Motivées par des normes de rejets en azote toujours plus sévères et par les besoins d'extension de certaines stations d'épuration, les agglomérations sont à la recherche de nouvelles technologies de traitement plus compactes et plus performantes. Dans ce sens, le procédé hybride, à lit fluidisé placé dans un réacteur de type boues activées (IFAS), est une nouvelle technologie de traitement du carbone et de l'azote très attractive. L'objectif de cette thèse est d'optimiser le dimensionnement du procédé IFAS en configuration trois bassins (anoxie/aérobie BA/aérobie IFAS) et d'apporter des recommandations sur la conduite du procédé (charge massique appliquée, température.). Pour cela, une double démarche expérimentale et numérique a été mise en place. Un pilote de 3 m3 alimenté en eau usée brute a été conçu, instrumenté et étudié pendant 2 ans au cours de 7 périodes stabilisées (entre 0,15 et 0,30 kgDBO5/kgMVSLM/j, température entre 10 et 22°C, et le séquençage de l'aération dans les bassins). La concentration en MES dans la liqueur mixte a été maintenue à 2,3 gMES/L et la concentration en oxygène entre 2 à 6 mgO2/L. Les capacités de nitrification du biofilm et de la liqueur mixte (NPRmax) ont été mesurées tous les 15 jours. Les performances d'élimination de l'azote (nitrification et dénitrification) et du carbone observées sont restées supérieur à 90% d'élimination pour une charge massique maximale de 0,30 kgDBO5/kgMVSLM/j entre 16 à 24°C. Le biofilm dispose d'une capacité de nitrification maximale de 0,90 gN/m2/j et tributaire des concentrations en oxygène dans la liqueur mixte (contraintes diffusionnelle). Le biofilm contribue en moyenne à hauteur de 60% du flux total nitrifié dans le réacteur IFAS pour des âges de boues < 5 jours à 16°C. La diminution du MLSRT en dessous de 4 jours a permis de limiter le développement des bactéries autotrophes dans la liqueur mixte (minimum 10% du flux total nitrifié par la liqueur mixte) mais pas de les supprimer totalement (apport de nitrifiante par détachement de biofilm) / Motivated by the increasingly demanding discharge consents and by the need to improve overall treatment capacity, water authorities are uninterruptedly examining better performing and more compact wastewater treatment technologies. Thanks to its compactness and to its capacity to treat both organic matter and nitrogen at an affordable cost, the IFAS process represents an attractive addition to improve retrofitting-activated sludge plants performance. The main objective of this thesis is to optimize IFAS process with regards to key operation parameters such as dimensioning, F/M ratio by combining experimental and mathematical modelling approaches. A 3 m3 pilot IFAS fed with raw wastewater was operated at the experimental hall of La Feyssine wastewater treatment plant, Villeurbanne, for a period of 2 years. The IFAS process was separated in 3 tanks to treat organic matter and total nitrogen separately (anoxic/aerobic, suspended/aerobic IFAS). The experimental study was divided in 7 periods with different steady state operation conditions each. The feasibility of nitrification at steady F/M ratios (between 0,1S to 0,30 kgBODS/kgMLVSS/d), at constant temperatures (between 10 - 22°C) and at different oxygen supply rates was investigated. TSS in mixed liquor were maintained at 2,3 gMLTSS/L and oxygen concentration between 2 to 6 mgO2/L. Biofilm mass and combined nitrification capacity of biofilm and mixed liquor (NPRmax) were measured on a weekly basis. The removal performance was up to 90% for nitrogen and carbon treatment with a maximal F/M ratio of 0,30 kgBODS/kgMLVSS/d between 16°C to 24 °C. The biofilm was able to nitrify 0,90 gN/m2/d (NPRmax) depending on the oxygen concentration in the mixed liquor (diffusional limitation). Under the operating conditions tested in this study, biofilm was responsible for 40 to 70% of NOx-N production in IFAS reactor during nitrification. Decreasing the MLSRT to less than 4 days limits the growth of autotrophic bacteria in the mixed liquor but does not halt it completely

