La thèse s’intéresse au contrôle de la température d’un front de combustion propagé dans un milieu poreux contenant du carbone fixe et des carbonates (CaCO3). L’objectif principal est de réduire la température, in situ (récupération d’huile ou production de gaz à partir d’un schiste bitumineux) ou dans un procédé (combustion de semicoke), afin de limiter la décarbonatation du milieu et les émissions induites de CO2. Le milieu réactif retenu pour réaliser les expériences en laboratoire est un schiste bitumineux préalablement broyé (0.5 à 2 mm) et pré-pyrolysé, appelé semicoke. Le front est propagé en co-courant. La première technique testée expérimentalement est l’ajout au semicoke d’un matériaux inerte (sable) et/ou d’un matériaux réactif (CaCO3) afin de faire varier le taux de carbone fixe et le taux de CaCO3 et ceci indépendamment. Nous montrons que l’augmentation de CaCO3 permet de baisser la température à 800 °C, mais pas en dessous, ce qui ne permet pas d’éviter la décarbonatation. Faire chuter le contenu en carbone fixe permet de baisser la température du front, voire d’atteindre l’extinction. Aux températures de propagation les plus basses, la décarbonatation est fortement limitée. En revanche le front ralentit car il n’utilise plus tout l’oxygène alimenté. La deuxième technique originale consiste à ajouter du CO2 (20 %molaire) dans l’air de combustion. Nous montrons que dans le cas d’un front chaud, ceci permet de réduire le taux de décarbonatation de 100% à 70%, et d’augmenter en parallèle la production de CO résultant de l’oxydation du carbone fixe, ce qui augmente le PCI du gaz produit. Sur un front plus froid, la décarbonatation qui était de 20% est totalement évitée par l’ajout de CO2. Enfin, des expériences sont proposées dans le mode de combustion “reaction trailing”, très peu connu et mis en oeuvre. Ce mode a l’intérêt majeur d’éviter les réactions de “Lower Temperature Oxidation” préjudiciables au rendement en huile ou en gaz d’un process in situ. Des expériences stables et répétables sont réalisées avec différents pourcentages d’oxygène dans le gaz alimenté. La température du front est directement liée à ce paramètre ; la décarbonatation est clairement limitée dans ce mode de propagation. Deux types de modélisation sont proposés. Un bilan de matière et d’énergie basé sur des expressions analytiques simples permet d’évaluer la température du front et sa vitesse de propagation. Un modèle numérique développé par l’IMFT se base sur des équations de transfert convectif/diffusif de chaleur et de matière, couplées aux réactions d’oxydation du carbone (en CO et en CO2) et de décarbonatation de CaCO3. Il décrit de façon très satisfaisante les expériences en mode “reaction leading” avec variation de la composition du milieu (première technique). / This PhD thesis focuses on the control of the smoldering front propagating in a porous medium containing fixed carbon and carbonates (CaCO3). The main objective is to reduce the front temperature, in situ (oil recovery or gas production from oil shale) or in process (combustion of semicoke), in order to limit the medium decarbonation and the resulting CO2 emissions. The reactive porous medium retained to realize the laboratory experiments is a crushed (0.5 to 2 mm) and pre-pyrolyed oil shale, called semicoke. The front propagates in co-current. The first technique experimentally tested is the addition to the semicoke of an inert material (sand) and/or a reactive material (CaCO3) to vary the contents of fixed carbon and of CaCO3, independently. We show that the increase of the CaCO3 content enables to reduce the temperature to 800 °C, but not below; this does not allow to avoid decarbonation. Bringing down the fixed carbon content enables to reduce the front temperature, see even to reach extinction. In the lowest temperatures of propagation, the decarbonation is strongly limited. On the other hand, the front slows down because it does not use all of the fed oxygen. The second original technique consists in adding CO2 (20 mol.%) to the oxidizer air. We show that for a hot front, the decarbonated fraction is reduced from 100% down to 70%, and the CO production at fixed carbon oxidation is increased; this leads to increase the LCV of the produced gas. For a cold front, the decarbonation which was 20%, is totally avoided by adding CO2. Finely, experiments are proposed in the “reaction trailing” combustion mode, little known and implemented. This mode has the major interest to avoid the reactions of “Lower Temperature Oxidation” prejudicial for oil or gas yields in in situ process. Stable and repeatable experiments are realized with different oxygen fractions in feeding gas. The front temperature is directly linked to this parameter; the decarbonation is clearly limited in this mode of propagation. Two types of modeling are proposed. A mass and thermal balance based on simple analytical expressions enables to evaluate the front temperature and velocity. A numerical model developed by IMFT is based on convective/diffusive heat and mass transfer equations coupled with the oxidation reactions (into CO and CO2) and CaCO3 decarbonation is proposed. It describes in a very satisfactory way the experiments in the “reaction leading” mode with variation of the medium composition (first technique).

