L'objectif principal de ce travail de thèse concerne l'étude de l' élimination de la DCO et de la nitrification dans une nouveau lit bactérien Multi-Section ( MSB ) . Après une caractérisation de l’hydrodynamique et du transfert d’oxygène de ce lit bactérien, les expériences biologiques menées sous des conditions opératoires contrastées (fortes et faibles charges organiques eteaux usées contenant ou pas des matières particulairs) ont été menées. En parallèle, des simulations avec le logiciel Biowin® ont été réalisées. Les principaux résultats sont résumés en suivant :- La rétention de liquide statique est majoritaire par rapport à la rétention dynamique que ce soit en présence ou en absence de biofilm. Le biofilm joue le rôle d’une "éponge" permettant un maintien de l’humidité du lit même à faible débit. Les expériences de DTS ont montré que le biofilm accroit le temps de séjour du liquide et conduit à une diminution de l’épaisseur du film liquide permettant ainsi de promouvoir le transfert de l'oxygène.- Le réacteur MSB montre une élimination efficace de la DCO (> 95 % ) et de la nitrification ( > 60 % de l’azote entrant), mais une accumulation de DCO particulaire a lieu dans le filtre ce qui conduira à un colmatage à terme. La nitrification cohabite avecl’élimination de la DCO même dans la première section et pour une charge organique élevée ce qui implique une bonne capacité d’oxygénation du MSB par l’aération naturelle.- Un modèle dynamique de MSB a été utilisé implémenté sur le simulateur - BioWin , afin d'obtenir la répartition des biomasses au sein du réacteur et d'évaluer le processus limitant dans chaque section. Le modèle partiellement calibré peut aider à estimer les besoins minimum d'oxygène pour la nitrification et peut rendre compte de la compétition entre la croissance hétérotrophe et la nitrification. / The main objective of this PhD work focused on the study of the COD removal and nitrification in a new designed Multi-Section Bioreactor (MSB). Hydrodynamic characterization of the reactor, biological experiments under contrasted conditions and simulations by Biowin® software were carried out:- Firstly, it was found that static liquid retention is the predominant part both without and with the presence of biofilm. Biofilm acts like a "sponge". RTD experiments showed that biofilm can promote liquid residence time, decrease the liquid film andpromote the oxygen transfer consequently.- Secondly, the MSB operated at contrasted organic loading rate (OLRs) and nitrogen loading rate (NLRs) showed that COD can be effectively removed (removal efficiency > 95%) and nitrification (> 60% of the N removal) occurred in this biofilter.Nitrification is efficient even in the first section implying no drastic oxygen limitation though only natural aeration is occurring.- Thirdly, a TF dynamic model has been used from a simulator - BioWin, in order to get more insights on the biomass distribution in the pilot and to assess the limiting process in each section of the bioreactor. Calibration of the model can help us to estimate theminimum oxygen requirement for nitrification for each zone inside the pilot and it can well represent the competition between heterotrophic growth and nitrification.

No meio científico são bastante utilizados os modelos matemáticos para avaliar as características hidrodinâmicas de reatores, porém a literatura é pobre em informações relativas à aplicação do equacionamento matemático em regime não-permanente. Neste trabalho foi aplicado um modelo matemático simulando a hidrodinâmica de reatores tubulares com dispersão para avaliar o efeito da variação de vazão afluente sobre os parâmetros hidrodinâmicos. As simulações foram efetuadas considerando vazão e volume constantes, vazão e volume variáveis e vazão variável e volume constante. Foi investigada a influência de dois tipos de ensaios estímulo-resposta, pulso e degrau, para aplicação de modelos matemáticos e determinação das curvas de distribuição do tempo de residência (DTR) experimentais. Teoricamente ambos devem fornecer os mesmos resultados embora o ensaio em pulso costume apresentar maior sensibilidade experimental. Conforme esperado, ambos os ensaios apresentaram os mesmos resultados finais. Também foram avaliados os traçadores empregados nos dois tipos de ensaios estímulo-resposta, pulso e degrau. Foram empregados três traçadores diferentes - verde de bromocresol, azul de bromofenol e eosina Y que proporcionaram curvas com diferentes características. Como ferramenta auxiliar da modelação foram estudas a determinação das curvas DTR experimentais com auxílio de duas técnicas