Les principaux points de dispersion des composés pharmaceutiques dans l’environnement sont les stations d’épuration des eaux usées. A partir de l’analyse de la base de données constituée au cours de ce travail, les quantités de ces composés trouvées dans ces installations peuvent être directement liées à celles de médicaments consommés. La situation, quant à leur élimination de la phase liquide, est contrastée. Ainsi certaines hormones sont éliminées avec des rendements importants mais d’autres ne le sont pas du tout. Les produits radio-contrastants à base d’halogènes et notamment d’iode, soupçonnés d’être cancérogènes, sont majoritairement non biodégradables. Les effets d’antibiotiques sur les boues activées ont été plus particulièrement étudiés du fait de leur consommation, de leur présence dans les milieux aquatiques et de leur action spécifique sur les bactéries. Des expériences permettant d’évaluer la toxicité de ces principes actifs ont été conduites sur des boues activées en réacteur discontinu, avec un suivi de la morphologie des flocs par analyse d’images de microscopie optique. Il a été ainsi observé que, selon la concentration utilisée, l’érythromycine et la tylosine, macrolides largement utilisés respectivement en médecine humaine et vétérinaire, inhibent l’élimination de la pollution organique et dégradent l’ensemble de la biomasse. Ces antibiotiques ont également un effet néfaste sur le métabolisme de l’azote, qu’il s’agisse de l’ammonification, de la nitritation et de la nitratation / The main sources of dispersion of pharmaceutical substances in environment are wastewater treatment plants. Based on the analysis of the database built during this project, the amounts of pharmaceutical substances found in plants can be directly related to the amount consumed. Regarding their elimination from the liquid phase, the situation is very disparate. The elimination yield of hormones can be null or very large. Halogen-based X-ray contrast media (or AOX) are mainly non biodegradable. The effects of antibiotics on activated sludge have been especially investigated due to their consumption, presence in aquatic environment and specific action on bacteria. Batch tests have been performed to evaluate the toxicity of these active pharmaceutical ingredients on activated sludge. Sludge morphology was monitored by analysis of light microscopy images. Depending upon the applied dose, erythromycin and tylosin, two macrolides widely used for human and animal health care, inhibit the elimination of organic pollution and damage biomass. These antibiotics have a deleterious effect on ammonification, nitritation and nitratation

L’impact de l’homme sur l’environnement mondial et sur la diversité et le fonctionnement des écosystèmes terrestres fait l’objet d’une attention croissante. De nombreuses études ont évalué les effets de facteurs du changement global tels sur les processus de cycle de l'azote du sol dans les prairies. Cependant, ces études n'ont pas pris en compte le fait que la modification du régime de précipitations avait également une influence sur le régime de dépôt d'azote. En outre, la réponse du cycle de l'azote dans les sols des prairies à de multiples facteurs du changement global agissant ensemble et parfois en même temps que des perturbations telles que les incendies, doit encore être étudiée. Cela limite fortement notre capacité à comprendre et à prévoir les effets du changement global sur les prairies. Dans ce travail de doctorat, deux expériences ont été menées: (i) une expérience en mésocosme pour évaluer les effets combinés d'une augmentation des dépôts d'azote et de changements dans la quantité et la fréquence des précipitations sur le cycle de l'azote édaphique dans une prairie semi-aride; (ii) une expérience in situ pour évaluer les effets combinés de l'augmentation de la concentration en CO2, du réchauffement, d’une modification des précipitations, du dépôt d'azote et d’un feu sur le cycle de l'azote du sol dans une prairie méditerranéenne. Cela permet d'étudier les effets de la combinaison de plusieurs facteurs de changement global (et d’une perturbation feu) sur l'abondance des communautés microbiennes du cycle de l'azote.Les groupes microbiens étudiés étaient les bactéries et les archées oxydant l'ammoniac (AOB et AOA, respectivement), les réducteurs de nitrite porteuses des gènes nirK ou nirS, et les réducteurs de N2O porteurs des gènes nosZI- et nosZII, plus les bactéries oxydant le nitrite du genre Nitrobacter et Nitrospira pour la prairie méditerranéenne. Les principaux résultats et conclusions sont les suivants: 1) Les réactions des différents groupes de (dé)nitrifiants aux scénarios de changement global différaient fortement quel que soit le type de prairie. Les AOB étaient principalement dépendant de la disponibilité en azote En revanche, dans les deux prairies, les AOA étaient plus sensibles à la dynamique de l'eau du sol que la dynamique de l'azote. L'abondance des Nitrobacter étaient principalement affectée par les facteurs de changement global affectant l'abondance de l'AOB, tandis que l'abondance des Nitrospira était davantage liée aux changements d'abondance des AOA dans la prairie méditerranéenne. 