On s'intéresse dans ce travail à la modélisation d'un écoulement diphasique gaz-liquide co-courant descendant dans les réacteurs à lit fixe de particules, procédé largement utilisé dans le domaine industriel. En raison de la complexité de l'écoulement, induite par les nombreuses configurations multiphasiques pouvant coexister au sein du lit, les modèles développés directement à l'échelle du réacteur sont généralement issus d'approches semi-empiriques, en considérant l'écoulement homogène. Or, il a été observé que des hétérogénéités locales, géométrique et hydrodynamique, telle qu'une mal-distribution de la phase liquide, entrainaient une diminution du taux de réaction et conduisait les modèles existants à surestimer la productivité d'un réacteur. La nécessité de prendre en compte les phénomènes microscopiques dans un modèle macroscopique à l'échelle du réacteur rend l'utilisation d'approches multi-échelles indispensable. L'écoulement étant cependant d'une nature complexe, le changement d'échelle ne peut se faire de façon directe et nécessite donc la mise en place d'outils de modélisation adaptés à une échelle intermédiaire. Dans une première étape, la méthode de simulation numérique directe ``Volume-Of-Fluid'' (VOF) est validée dans le cas d'un film ruisselant dans un tube capillaire. Cette méthode est ensuite utilisée, à l'échelle microscopique, afin de proposer et de valider des relations de fermeture pour un modèle de type ``réseau de pores'' pouvant être utilisé à une échelle intermédiaire, celle du Volume Elémentaire Représentatif. Ce changement d'échelle est tout d'abord effectué dans le cas d'un lit fixe en deux dimensions, c'est-à-dire un empilement de cylindres entre deux plaques. Cette configuration permet la mise en place d'un dispositif expérimental qui, couplé à des simulations VOF 2D à plus grande échelle, valide l'approche de type "réseau de pores" adoptée. Le modèle réseau est ensuite étendu au cas d'un lit fixe réel, c'est-à-dire en trois dimensions, dont la géométrie est obtenue par micro-tomographie. Les lois de comportement locales sont redéfinies à l'aide de simulations numériques directes à l'échelle microscopique. Les résultats provenant de simulations de type « réseaux de pore » sont ensuite confrontés, dans le cas d'une répartition homogène des phases, aux modèles 1D habituellement utilisés pour les écoulements diphasiques en lit fixe. Enfin, une campagne expérimentale est menée afin d'observer, par imagerie scanner, l'étalement d'un jet de liquide sur un empilement de grains. Une comparaison qualitative est ensuite effectuée entre les observations expérimentales et les simulations numériques réseaux dans le cas spécifique de l'étalement d'un jet de liquide / We study in this work the modelling of two-phase cocurrent downflows in fixed bed reactors, a process widely used in industry. Due to the flow complexity, i.e., the presence of different interface configurations and, therefore, different phase interactions, most models have been developed using empirical approaches, with the assumption of a homogeneous flow in the reactor. However, several studies showed that local heterogeneities, geometric and hydrodynamic, such as the liquid distribution, could have a great influence on the flow at the reactor-scale and, therefore, on the reactor performance. Consider the microscopic phenomena in a macroscopic model require the use of multi-scale approaches. However, due to the flow complexity, the upscaling cannot be done directly and requires the development of modelling tools suitable for an intermediate scale. In a first step, the direct numerical method \ Volume-Of-Fluid" (VOF) is validated in the case of a two-phase flow in a capillary tube with the presence of a thin film. Then, this method is used, at a microscopic level to propose and validate closure laws for a pore-network model which will be used to simulate the flow at the intermediate scale. This upscaling approach is first tested in a two-dimensional case,i.e., an array of cylinders between two walls. This configuration allows the set up of an experimental approach, coupled with 2D VOF simulations at the intermediate scale, in order to validate the pore-network approach. The pore-network approach is then extended to a real fixed bed, i.e. in three dimensions, whose geometry is obtained by micro-tomography. Local laws of the pore-network model are redefined using direct numerical simulations at a microscopic scale. Pore-network simulations are then compared, for a homogenous phase distribution, with 1D models typically used for two-phase flow in fixed beds. Finally, an experimental campaign was set up to observe, by imaging scanner, the spreading of a liquid jet on a fixed bed pilot. A qualitative comparison is then performed between experimental observations and pore-network simulations in the specific case of the spreading of a liquid jet