distintas. Para calibrar o modelo matemático proposto foram utilizados dados de reatores em escala de bancada com diferentes configurações submetidas a variações de vazões afluentes. Os dados de um reator UASB em escala piloto - submetido a variações cíclicas de vazão afluente de 40 e 60% - foram empregados para calibrar e verificar o modelo matemático proposto. Os resultados encontrados com o modelo matemático proposto nesta pesquisa demonstraram que a variação de vazão afluente não deve ser negligenciada. O modelo utilizado representou adequadamente o reator UASB. Seus resultados, quando comparados aos modelos matemáticos que não consideram a variação de vazão, mostraram que para flutuações de vazão elevadas, vazões com valores até 60% maiores do que a vazão média, os valores dos coeficientes de difusão diferem significativamente em função das hipóteses empregadas no desenvolvimento do modelo matemático. / Mathematical models for hydrodynamic characteristics evaluation of reactors are commonly used however there is a lack of information in the literature concerning the application of mathematical modeling for non-steady state flow. In this thesis, it is presented a non-steady mathematical model to simulate the hydrodynamic behavior of pipe flow reactors with diffusion in order to evaluate the effect of the variation of the influent flowrate in the hydrodynamic parameters. The simulations were performed considering constant flowrate and volume, variable flowrate and volume and, variable flowrate and constant volume. It was investigated the influence of two types of stimulus-response assays, pulse and step function, on the application of mathematical models and the determination of the experimental retention time distribution curves. Theoretically, both tests should provide the same results although the pulse stimulus assay usually presents higher experimental sensitivity. As it was expected, both tests presented the same final results. The tested tracers were also evaluated in relation to the pulse and step stimulus-response tests. Three tracers were tested (bromocresol green, bromophenol blue and eosin Y) and it was shown that they provided different curves. It was studied the construction of the experimental retention time distribution curves using two procedures as an auxiliary tool for modeling. The proposed mathematical model was calibrated with data of bench scale reactors submitted to different cyclical variations of flowrates. Moreover, data of UASB reactor in pilot scale - submitted to 40 and 60% of cyclical variations of flowrates were utilized to calibrate and verify the obtained mathematical model. The results found with the mathematical model proposed in this research showed that the variations in influent flow rate can not be neglected. The model adequately represented a pilot scale UASB reactor. The results showed that the diffusion coefficients differ significantly for high flowrate fluctuations, when compared to other mathematical models that do not incorporate variable flowrate, depending upon the hypothesis used to derive the model.

Ce travail porte sur l'étude de fours tournants équipés de releveurs. Ce sont des contacteurs gaz/solide largement répandus dans de nombreux secteurs industriels mettant en oeuvre des solides divisés. Cependant en raison d'une faible connaissance du fonctionnement de ces équipements notamment en matière d'écoulement ou de transfert thermique, leur utilisation repose encore beaucoup sur le savoir faire des opérateurs acquis avec le temps. Ainsi ce travail vise à fournir aux ingénieurs des outils de connaissance et d'extrapolation pour les accompagner dans les phases de dimensionnement, mais aussi d'optimisation de procédés existants, en particulier pour des fours tournants en chauffage indirect et équipés de releveurs. La première partie de cette étude porte sur l'influence des conditions opératoires sur l'hydrodynamique des solides divisés de forme et taille différentes. Pour ce faire, des procédures expérimentales pour la mesure de distribution des temps de séjours des particules solides ont été mises en oeuvres. Deux pilotes de four tournant ont été utilisés. Ces derniers ont un ratio longueur sur diamètre équivalent mais un ratio de taille de 2. L'hydrodynamique des fours a été caractérisée quantitativement à partir des résultats expérimentaux en terme de temps de séjour des solides, taux de remplissage du four ainsi que de la dispersion axiale des particules. Ces derniers ont été modélisés par analyse dimensionnelle dans un souci de généralité en prenant en compte la présence d'éléments internes (releveurs, grille) ou diaphragmes en sortie, mais aussi des paramètres opératoires tels que la vitesse de rotation du tube, son inclinaison ou le débit des particules solides. La seconde partie de cette étude s'intéresse aux processus de transfert thermique dans les fours tournants en chauffage indirect et équipés de releveurs. Cette étude repose sur la mesure des profils de température à la paroi, dans la phase gazeuse et le lit de particules solides. L'analyse de ces profils de température se focalise sur la détermination des coefficients de transfert de chaleur entre la paroi et le lit de solides d'une part, et entre la paroi et le gaz d'autre part. Une méthode d'analyse globale de système mince et un bilan global intégrant la puissance fournie pour la chauffe sont utilisés pour la détermination de ces coefficients de transfert. Les résultats obtenus permettent d'une part de mettre en évidence l'effet des releveurs ainsi que l'influence des paramètres opératoires sur ces coefficients de transfert de chaleur et d'autre part d'établir par analyse dimensionnelle des modèles pour ces derniers. Enfin, ce travail se termine par la mise en place d'un modèle dynamique simplifié de four tournant en chauffage indirect permettant la détermination des profils de température le long du four et pouvant être facilement adapté à divers procédés. / The present work addresses a fundamental study on flighted rotary kilns. They are gas-solid reactors, used in a variety of industries to process heterogeneous media. However, operating these kilns mainly relies on the know-how of operators due to insufficient fundamental understanding. The aim of this work is to provide engineers with relevant tools and models to assist in the design stage and the performance improvement of existing operating process units, in particular indirectly heated rotary kilns, inclined and equipped with lifters. In the first part, we studied the effects of operating parameters on the flow of materials of differing properties and shape. For this purpose, residence time distribution measurements were performed through experimental stimulus response tests. Two pilot-scale rotary kilns with similar length-to-diameter ratios, but a dimension ratio of about two were used in this study. We focused on the effects of lifter shape and configurations. The effects of the rotational speed, the kiln slope, the mass flow rate and the exit dam height were also analyzed. The flow of solids was quantitatively characterized primarily by the experimental mean residence time, hold-up, and axial dispersion coefficient. Using a dimensional analysis, models were established to predict the mean residence time, the filling degree and the axial dispersion coefficient, providing basic information on the kiln design, solid particle properties and operating conditions. In the second part, we studied the heat transfer mechanisms occurring in the flighted rotary kiln by measuring temperature profiles at the wall, the freeboard gas and the bulk of solids. Analysis of the temperature profiles focused on two main issues: assessment of the heat transfer coefficient between wall and gas, and assessment of the heat transfer coefficient between wall and solid particles. The lumped system analysis and a heat balance using the power supplied for the heating were applied to determine the experimental heat transfer coefficients. The effects of operating conditions and lifting flights were analyzed. Both heat transfer coefficients were then correlated through dimensional considerations. Lastly a global dynamic model mainly based on the models developed in this study can be used to determine wall, gas and bulk solids axial temperature profiles in an indirectly heated flighted rotary kiln. This global model needs to be completed with specific models related to a reaction so as to be used as a framework for the simulation of specific industrial rotary kilns.

L’enrobage à sec par action mécanique permet de formuler des particules composites dont les fonctionnalités et les propriétés physiques, comme l’écoulement, sont améliorées et cela sans l’ajout de solvant ou de liant. Actuellement la plupart des procédés d’enrobage à sec sont conduits en mode discontinu. L’objectif de ce travail est donc de développer et d’étudier une opération d’enrobage à sec par un procédé continu innovant, une extrudeuse bi-vis corotative sans filière, constituant une rupture technologique dans son domaine. Dans le cadre de ce travail, des sphères de cellulose microcristalline, appelées particules hôtes sont enrobées avec soit des talcs de différentes granulométries soit