El tema d'estudi d'aquesta tesi és l'eliminació biològica de nitrogen d'aigües amb alta càrrega d'amoníac, més concretament, el procés de nitrificació (l'oxidació de l'amoni a nitrat). Aquesta reacció en dos passos, catalitzada per dos tipus de microorganismes (AOB i NOB), pot patir problemes d'inhibicions per amoníac i àcid nitrós. Això és especialment important quan es tracta aigua amb alta concentració d'amoni i per tant, es necessita un control del procés adequat. Tot i així, aquestes inhibicions es poden utilitzar per a aconseguir nitrificació parcial (l'oxidació de l'amoni a nitrit), la qual combinada amb el procés de desnitrificació, aporta beneficis importants pel què fa a la utilització dels recursos.En aquesta tesi es mostra el desenvolupament i calibratge d'un model matemàtic per a descriure la cinètica i l'estequiometria de la nitrificació considerant les inhibicions mencionades anteriorment i tenint en compte els dos tipus de bacteris nitrificants i també els bacteris heteròtrofs. Es varen dissenyar experiments específics per a l'optimització dels paràmetres del model i amb l'ajuda d'eines d'identificabilitat de paràmetres, aquests experiments es van analitzar i millorar. Les constants d'afinitat pel substrat i els coeficients d'inhibició per substrat es van determinar dues vegades utilitzant biomasses diferents i es van obtenir resultats diferents. Això indicà que aquests paràmetres són variables i depenen de l'aclimatació de la biomassa. Es va utilitzar la tècnica d'hibridació fluorescent in situ (FISH) per a la detecció i quantificació de les fraccions bacterianes. Per a la detecció de la fluorescència es van utilitzar un microscopi d'epifluorescència, un microscopi confocal i un citòmetre de flux. Els resultats obtinguts es van comparar entre ells i es van discutir els seus avantatges i inconvenients tenint en compte la precisió dels resultats, la velocitat de l'anàlisi i la disponibilitat de l'equip. La millor metodologia va resultar ser l'observació del FISH amb el microscopi confocal encara que la citometria de flux no es va poder investigar prou a fons. El model matemàtic desenvolupat i calibrat en aquesta tesi es va utilitzar per a l'optimització de la posada en marxa d'un sistema de nitrificació completa. Es van optimitzar dues estratègies de control que posteriorment es van implementar experimentalment partint d'un inòcul procedent dels llots d'una estació de tractament d'aigües residuals urbanes. El controlador dissenyat es basava en la mesura de la velocitat del consum d'oxigen (OUR) en l'últim reactor del sistema i actuava sobre la càrrega d'entrada. Els resultats obtinguts es van comparar amb els resultats d'una posada en marxa amb control manual i es va demostrar que el control automàtic permet disminuir el temps de posada en marxa i augmentar l'estabilitat del procés. Posteriorment, els resultats experimentals es van simular amb el model matemàtic obtenint un bon ajust. Finalment, el nou model es va utilitzar per a fer prediccions del comportament del sistema a curt i llarg termini. L'enriquiment de la biomassa en microorganismes nitrificants es va comprovar mitjançant el FISH i la microscòpia confocal. La biomassa que es va obtenir després de la última posada en marxa del sistema es va utilitzar per a aconseguir la nitrificació parcial treballant a 25 ºC, 1.1 mg O2 L-1, pH de 8.3 i amb un set point d'OUR apropiat en el control automàtic. La nitrificació parcial es va mantenir de forma estable durant uns 120 dies amb una càrrega mitjana de 0.5 g N g-1 SSV d-1. L'anàlisi microbiològic amb FISH va demostrar que la població de NOB havia estat eliminada del sistema. Posteriorment, el sistema de control es va millorar amb l'adició de dues regles de control expert que van permetre l'operació estable del sistema davant d'importants pertorbacions externes. / Biological nitrogen removal of high-strength ammonium wastewater was studied in this thesis, particularly, the nitrification process (the oxidation of ammonium to nitrate). This two-step reaction, catalyzed by two kinds of bacteria (AOB and NOB), can suffer serious inhibition problems due to ammonia and nitrous acid when dealing with highly concentrated ammonium wastewater and therefore it requires adequate process control. However, these inhibitions can be used to achieve partial nitrification (the oxidation of ammonium to nitrite), which coupled to a denitrifying process leads to significant benefits in terms of use of resources.A mathematical model describing the kinetics and the stoichiometry of the nitrification process was developed and calibrated. It considered the aforementioned inhibitions and took into account both kinds of nitrifying bacteria and also heterotrophic bacteria. Specific experiments were designed for parameter estimation and parameter identifiability tools were used to analyze and improve them. Optimal experimental designs were used to calibrate most of the model parameters and the obtained values were compared with values found in the literature. Affinity constants for substrate and substrate inhibition coefficients were estimated twice using