La gazéification étagée de biomasse permet la production d'un gaz de synthèse propre, facilement valorisable en énergie électrique et/ou thermique. Néanmoins, l'optimisation de ces procédés en termes de rendement de conversion et de souplesse vis-à-vis de la nature de la biomasse constitue un enjeu industriel fort. Dans cette thèse, nous avons étudié spécifiquement une étape clef du procédé : la gazéification du charbon en lit fixe continu. La granulation est la solution proposée pour valoriser des biomasses de faible granulométrie ou densité. Ainsi les comportements de deux charbons de bois - issus de plaquettes forestières et de granulés - ont été étudiés en parallèle à partir d'outils expérimentaux et numériques.Dans un premier temps des expérimentations ont été menées sur un réacteur pilote, très largement instrumenté, reproduisant cette zone du procédé. Les profils mesurés de température, de composition des gaz, de densité du lit et de vitesse des particules constituent une base de données unique, révélatrice du comportement du réacteur. Nous avons ainsi pu localiser en haut du lit une zone très réactive d’épaisseur inférieure à 5 cm, ou encore un tassement significatif du lit entrainant une chute de la vitesse des particules dans un rapport de 8. La gazéification de charbons de granulés conduit aux mêmes taux de conversion finale et compositions du gaz de synthèse que celle de charbons issus de plaquettes forestières. Dans un deuxième temps, nous avons développé un modèle numérique de la zone d'étude, basé sur la résolution des équations de conservation couplées aux cinétiques des réactions, à l'aide du logiciel COMSOL. La prise en compte du tassement du lit, et de la cinétique apparente des réactions hétérogènes à l'échelle particule dans les termes sources réactionnels, sont les deux spécificités du modèle. Ce dernier permet de reproduire de manière satisfaisante les profils des grandeurs physiques mesurés pour diverses conditions opératoires et pour les deux charbons de l'étude. L'exploitation de ce modèle apporte des informations nouvelles et complémentaires de l’expérience ; il permettra à terme d'optimiser le procédé industriel / Multi-stage gasification of biomass leads to the production of a clean synthetic gas that can easily be used for electrical and/or thermal energy. However, optimization of these processes in terms of conversion yield and flexibility regarding the type of biomass is a major industrial challenge. To that end, a key stage of the process was specifically studied in this thesis: char gasification in a continuous fixed bed reactor. Granulation is the solution proposed for making use of low density or small particle-size biomasses. The performance of two wood chars – made from wood chips and pellets – was studied at the same time using experimental and numerical tools. Experiments were first conducted in a very highly instrumented pilot reactor, reproducing this zone of the process. The profiles measured, namely temperature, gas composition, bed density and particle velocity formed a unique database revealing reactor performance. A very reactive zone under 5 cm thick was thus located at the top of the bed, or even significant compaction leading to a drop in particle velocity, in a ratio of 8. Granular char gasification led to the same final conversion rates and synthetic gas compositions as for the chars derived from wood chips. A numerical model of the study zone was then developed, based on solving conversion equations combined with reaction kinetics, using COMSOL software. Taking into account bed compaction and the apparent kinetics of the heterogeneous reactions on a particle scale in the reaction source terms were two specificities of the model. It enabled satisfactory reproduction of the profiles of the physical magnitudes measured, for various operating conditions and for the two charsstudied. Use of this model is already providing new and complementary experimental information; it will eventually make it possible to optimize the industrial process

Trois techniques de mesure différentes ont été utilisées pour étudier la distribution des fluides dans un lit fixe : la tomographie à fils, le collecteur de liquide et un ensemble de thermistances. La tomographie à fils, dont la première application dans le cadre des lits fixes est décrite ici, a permis, tout comme le collecteur de liquide, d’obtenir des résultats intéressants concernant l’influence de paramètres tels que la distribution initiale, le type de chargement et les débits de fluides sur la distribution du liquide. L’étude a notamment montré l’importance de bien définir la maldistribution de liquide en termes de la grandeur mesurée et a apporté un regard critique vis-à-vis des consensus généraux concernant l’effet sur la distribution de liquide de paramètres tels que le débit de gaz (dont les expériences ont montré qu’elle dépend du distributeur utilisé) et le type de chargement (l’hypothèse selon laquelle le chargement dense disperse mieux le liquide dans la direction radiale par rapport au chargement lâche n’a pas été vérifié). Une étude réalisée en régime à