Dans le contexte du développement de l’hydrogène-énergie, de nouvelles voies de production renouvelables sont étudiées, parmi lesquelles la fermentation obscure est un processus biologique convertissant la biomasse. Dans cette étude, ce procédé a été optimisé en réacteur agité semibatch par la sélection de cultures mixtes (boues de station d’épuration) et l’optimisation des paramètres de fermentation associés (température, ajout de substrat, régulation du pH). La présence majoritaire de bactéries du genre Clostridium a été observée dans le milieu fermentaire. Différents modes d’extraction des gaz produits ont été évalués, permettant d’intensifier le procédé par l’utilisation d’un gaz de balayage (N2 ou CO2). La mise en œuvre efficace en fonctionnement continu d’un bioréacteur membranaire dans une configuration d’extraction gaz/liquide a permis d’améliorer le rendement (> + 90%) et la productivité en H2 (> + 300%) par rapport au mode de fonctionnement continu en réacteur agité. Enfin, l’utilisation d’un substrat réel (bourbes viticoles) a permis de prouver la faisabilité du procédé dans une perspective d’industrialisation. / In the context of the development of hydrogen-energy, new renewable production ways are studied, among which dark fermentation is a biological process converting the biomass. In this study, this process was optimized for a semibatch reactor by the selection of mixed cultures (waste water treatment plant sludges) and the optimization of associated parameters of fermentation (temperature, add of substrate, pH regulation). The presence in majority of bacteria from the genus Clostridium was observed in the fermentation broth. Different extraction modes of the produced gas were evaluated, allowing to intensify the process by the use of a sparging gas (N2 or CO2). The successful implementation in continuous mode of a membrane bioreactor in a configuration of gas/liquid extraction allowed an increase in H2 yield (> + 90%) and productivity (> + 300%) compared to the continuous stirred tank reactor. Finally, the use of a real substrate (winery waste) allowed to prove the feasibility of this process in the prospect of industrialization.

No description available.

Landfilling is the most widely used method for the disposal of municipal solid wastes (MSW) in the United States due to its simplicity and low cost. According to the 2014 report on Advancing Sustainable Materials Management by the USEPA, only 34% of the total MSW generated in the US was recycled, while 13% was combusted for energy recovery. In 2014, 53% of the MSW generated, (i.e. 136 million tons) in the US was landfilled. The treatment of landfill leachates, generated by percolation of water through the landfill, primarily due to precipitation, has been found to be one of the major challenges associated with landfill operation and management. Currently, leachates from most landfills are discharged into wastewater treatment plants, where they get treated along with domestic sewage. Issues associated with treatment of landfill leachates due to their high nitrogen and heavy metal content have been widely studied. Recently, it has been observed that the organic carbon in landfill leachates, specifically humic and fulvic acids (together referred to as "humic substances") contain aromatic groups that can absorb large amounts of ultraviolet (UV) light, greatly reducing the UV transmissivity in wastewater plants using UV disinfection as the final treatment step. This interference with UV disinfection is observed even when landfill leachates constitute a very small fraction (of the order of 1%) of the total volumetric flow into wastewater treatment plants. Humic substances are present as dissolved organic matter (DOM) and typically show very low biodegradability. Removing these substances using chemical treatment or membrane processes is an expensive proposition. However, the concentrations of humic substances are found to be reduced in leachates from landfill cells that have aged for several years, suggesting that these substances may be degraded under the conditions of long-term landfilling. The primary objective of this research was to use a two-stage process employing thermophilic pretreatment followed by a mesophilic anaerobic membrane bioreactor (AnMBR) to mimic the conditions of long-term landfilling. The AnMBR was designed to keep biomass inside the reactor and accelerate degradation of biologically recalcitrant organic carbon such as humic substances. The treatment goal was to reduce UV absorbance in raw landfill leachates, potentially providing landfills with an innovative on-site biological treatment option prior to discharging leachates into wastewater treatment plants. The system was operated over 14 months, during which time over 50% of UV-quenching organic carbon and 45% of UV absorbance was consistently removed. To the best of our knowledge, these removal values are higher than any reported using biological treatment in the literature. Comparative studies were also performed to evaluate the performance of this system in treating young leachates versus aged leachates. Next-generation DNA sequencing and quantitative PCR (qPCR) were used to characterize the microbial community in raw landfill leachates and the bioreactors treating landfill leachate. Analysis of microbial community structure and function revealed the presence of known degraders of humic substances in raw as well as treated landfill leachates. The total number of organisms in the bioreactors were found to be higher than in raw leachate. Gene markers corresponding to pathogenic bacteria and a variety of antibiotic resistance genes (ARGs) were detected in raw landfill leachates and the also in the reactors treating leachate, which makes it necessary to compare these ARG levels with wastewater treatment in order to determine if leachates can act as sources of ARG addition into wastewater treatment plants. In addition, the high UV absorbance of leachates could hinder the removal of ARBs and ARGs by UV disinfection, allowing their release into surface water bodies and aiding their proliferation in natural and engineered systems. / Ph. D.