2）Dans la prairie californienne où deux dépôts d'azote élevés avaient lieu chaque année, l'effet de l'azote dominait les effets du changement global. En revanche, dans la prairie chinoise, les dépôts d’azote simulés par des apports chroniques couplés aux événements de précipitation n’augmentaient pas l’abondance des dénitrifiants et ne faisaient que légèrement augmenter les émissions de N2O. 3） Pour les deux prairies, l'interaction entre les facteurs du changement global sur le cycle de l'azote du sol ne pouvait pas être prédite simplement en étudiant les effets d'un ou de deux facteurs. Ces effets interactifs ont pu être expliqués par des effets sur des variables environnementales clés telles que l'humidité du sol, la disponibilité de l'azote minéral, le pH et la croissance des racines. Ces résultats démontrent qu'il est impossible de prédire comment les (dé)nitrifiants et la (dé)nitrification répondent aux scénarios de changement global impliquant de multiples facteurs uniquement à partir de la connaissance d'effets de facteurs étudiés isolément. Cela nécessite donc des études plus approfondies dans le domaine de la biologie des changements globaux. La modélisation et l'évaluation de la généralité de ces effets d'interaction complexes constituent donc une priorité majeure pour les chercheurs qui veulent prédir les réponses du cycle de l'azote dans le sol au changement global et les rétroactions sur le climat. / The impact of global environmental changes on the diversity and functioning of terrestrial ecosystems has received increasing attention. Many studies evaluated the effects of single -and less often multiple- global change factors on soil N cycling processes in grasslands. However, these studies have not recognized that altered precipitation regime also has an influence on wet N deposition regime. Further, the response of grassland soil N cycling to co-occurring multiple global change factors and disturbance like fire, and how N cycling response to fire could differ under different global change scenarios, remains unclear. This strongly restricts our ability to understand and predict global change effect on grasslands. In this work, two experiments were conducted: (i) a mesocosm experiment to assess the combined effects of increased N deposition and changes in both the amount and frequency of rainfall on soil N cycling in a semi-arid Monsoon grassland; and (ii) an in situ experiment to assess the combined effects of elevated CO2, warming, increased precipitation, N deposition and fire on soil N cycling in a Mediterranean grassland. This allows studying the -possibly interactive- effects of several global change factors on the abundances of soil N-cycling microbial communities. The microbial groups studied were ammonia oxidizing bacteria and archaea (AOB and AOA, respectively), nirK- and nirS-nitrite reducers, nosZI- and nosZII-N2O reducers, plus Nitrobacter and Nitrospira for the Mediterranean grassland. The main results and conclusions are: 1）The responses of different groups of soil (de)nitrifiers to global change scenarios differed strongly regardless the grassland type. AOB were mostly driven by N. In contrast, AOA were more sensitive to soil water dynamics than N dynamics in both grasslands. Nitrobacter abundance was mostly affected by global change factors through their effects on AOB abundance, whereas Nitrospira abundance was more related to changes of AOA in the Mediterranean grassland. Similarly, nirK- and nirS-harboring nitrite reducers and nosZI-harboring N2O reducers were more sensitive to N deposition than nosZII-harboring N2O reducers, and nirK- and nirS-bacteria positively responded to reduced precipitation. This highlights niche differentiation between them and indicates that the balance between them may be altered in the future; 2）In the Mediterranean grassland, where high N deposition was simulated by two N addition events each year, the N effect dominated global change effects. In contrast, in the Monsson grassland, chronic wet N deposition did not increase denitrifier abundance and only weakly increased soil N2O emissions. This was explained by the efficient capture of added N by the dominant grass species and by the increased plant growth leading to increased transpiration and decreased soil moisture. 3）For both grasslands, the interaction between global change factors on soil N cycling could not be predicted simply by studying the effects of one or two factors. These interactive effects were explained by effects on key environmental variables like soil moisture, mineral N availability, pH and belowground plant growth.These results demonstrates the limitation of predicting how (de)nitrifiers respond to global change scenarios involving multiple factors only from studying single factor effects. Particularly, interactive effects were observed between N deposition, decreased precipitation amount and altered precipitation frequency in the Monsoon grassland; and between fire, N deposition, warming, elevated precipitation and elevated CO2 in the Mediterranean grassland. This calls for more comprehensive studies in the global change biology domain. Modelling and evaluating the generality of these complex interaction effects is thus a high priority for research to predict the responses of soil N cycling processes to global change and feedbacks on climate in the future