haute interaction a permis aussi d’observer la relation étroite qui existe entre la distribution initiale et le régime d’écoulement / Three different measuring techniques were used to study the fluid distribution inside a trickle-bed reactor: the wire mesh tomography, the liquid collector and a set of thermistors. The liquid collector and specially the wire mesh tomography, whose first application in trickle bed reactors is described here, yielded interesting results concerning the influence of variables such as the initial liquid distribution, the loading method and the fluid flow rates on liquid maldistribution. Among the main observations, the study illustrates the importance of well defining liquid maldistribution in terms of the measured quantity and prompts to some caution when referring to some “normally accepted facts” like the advantages in terms of liquid distribution obtained when increasing the gas flow rate (which depends, according to this study, on the quality of initial liquid distribution) or when using a dense loading of the catalyst (the hypothesis according to which, compared with a sock loading, dense loading favors radial dispersion was not verified by the study). Also, a study performed under high interaction conditions showed the intimate relationship between the inlet distribution and the flow regime observed inside the reactor

O projeto consistiu na concepção e avaliação do desempenho de um sistema anaeróbio-aeróbio para tratamento de esgoto sanitário. O leito do reator foi dividido em quatro compartimentos de igual volume. Foi usada espuma de poliuretano para imobilização da biomassa e, para facilitar a partida do reator, esse material suporte foi previamente inoculado. O projeto teve três fases distintas: na primeira etapa, foi observada a importância da concentração de biomassa anaeróbia no desempenho de reator anaeróbio a princípio operado com metade do leito reacional com espuma e, a seguir, com o leito todo preenchido com espuma. Na segunda etapa, foram testados diferentes tempos de detenção hidráulica no reator que operou apenas em condições anaeróbias. Na última etapa foi operado o reator combinado anaeróbio-aeróbio. Ficou constatada a importância da concentração de microrganismos no desempenho do reator anaeróbio, pois com o aumento da quantidade de espuma, o reator atingiu resultados melhores e maior estabilidade operacional. Foi comprovada a influência do tempo de detenção hidráulica (TDH) no desempenho do reator. Tempos de detenção muito altos acarretam problemas de transferência de massa líquido-sólido, e baixos TDH dificultam adequada ação dos microrganismos. O melhor resultado para o reator em operação exclusivamente anaeróbia foi para o TDH de 10 horas, no qual se conseguiu reduzir a DQO de amostra bruta de 389 +/- 70 mg/L para 137 +/- 16 mg/L, em média. Para o reator operado anaeróbio-aeróbio a DQO de amostra bruta decresceu de 259 +/- 69 mg/L para 93 +/- 31 mg/L, em média. A comparação de todos os resultados obtidos, evidenciou a importância do pós-tratamento aeróbio na remoção de parcela de matéria orgânica não removida em tratamento unicamente anaeróbio. / The project consisted in the design and performance evaluation of an anaerobic-aerobic system for wastewater treatment. Polyurethane foam was used for biomass immobilization and, to smooth the reactor start-up, this supporting material was previously inoculated. The project was divided in three distinct phases. In the first one, the importance of the anaerobic biomass concentration was observed in the performance of the anaerobic reactor in a way to operate the reactor primarily with half of the reaction bed filled with foam and subsequently operate it with the bed completely filled with foam. In the second phase, different times of hydraulic retention were tested with the reactor operating exclusively in anerobic conditions. In the third and last phase, an anaerobic-aerobic combined reactor was operated. It was possible to confirm the importance of microorganism concentration in the performance of the anaerobic reactor, since the increase in the amount of foam allowed the reactor to reach better results and greater operational stability. The influence of the hydraulic retention time in the reactor performance was also proved. Very high retention times cause problems in the liquid-solid mass transference, while low retention times do not allow an adequate action of microorganisms. The best result for the reactor with an exclusive anaerobic operation was the 10 hour retention time, when it was possible to reduce the COD of a 389 +/- 70 mg/L gross sample to a 137 +/- 16 mg/L in average. On the other hand, for the anaerobic-aerobic operating reactor, the COD of a gross sample dropped from 259 +/- 69 mg/ L to 93 +/- 31 mg/L in average. Finally, comparing all the obtained results, it was possible to verify the importance of the anaerobic post treatment in the removal of a part of the organic matter not removed in an exclusively anaerobic treatment.