different sludges and, as a result, different values were found indicating that they change depending on the biomass acclimation. This model was coupled to the hydraulic model of the experimental system (pilot plant) and was implemented in Matlab ®. Fluorescence in situ hybridization (FISH) was used for bacterial fractions detection and quantification. Several equipments were used for fluorescence detection: an epifluorescence microscope, a confocal microscope and a flow cytometer. Biomass fractions were determined with each of the equipment and also with simulations. Obtained results were compared and the advantages and disadvantages of the tested methodologies were discussed considering the accuracy of the results, the speed of the analysis and the availability of the equipment. FISH combined with confocal microscopy turned out to be the best technique for nitrifying biomass quantification although flow cytometry could not be extensively investigated.The start-up of a complete nitrification system was optimized by means of mathematical simulation using the previously developed and calibrated method. Two automatic control strategies were optimized and implemented in the experimental system by using sludge from a municipal wastewater treatment plant as inoculum. The controller was based on the measurement of the oxygen uptake rate (OUR) in the last reactor of the system and actuated over the nitrogen loading rate. Results were compared with a start-up performed with manual control and it was demonstrated that automatic control decreased the length of the start-up and increased its stability. Then, experimental results were simulated with the nitrification model. Model predictions agreed well with experimental data. The final model was useful for both long- and short-term prediction. The sludge enrichment in nitrifying bacteria was checked with FISH and confocal microcopy.The nitrifying sludge obtained after the last start-up contained both AOB an NOB and was used to achieve partial nitrification. Some environmental conditions and the automatic control strategy were changed in order to inhibit NOB and wash them out of the system. Partial nitrification with an effluent devoid of nitrate was achieved at 25 ºC, 1.1 mg O2 L-1 and pH of 8.3 using the appropriate OUR set point for the automatic controller. Partial nitrification was run for 120 days with an averaged nitrogen loading rate of 0.5 g N g-1 VSS d-1. FISH analysis demonstrated that NOB were completely washed out. The control strategy was improved by the addition of two expert rules and stable operation was maintained even when external disturbances were provoked. Finally, a model-based study was performed to test the partial nitrification start-up strategy under different conditions and system configurations.

Ammonia removal is an important problem that Canadian municipalities are encountering in their wastewater treatment systems due to ammonia’s adverse environmental effects and its increasingly stringent discharge standards. Nitrogen compounds are generally removed from wastewater by a combination of nitrification and denitrification. In full nitrification, ammonia is first biologically oxidized to nitrite, which is then oxidized to nitrate by nitrite-oxidizing bacteria. In denitrification, the resulting nitrate has to be first reduced to nitrite in order to be converted to nitrous oxide, then nitric oxide, and finally to nitrogen gas. Since, nitrite is an intermediary compound in both nitrification and denitrification, it may be more efficient to produce a partial nitrification up to nitrite and then denitrification starting from this nitrite. In this research, EnviroPro Designer was used to simulate, optimize and compare process models for both full nitrification and partial nitrification. The Full System model simulates the traditional full nitrification followed by denitrification. Partial System-1 model simulates the partial nitrification process followed by denitrification directly from nitrite. Partial System-1 significantly reduced the ammonia and domestic waste concentrations in the effluent while achieving 1.5 times faster denitrification rates and utilizing 33% less oxygen. Partial System-1 was further optimized to develop a novel nitrogen removal process, Partial System-3, which incorporated an additional third anoxic stage while the aerobic stage in sludge treatment was removed. Partial System-3 successfully reduced the ammonia and nitrite concentrations in the effluent to values well within the current guidelines while consuming 50% less oxygen than the Full System, which reflected favorably on utility savings. It also showed 2 times faster denitrification rates, and displayed superior domestic waste consumption. Furthermore, the capital and operational costs were less than other nitrogen removal systems investigated in this thesis. The novel Partial System-3 appears to be the best option for removal of nitrogen from medium to high strength wastewater, and further experimental research is required to confirm the kinetic and yield constants assumed in the simulations.