La nitrification dans les sols est un processus particulièrement critique dans les systèmes pauvres en nutriments comme la savane de Lamto (Afrique de l'Ouest) où l'azote est considéré comme le facteur limitant principal de la production primaire. Les faciès dominés par la Graminée Hyparrhenia diplandra sont connus pour exprimer de faibles potentiels de nitrification et ainsi éviter les pertes de nitrate. Nous avons utilisé des sites à faible/fort potentiel de nitrification comme modèles afin d'étudier si la végétation pouvait inhiber la nitrification, et les possibles conséquences en termes de performance de l'écosystème et de cycle de nutriments. Nous avons montré la coexistence de sites à forts et faibles potentiels de nitrification. La stabilité de ces deux systèmes a été abordée via l'activité nitrate réductase d'H. diplandra, montrant une différence stable de modalité de nutrition entre sous-populations des deux sites. Nous avons démontré un contrôle direct in situ des sous-populations d'H. diplandra sur la nitrification par une balance inhibition/stimulation. Cette conclusion a été étayée par l'observation de corrélations négatives entre densité racinaire et nitrification en site non nitrifiant. La production épigée et le ratio épigée-hypogée du couvert en site nitrifiant sont très inférieurs au site non nitrifiant. On a observé chez les H. diplandra du site nitrifiant des indices de taille et de croissance inférieurs en serre, in situ et décroissant quand elles sont mélangées in situ aux individus du site non nitrifiant, suggérant une moins bonne compétitivité peut-être due à une moins bonne accessibilité à la ressource lumière. Ces résultats suggèrent une moins bonne accessibilité à l'azote du couvert en site nitrifiant et l'existence de sous-populations de Graminées exprimant diverses caractéristiques intrinsèques différentes. De futures recherches devront s'intéresser au mécanisme d'inhibition et à la stabilité et dynamique de ces deux systèmes contrastés.

<p>New possibilities of nutrients removal by additions of magnesium compounds were studied in primary treatment and supernatant of side stream in wastewater treatment. The precipitation product from this method is magnesium ammonium phosphate (MAP) socalled struvite. High efficiencies on NH4-N and PO4-P removals have been demonstrated up to over 90 % respectively in side stream from dewatering of digested sludge. In order to find out the nutrient removal efficiency in raw wastewater and the feasibility of MAP recycling in wastewater treatment, the postulations of combining MAP and nitrification-denitrification process, and MAP and partial nitritation-anmmox process were carried out by experimental works in the laboratory at Land and Water Resources Department, KTH. It was found that 92-97 % of PO4-P and 57 % of NH4-N were removed from raw wastewater by Mg2+ addition at pH10 to pH10.5. The research work revealed that recycling of MAP by nitrification-denitrification and partial nitritation-anmmox processes may be a feasibly process combination. In MAP and nitrification -denitrification process, the released ammonium was mostly oxidized to nitrate in nitrification phase and ready for denitrification. Based on presented results on MAP and partial nitritation-anmmox process, it was found that the released ammonium was consumed by anammox bacteria.</p>

Nitrification is a biological oxidation of NH3 to NO2- and then to NO3-. Understanding how the nitrifier community responds to agricultural management is essential because the community composition is complex and functional distinction of subgroups occurs. Better managing nitrifiers could benefit the environment by increasing nitrogen (N) fertilizer use efficiency, decreasing NO3- leaching, and reducing NO and N2O emissions. This study examined how long-term N fertilization and tillage influenced nitrifier density, ratios, nitrification rates, and the community structure of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and nitrite-oxidizing bacteria (NOB). The study site was a long-term (>40 years) continuous maize (Zea mays L.) experiment with three N fertilization rates (0, 168, and 336 kg ha-1) and either no-tillage (NT) or plow tillage (PT). Most Probable Number method was used to estimate the density of AOB and NOB; the shaken slurry method was used to measure potential nitrification rates; PCR-denaturing gradient gel electrophoresis (DGGE) was used to analyze nitrifier