Mathematical models of a nitritation: anaerobic ammonia oxidation (anammox)-coupled biofilm in a counter-diffusion hollow fiber membrane bioreactor (HFMBR) and a nitritation: anammox-coupled biofilm in a co-diffusion rotating biological contactor (RBC) were developed and implemented using AQUASIM. Four different start-up scenarios on the nitritation: anammox-coupled biofilm in an HFMBR were investigated. The supply of oxygen was simulated with the flow through the lumen of the hollow fiber membrane. For the four scenarios, two scenarios investigated the start-up when nitrite was supplied in the feed while the other two scenarios investigated when the source of nitrite was through nitritation only. The results showed that the presence of nitrite in the feed facilitated the start-up of the reactor. In addition, the results also showed that increasing oxygen flux through the membrane up to a certain ratio of ammonia flux with oxygen flux affected reactor performance by improving nitrogen removal and reducing start up time. For the nitritation: anammox-coupled biofilm in an RBC, four different process options were investigated: the number of reactors, the initial anammox (AnAOB) biomass fraction, the bulk oxygen concentration and the maximum biofilm thickness. Modeling results revealed that the steady state total nitrogen removal in RBC reactors in series occurred primarily in the first and second reactors. It is concluded that the number of reactors in series dictates the effluent performance and, therefore, this number can be selected depending upon the desired total nitrogen removal. Simulation results also revealed that increasing the initial AnAOB biomass fraction from 0.01% to 1.0% had no effect in the steady state nitrogen removal but had an effect in the required time to reach the steady state total nitrogen removal and the maximum biofilm thickness. Modeling results of the third process option showed that increasing the bulk oxygen concentration in the reactor from 0.2 g/m3 to 5 g/m3 linearly increased the steady state total nitrogen removal and reduced the time to reach the maximum biofilm thickness. Beyond 5 g/m3, steady state total nitrogen removal decreased. In addition, simulation results revealed that the thicker biofilm clearly showed a more linear correlation between the increase in bulk oxygen concentration and the increase in the steady state total nitrogen removal within a range of bulk oxygen concentrations. The results showed that RBC performance could be controlled by several process options: the number of reactors in series, initial biomass fraction, the bulk oxygen concentration and the maximum biofilm thickness. The mathematical modeling results for the HFMBR and RBC have shown that both have potential as carriers for nitritation: anammox-coupled biofilms targeted at the removal of nitrogen in the wastewater. / Master of Science

Enhanced biological phosphorus removal (EBPR) was researched from the performance of a modified University of Cape Town (UCT), anaerobic-anoxic/nitrifying-aerobic process. The work focussed on high P influent where milk was compared to carbohydrates as exogenous added carbon and typical settled sewage. The results confirmed that at equal COD load in the influent (minimum COD:P (250:5) ratio for EBPR), milk always provided sufficient soluble substrate than the carbohydrate mix, but also improved the EBPR performance. The laboratory scale treated 10L/day where 2 parallel treatment trains for milk and an equivalent carbohydrate mix as supplement to compare and study the P sequestration from hypothesised P ligands in milk and easily assimilable carbon (AOM) after fermentation for biological P uptake. The aerobic bioreactors used submerged flat sheet membranes (AeMBR) to improve the effluent quality and reduce the suspended solid residues. The results suggested