du stéarate de magnésium, nommées particules invitées. Dans un premier temps, le comportement des particules hôtes est étudié dans le procédé. Les particules sorties du procédé sont analysées par microscopie électronique à balayage, par granulométrie laser et par voluménométrie. Pour la configuration de vis présentant que des éléments de transport, la vitesse de rotation des vis (25 à 200 rpm) et le débit d’alimentation (0,5 à 2 kg/h) choisis influencent le taux de remplissage dans le fourreau, et pour un taux supérieur à environ 14 % : la quantité de particules endommagées est négligeable. Un taux de remplissage faible favorise les frictions particules-particules ou particules-métal au niveau de l’entrefer. L’ajout de zones de mélanges dans la configuration des vis accentue ce phénomène de brisure par l’augmentation des contraintes de cisaillement. Par ailleurs, des masses retenues de la poudre dans le fourreau évoluent linéairement en fonction de la masse de poudre transportée en un tour de vis pour différentes configurations de vis. Ces relations laissent penser à l’existence d’un volume mort. Les mesures de distribution de temps de séjour mettent en évidence par l’application d’un modèle d’association de réacteurs idéaux, la présence d’écoulement piston et d’un volume mort. Dans un second temps, la faisabilité d’une opération d’enrobage à sec par le procédé étudié est analysée. Une couche d’enrobage continu de talc modifiant le comportement hydrophile des particules hôtes, est obtenue pour une vitesse de rotation de vis de 50 rpm et une configuration de vis cisaillante. Le type de particules invitées influence la morphologie de la couche d’enrobage : de type film avec le stéarate de magnésium et de type discret avec le talc micronisé. Néanmoins les propriétés de taille, d’écoulement, de compressibilité des particules composites sont semblables à celle des particules hôtes, seule la propriété de mouillabilité est modifiée. La présence de stéarate de magnésium diminue le temps de séjour des particules dans le procédé grâce à son caractère lubrifiant. / Dry particle coating with mechanical action allows the production of composite particles whose functionalities and physical properties, such as flowability, are improved thanks to the absence of solvent or binder. Currently, most of dry particle coating processes are carried out in a discontinous mode. The objective of this work is thus to develop and study a dry particle coating operation with a continuous innovative process, twin screw co-rotating extruder without die, constituting a technological rupture in this application field. For this, spherical particles of microcristalline cellulose, as host particles, are coated with either talc particles of two sizes or magnesium stearate particles (MgSt), as guest particles. Firstly, the host particles behaviour is studied in the process. The exiting particles are analyzed by scanning electronic microscopy, laser granulometry and tapping test. Regarding the transport configuration, the chosen screw speed (between 25 an 200 rpm) and the feed rate (between 0.5 and 2 kg/h) have an important influence on the filling level in the barrel. For a filling level superior to approximatly 14 %, the quantity of broken particles is not significant. A low filling level facilitates the particle-particle or particle-metal friction in the barrel gap. When more mixing zones are added to the screw configuration, the shear stresses increase and, therefore, the breakage particle phenomenon becomes more prominent. Futhermore, the retained powder mass increases linearly when the transported mass in one screw turn increases for all the screw configurations. These evolutions suggest the existence of a dead volume. The residence time distribution mesurements highlight, thanks to the application of flowing model, the presence of plug-flow and a dead volume. Secondly, the feasibility of using the process for dry particle coating is analyzed. A continuous coating layer of talc modifiying the hydrophilic behaviour of the host particles is obtained for a low screw rotation speed (50 rpm) and a screw configuration with one mixing zone. The type of guest particles influence the morphology of the coating layer: film layer with the MgSt particles and discontinous layer with the micronized talc. However, size, flow and compressibility of the coated particles are similar to the ones of the initial host particles, only the wettability properties are modified. The presence of MgSt decreases the particle mean residence time in the process thanks to its lubricant action.

No description available.

