The composition of gut microbes affects host weight, immune function, and disease status, and is sensitive to diet, environment, and pharmaceutical exposure. The gut microbiome modulates the toxicity and bioavailability of chemical stressors, however the effects of chemicals on the gut microbiome of aquatic biota are largely unknown. The Waterloo and Kitchener wastewater treatment plants (WWTPs) release effluents containing antibiotics, pharmaceuticals, and other contaminants into the Grand River (ON) that may negatively affect the gut microbiome of downstream organisms. In this study done in Fall 2018, I collected freshwater mussels (Lasmigona costata), several species of insect larvae, and riparian spiders (Tetragnathidae) from sites upstream and downstream of these WWTPs. The gut microbiome was analyzed following the extraction, PCR amplification, and sequencing of bacterial DNA using the V3-V4 hypervariable regions of the 16S rRNA genetic barcode. Changes in the relative abundance of major gut microbiome phyla were observed in all targeted aquatic organisms downstream of WWTPs except Hydropsychidae. Shannon alpha diversity, a measure of bacterial abundance and evenness, differed significantly among sites for mussels (one-way ANOVA: F=7.894, p=0.001), spiders (F=4.788, p=0.01), Perlidae (F=3.1, p=0.0056), Hydropsychidae (F=3.674, p=0.0014), and Heptageniidae (F=2.715, p=0.0143), but not for Baetidae and Ephemerellidae. In sites downstream of the Waterloo WWTP, alpha diversity decreased in spiders, while in sites downstream of the Kitchener WWTP diversity decreased in mussels and Perlidae, while increasing for spiders. Bray-Curtis beta diversity, a measure of dissimilarity between bacterial communities, was significantly dissimilar among sites in all invertebrate taxa (Permanova: p<0.02). Upstream sites differed from downstream Waterloo sites in spiders, Perlidae, and Hydropsychidae (Adonis pairwise: p<0.05), while upstream mussels, spiders, Perlidae, and Hydropsychidae differed from downstream Kitchener sites (p<0.05). Additionally, effluent-derived bacteria were found in the microbiomes of aquatic invertebrates downstream of the WWTPs and not upstream. Taxa was also a significant driver of bacterial composition and diversity in invertebrates. These results indicate that the gut microbiome of downstream organisms differed from the bacterial composition observed in the same invertebrate taxa upstream of the WWTPs, potentially leading to altered host health. This adds to our understanding of how chemical stressors impact the gut microbiome of aquatic and riparian biota; however, future studies are needed to investigate linkages between the gut microbiome and health of these species. / Thesis / Master of Science (MSc)

This research was prompted by a field study performed at the Celanese Corporation Wastewater Treatment Plant, Narrows, VA., in which calcium chloride addition had improved sludge characteristics that were believed to have deteriorated because of sodium hydroxide additions for pH control. Research objectives were to determine whether the observed improvements during the full-scale plant study were caused by the addition of divalent cations and whether the deterioration of the sludge was due to sodium ion additions. Bench-scale, activated sludge reactors were fed wastewater from the Celanese plant to model plant conditions. Sodium was added in an attempt to cause deterioration of the sludge characteristics. Magnesium and calcium were used as divalent cations to try to improve the sludge characteristics. Results of the study indicated that the magnitude of the effects seen in the full-scale plant study could not be reproduced in the laboratory. Magnesium produced little or no effect on the system and calcium improved the sludge characteristics slightly. Sodium caused deterioration of the sludge but not as dramatically as the full-scale study. This suggested that sodium alone did not adversely affect the sludge but rather, sodium hydroxide might have been combined with organics in the waste which then affected the system. / Master of Science

Cette thèse porte sur la modélisation des réacteurs membranaires anaérobies. Dans une première partie, nous proposons une analyse mathématique générique d'un modèle de digestion anaérobie en deux étapes appelé AM2. La principale limitation du développement des réacteurs membranaires étant le risque de colmatage, nous proposons, dans une seconde partie, d'étendre le modèle AM2 en incorporant une nouvelle variable d'état modélisant la dynamique des Produits Microbiens Solubles (SMP) dont le rôle dans le colmatage des membranes a été démontré. Une étude mathématique exhaustive de ce nouveau modèle appelé AM2b est réalisée pour comprendre et comparer les comportements qualitatifs des deux modèles. Dépendant des conditions de fonctionnement et des valeurs des paramètres biologiques utilisées, nous montrons que ce nouveau modèle peut se comporter comme le modèle initial AM2, ou, au contraire, présenter un comportement qualitatif très différent. L'étape suivante sera d'utiliser ce modèle pour la synthèse de