extra benefits from adding calcium chloride (CaCl2) (200 ml at 250 mM/day or 200 mg/L treated) to form P complexes both in the anaerobic and aerobic zones (100 ml CaCl2 250mM/zone/day). To complete P removal a calcium phosphate (CaPO4) further treatment stage (post membrane final effluent (F.E.)) was added for nucleation. The combination of, A2O-N, exogenous carbon and calcium addition improved the performance of the EBPR, and enabled the laboratory units to achieve less than the 1 mg/L P required by the EU Directive. The process was tested at higher than normal P loads (maximum 100 mg/L) (domestic wastewater influent 15 mg/L). Experiments with influent P load ≤ 50mg/L, with 1% milk as AOM were compared to the carbohydrate mix and could remove soluble P to less than 1mg/L above 97% and less than 2 mg/L more than 99% of the in the time respectively. With an influent P load of 60mg/L (maximum 100 mg/L), the soluble P in the F.E. with milk was below 5 mg/L and below 8 mg/L with carbohydrates mix. The results showed that most of the phosphorus was retained by the sludge during the anoxic-aerobic phases. The remaining phosphate in the F.E. was able to pass through AeMBR pore size (0.4 μm) and needed to be chelated by the nucleation process. The results indicated this A2O-N modifications achieved stable nutrient removal and also offered the potential for more sustainable phosphorus recovery. The EBPR without AOM was 25% less efficient compared to milk and never achieved the E.U standard of 1mg/L in final effluent. The flat sheet membrane always achieved a NTU final effluent below 1 and the TOC always greater than 90% removal or less than the EU 125 standard regardless of the feeding COD/P ratio.

L'utilisation de souches de levures sélectionnées pour réaliser la FA est une pratique très répandue en œnologie. Après le développement de l'utilisation de levains de souche pure de Saccharomyces, l'innovation est aujourd'hui dans la mise en œuvre de levains mixtes de Saccharomyces et de non-Saccharomyces qui permettent de diversifier les produits finaux obtenus. La problématique réside dans l'existence d'interactions entre les souches rendant difficile la maîtrise de la fermentation. T. delbrueckii présente dans la flore indigène du mout de raisin est une des levures non-Saccharomyces les plus appropriées pour entrer dans la composition de ces levains mixtes. En effet, elle présente une bonne capacité fermentaire et peut permettre d'augmenter la complexité aromatique du vin ou encore de réduire son acidité volatile. L'objectif de ce travail était d'étudier les interactions pendant la FA entre des souches sélectionnées pour l'oenologie : une T. delbrueckii et une S. cerevisiae. Pour cela des expériences ont été réalisées dans des milieux synthétiques simulant le moût de raisins blancs. Le comportement des souches pures a tout d'abord été caractérisé. Il a été montré que la souche S. cerevisiae avait de meilleures performances fermentaires d'un point de vue cinétique que la souche T. delbrueckii. Toutefois, T. delbrueckii a montré des capacités acceptables pour épuiser les sucres et surtout a permis d'obtenir des profils aromatiques différents. Le comportement vis-à-vis de l'oxygénation des moûts de ces deux levures est assez semblable, T. delbrueckii étant cependant beaucoup plus sensible à ce paramètre que S. cerevisiae. L'interaction entre ces deux levures a ensuite était étudiée dans un bioréacteur à membrane sous anaérobie stricte dans différentes conditions : composition en azote assimilable du milieu et stratégie d'inoculation. Il a été clairement mis en évidence que T. delbrueckii était affectée par la présence de S. cerevisiae. Le type d'interaction soupçonné est celui d'amensalisme lié à l'excrétion par S. cerevisiae d'un constituant toxique pour T. delbrueckii. Dans ces conditions, la stratégie d'inoculation