Um reator anaeróbio horizontal de leito fixo foi operado a escala de laboratório, visando verificar sua capacidade de degradação de fenol. O RAHLF foi construído em vidro de borosilicato com 100 cm de comprimento e 5,04 cm de diâmetro, preenchido com lodo anaeróbio imobilizado em matrizes de espuma de poliuretano. Prévio à realização do experimento o reator foi operado com substrato sintético, contendo como fontes de carbono glicose, ácido acético e ácido fórmico, atingida a estabilização da matéria orgânica para uma carga orgânica de 1028 mg/L, correspondente a uma remoção de DQO de 98%, foi iniciada a adição de fenol começando com uma concentração de 50 mg/L como única fonte de carbono. A concentração de fenol adicionada variou de 50 a 1200 mg/L e sua degradação foi avaliada através de determinação cromatográfica, utilizando cromatografia gasosa e parâmetros físico-químicos como pH, ácidos voláteis, alcalinidade e DQO. O RAHLF foi operado com um tempo de detenção hidráulica (TDH) de 12,3 horas. Com 50 mg/L, após 33 dias o reator atingiu uma remoção de fenol de 97%. Com 100 mg/L e depois de 148 dias de operação não foi detectado fenol no efluente do reator. Com 300 mg/L e após 58 dias de operação o reator apresentou 99% de remoção e uma concentração no efluente de 0,85 mg/L. Com 600 mg/L, 900 mg/L e 1200 mh/L, após 47, 29 e 7 dias de operação o reator alcançou remoções de 99%. Em todas as concentrações foi observado o predomínio de Methanosaeta, Methanobacterium e cocosmetanogênicos. Em relação à bactéria oxidadora de fenol foi observado o predomínio de coco-bacilos. As altas remoções de fenol observadas neste trabalho são devidas provavelmente à utilização de células imobilizadas. / A bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor was assayed aiming to verify its potential use for phenol degradation. The HAIB reactor consisted of a bore-silicate tube (100 cm long; 5.04 cm diameter) filled with polyurethane foam matrices containing immobilized anaerobic sludge. Before being subjected to phenol, the reactor was fed with synthetic substrate at the influent chemical oxygen demand (COD) of 1,028 mg/L achieving 98% of COD removal efficiency. Thereafter, phenol as the sole carbon source was added under step-increasing concentrations from 50 to 1,200 mg/L. Phenol degradation was evaluated by gas chromatographic analysis of influent and effiuent samples. Process monitoring included determinations of pH, volatile acids, alkalinity and COD. The HAIB reactor was operated at a constant hydraulic detention time (HDT) of 12,3 hours. After 33 days with 50 mg/L of phenol in the influent, the reactor achieved 97% of phenol removal efficiency. Successful phenol degradation (efficiency removal of 99%) occurred for influem concentrations of 100, 300, 600, 900 and 1,200 mg/L after 148, 58, 47, 29 and 7 days, respectively. The predominance of Methanosaeta, Methanobacterium and methanogenic cocci could be observed in all the operating conditions, besides the presence of phenol-oxidizing microorganisms as irregular rods. The results indicate that phenol degradation at very high rates can be accomplished in HAIB reactors containing acclimatized biomass.

A atividade industrial diversificada tem sido responsável pelo lançamento, no ambiente, de resíduos que contém materiais tóxicos e/ou de difícil degradação. Benzeno, tolueno, etilbenzeno e xilenos (BTEX) são compostos importantes, por estarem presentes em águas superficiais e subterrâneas, geralmente a partir de contaminações por derivadas de petróleo. Enquanto a degradação aeróbia de BTEX já está amplamente entendida e descrita, a aplicação de processos anaeróbios de tratamento, indicados na década de 80 ainda requer mais estudos. Reatores anaeróbios horizontais de leito fixo de bancada preenchidos com cubos de espuma de poliuretano, contendo lodo anaeróbio proveniente de diversas fontes trataram a água residuária sintética a base de proteínas, carboidratos, lipídios, contendo solução etanólica de BTEX e solução de BTEX em detergente comercial; e solução etanólica de BTEX como únicas fontes de carbono. A influência da adição de nitrato e sulfato como aceptores de elétrons na degradação anaeróbia também é discutida. Os reatores foram capazes de remover BTEX nas concentrações testadas de até 15,0 mg/L de cada composto, com tempos de detenção hidráulica de 11,4 horas e 13,5 horas. Os reatores forneceram condições excelentes para o desenvolvimento de biofilme complexo capaz de degradar BTEX, contendo organismos degradadores de BTEX, acetogênicos, acetoclásticos e hidrogenotróficos. Arqueas metanogênicas representaram menos de 0,5% do total de organismos anaeróbios na biomassa dos reatores. O modelo cinético de primeira ordem com residual foi o que melhor representou os dados experimentais e as velocidades de degradações de BTEX, estimadas neste trabalho, foram cerca de 10 a 94 vezes maiores que as encontradas na literatura, em ensaios realizados em microcosmos. / The diversified industrial activity has been responsible for discharge in the environment of toxic and/or difficult degradation compounds. Benzene, toluene, ethylbenzene and xylenes (BTEX) are important compounds present in surface and ground waters, usually from petroleum products contamination. While BTEX aerobic degradation is extensively understood and described, anaerobic treatment application, started in the eighties, associated to fundamental studies need to be improved. Bench-scale horizontal-flow anaerobic immobilized biomass reactors filled with polyurethane foam matrices, containing immobilized anaerobic biomass from various sources, treated synthetic substrate containing protein, carbohydrates, lipids, BTEX solution in ethanol and BTEX solution in commercial detergent, as well as BTEX solution in ethanol as the sole carbon source. The influence of the addition of nitrate and sulfate as electron acceptors on anaerobic degradation is also discussed. The reactors were able to remove up to 15.0 mg/L of each BTEX compound, with hydraulic detention time of 11.4 hours and 13.5 hours. The reactors provided excellent conditions for developing a complex biofilm with BTEX-degraders, acetogenic, acetoclastic and hydrogenotrophic microorganisms. Methanogenic archaea were found to represent less than 0.5% of the total anaerobic organisms in the biomass inside the reactors. Residual first order kinetic model fitted well the experimental data and the BTEX degradation rates, estimated in this work, were about 10- to 94-fold higher than those found in the literature, in microcosms studies.