régulateurs. Toutefois, le manque de capteurs en-ligne nous a amené, dans une troisième partie, à procéder à la synthèse d'un certain nombre d'observateurs d'état classiques. Au regard des caractéristiques spécifiques des bioprocédés, cette dernière partie se termine par la proposition de nouvelles pistes pour l'estimation d'état et de paramètres par des méthodes stochastiques, notamment les filtres particulaires dont nous présentons brièvement le principe. / This thesis focuses on the modeling of anaerobic membrane reactors. In the first part, we propose a generic mathematical analysis of a two-step model of the anaerobic digestion called AM2. The main limitation in the development of membrane reactors being the risk of clogging, we propose in a second part, to extend the AM2 model by incorporating a new state variable modeling the dynamics of the so-called Soluble Microbial Products (SMP) whose role in the clogging of the membranes has been demonstrated. A complete mathematical study of this new model called AM2b is realized to understand and compare the behavior of both models. Depending on operating conditions and on the model parameters values, we show that this new model can behave as the initial model AM2, or, conversely, have a completely different qualitative behavior. The next step is to use this model for the synthesis of controllers. However, the lack of online sensors led us to a third part where we carry out the synthesis of several state observers. In view of the specific characteristics of bioprocesses, this last part ends by proposing new ways to estimate both state and parameters using stochastic methods, including particulate filters which the concepts are briefly reviewed.

La présence de micropolluants dans tous les milieux aquatiques est aujourd'hui une préoccupation importante. La réduction des émissions de micropolluants organiques vers le milieu aquatique par les stations d'épuration (STEP) domestiques est donc un enjeu important. Ce travail porte sur l'amélioration du traitement de ces substances par les traitements secondaires et tertiaires des STEP. En premier lieu, l'objectif a été de mieux comprendre les processus d'élimination des micropolluants organiques lors de leur passage au sein d'un procédé de type boues activées aération prolongée (BA-AP). Notre travail a consisté à proposer un outil permettant de prévoir a priori le comportement de substances organiques en BA-AP par rapport à certaines de leurs propriétés physico-chimiques (i.e. constante de Henry, log Dow, structure moléculaire). La démarche adoptée a consisté à sélectionner des données de rendements d'élimination fiables et robustes, puis à les associer aux caractéristiques physico-chimiques des substances. La méthode développée est simple ; elle nécessite de connaitre uniquement des paramètres physico-chimiques facilement accessibles et la structure moléculaire des substances. Elle constitue donc une alternative crédible aux méthodes faisant intervenir la modélisation. Cette méthode permet une prédiction a priori du niveau de traitement d'une substance (rendement supérieur ou inférieur à 70%) par les traitements secondaires existants. Dans un second temps, l'objectif a été de proposer une étape de traitement tertiaire, spécifique à l'élimination de micropolluants organiques réfractaires aux traitements secondaires. Le procédé proposé est une filtration sur support fin spécifique capable de retenir par des processus d'adsorption les substances ciblés (i.e. phytosanitaires et substances pharmaceutiques dont l'élimination est insuffisante en traitement secondaire conventionnel). Une étude bibliographique a permis tout d'abord de dresser un état des lieux sur les adsorbants utilisés et leur capacité d'adsorption. Suite à cette étude, la zéolite et l'argile expansée ont été retenus ; les potentialités d'adsorption de ces deux matériaux ont été étudiées à l'échelle laboratoire (tests en réacteur fermé) et à l'échelle pilote (suivi des performances de réacteurs à garnissage drainé à écoulement horizontal). Les tests d'adsorption en réacteur fermé montrent que les matériaux choisis (argile expansée et zéolite) possèdent une potentialité pour adsorber les substances étudiées (14 substances soient 10 pharmaceutiques et 4 pesticides). Le suivi des réacteurs ouvert confortent les résultats obtenus en réacteur fermé et démontrent que les matériaux étudiés possèdent un potentiel pour l'adsorption des substances ciblées, et ce y compris dans des conditions de filtration lente, proches des conditions réelles. Les résultats obtenus démontrent le potentiel de matériaux minéraux microporeux à éliminer des micropolluants organiques de la phase dissoute et ainsi à se substituer au charbon actif, matériau onéreux et peu adapté aux petites collectivités. / The aim of the present work was to propose solutions to reduce organic micropollutants emissions by wastewater treatment plants (WWTP). First, the objective was to improve the comprehension of micropollutants behaviour in nitrifying activated sludge process. The use of a reliable removal efficiency dataset allowed setting up a