communities. Tillage, fertilization, and their interaction all significantly influenced the AOB and NOB densities, the ratio of AOB to NOB, and potential nitrification rate. Nitrifier densities and potential nitrification rates increased with increased N fertilization; NOB density increased faster than AOB density with fertilization. The influence of tillage on nitrification was different for different fertilization rates. The trends for nitrifier density and potential nitrification rate were not consistent. Nitrifier community structure was influenced by sample season, N fertilization rates, tillage, and their interaction. Different nitrifier groups had different responses to the treatments. The AOB became more diverse with increasing N input; tillage rather than N fertilizer played a dominant role affecting the AOA community; two NOB genera had different responses to N fertilization rates: Nitrobacter diversity increased with more N applied; Nitrospira was the opposite. Unique bands/members were discovered in different treatments, manifesting environmental selection. Long-term field trials were useful in better understanding how soil management influenced the relationship between nitrifier densities, nitrification rates, and community structure, which may facilitate new approaches to optimize nitrification and provide new clues to discover which environmental factors most influence the nitrifier community in agroecosystems.

Nous avons étudié l’application de plusieurs mesures d’isotopes stables afin de caractériser les processus du cycle de l’azote et les sources d’azote dans les lacs tempérés à diverses échelles spatiales et temporelles. Les résultats d’une étude à travers 65 lacs sur un gradient trophique ont démontré que le ratio d’isotopes stables d’azote (δ15N) des sédiments de surface est un indicateur de l’importance relative des sources d’azote anthropique, mais que ce ratio peut être altéré par la diagenèse. La mesure du δ15N des sédiments demeure néanmoins un outil permettant de déterminer à long terme le changement des charges en azote anthropique aux écosystèmes lacustres et les causes de l’eutrophisation de ces systèmes. Nos résultats d’une étude sur la variation saisonnière de plusieurs isotopes stables dans trois lacs peu profonds situés sur un gradient trophique et ayant différents régimes de stratification ont démontré que cette approche est prometteuse dans les lacs mésotrophes et stratifiés. Dans ces systèmes, le δ15N de la matière organique particulaire (MOP) aurait le potentiel de déterminer les sources d’azote assimilées par le phytoplancton. Cependant les mesures d’isotopes stables du carbone (δ13C) et du ratio C:N indiquent que les apports de matières organiques du bassin versant peuvent altérer les relations observées. Nous avons également constaté une déviation de la relation 1:1 entre les isotopes stables d’azote et d’oxygène (δ18O) du nitrate (NO3-) indiquant son assimilation et sa nitrification simultanée. Cette application est particulièrement prometteuse puisque la nitrification est méconnue dans les lacs et peut exacerber les effets de l’eutrophisation. / We studied the application of multiple stable isotopes measures with the overall objective of improving our understanding of nitrogen cycling and sources in temperate lakes over different spatial and temporal scales. Results from our study across 65 lakes on a trophic gradient demonstrated that surface sediment nitrogen stable isotope ratio (δ15N) is an indicator of the relative importance of anthropogenic N loads, but that diagenesis can alter this ratio. Nevertheless, sediment core δ15N is a powerful proxy for the determination of longterm changing anthropogenic N loads to lake ecosystems and the causes of lake eutrophication. Results from our second study on multiple stable isotopes seasonal variation in three shallow lakes along a trophic gradient and with different stratification regimes have demonstrated that such an approach is particularly promising in mesotrophic and stratified lakes. In these systems, our results showed that the suspended particulate organic matter (SPOM) δ15N could be used to assess the nitrogen sources assimilated by phytoplankton. However, measurement of carbon stable isotopes (δ13C) and C:N ratios from the SPOM showed that the observed relationships can be altered by watershed derived organic matter. We have also found a deviation from the 1:1 relationship between nitrogen and oxygen stable isotopes (δ18O) of nitrate (NO3-) indicating a simultaneous NO3- assimilation and nitrification in our stratified system. The application of dual nitrate isotopes is promising in the study of nitrification since this process is not well understood in lakes and can increase the severity of eutrophication symptoms.