A intensificação da degradação ambiental impulsionada pelas atividades antrópicas tem comprometido a qualidade da água. A presença de metais potencialmente tóxicos no ambiente provoca diversos impactos na fauna e flora, como, por exemplo, o processo de magnificação trófica. Assim, é fundamental que estudos de adsorção desses contaminantes sejam realizados, a fim de buscar novos métodos que permitam a remoção dos mesmos no meio aquático. O metal crômio está nos efluentes de diversos processos industriais, como curtumes, refino de petróleo, galvanoplastia, soldagem e cromagem. Esse metal na forma hexavalente possuí efeito tóxico a biota e riscos à saúde humana, indicando a necessidade da realização de estudos para sua remoção de efluentes industriais e corpos d\'água. O biopolímero quitosana tem sido reportado em diversos estudos como bioadsorvente de alto potencial de retenção de metais, por conta da presença de amino-grupos em sua estrutura. Além disso, a quitosana possui propriedades singulares e é obtida da quitina, um dos biopolímeros mais abundantes na natureza. Com a finalidade de avaliar a capacidade de adsorção de Cr (VI) pelo biopolímero quitosana em forma de pérolas (P-QTS), realizou-se ensaios de adsorção em processo contínuo com diferentes concentrações do metal cromo em coluna de leito fixo, preenchida pelo material adsorvente (P-QTS). Além disso, realizou-se testes de toxicidade com os organismos Daphnia magna, Allonais inaequalis e Chironomus xanthus no afluente e efluente da coluna de adsorção, buscando avaliar a toxicidade dessas amostras para os organismos e a consequente eficácia do tratamento da solução de dicromato de potássio na coluna de leito fixo com as P-QTS. As curvas de ruptura indicaram que para as maiores concentrações de K2Cr2O7 houve intensificação da saturação da CALF (coluna de adsorção de leito fixo), e, consequentemente, a zona de transferência de massa (ZTM) se deslocou no sentido descendente do leito fixo da coluna de adsorção. A razão C/Co (concentração efluente/concentração afluente) aumentou de maneira significativa no decorrer do ensaio para as maiores concentrações afluentes (25 e 28,5 mg L-1) de K2Cr2O7 alcançando valores de até 0,4, e, isso demonstra a saturação de parte das P-QTS na coluna de leito fixo. De maneira geral, a remoção de Cr VI foi alta (superior a 50% e atingindo a máxima de 98%) para os tempos estudados na presente pesquisa, sendo maior nos menores tempos (60 e 120 min) do ensaio, estado em que os sítios ativos para adsorção das P-QTS provavelmente estavam livres. Da extração do cromo das P-QTS obteve-se valor máximo de 8,18 mg g-1 e mínimo de 0,42 mg g-1 de massa adsorvida por massa de adsorvente, o que indica variação de acordo com a concentração da solução de K2Cr2O7 afluente a CALF, ou seja, para as maiores concentrações, maior a quantidade adsorvida de Cr VI por massa de adsorvente (P-QTS). Alguns pesquisadores obtiveram relação de 2,6 mg de crômio (III) /g de quitosana indicando que as P-QTS na coluna de leito fixo possuem boa capacidade de adsorção. Os testes de toxicidade mostraram diferentes sensibilidades dos organismos-teste às soluções de dicromato de potássio, sendo na ordem decrescente: Chironomus xanthus < Allonais inaequalis < Daphnia magna. A coluna de adsorção de leito fixo diminuiu, de modo geral, a mortalidade dos organismos-teste comparando o afluente e efluente, principalmente das amostras efluentes de menor tempo (60 e 120 min) de ensaio de adsorção. A média de comprimento das larvas de C. xanthus reduziu (10,07 mm > 8,34 mm > 4,59 mm), de modo geral, a medida que o tempo de ensaio (60, 120 e 180 min) aumentou, indicando aumento da concentração de Cr VI nos efluentes. / The intensification of environmental degradation driven by anthropic activities has led to a decrease in water quality. The presence of potentially toxic metals in the environment causes several impacts on fauna and flora, such as the trophic magnification process. Thus, it is fundamental that adsorption studies of these contaminants are carried out in order to search for new methods that allow their removal in the aquatic environment. Chromium metal is in the effluents of various industrial processes, such as tanning, petroleum refining, electroplating, welding and chrome plating. The chromium in the hexavalent form has a toxic effect on biota and risks to human health, indicating the need to carry out studies to your removal of industrial effluents and water bodies. The biopolymer chitosan has been reported in several studies as bioadsorbent with high potential for metal retention, due to the presence of amino groups in its structure. In addition, chitosan has unique properties and is obtained from chitin, one of the most abundant biopolymers in nature. In order to evaluate the Cr (VI) adsorption capacity of the chitosan biopolymer in the form of beads (P-QTS), adsorption tests were carried out in continuous process with different concentrations of the chromium metal in a fixed bed column, filled by adsorbent material (P-QTS). Besides that, toxicity tests were carried out with the organisms Daphnia magna, Allonais inaequalis and Chironomus xanthus on the affluent and effluent of the adsorption column, seeking to evaluate the toxicity of these samples to the organisms and the consequent effectiveness of the treatment of potassium dichromate solution in the fixed bed column with the P-QTS. The