removal efficiency prediction method only from the micropollutants physico-chemical characteristics (i.e. log Kow, Henry constant and molecular structure). This method represents a first progress through a better micropollutants removal by the existing secondary WWTP. Second, the aim was to set up a tertiary stage process to enhance the removal of micropollutants refractory to conventional WWTP. This tertiary stage process is a filtration of the secondary effluent by adsorbent materials that could represent a credible alternative to expensive materials such as activated carbons. Experimental approaches at different scales (lab and pilot) demonstrated that some alternative materials such as expanded clay and zeolite have the potential to adsorb refractory substances (e.g. pesticids and pharmaceuticals) and thus to decrease the concentration of organic micropollutants in effluent.

Ce travail a permis d'acquérir de nouvelles connaissances sur la micropollution issue de l'activité domestique. Un état des lieux a été réalisé sur la présence de certains micropolluants dans les eaux usées (dans les phases liquide et solide) de deux zones urbaines, résidentielle et mixte (habitats, hôpital, administrations), et dans deux stations d'épuration (STEP) biologiques. Les micropolluants étudiés ont été choisis selon leurs usages et en fonction de leurs propriétés physico-chimiques afin de mieux appréhender leur répartition entre les phases liquides et solides. Dans un premier temps, les méthodes d'extraction et d'analyse des micropolluants dans les matrices liquides (eau usée et eau traitée) et solides (matières en suspension et boue) ont été développées et validées. Les prélèvements d'eaux usées dans les égouts des deux zones urbaines ont mis en évidence différents usages de certains composés en fonction de la zone urbaine et de la saison (été ou hiver). Les mesures des concentrations en micropolluants en entrée et en sortie de STEP dans les eaux et les boues ont permis d'évaluer leurs rendements d'élimination et ont révélé une différence d'efficacité entre les deux STEP biologiques. Une étude statistique a montré qu'il existe des corrélations entre les concentrations en micropolluants et en macropolluants (DCO, ammonium, et turbidité) en entrée et en sortie de chacune des STEP étudiées. L'effet des micropolluants sur l'activité bactérienne a été examiné en conditions de laboratoire par des tests de toxicité sur Escherichia coli et par des expériences sur la biomasse de STEP en réacteur batch / This work allowed to acquire new knowledge on micropollution issued from household activities. The occurrence of some micropollutants in urban wastewater (liquid and solid phases) of two urban areas, residential and mixed (houses, hospital, administrations), and in two biological wastewater treatment plants (WWTPs) was assessed. The studied micropollutants were chosen according to use and as function of their physical and chemical properties in order to consider their partitioning between liquid and solid phases. Firstly, the methods for the extraction and the analysis of micropollutants in liquid and solid matrices (wastewater and treated water, suspended matter and sludge) were developed and validated. Wastewater sampling in the sewers of the two urban catchments showed some differences of the use of certain compounds according to the catchment and to the season (summer or winter). Measurements of micropollutant concentrations at the inlet and outlet of the plants, on water and sludge, allowed to assess their removal yields and revealed a difference of efficiency of the two biological WWTPs. A statistical treatment showed that there are some correlations between concentrations of micro and macropollutants (COD, ammonium and turbidity) at the inlet and at the outlet of each studied WWTPs. The effect of the target micropollutants on bacterial activity was evaluated under laboratory conditions, by toxicity tests on Escherichia coli, and by experiments on biological sludge in batch reactors

Wastewater treatment is essential to protecting the environment and human welfare. Although chlorination is widely used, the environmental and health concerns associated with chlorine are growing. Treatment facilities are implementing alternative technologies, though the cost and efficiency associated with these practices leave much room in the wastewater field for innovation. Hydropath Technologies Limited introduced a piece of equipment that uses the properties of a transformer to pass an alternating electric current through the pipe and into the contents of the channel. Hydroflow claims that the charged microorganisms react with the oppositely charged water molecule to force osmosis and kill the cell. Disinfection capabilities of three Hydroflow models with varying voltages are tested using municipal wastewater from the secondary clarifier using Escherichia coli concentration as the unit for quantification. After testing the results surrounding theses experiments cannot support the hypothesis that the Hydroflow technology could replace chlorination for municipal wastewater disinfection.