L’objectif de cette thèse était d’identifier les principaux indicateurs de disponibilité de l’azote dans les sols forestiers et ensuite de déterminer les mécanismes impliqués dans le contrôle de la minéralisation de l’azote et de la nitrification par les essences forestières. Différents indicateurs de la disponibilité en azote des sols ont été comparés dans 50 hêtraies du Nord Est de la France représentant une large gamme de type de sol. L’effet des essences a été étudié sur un cambisol hyperdystric acide dans le site de Breuil (Morvan, France). Le potentiel net de minéralisation de l’azote est corrélé négativement avec le pH du sol et positivement avec le rapport C/N microbien. Le pourcentage de nitrification est fortement corrélé à une combinaison du pH avec le rapport C/N du sol ou à la composition de la végétation. Dans le site de Breuil, le pourcentage de nitrification du sol est élevé sous le hêtre, le pin laricio et le douglas tandis qu’il est très faible sous le Sapin, l’Epicéa et la forêt native (taillis sous futaie à base de hêtre et de chêne). La permutation des carottes de sols entre ces peuplements montre que sous les peuplements forts nitrifiants, la colonisation racinaire est lente et le pourcentage de nitrification est stimulé très rapidement (<16 mois). Sous les peuplements peu nitrifiants, la colonisation racinaire est très rapide mais la réduction du pourcentage de nitrification est assez lente (>28 mois). Par ailleurs, la coupe à blanc stimule très rapidement la nitrification sous la forêt native. L’ensemble de ces résultats converge vers un contrôle fort du cycle de l'azote par les racines, mais le mécanisme exact reste inconnu. / The aim of this thesis was to identify the main indicators of N availability in forest soils and thereafter to determine mechanisms by which tree species control soil N mineralization and nitrification. Various indicators of N availability were compared within 50 beech forests covering a large range of soil types in northeastern France. Thereafter, the effect of six tree species was studied in an acidic cambisol hyperdystric at the experimental site of Breuil (Morvan, France). Potential net N mineralization was negatively correlated with soil pH and positively with microbial C/N ratio. Percent nitrification was strongly correlated with the combination of soil pH and soil C/N or with the combination of Ellenberg’s indices of N availability or Ecoplant C/N and Ellenberg’s indices of acidity (R) based on the vegetation community composition. At the Breuil experimental site, the percent nitrification was high in beech, Corsican pine and Douglas fir plantations whereas it was very low in the Nordmann fir and the spruce plantations and the native forest stands (an old coppice with standard dominated by beech and oak). The exchange of soil cores between stands showed that under the « High nitrifying stands », root colonization was low and percent nitrification was quickly stimulated (<16 months). In « Low nitrifying stands », root colonization was very quick but percent nitrification decreased slowly (>28 months). Percent nitrification was quickly stimulated by clear felling of the native forest. Our results converge toward a strong influence of roots on the nitrogen cycle in forest ecosystems but it needs further efforts to identify the mechanism.