breakthrough curves indicated that for the higher concentrations of K2Cr2O7 there was an increase in the saturation of the CALF (fixed bed adsorption column), and consequently the mass transfer zone (ZTM) moved downwards from the fixed bed of the column of adsorption. The C/Co (affluent concentration/effluent concentration) ratio increased significantly during the test for the highest affluent concentrations, reaching values of up to 0.4 for the affluent concentrations of 25 and 28.5 mg L-1 of K2Cr2O7, and this demonstrates the saturation of part of the P-QTS in the fixed bed column. The removal of Cr VI was high (higher than 50% and reaching a maximum of 98%) for the times studied in the present study, but it was higher in the lower times (60 and 120 min) of the test, in which the active sites for adsorption of P-QTS probably were free. From the extraction of chromium from P-QTS, a maximum value of 8.18 mg g-1 and a minimum of 0.42 mg g-1 was obtained, which indicates variation according to the concentration of the K2Cr2O7 solution affluent to CALF, i.e the adsorbed amount of Cr VI per adsorbent mass (P-QTS) is higher at higher concentrations. Some authors have obtained a ratio of 2.6 mg of chromium (III) / g of chitosan indicating that the P-QTS in the fixed bed column have good adsorption capacity. The toxicity tests showed different sensitivities of the test organisms to the solutions of potassium dichromate, being in descending order: Chironomus xanthus < Allonais inaequalis < Daphnia magna. The fixed-bed adsorption column decreased the mortality of the test organisms by comparing the affluent and the effluent, mainly from the effluent samples with the shortest adsorption test time (60 and 120 min). The mean length of the C. xanthus larvae decreased (10.07 mm> 8.34 mm> 4.59 mm), generally as the test time (60, 120 and 180 min) increased, indicating rise in Cr VI concentration in the effluents.

Este trabalho apresenta as avaliações de desempenho, das demandas operacionais e dos fatores intervenientes no aumento da escala da unidade piloto do Reator anaeróbio Horizontal de Leito Fixo (RAHLF) no tratamento de esgoto sanitário após passagem por peneira com malha de 1 mm, durante dois anos de operação. O reator dispunha de volume total de 237,5 1, construídos com tubos comerciais de PVC de 14,5 cm de diâmetro (D), dispostos em cinco módulos horizontais em série de 2,88 m, perfazendo um comprimento total de (L) de 14,4 m e relação de total de L/D de 100. O suporte de imobilização de biomassa, espuma de poliuretano em matrizes cúbicas de 1 cm de aresta, mostrou-se adequado ao desenvolvimento do biofilme. Em partida, sem inoculação prévia, ocorreu a sua consolidação a partir de 70 dias, com predominância de morfologia semelhante a Methanosaeta sp. em relação a da Methanosarcina. Em torno de 90 dias com afluente de 350 mg/l de DQO, observe-se a melhor qualidade do efluente, com valor de 100 mg/l de DQO. Em longa operação ocorreu queda de rendimento e menor reprodutibilidade das previsões do projeto, atribuída aos constantes entupimentos e ineficácia das operações de limpeza, com o comprometimento de volume reacional verificados por estudos de hidrodinâmica. Da investigação das origens dos equipamentos observou-se tratar mais de um efeito local e qualitativamente relacionado à biomassa retida que propriamente quantitativo e extensivo ao longo de todo reator, com produção continuada de polímeros extracelulares, promovendo um efeito sinérgico com os predominantes organismos filamentosos e com os sólidos particulados retidos no leito. Diante das potencialidades desta configuração de reator apontam-se alternativas de mitigação dos entupimentos e o direcionamento dos estudos necessários para novo aumento de escala para o tratamento de esgoto sanitário. / This work evaluated the performance, the operational demands and the intervenient factors in the scale-up of the horizontal flow anaerobic immobilized biomass (HAIB) reactor pilot unit, treating domestic sewage previously screened. The operation was monitored for two years. The five- module (2.88 m length each) reactor volume was 237.5 liters and it was built with commercial PVC pipes of 14.5 cm of diameter (D), resulting in a total length (L) of 14.4 m and in a total ratio L/D of approximately 100. The immobilization support, cubic matrices of polyurethane foam (1 cm edge), showed to be suitable for the anaerobic biofilm development. During the start-up, without previous inoculation, the biofilm seemed to be consolidated after 70 days, and Methanosaeta sp. morphology predominated, in detriment of Methanosarcina. With an affluent of 350 mg COD/L, the best reactor performance was observed in about 90 days of operation (100 mg COD/L in the effluent). However, with the continuous operation, its performance decreased and the project predictions did not seem to fit anymore. These facts were probably due to the frequent cloggings ant the inefficiency of the backwashing procedures, leading to a decreasing of the operational volume. The origin of the clogging seemed to be related to the extracellular polymer production, linked to a synergic effect with the filamentous organisms and the particulate solids in the bed. Despite these operational problems, there were found alternatives to mitigate the clogging, and studies about a new scale-up methodology, in order to treat domestic sewage, were strongly recommended.