Vid Hammarby Sjöstadsverk drivs en pilotanläggning som är en mindre skala av det framtida avloppsreningsverket i Henriksdal. Delar av reningsprocessen består av membranbioreaktorer. I pilotanläggningen finns en zon kallad RAS-DeOx dit returslammet från membrantankarna och rejektvattnet från slambehandlingen leds. Luftning av membrantankarna gör att returslammet är syrerikt och rejektvattnet innehåller mycket ammonium.Zonen fungerar som ett nitrifikationssteg då syret i returslammet kan oxidera ammoniumet från rejektvattnet. Dessutom kan zonen minska syrehalterna i returslammet för att undvika att det hamnar i pilotanläggningens fördenitrifikation. För att få bättre uppfattning om vad som sker i zonen och hur denna fungerar som ett nitrifikationssteg studerades nitrifikation, denitrifikation och syreförbrukningen i zonen. För att utvärdera RAS-DeOx-zonen belastades den med olika nivåer av ammonium från rejektvattnet vid olika hög luftning i membrantankarna. Detta utfördes både experimentellt direkt på pilotanläggningen och i en simuleringsstudie där processimuleringar genomfördes i en simuleringsmodell. I modellen utvärderades även två styrstrategier för zonen.Resultaten från studierna visade att både nitrifikation och denitrifikation förekom i zonen. Jämfört med simuleringsstudien varierade omfattningen av nitrifikation och denitrifikation mer i den experimentella studien. Båda studierna visade att det fanns risk att syre hamnande i pilotanläggningens fördenitrifikation. Styrstrategierna visade att det inte var fördelaktigt för pilotanläggningens resurseffektivitet att zonen luftades vid hög ammoniumbelastning från rejektvattnet. Det visade sig också att det var ingen större skillnad när det gällde pilotanläggningens prestation vid högt, lågt eller styrt returflöde för zonen. Däremot skiljde sig prestationen mer avseende luftning och koldosering.Utöver att det förekom nitrifikation och denitrifikation i zonen bedömdes den även fungera som ett nitrifikationssteg för ammoniumet i rejektvattnet. Dessutom minskade den syrehalterna i returslammet. Hur väl ammonium nitrifierades och syre förbrukades i zonen berodde på förhållandena i pilotanläggningen och förhållandet mellan mängden ammonium och syre i zonen. / At Hammarby Sjöstadsverk there is a pilot plant which is a smaller version of the future wastewater treatment plant at Henriksdal. Parts of the treatment process steps are membrane bioreactors. There is a zone in the pilot plant which is called RAS-DeOx to where the return activated sludge from the membrane tanks and the reject water from the sludge treatment are pumped. The return activated sludge contains oxygen since the membranetanks are aerated and the reject water has high contents of ammonium.The zone works as a nitrification step for the ammonium in the reject water, and also reduces the oxygen levels in the return sludge to avoid oxygen in the pilot plant's pre-denitrification step. To aquire a better understanding of what occurs in the zone and how it functions as a nitrification step; nitrification, denitrification and oxygen consumption was studied in the zone. To evaluate the RAS-DeOx-zone it was loaded with different loads of ammonium from the reject water at different levels of aeration in the membrane tanks. This was evaluated both experimentally at the pilot and in a simulation model of the pilot. In the simulation model two control strategies for the zone were also evaluated.It was shown that both nitrification and denitrification occurred in the zone. Furthermore, both studies showed that there is a risk that oxygen occurs in pilot's pre-denitrification step if the ammonium load in zone was low. Then, all of oxygen in the zone was not consumed. As for the control strategies, it was shown that the benefits were low for the resource efficiency of the pilot when the zone was aerated during high loads of ammonium. The performance of the pilot was similiar for high, low and regulated return flows for the zone, but the aeration and carbon dosage in the pilot differed.Besides that both nitrification and denitrification occurred in the zone, it was also functioning as a nitrification step for the ammonium from the reject water. The oxygen from the return sludge was reduced as well. The extent of nitrification and consumption of oxygen in the zone depended on the circumstances in the pilot and the relationship between the amount of oxygen and ammonium.