Considere um meio caracterizado por $N$ pontos cujas coordenadas são geradas aleatoriamente de maneira uniforme nas arestas unitárias de um hipercubo $d$-dimensional. Um caminhante parte de cada ponto deste meio desordenado e se movimenta obedecendo à regra determinista de ir para o ponto mais próximo que não tenha sido visitado nos últimos $mu$ passos. Este processo foi denominado de caminhada determinista do turista. Cada trajetória gerada por esta dinâmica possui uma parte inicial não-periódica de $t$ passos (transiente) e uma parte final periódica de $p$ passos (atrator). As probabilidades de vizinhança são expressas através da fórmula de Cox, que é parametrizada pela função beta incompleta normalizada $I_d = I_{1/4}[1/2,(d+1)/2]$. Enfati-zamos aqui que a distribuição relevante é $S_{mu,d}^{(N)}(t,p)$, a distribuição conjunta de $t$ e $p$, que tem como casos particulares as distribuições marginais, previamente estudadas. O objetivo deste estudo é obter analiticamente estas distribuições para a caminhada determinista do turista sem memória no espaço euclideano, no modelo de distâncias aleatórias (que corresponde ao limite $d ightarrow infty$) e no modelo de mapeamento aleatório (que é um caso limite das redes de Kauffman). As distribuições analíticas obtidas foram validadas através de experimentos numéricos. A distribuição conjunta de tempos de transiente e período de atratores, no limite termodinâmico para uma dimensionalidade arbitrária vale: $S_{1,d}^{(infty)}(t,p) = [Gamma(1+I_d^{-1}) cdot (t+I_d^{-1})/Gamma(t+p+I_d^{-1})] cdot delta_{p,2}$, onde $t=0,1,2,ldots,infty$; $Gamma(z)$ é a função gama e $delta_{i,j}$ é o delta de Kronecker. A caminhada determinista do turista sem memória no modelo de mapeamento aleatório produz uma distribuição de períodos não-trivial ($S_{0,rm}^{(N)}(p) propto p^{-1}$), que é obtida de $S_{0,rm}^{(N)}(t,p) = Gamma(N)/{Gamma[N+1-(t+p)]N^{t+p}}$, onde enfatizamos que o número de pontos explorados $n_e=t+p$ é a grandeza fundamental nos problemas considerados. / Consider a medium characterized by $N$ points whose coordinates are randomly generated by a uniform distribution along the unitary edges of a $d$-dimensional hypercube. A walker leaves from each point of this disordered medium and moves according to the deterministic rule to go the nearest point which has not been visited in the preceding $mu$ steps. This process has been called the deterministic tourist walk. Each trajectory generated by this dynamics has an initial non-periodic part of $t$ steps (transient) and a final periodic part of $p$ steps (attractor). The neighborhood probabilities are given by the Cox formula, which is parameterized by the normalized incomplete beta function $I_d = I_{1/4}[1/2,(d+1)/2]$. Here we stress that the relevant distribution is the joint $t$ and $p$ distribution $S_{mu,d}^{(N)}(t,p)$, which has as particular cases, the marginal distributions previously studied. The objective of this study is to obtain analytically these distributions for the memoryless deterministic tourist walk in the euclidean space, random link model (which corresponds to $d ightarrow infty$ limit) and random map model (which is a limiting case of the Kauffman model). The obtained distributions have been validated by numerical experiments. The joint transient time and attractor period distribution in the thermodynamic limit for an arbitrary dimensionality is: $S_{1,d}^{(infty)}(t,p) = [Gamma(1+I_d^{-1}) cdot (t+I_d^{-1})/Gamma(t+p+I_d^{-1})] cdot delta_{p,2}$, where $t=0,1,2,ldots,infty$; $Gamma(z)$ is the gamma function and $delta_{i,j}$ is the Kronecker's delta. The memoryless deterministic tourist walk in the random map leads to a non-trivial cycle distribution ($S_{0,rm}^{(N)}(p) propto p^{-1}$), which is obtained from $S_{0,rm}^{(N)}(t,p) = Gamma(N)/{Gamma[N+1-(t+p)]N^{t+p}}$, where we stress that the number of explored points $n_e=t+p$ is the fundamental quantity in the considered problems.