Submeteu-se um Reator Anaeróbio Horizontal de Leito Fixo (RAHLF) de bancada, ao aumento progressivo da concentração de matéria orgânica afluente, e a cargas de choque orgânicas, com o objetivo de verificar-se seu desempenho e estabilidade operacional. O RAHLF foi construído com um tubo de boro-silicato de 100 cm de comprimento, 5,0 cm de diâmetro e 1995 ml de volume total e preenchido com lodo anaeróbio imobilizado em matrizes de espuma de poliuretano. O reator foi alimentado, inicialmente, com substrato composto principalmente de carboidratos em concentrações, expressas como Demanda Química de Oxigênio (DQO) de, aproximadamente, 200, 1000 e 2000 mg/l. Posteriormente, os carboidratos foram substituídos por metanol e ácidos voláteis, em concentrações totais, aproximadas, de 2000, 3000, 4000 e 5000 mg DQO/l. Atingido o estado estacionário para cada condição operacional, foram aplicadas cargas de choque, aumentando-se em três vezes o valor da DQO afluente, durante período equivalente ao tempo de detenção hidráulica (sete horas). O sistema apresentou problemas operacionais durante os experimentos com carboidratos, quando submetido a 2000 mg DQO/l, correspondente à taxa volumétrica de carregamento orgânico de 8,77 KgDQO/m3.d. Não foi verificado qualquer problema operacional durante os experimentos com substrato contendo metanol e ácidos voláteis, e o reator apresentou eficiência de remoção de DQO superior a 90%. Para o experimento com DQO afluente igual a 2000 mg/l, os parâmetros cinéticos foram estimados a partir de modelo cinético de 1ª ordem, obtendo-se valor de k1 igual a 0,049 h-1, nos demais experimentos ajustou-se modelo cinético de 2ª ordem com valor médio de k2 equivalente a 2,0 x 10-4 l/mg.h Foram aplicadas cargas de choque orgânicas equivalentes a, aproximadamente, 17; 27; 40 e 47 kgDQO/m3.d. Os efeitos das sobrecargas orgânicas no reator foram transientes em todos os casos, tendo o reator voltado à condição inicial em, no máximo, 15 horas após o início das sobrecargas. / A Horizontal flow Anaerobic lmmobilized Sludge Reactor (HAIS) was subjected to progressively increasing concentrations of organic effluent material and to organic shock loads with the purpose of investigating its operational performance and stability. The HAIS, consisting of a 100 cm long, 5 cm diameter borosilicate tube with a total volume capacity of 1995 mL, was filled with anaerobic sludge immobilized in foam and polyurethane matrixes. The reactor was initially fed with a substrate composed mainly of carbohydrates in concentrations, expressed as Chemical Oxygen Demand (COD), of approximately 200, 1000 and 2000 mg/L. These carbohydrates were later replaced by methanol and volatile acids in total concentrations of 2000, 3000, 4000 and 5000 mg COD/L. Shock loads were applied after each operational condition became stationary, with the effluent COD tripled for a period equivalent to the hydraulic detention time (seven hours). The system presented operational problems during the experiments with carbohydrates when subjected to 2000 mg DQO/l, which corresponded to a volumetric organic load index of 8,77 Kg COD/m3.d. No operational problems were detected during the experiments with substrates containing methanol and volatile acids, and the reactor presented a COD removal efficiency of over 90%. The kinetic parameters for the COD effluent with 2000 mg/L were estimated based on a first arder kinetic model, which resulted in a k1 value of 0,049 h-1, while a kinetic model of the second order was used for the remaining experiments, with a mean value of k2 equivalent to 2,0 x 10-4 L/mg.h. Organic shock loads of approximately 17; 27; 40 and 47 kg COD/m3.d were applied. The effects of the organic overloads on the reactor were transient in every case, with the reactor returning to its initial condition at the most 15 hours after the beginning of the overloads.