O fósforo é apontado como o principal responsável pelo enriquecimento nutricional de mananciais de abastecimento público, desencadeando por meio do fenômeno de eutrofização, a floração de grupos algais tóxicos e, portanto a sua remoção passa a ter grande significado para a saúde pública e para o meio ambiente. O presente trabalho foi desenvolvido com os objetivos de: avaliar a eficiência de remoção de fósforo do efluente de um sistema convencional de lodos ativados (Estação de Tratamento de Esgotos de Barueri) pelo lodo de uma estação de tratamento de água, que utiliza sulfato de alumínio como coagulante (Estação de Tratamento de Água do Alto Cotia) e verificar a influência das seguintes variáveis nesta remoção: tempo de permanência do lodo no decantador, dosagem de lodo, potencial zeta, teor de matéria orgânica no lodo, pH da mistura lodo/efluente e uso de polímero na coagulação/floculação da água bruta. Para o desenvolvimento prático da pesquisa, foram realizados ensaios de jarros, variando as condições operacionais, de tal forma a averiguar o efeito das variáveis mencionadas anteriormente na remoção do fósforo. Observou-se que esta remoção era dependente do pH; da dosagem de lodo; do tempo de permanência do mesmo no decantador; do tempo de mistura e da presença de polímero. Independia do potencial zeta e do tempo de sedimentação. A máxima remoção obtida foi de 100% (concentração inicial de 2,9 mg P/L), em pH de 4,5, com dosagem de 37 mg lodo/L, tempo de mistura de 15 minutos a 40 s-1 de gradiente, tempo de sedimentação de 30 minutos, tempo de permanência do lodo no decantador de 80 dias, sem polímero. Nestas condições, a concentração de fósforo do efluente tratado foi de 0,01mg P/L. Os resultados obtidos no presente trabalho sinalizam uma alternativa tecnológica, que pode vir a ser utilizada em projetos sustentáveis, em que as estações de tratamento de esgotos e estações de tratamento de água sejam planejadas de forma integrada, considerando o reaproveitamento e encaminhamento do lodo de ETA como insumo a ser utilizado no fim do processo de tratamento de esgotos para remoção de fósforo do efluente final, em consonância com os conceitos de produção mais limpa na busca da qualidade. / Phosphorus is considered as the main responsible for the nutritional enrichment of reservoirs of public drinking water supplies, because eutrophication process has resulted in toxic algae blooms, and therefore its removal has a great significance since these toxins represent a public health risk and environment. The aim of this research work was to evaluate the efficiency of removal of phosphate from activated sludge process (Barueri Wastewater Treatment Plant) by sludge from water treatment plant that uses aluminum sulfate as coagulant (WTP Alto Cotia) and verify the influence of following operational parameters in this removal: aging of sludge, sludge dose, zeta potential, mixing time, sedimentation time, concentration of organic matter, pH and use of polymer in coagulation/flocculation process. For the experimental research, the jar tests were operated with different conditions. The removal of phosphate was dependent of pH, sludge dose, aging of sludge, mixing time and presence of polymer. It was independent of zeta potential and sedimentation time. It was verified that maximum efficiency of phosphate removal was around 100% (initial concentration = 2,9 mgP/L), in pH 4,5 with the use of 37 mg of sludge from Alto Cotia Water Treatment Plant per liter of effluent from Barueri Wastewater Treatment Plant, with a mixing time of 15 minutes at 40 s-1, 30 minutes for sedimentation time, 80 days for aging of sludge, without polymer. Under these conditions it was obtained phosphate concentrations around 0,01mgP/L. Results obtained in this research work show a technological alternative, that can be used in projects, that sewage and water treatment plants can be planned together, considering the reuse and forwarding the water treatment plant sludge as beneficial use in the end of the sewage treatment process for the phosphorus removal, in consonance with concepts of a cleaner production practices in Environmental Management Systems.