recommandée est l'ensemencement séquentiel des levures : T. delbrueckii en début de fermentation, puis l'ajout de S. cerevisiae 48 h après. Ceci permet à T. delbrueckii de se développer et d'exprimer son potentiel aromatique avant que S. cerevisiae ne soit introduit pour assurer une fin rapide de la fermentation. Toutefois, nous avons montré que même dans ces conditions, l'implantation de T. delbrueckii n'était pas garantie car, le moût n'étant pas stérile, une présence, même faible, de S. cerevisiae dans la flore naturelle peut inhiber sa croissance. Par ailleurs, il a été mis en évidence que dans les mouts à faible teneur en azote initial, ce constituant pouvait être épuisé au moment de l'inoculation de S. cerevisiae. Dans ces conditions, S. cerevisiae ne peut se développer et l'achèvement de la fermentation est alors problématique. / The use of the selected yeast strains to realize the alcoholic fermentation is very prevalent practice in vinification. After the development of utilization of the preparation of pure Saccharomyces cerevisiae strain, the innovation is now to apply the mixte starter cultures of Saccharomyces and non-Saccharomyces that allow to diversifying the obtained final products. The problem resides in the existence of interactions between the strains giving the difficulty to controle the fermentation. Torulaspora delbrueckii present in the indigenous flora of the grape must is one of the most appropriate non-Saccharomyces yeasts to enter in the composition of these multistater cultures. In fact, this strain has been presented a good fermentative capacity and could allow to increasing not only the aromatic complexity of wine, but also to reducing its volatile acidity. The objective of our work is to study the interactions during the alcoholic fermentation between the selected strains for enology: one T. delbrueckii and one S. cerevisiae. For this reason, the experiments were realized in the synthetic mediums simulated to the white grape must. The behaviours of the pure strains were firstly characterized. It was shown that the S. cerevisiae strain had the best fermentative performances, a critical point in comparaison with the T. delbrueckii strain. Nevetheless, T. delbrueckii showed the acceptable capacities to exhaust the sugars and especially to allow us to obtain the different aromatic profiles to that of S. cerevisiae. The behaviour via the oxygenation to the musts of these two yeasts is enough close, T. delbrueckii being however much more sensible to that parameter than . cerevisiae. The interactions between these two yeasts were then studied in a membrane bioreacteur under strict anaerobie in different conditions: composition in assimilable nitrogen of the medium and strategy of inoculation. It has been clearly demonstrated that T. delbrueckii has been affected by the presence of S. cerevisiae. The suspected type of this interaction is the amensalism one bound to a toxic compound excreted by S. cerevisiae. In these conditions, the recommended inoculation strategy is the sequential culture of these yeasts: T. delbrueckii at the beginning of the fermentation, then the addition of S. cerevisiae after 48 h. This allows T. delbrueckii to develop and express its potentiel of aromatic production before the S. cerevisiae is introduced to assure a rapid finish of the fermentation. However, we showed that even in these conditions, T. delbrueckii growth has been not guaranteed because of, since the must is not sterilized, a presence even small of S. cerevisiae in the natural flore can inhibite the croissance of the former. It has been also demonstrated that in the must with low intitial nitrogen content, this compound could be exhausted at the moment of the S. cerevisiae inoculation. In these conditions, S. cerevisiae can not develop and the achievement of the fermentation is yet problematic.