Considere um meio desordenado constituído por $N$ pontos cujas coordenadas são geradas aleatoriamente de maneira uniforme e independente nas arestas unitárias de um hipercubo $d$-dimensional. As probabilidades de vizinhança entre os pares de pontos deste meio são expressas através da fórmula de Cox. Um caminhante parte de um dado ponto deste meio desordenado e se movimenta obedecendo à regra determinista de ir para o ponto mais próximo que não tenha sido visitado nos últimos $\\mu$ passos. Este processo foi denominado de caminhada determinista do turista. Cada trajetória gerada por esta dinâmica possui uma parte inicial não-periódica de $t$ passos (transiente) e uma parte final periódica de $p$ passos (atrator). Neste trabalho, obtemos analiticamente algumas distribuições estatísticas para a caminhada determinista do turista com memória $\\mu$ arbitrária em sistemas unidimensionais e com memória $\\mu=2$ no modelo Random Link (que corresponde ao limite $d ightarrow 1$). Estes resultados nos permitiram compreender o papel da memória no comportamento exploratório do turista e explicar a equivalência não-trivial entre o modelo Random Link e o modelo Random Map (que é um caso limite das redes de Kauffman). Enfatizamos que o número de pontos explorados pelo turista é a grandeza fundamental nos problemas considerados. As distribuições analíticas obtidas foram validadas através de experimentos numéricos. Também obtivemos uma dedução alternativa para a fórmula de Cox, apresentando os resultados finais em termos de distribuições estatísticas elementares. / Consider a medium characterized by $N$ points whose coordinates are randomly and independently generated by a uniform distribution along the unitary edges of a $d$-dimensional hypercube. The neighborhood probabilities between any pair of points in this medium are given by the Cox formula. A walker leaves from each point of this disordered medium and moves according to the deterministic rule to go the nearest point which has not been visited in the preceding $\\mu$ steps. This process has been called the deterministic tourist walk. Each trajectory generated by this dynamics has an initial non-periodic part of $t$ steps (transient) and a final periodic part of $p$ steps (attractor). In this work, we obtain analytically some statistical distributions for the deterministic tourist walk with arbitrary memory $\\mu$ in one-dimensional systems and with memory $\\mu=2$ in the random link model (which corresponds to $d ightarrow 1$ limit). These results enable us to understand the main role played by the memory on the tourist\'s exploratory behavior and explain the non-trivial equivalence between the random link model and the random map model (which is a limiting case of the Kauffman model). We stress that the number of explored points is the fundamental quantity in the considered problems. The obtained distributions have been validated by numerical experiments. We also obtain an alternative derivation for the Cox formula, writing the final results in terms of known statistical distributions.

Podemos considerar a caminhada determinista do turista como um processo do tipo dinâmico, que ocorre sobre uma rede composta por N pontos. Os pontos são gerados de maneira aleatória, no espaço euclidiano d dimensional. Um caminhante, partindo de um ponto qualquer do meio desordenado, se movimenta seguindo uma regra determinista de ir para o ponto mais próximo que não tenha sido visitado nos últimos ?= µ - 1 passos. Cada uma das trajetórias geradas através dessa dinâmica possui uma parte inicial não periódica de t passos, denominada transiente, e uma parte final, periódica, de p passos, denominada atrator. Devido ao custo computacional de memória, só é possível simular sistemas com N ? O(103) e µ << N. Neste estudo uma nova implementação na estrutura de armazenamento de dados, no modelo numérico do turista, nos permitiu obter algumas distribuições estatísticas para a caminhada, com valores de memória µ ? O(N). Com estes resultados verificamos a eficiência da estrutura proposta e avançamos no conhecimento acerca do comportamento do turista em caminhadas com memória da ordem de N. Também neste trabalho, obtivemos resultados numéricos interessantes, que serviram para explicar a formação de atratores com determinados períodos na caminhada determinista do turista unidimensional, bem como a não formação de atratores com períodos 2µ+1, 2µ+2 e 2µ+3.não são constituídos. Também neste trabalho, uma nova implementação na estrutura de armazenamento de dados, no modelo numérico do turista, nos permitiu obter algumas distribuições estatísticas para a caminhada, com valores de memória ? muito acima do que se tinha alcançado anteriormente. Com estes resultados verificamos a eficiência da estrutura proposta, e avançamos o conhecimento a cerca do comportamento do turista em sistema da ordem de N. / We may consider the deterministic tourist walk as a dynamic process performed over a landscape of N points. These points are randomly spread on a d dimensional euclidean space. A walker leaves from any point of that landscape and moves according to the deterministic rule of going to the nearest point that has not been visited in the last ?= µ - 1 steps. Each trajectory generated by this dynamics has an initial non-periodic part of t steps, called transient, and a final periodic one of p steps, called attractor. Due to computational costs of memory usage, it is possible to simulate only small sistems, with N ? O(103) and µ << N. In this work, we propose a new implementation of the structure for data storage. The numerical model of the tourist walk, allowed us to obtain some statistical distributions for the walk with a memory value µ ? O(N). Moreover, in this study we obtain interesting and useful numerical results to explain the presence of some specific attractors in deterministic walk in one-dimensional space and the absence of attractors with periods 2µ+1, 2µ+2 and 2µ+3. are not made. In this work, we propose a new implementation of the structure for storing data, the numerical model of the tourist, has allowed us to obtain some statistical distributions for the walk with a memory value ? over and above what had been achieved previously. With these results, we verifed the efficiency of the HL structure proposed, and advance knowledge about the behavior of the tourist walk in the order of N.

