantified the fouling dynamics of fine pore diffusers. A diffuser fouling physical treatment (reverse flexing, RF) method was able to mitigate fouling of the fine pore diffusers by preventing an increase in DWP normally observed in fouled fine pore diffusers. The RF treatment method reduced fouling by 35 % as compared to the control diffuser (without reverse flexing). This will reduce the pressure burden and air blower energy requirement. The second study objective evaluated the impact of different wastewater characteristics and removal in different stages on aeration efficiency. Test results in this study showed that surfactant and particulate COD fractions were the major characteristics constituents contained in wastewater that depressed aeration efficiency defined by OTE and alpha. Soluble COD did not show any inhibiting effect on OTE and alpha. The third study objective evaluated three different optimized wastewater treatment technologies of surfactant removal during aeration treatment process; 1) High rate activated sludge (HRAS) with contactor-stabilization technology (The contactor stabilization process) (HRAS-CS); 2) HRAS bioaugmented (BioAug) with nitrification sludge (Nit S); and 3) Bioaugmented HRAS with an anaerobic selector phase (An-S) configuration. All three technologies increased surfactant removal through enhanced biosorption and biodegradation to various degrees when compared the conventional high rate activated sludge treatment, but the An-S treatment technology achieved the highest surfactant removal and alpha improvement. The study also established the optimum performance process conditions for each optimized treatment technology.