A presente pesquisa teve por objetivo avaliar a produção biológica de hidrogênio em longo prazo, e os impactos da separação das principais etapas da digestão anaeróbia, acidogênese e metanogênese, sobre a eficiência do tratamento em reatores de leito fixo estruturado e sobre o desempenho da filtração em biorreatores com membrana. O efluente utilizado foi à base de sacarose e a temperatura foi mantida em 30ºC. Na primeira etapa experimental, avaliou-se a produção de H2 em três configurações de reatores: leito fixo estruturado (FB), UASB granular (UG) e UASB floculento (UF-1). Na segunda etapa experimental, um reator UASB acidogênico (UF-2) foi combinado a um reator metanogênico de leito fixo estruturado (RM). Um reator de estágio único de leito fixo estruturado (RU) foi operado em paralelo. Na última etapa experimental, foram avaliados dois biorreatores anaeróbios conjugados com módulos externos de membranas tubulares, nomeadamente 1-AnMBR, que foi alimentado com efluente bruto, e 2-AnMBR, que foi alimentado com efluente acidificado. Na primeira etapa, sob um TDH de 3,3 h (COV = 33 gDQO.L-1d-1), os reatores FB, UG e UF-1 apresentaram produção de H2 contínua, porém instável, com rendimentos de aprox. 1,5, 0,8 e 1,2 molH2.mol-1sacaroseconsumida, respectivamente. O reator UF-1 apresentou uma estabilidade relativamente melhor e, por isso, esta configuração foi utilizada nos experimentos seguintes. No reator UF-2, aumentou-se o TDH para 4,6 h (COV = 25 gDQO.L-1d-1), o que significativamente promoveu a melhoria do desempenho. Nenhum alcalinizante foi adicionado e o pH do efluente permaneceu em torno de apenas 2,7. Contudo, uma produção de H2 contínua, estável e por longa duração foi atingida, de 175 mLH2.L-1h-1 (= 4,2 LH2.L-1d-1), com rendimento de 3,4 molH2.mol-1sacaroseconsumida, concomitante com a produção de ácido acético e etanol. Nos reatores metanogênicos, o TDH aplicado foi gradativamente reduzido (53-18 h no RM e 56-23 h no RU). Após os sistemas atingirem estabilidade, os valores de DQO permaneceram inferiores no efluente do RM, sobretudo pela redução da concentração de SSV, equivalente a 92 mg.L-1, enquanto que no RU essa concentração foi de 244 mg.L-1. No final da operação, o rendimento energético do sistema de dois estágios foi de 20,69 kJ.g-1DQOadicionada, sendo 90% proveniente do CH4 e 10% do H2. Este rendimento foi 34% maior do que o obtido no reator de estágio único, que foi de 15,48 kJ.g-1DQOadicionada. Por fim, avaliando-se o desempenho da filtração nos biorreatores com membrana, verificou-se que a permeabilidade operacional foi, na maior parte do tempo, superior no 2-AnMBR. A pré-acidificação do efluente levou à redução de cerca de 56-59% na concentração de sólidos voláteis suspensos e totais no 2-AnMBR e à modificação no perfil do tamanho das partículas. No 1-AnMBR, porém, não havia partículas de pequenas dimensões, tais quais encontradas no reator acidogênico, indicando reduzido crescimento suspenso de bactérias acidogênicas. Embora os valores de fluxo crítico tenham sido muito semelhantes para ambos os AnMBR, testes de resistência específica da torta indicaram maior resistência do lodo do 1-AnMBR (1,02 x 1018 m-1), comparado ao lodo do 2-AnMBR (1,03 x 1012 m-1) e ao lodo acidogênico (7,44 x 1011 m-1). Portanto, essa pesquisa demonstrou, por meio da aplicação do tratamento anaeróbio em dois estágios, a viabilidade da produção contínua de hidrogênio em pH extremamente ácido e com mínimos requerimentos operacionais, a redução da concentração de sólidos suspensos no efluente de reatores de leito fixo estruturado, o potencial de aumento da recuperação de bioenergia e de redução da incrustação em membranas de ultrafiltração. / This study assessed long-term hydrogen production and the impacts of separating the main stages of anaerobic digestion (acidogenesis and methanogenesis) on treatment efficiency in structured fixed-bed reactors and on filtration performance in anaerobic membrane bioreactors. Sucrose based wastewater was used and the temperature was maintained at 30°C. In the first experimental phase, H2 production was evaluated in three different acidogenic reactors: structured fixed-bed (FB), granular UASB (UG) and flocculated UASB (UF-1). In the second experimental phase, an acidogenic UASB reactor (UF-2) was combined with a structured fixedbed methanogenic reactor (RM). A single-stage structured fixed-bed reactor (RU) was operated in parallel. In the last experimental phase, two sidestream anaerobic membrane bioreactors were evaluated: 1-AnMBR, which was fed with raw effluent; and, 2-AnMBR, which was fed with biologically acidified effluent. During the first operational phase, under an HRT of 3.3 h (OLR = 33 gCOD.L-1d-1), the FB, UG and UF-1 reactors showed