O objetivo deste trabalho foi avaliar o efeito inibidor dos sais NaCl, MgCl2 e CaCl2, em mistura e separadamente, nas comunidades microbianas em sistema descontínuos e contínuos para o tratamento de esgoto sanitário de regiões de escassez hídrica. Foi avaliado o estabelecimento da nitrificação e desnitrificação simultânea (NDS) sem o controle da concentração de oxigênio dissolvido mediante à aeração contínua por meio de reatores contínuos de leito fixo estruturado na presença (Reator salino, RS) e ausência (Reator Controle, RC) dos sais de estudo. Nos sistemas descontínuos, um planejamento fatorial e ensaios complementares isotônicos para as pressões osmóticas (PO) de 5, 15 e 30 atm foram realizados para a comunidade nitrificante e para a comunidade desnitrificante afim de investigar os efeitos de inibição, antagonismo, sinergismo e estímulo dos sais em mistura e separadamente. Os efeitos dos sais foram diferentes para as comunidades nitrificante e desnitrificante e as maiores taxas específicas de nitrificação e desnitrificação obtidas foram de 0,11 mgN gSSV-1 min-1 e 0,065 mgN gSSV-1 min-1, respectivamente. Os ensaios em batelada permitiram inferir que o efeito de inibição de cada sal é distinto quando em mistura ou separadamente, independentemente da PO aplicada e que o efeito de toxicidade específica de cada sal é superior ao efeito de inibição da PO do meio, podendo estar relacionado à capacidade de osmoregulação dos microrganismos por solutos compatíveis. Nos reatores contínuos, a NDS foi estabelecida sob aeração contínua com concentrações médias de OD de 6 mg L-1, alcançando eficiências de oxidação de NH4+ e de remoção de N-Total de 60% e 56,3% no RC e 95,9% e 65,8% no RS na Fase 1 com PO de 1,7 atm. Isto evidenciou que a presença dos sais em concentração moderada foi benéfica ao sistema nas condições estudadas e para os inóculos aplicados. A deficiência da remoção de N-total em relação ao que foi nitrificado foi atribuída à falta de doadores de elétrons suficientes para promover a desnitrificação heterotrófica. A remoção de DQO no RS foi pouco afetada pelo aumento da PO, tendo eficiência reduzida de 97,2% para 86,2% com o aumento da PO de 1,7 para 9 atm. Análises de PCR/DGGE indicaram que a diversidade microbiana de ambientes salinos é tão grande ou maior que a de ambientes de água doce e o sequenciamento genético evidenciou que os inóculos possibilitaram a inserção de populações capazes de atuar no ciclo do nitrogênio sob condições de elevada salinidade, destacando-se os gêneros Aeromonas, Rheinhemera, Azospirillum, Thioalkalivibrio e Pseudoalteromonas. / The aim of this research was to evaluate the inhibitory effect of NaCl, MgCl2 and CaCl2 salts, in mixture and separately, on microbial communities in batch and continuous systems for the treatment of wastewater from regions with water scarcity. The establishment of simultaneous nitrification and denitrification process (SND) was assessed without dissolved oxygen control and under continuos aeration in structured bed reactors in the presence (Saline Reactor, SR) and absence (Control Reactor, CR) of the studied salts. In the batch reactors, a factorial design and complementary isotonic experiments for the osmotic pressures (OP) of 5, 15 and 30 atm were performed to investigate the effects of inhibition, antagonism, synergism, and stimulation of the salts alone and in mixture. The salts caused distinct effects on the nitrifying and denitrifying communities and the highest nitrification and denitrification specific rates obtained were 0.11 mgN gSSV-1 min-1 and 0.065 mgN gSSV-1 min-1, respectively. In the studied conditions, the results of the batch experiments showed that the inhibitory effect of each salt is different when they are alone or in mixture, regardless of the applied OP. It was observed that the microbial communities are more negatively affected by the specific toxic effect of each salt than by the unspecific inhibitory effect of the OP, which may be related to the osmoregulation capacity of the microorganisms by compatible solutes system. In the continuous reactors CR and SR, SND was established under continuous aeration at average DO concentrations of 6 mg L-1, achieving NH4+ oxidation and total nitrogen removal efficiencies of 60% and 56.3% in CR, and 95.9 % and 65.8% in SR in Phase 1 with OP of 1.7 atm. This data indicates that the presence of the salts in moderate concentration was beneficial to the system for the studied conditions and inoculum. The total nitrogen removal did not achieve higher efficiencies possibly due to the lack of electron donors, which supports heterotrophic denitrification. The COD removal in the SR was not greatly affected by the increase on OP as the efficiency reduced from 97.2% to 86.2% as the OP increased from 1.7 to 9 atm. PCR/DGGE analyses indicated that the microbial diversity of saline environments is as great as in freshwater ones. Genetic sequencing of the biomass showed the presence of bacterial populations capable of consuming oxidized and reduced forms of nitrogen under high osmotic pressure such as the genus Aeromonas, Rheinhemera, Azospirillum, Thioalkalivibrio and Pseudoalteromonas.