Cette thèse traite de l’analyse et de la synthèse de multimodèles pour la simplification de modèles, l’estimation d’état et le diagnostic des systèmes non linéaires caractérisés par une ou plusieurs échelles de temps. Ces travaux visent, dans un premier temps, à développer une procédure systématique de transformation d’un système non-linéaire en le récrivant sous une forme multimodèle, en évitant quelques inconvénients majeurs : la transformation est réalisée sans perte d’information, le choix de différents points de fonctionnement n’est plus nécessaire, le choix de variables de prémisse est réalisé d’une façon systématique. De plus, la méthode offre le choix entre différents multimodèles. Ce degré de liberté sera utilisé pour faciliter les études de contrôlabilité, d’observabilité et d’analyse de stabilité. Dans un deuxième temps, l’obtention de la forme à perturbations singulières d’un système non linéaire est proposée, en éliminant quelques contraintes structurelles et en rendant l’identification et la séparation des échelles de temps indépendante de la structure du modèle. Dans un troisième temps, la synthèse de plusieurs observateurs robustes vis-à-vis des perturbations, des erreurs de modélisation et des entrées inconnues a été réalisée afin dereconstruire l’état et l’entrée inconnue du système. La difficulté de cette étude provient du fait que le multimodèle utilisé dépend de variables de prémisse non mesurables, situation qui n’est pas intensivement étudiée, alors qu’elle est naturellement issue de l’approche par transformation système non linéaire!multimodèle. Ensuite, le diagnostic de défauts de systèmes est réalisé au moyen de bancs d’observateur à entrées inconnues permettant la génération et la structuration de résidus indicateurs de défauts. Finalement, tous les travaux proposés sont appliqués au modèle d’une station d’´epuration, Activated Sludge Model No.1, qui est largement utilisé dans le domaine du traitement des eaux usées / This thesis deals with analysis and synthesis of multiple model structures for model simplification, state estimation and diagnosis of nonlinear systems represented by one or several time-scales. This work aims, at first, to develop a systematic procedure to transform a nonlinear system into a multiple model form, by avoiding some major drawbacks : the transformation causes no information loss, the choice of the different operating points is no more necessary, the choice of the premise variables is realized in a more systematic way. Furthermore, the method gives the possibility of choosing between different multiplemodel structures. This degree of freedom will be used to ease the controllability, observ-ability, stability analysis studies. Secondly, the derivation of a singularly perturbed form for a multiple time scale non linear system is proposed, by eliminating some structuralconstraints and by making the identification and the separation of the time-scales independent to the model structure. Thirdly, the robust observer synthesis with respect to perturbations, modeling errors and unknown inputs are presented for state and unknowninput estimation. The difficulty of these studies comes from the fact that the multiple model depends on unmeasurable premise variables, this case being not intensively studied, whereas it results naturally from the method of transformation nonlinear system - multiple model. Afterward, fault diagnosis is performed using banks of observer to generate andstructure residual signals. Finally, this works are applied to a model of wastewater treatment plant, Activated Sludge Model No.1 (ASM1) that is largely used in the concerned fiel

För att kunna möta framtidens striktare reningskrav för avloppsvatten och en ökad belastning på grund av befolkningstillväxt bygger Stockholm Vatten och Avfall (SVOA) om Henriksdals reningsverk inom projektet Stockholms Framtida Avloppsvattenrening (SFA). En av de större förändringarna i det framtida Henriksdals reningsverk är införandet av MBR-teknik, där slam och vatten avskiljs genom membranfiltrering. Separationen medför förändrade egenskaper hos slammet då en större andel av partiklarna kan avskiljas från utgående vatten jämfört med avskiljning från konventionella sedimentationsbassänger. På Hammarby Sjöstadsverk drivs en pilotanläggning där MBR-teknik undersöks inför implementering i framtida Henriksdals reningsverk. Denna studie har undersökt skillnader i mängd partiklar, organiskt innehåll, filtrerbarhet, sedimenteringsegenskaper och förtjockningskapacitet hos överskottslam från MBR-linjen på Hammarby