continuous but unstable H2 production, with yields of approximately 1.5, 0.8 and 1.2 molH2.mol-1sucroseconsumed, respectively. The UF-1 reactor showed relatively better stability; therefore, this configuration was used in the next experiments. In the UF-2 reactor, the HRT was increased to 4.6 h (OLR = 25 gCOD.L-1d-1), which significantly improved the overall performance. No alkalizing agent was added, and effluent pH values remained around only 2.7. However, continuous, stable and long-term H2 production was achieved of 175 mLH2.L-1h-1 (= 4.2 LH2.L-1h-1), with yields of 3.4 molH2.mol-1sucroseconsumed, concomitant with acetic acid and ethanol production. In the methanogenic reactors, the HRT was gradually reduced and, when the systems reached stability, COD values remained lower in the RM effluent. This was mainly due to the reduction of VSS concentrations, equivalent to 92 mg.L-1, while in the RU this value was 244 mg.L-1. At the end of the operation, the energy yield of the two-stage system was 20.69 kJ.g-1CODadded with 90% coming from CH4 and 10% from H2. This yield was 34% greater than that obtained in the single-stage system, which was 15.48 kJ.g-1CODadded. Finally, regarding the filtration performance in the membrane bioreactors, the operational permeability was higher in the 2- AnMBR most of the time. The pre-acidification of the effluent led to the 56-59% reduction in the volatile total and suspended solid concentrations, and to modification in the particle size profile in the 2-AnMBR. Nevertheless, in the 1-AnMBR, there were no small particles such as were found in the sludge of the acidogenic reactor, indicating less suspended growth of acidogenic biomass. Although the critical flux values were very similar for both AnMBRs, a higher specific cake resistance was verified in the 1-AnMBR sludge (1.02 x 1018 m-1), as compared to the 2-AnMBR sludge (1.03 x 1012 m-1) and to the acidogenic sludge (7.44 x 1011m-1</sup). Therefore, this study demonstrated, through the application of two-stage anaerobic treatment, the viability of continuous hydrogen production in extreme acid pH and with minimum operating requirements, the reduction of solid concentrations in the effluent of structured fixed bed reactors, as well as the potential for increased bioenergy recovery and for fouling reduction of ultrafiltration membranes.

A conversão enzimática da sacarose pela ação sucessiva da invertase e da glicose oxidase (GOD), permite obter produtos de maior valor agregado, a saber, frutose e o ácido glicônico, dois produtos de amplo uso na indústria farmacêutica, alimentícia e química. Foi estudada a aplicação da invertase imobilizada em resinas aniônicas do tipo Dowex&#174; (um copolímero de poliestireno-divinilbenzeno) sobre a hidrólise da sacarose bem como a oxidação da glicose pela glicose oxidase solúvel ou imobilizada no mesmo suporte em separado (sistema bifásico), utilizando-se um reator de membrana acoplado à membrana de ultrafiltração (100kDa) ou de microfiltração (5&#181;m). Posteriormente, avaliou-se o desempenho de ambas as formas de enzimas, solúveis ou imobilizadas num sistema monofásico empregando o mesmo reator. A bioconversão executada em sistema bifásico permitiu a obtenção de xarope de frutose da ordem de 70% através da separação de glicose e frutose utilizando-se a resina catiônica 50W:8-100. O rendimento de 96,6% e 67,4% para as formas solúveis e imobilizadas respectivamente foram obtidas em sistema monofásico. O não desprendimento das enzimas dos suportes viabilizou o uso da membrana de microfiltração, trazendo vantagens à operação de biorreator com membrana. / The enzymatic conversion of sucrose through a successive action of invertase and glucose oxidase (GOO) allows the obtainment of products with higher commercial value, fructose and gluconic acid, which are widely used in pharmaceutical, food and chemical industries. Invertase and GOO immobilized on Dowex&#174; anionic resin (a polystyrene divinylbenzene copolymer) as well as soluble GOD were used in a membrane bioreactor (MS) for sucrose hydrolysis and glucose oxidation. The MB was coupled with a UF-membrane (100kDa) or a MF-membrane (5&#181;m). The bioconversion was conducted in two steps (biphasic system) as well as in one step (monophasic system). The bioconversion operated in a biphasic system permitted obtaining a fructose syrup with a concentration of about 70% through a separation of glucose and fructose using a cationic resin, 50W:8-100. As for the monophasic system, the yield of 96.6% and 67.4% for soluble and immobilized forms were attained respectively. No leakage of the enzymes from the support allowed the use of a microfiltration membrane, adding advantages to the membrane bioreactor operation.