Esta pesquisa teve o objetivo de avaliar o pós-tratamento de um Reator UASB com Filtro Biológico Aerado Submerso, no intuito de verificar sua eficácia na nitrificação, submetendo o mesmo a diferentes taxas de recirculação do lodo do decantador final para a entrada do FBAS. A necessidade do pós-tratamento, deve-se ao fato do efluente do reator UASB, mesmo tendo uma boa eficiência na remoção de matéria orgânica, seu efluente não atende a Legislação ambiental brasileira, logo, o pós-tratamento tem o principal papel de completar a remoção de matéria orgânica, e também efetuar a remoção de nitrogênio amoniacal, que de acordo com a Resolução CONAMA Nº 357, de 17 de março de 2005, o padrão de lançamento é de até 20 mgN/L. Esse estudo foi desenvolvido em unidade de escala piloto, em três regimes distintos de operação, situada no Centro Tecnológico de Hidráulica ? CTH, constituída por um FBAS com um volume útil de 605 L, seguido de decantador, tratando o efluente de um reator UASB de 25 m3. Os três regimes de operação tiveram tempo de duração de 75, 80 e 54 dias, respectivamente, com vazões de alimentação de 500 L/h nos dois primeiros regimes e 200 L/h no regime 3. As taxas de recirculação foram respectivamente 0,2, 0,4 e 0,8, para os regimes 1, 2 e 3. Esses três regimes de operação apresentaram as seguintes taxas de aplicação superficial, respectivamente: DQO (35, 40 e 16 g DQO/m2.dia); DBO (16, 14 e 7 g DBO/m2.dia) e NKT (8,8, 8,7 e 3,1 g NKT/m2.dia). Foram realizadas análises de DBO, DQO, sólidos em suspensão, nitrogênio amoniacal e Kjeldahl, nitrito, nitrato e alcalinidade, onde o regime de operação 3 apresentou os melhores resultados, produzindo um efluente final com as seguintes concentrações médias: 78 mg/L (DQO), 28 mg/L (DBO), 27 mg/L (SST), 12 mg/L (NKT), 10 mg/L (NH3/NH4 +) e 23,4 mg/L (NO3 -). As eficiências de remoção observadas foram: 68% (DQO), 76% (DBO), 79% (SST), 75% (NKT) e 75% (NH3/NH4 +). / This study aimed at to evaluate the post-treatment of UASB reactor with aerated submerged biological filter, with the objective of verifying your effectiveness in the nitrification process, submitting it to different sludge recirculation rates from the final settling tank to the entrance of FBAS. The necessity of the post-treatment is due to the fact of the UASB reactor effluent, although tends a good efficiency in the removal of organic matter, it doesn't to meet the standards of Brazilian environmental legislation, therefore, the post-treatment has the main paper of completing the organic matter removal, and also to ammonia nitrogen removal, that in agreement with the Resolution CONAMA N. 357, of march 17, 2005, the release pattern for this parameter is 20 mgN/L. This study was developed in a pilot plant with three different operational regimes, located in ?Centro Tecnológico de Hidráulica ? CTH?, constituted by a FBAS with an useful volume at 605 L, following by settling tank, treating the effluent from 25 m3 UASB reactor. The three operation regimes had time of duration of 75, 80 and 54 days, respectively, with feeding flows at 500 L/hour in the first two regimes and 200 L/hour in the regime 3. The sludge recirculation rate were 0,2, 0,4 and 0,8, for the regimes 1, 2 and 3, respectively. The three operation regimes introduced these superficial aplication rates, respectively: COD (35, 40 and 16 g COD/m2.day); BOD (16, 14 and 7 g BOD/m2.day) and NKT (8,8, 8,7 and 3,1 g NKT/m2.day). Analyses of parameters were accomplished as BOD, COD, solids in suspension, ammonia nitrogen and total Kjeldahl nitrogen, nitrite, nitrate and alkalinity, where the operation regime 3 presented the best results, producing a final effluent with these average concentrations: 78 mg/L (COD), 28 mg/L (BOD), 27 mg/L (TSS), 12 mg/L (NKT), 10 mg/L (NH3/NH4 +) and 23,4 mg/L (NO3 -). The observed efficiency removal were: 68% (COD), 76% (BOD), 79% (TSS), 75% (NKT) and 75% (NH3/NH4 +).