Sjöstadsverk (ÖS-MBR) och Henriksdals reningsverk (ÖS-CAS). Detta för att ge underlag till optimering av framtida slambehandling på Henriksdals reningsverk. Därutöver har massbalans för förtjockningsförsöken beräknats. Resultatet av studien visar att egenskaperna hos ÖS-MBR och ÖS-CAS skiljer sig tydligt för torrsubstans (TS), totalt suspenderade partiklar (TSS) och filtrerbarhet (TTF). Ingen skillnad i slamvolymindex (SVI) kunde verifieras i studien. Efter förtjockning av slammen i en trumsil, med olika polymertillsats, uppvisade ÖS-MBR högre TSS i rejektvattnet än ÖS-CAS. Denna skillnad indikerar att partiklar i ÖS-MBR har mindre benägenhet att binda till polymeren som användes, än partiklar i ÖS-CAS. Det är därför av betydelse att pröva ut rätt typ av polymer vid förtjockning av ÖS-MBR, för att nå målet på en TSS under 1000 mg/L i rejektvattnet. Därtill uppvisade ÖS-MBR högre TS i det förtjockade slammet än ÖS-CAS. Detta skulle kunna indikera att ÖS-MBR är lättare att förtjocka än ÖSCAS, men det kunde dock inte bekräftas av massbalanserna. Slutligen kunde denna studie inte samstämmigt visa på en skillnad i potentialen att förtjocka de båda slammen då fördelningen av partiklar mellan förtjockat slam och rejektvatten varierade i varje försök. Däremot minskade TSS i rejektvattnet med högre dos av polymer medan samma samband inte gällde för TS i det förtjockade slammet där dosen polymer, efter en viss mängd, hade en begränsad påverkan på TS. En viktig aspekt som påverkade förtjockningskapaciteten i denna studie var igensättning av trumsilen. Centrifuger, som kommer att användas i framtida Henriksdals reningsverk, kommer inte uppvisa samma typ av störningar i driften. / To comply with future stricter regulations on treated wastewater and an increasing load on the system due to a growing population, the Stockholm Vatten och Avfall Company (SVOA) is upgrading the Henriksdal wastewater treatment plant within the project Stockholm’s Future Wastewater Treatment (SFA). One of the main changes in the future plant is the introduction of MBR-treatment, where sludge and water will be separated through the use of membranes. This separation will change the composition of the sludge by removing a larger fraction of particles from the effluent than what can be achieved in conventional sedimentation basins. Hammarby Sjöstadsverk operates a pilot plant with a MBR-process, where the technology is evaluated before the implementation in the future Henriksdal wastewater treatment plant. This study examines the difference in the sludge characteristics, i.e. sedimentation, filterability, and the potential for thickening of excess sludge from the MBR-process in Hammarby Sjöstadsverk (ÖS-MBR) and from the activated sludge process in the current Henriksdal wastewater treatment plant (ÖS-CAS). Furthermore, a mass balance and a sensitivity analysis has been used within this study. The study aimed at providing decision support for optimisation of the sludge treatment at the future Henriksdal wastewater treatment plant once the MBR process is implemented. The results of this study show that the characteristics of ÖS-MBR and ÖS-CAS differ considerably in total solids (TS), total suspended solids (TSS) and filterability (TTF). No difference in sludge volume index (SVI) could be verified between the two types of sludges. After thickening in a rotary drum screen with different doses of polymer, the TSS in the reject water was higher for the ÖS-MBR than the ÖS-CAS. This difference indicates that particles in ÖS-MBR are less attracted to the particular thickening polymer used, than the particles in ÖS-CAS. Therefore, it is important to select the correct type of polymer when thickening ÖS-MBR in order to reach the target TSS of 1000 mg/L in the reject water. In addition, the thickened ÖS-MBR showed higher TS than ÖS-CAS. This could indicate that ÖS-MBR would be easier to thicken; however, this is not confirmed by the mass balances. In the end, this study could not conclusively show any trend in the level of thickening between the two types of sludges because the distribution of particles varied in each trial. Nevertheless, while a higher dosage of polymer evidently reduced the TSS in the reject water, the same was not true for the TS in the thickened sludge, which seems to be less affected by the dose of polymer after a certain level. An important consideration in this study was the clogging of the drum screen. However, centrifuges, which will be used in the future Henriksdal wastewater treatment plant, do not have the same operational problems.