A conversão enzimática da sacarose pela ação sucessiva da invertase e da glicose oxidase (GOD), permite obter produtos de maior valor agregado, a saber, frutose e o ácido glicônico, dois produtos de amplo uso na indústria farmacêutica, alimentícia e química. Foi estudada a aplicação da invertase imobilizada em resinas aniônicas do tipo Dowex&#174; (um copolímero de poliestireno-divinilbenzeno) sobre a hidrólise da sacarose bem como a oxidação da glicose pela glicose oxidase solúvel ou imobilizada no mesmo suporte em separado (sistema bifásico), utilizando-se um reator de membrana acoplado à membrana de ultrafiltração (100kDa) ou de microfiltração (5&#181;m). Posteriormente, avaliou-se o desempenho de ambas as formas de enzimas, solúveis ou imobilizadas num sistema monofásico empregando o mesmo reator. A bioconversão executada em sistema bifásico permitiu a obtenção de xarope de frutose da ordem de 70% através da separação de glicose e frutose utilizando-se a resina catiônica 50W:8-100. O rendimento de 96,6% e 67,4% para as formas solúveis e imobilizadas respectivamente foram obtidas em sistema monofásico. O não desprendimento das enzimas dos suportes viabilizou o uso da membrana de microfiltração, trazendo vantagens à operação de biorreator com membrana. / The enzymatic conversion of sucrose through a successive action of invertase and glucose oxidase (GOO) allows the obtainment of products with higher commercial value, fructose and gluconic acid, which are widely used in pharmaceutical, food and chemical industries. Invertase and GOO immobilized on Dowex&#174; anionic resin (a polystyrene divinylbenzene copolymer) as well as soluble GOD were used in a membrane bioreactor (MS) for sucrose hydrolysis and glucose oxidation. The MB was coupled with a UF-membrane (100kDa) or a MF-membrane (5&#181;m). The bioconversion was conducted in two steps (biphasic system) as well as in one step (monophasic system). The bioconversion operated in a biphasic system permitted obtaining a fructose syrup with a concentration of about 70% through a separation of glucose and fructose using a cationic resin, 50W:8-100. As for the monophasic system, the yield of 96.6% and 67.4% for soluble and immobilized forms were attained respectively. No leakage of the enzymes from the support allowed the use of a microfiltration membrane, adding advantages to the membrane bioreactor operation.

The thesis involves the development and implementation of a new and robust control system based on permeability trends but at the same time capable of reducing aeration proportionally to permeate flux. Permeability was made a key parameter for directly comparing temporary changes in membrane performance. Transmembrane pressure and flux were gathered every 10 seconds and permeability values were automatically calculated; different mathematical algorithms were applied for the signal filtering of on-line data. Short term and long term permeability trends were compared once a day, and a control action was applied proportionally to the short term/long term permeability ratio without exceeding the aeration flow recommended by the membrane suppliers. / El treball presentat a la tesi inclou el desenvolupament i la implementacio d’un nou sistema de control robust basat en les tendencies de la permeabilitat i, al mateix temps, capac de reduir l’aeracio de forma proporcional al flux de permeat. S’ha seleccionat la permeabilitat com el parametre clau per comparar directament els canvis temporals en el funcionament de les membranes. La pressio transmembrana i el flux es mesuren cada 10 segons i llavors la permeabilitat es calcula automaticament. El senyal de les dades recollides en linia es filtra adequadament mitjancant diversos algoritmes matematics. L’algoritme de control compara diariament una tendencia a curt termini de la permeabilitat amb una tendencia a llarg termini de la permeabilitat, i s’aplica una accio de control proporcional al quocient de les dues tendencies, sense excedir mai el cabal d’aeracio recomanat pels fabricants de membranes.