Podemos considerar a caminhada determinista do turista como um processo do tipo dinâmico, que ocorre sobre uma rede composta por N pontos. Os pontos são gerados de maneira aleatória, no espaço euclidiano d dimensional. Um caminhante, partindo de um ponto qualquer do meio desordenado, se movimenta seguindo uma regra determinista de ir para o ponto mais próximo que não tenha sido visitado nos últimos ?= µ - 1 passos. Cada uma das trajetórias geradas através dessa dinâmica possui uma parte inicial não periódica de t passos, denominada transiente, e uma parte final, periódica, de p passos, denominada atrator. Devido ao custo computacional de memória, só é possível simular sistemas com N ? O(103) e µ << N. Neste estudo uma nova implementação na estrutura de armazenamento de dados, no modelo numérico do turista, nos permitiu obter algumas distribuições estatísticas para a caminhada, com valores de memória µ ? O(N). Com estes resultados verificamos a eficiência da estrutura proposta e avançamos no conhecimento acerca do comportamento do turista em caminhadas com memória da ordem de N. Também neste trabalho, obtivemos resultados numéricos interessantes, que serviram para explicar a formação de atratores com determinados períodos na caminhada determinista do turista unidimensional, bem como a não formação de atratores com períodos 2µ+1, 2µ+2 e 2µ+3.não são constituídos. Também neste trabalho, uma nova implementação na estrutura de armazenamento de dados, no modelo numérico do turista, nos permitiu obter algumas distribuições estatísticas para a caminhada, com valores de memória ? muito acima do que se tinha alcançado anteriormente. Com estes resultados verificamos a eficiência da estrutura proposta, e avançamos o conhecimento a cerca do comportamento do turista em sistema da ordem de N. / We may consider the deterministic tourist walk as a dynamic process performed over a landscape of N points. These points are randomly spread on a d dimensional euclidean space. A walker leaves from any point of that landscape and moves according to the deterministic rule of going to the nearest point that has not been visited in the last ?= µ - 1 steps. Each trajectory generated by this dynamics has an initial non-periodic part of t steps, called transient, and a final periodic one of p steps, called attractor. Due to computational costs of memory usage, it is possible to simulate only small sistems, with N ? O(103) and µ << N. In this work, we propose a new implementation of the structure for data storage. The numerical model of the tourist walk, allowed us to obtain some statistical distributions for the walk with a memory value µ ? O(N). Moreover, in this study we obtain interesting and useful numerical results to explain the presence of some specific attractors in deterministic walk in one-dimensional space and the absence of attractors with periods 2µ+1, 2µ+2 and 2µ+3. are not made. In this work, we propose a new implementation of the structure for storing data, the numerical model of the tourist, has allowed us to obtain some statistical distributions for the walk with a memory value ? over and above what had been achieved previously. With these results, we verifed the efficiency of the HL structure proposed, and advance knowledge about the behavior of the tourist walk in the order of N.

Degradation of water resources has become one of the most pressing global concerns currently facing mankind. Constructed Wetlands (CWs) represent a concept to combat deterioration of water resources by acting as buffers between wastewater and receiving water bodies. Still, constructing wetlands for the sole purpose of wastewater treatment is a challenging task. To contribute to this research area, the fundamental question raised in this doctorate thesis was: how do factors such as vegetation and residing water movements (hydraulics) influence wastewater treatment in CWs? Also, effects of different data analysis methods for results of CW hydraulics and wastewater treatment were investigated. Research was focused on  phosphorus (P), ammonium-nitrogen (NH4+-N) and solids (TSS) in wastewater and o n P in macrophyte biomass. Studies were performed in pilot-scale free water surface (FWS) CW systems in Kenya (Chemelil) and Sweden (Halmstad) and as computer simulations. Results from the Chemelil CWs demonstrated that meeting effluent concentration standards simultaneously for all water quality parameters in one CW was difficult. Vegetation harvest, and thus nutrient uptake by young growing macrophytes, was important for maintaining low effluents of NH4+-N and P, especially during dry seasons. On the other hand, mature and dense vegetation growing for at least 4 months secured meeting TSS standards. Phosphorus in above-ground green biomass accounted for almost 1/3 of the total P mass removal, demonstrating high potential for P removal through macrophyte harvest in CWs. Also, results suggested that harvest should be species-specific to achieve high P removal by macrophytes and overall acceptable wastewater treatment in CWs. Still, different methods to estimate evapotranspiration (ET) from the Chemelil CWs showed that water balance calculations greatly impacted estimations of wastewater treatment results. Hydraulic tracer studies performed in the Chemelil and Halmstad CWs showed that mature and dense emergent vegetation in CWs could reduce effective treatment volumes (e-values), which emphasized the importance of regulating this type of vegetation. Also, it was shown that hydraulic tracer studies with lithium chloride performed in CWs with dense emergent vegetation had problems with low tracer recoveries. This problem could be reduced by promoting the distribution of incoming tracer solution into the CW using a barrier near the CW inlet pipe. Computer simulation results showed that the choice of tracer data analysis method greatly influenced quantifications of CW hydraulics and pollutant removal. The e-value could be 50% higher and the pollutant removal 13% higher depending upon used method. Moreover, unrealistic evalues (above 100%) in published literature could to some extent be explained by tracer data analysis method. Hence, to obtain more reliable hydraulic data and wastewater treatment results from CWs, more attention should be paid to the choice of tracer data analysis method. / Konstruerade våtmarker representerar ett koncept för möjligheten att nå en hållbar vattenresurshantering genom att agera som ”filter” mellan föroreningskälla och viktiga vattenresurser såsom sjöar och hav. Mycket kunskap saknas däremot om hur man konstruerar våtmarker med en optimal och pålitlig vattenreningskapacitet. Den här avhandlingen undersöker därför hur vegetation och vattnets väg genom våtmarken (hydrauliken) påverkar avloppsvattenrening i våtmarker. Dessutom undersöktes hur valet av dataanalysmetod av insamlad data påverkar resultaten. Studier genomfördes i Kenya och Sverige i experimentvåtmarker (ca. 40-60 m2) och inkluderadedatainsamling av vattenkvalité, hydraulik (spårämnesexperiment) samt biomassa och fosfor i biomassan av två olika våtmarksväxter. Dessutom genomfördes datorsimuleringar. Resultaten från Kenya visade att växtskörd och efterföljande näringsupptag av nyskördade växter var viktig för att uppnå låga utgående koncentrationer av fosfor och ammonium i en tropisk våtmark, speciellt under torrsäsongen. Däremot var en välutvecklad och tät vegetation viktig för reningen av partiklar. Fosfor i grön växtbiomassa representerade cirka 1/3 av våtmarkernas totala fosforrening, vilket påvisade potentialen i att genom skörd ta bort fosfor från avloppsvatten m.h.a. konstruerade våtmarker. Resultaten pekade också på att skörden bör vara art-specifik för att uppnå en hög fosforrening och generellt bra vattenreningsresultat. Dock visade olika beräkningsmetoder att vattenbalansen i en tropisk våtmark markant kan påverka vattenreningsresultaten. Resultaten från spårämnesexperimenten demonstrerade att den effektiva våtmarksvolymen för vattenrening blev mindre vid hög täthet av övervattensväxter. Detta pekade på att regelbunden växtskörd var viktig för att uppnå god vattenrening i våtmarker. Experiment med spårämnet litium visade att man kan få felaktiga resultat p.g.a. att en del spårämne fasthålls på botten i våtmarken om denna har mycket övervattensväxter. Därför bör spridningen av spårämnet i sådana våtmarker underlättas m.h.a. en spridningsbarriär nära inloppsröret. Simuleringar visade också att valet av dataanalysmetod av spårämnesdata starkt kan påverka resultaten och därmed också vår tolkning av en våtmarks hydraulik och reningskapacitet. Den effektiva volymen kunde vara 50% högre och reningseffekten 13% högre beroende på vilken metod som användes. Likaså kan valet av dataanalysmetod ha bidragit till överskattade och orealistiska effektiva volymer (över 100%) i artiklar publicerade de senaste 25 åren. Genom att fokusera mer på valet av dataanalysmetod och t.ex. jämföra resultaten från två olika metoder kan man minimera risken för bristfälliga resultat och därmed felaktiga slutsatser om en våtmarks vattenreningskapacitet.