Ammonia removal is an important problem that Canadian municipalities are encountering in their wastewater treatment systems due to ammonia’s adverse environmental effects and its increasingly stringent discharge standards. Nitrogen compounds are generally removed from wastewater by a combination of nitrification and denitrification. In full nitrification, ammonia is first biologically oxidized to nitrite, which is then oxidized to nitrate by nitrite-oxidizing bacteria. In denitrification, the resulting nitrate has to be first reduced to nitrite in order to be converted to nitrous oxide, then nitric oxide, and finally to nitrogen gas. Since, nitrite is an intermediary compound in both nitrification and denitrification, it may be more efficient to produce a partial nitrification up to nitrite and then denitrification starting from this nitrite. In this research, EnviroPro Designer was used to simulate, optimize and compare process models for both full nitrification and partial nitrification. The Full System model simulates the traditional full nitrification followed by denitrification. Partial System-1 model simulates the partial nitrification process followed by denitrification directly from nitrite. Partial System-1 significantly reduced the ammonia and domestic waste concentrations in the effluent while achieving 1.5 times faster denitrification rates and utilizing 33% less oxygen. Partial System-1 was further optimized to develop a novel nitrogen removal process, Partial System-3, which incorporated an additional third anoxic stage while the aerobic stage in sludge treatment was removed. Partial System-3 successfully reduced the ammonia and nitrite concentrations in the effluent to values well within the current guidelines while consuming 50% less oxygen than the Full System, which reflected favorably on utility savings. It also showed 2 times faster denitrification rates, and displayed superior domestic waste consumption. Furthermore, the capital and operational costs were less than other nitrogen removal systems investigated in this thesis. The novel Partial System-3 appears to be the best option for removal of nitrogen from medium to high strength wastewater, and further experimental research is required to confirm the kinetic and yield constants assumed in the simulations.

Made available in DSpace on 2017-05-12T14:47:11Z (GMT). No. of bitstreams: 1 Angelica _Chini.pdf: 1719142 bytes, checksum: cacffbf4d6a7bd7dd87a559756ed1238 (MD5) Previous issue date: 2015-02-13 / Nitrogen is an essential nutrient for the survival of living organisms, and although abundant as a gas (N₂), it is largely inaccessible in this form to most beings. Nitrogen only becomes accessible when converted into, for example, ammonia, nitrite and nitrate. These substances can be found in high concentrations in effluents, such as swine wastewater, generating a high concentration of nutrients, which may cause damage to the environment and to public health. Biological processes are widely used to remove high nutrients loads. In this context, anammox, partial nitritation (PN) and their combination, as deammonification, are being studied for nitrogen removal. The deammonification consists in ammonia oxidation by PN and that generates substrate to anammox activity; therefore, it must have partial nitrification control to prevent nitrite accumulation. The nitrite concentration in the reactor can inhibit the anammox process, which can be controlled with different strategies, such as aeration and reactor configuration. Considering this, the present study aimed to evaluate two reactors configurations suspended and expanded sludge, for reactor configuration evaluation on deammonification process. For this, two up flow reactors were used with intermittent feeding and aeration at 30 min cycles (15 min on/ 15 min off), one with suspended and the other with expanded bed. These possess working volume of 1 L, 55 g (w/v) of biofilm plastic carrier, the temperature was maintained at 25 °C, HRT 9 h, circulation input flow rate of 2.70 L.d⁻¹ and recirculation flow rate was 2.5 times the input and it was fed with synthetic medium. It was possible to establish deammonification process in the two reactors and the experiments were carried out: phase I and III were unstable (air flow rate of 30 mL.min⁻¹.L⁻¹) and phase II was stable (air flow rate of 20 mL.min⁻¹.L⁻¹). Thus, in the tested process conditions, it was inferred that the ideal air flow rate was of 20 mL.min⁻¹.L⁻¹. The expanded biomass reactor configuration achieved better nitrogen removal efficiencies, being 1.23 more efficient than suspended bed, thus being considered the best option for the process under study. In the anammox and nitrifying quantification, there were no significant changes in the suspended bed reactor, only nitrifying growth in phase III. For the expanded bed reactor, anammox bacteria increased in phase II. The results showed that the expanded bed reactor presented a performance 23.06% more efficient than the suspended bed reactor. / O nitrogênio é um dos nutrientes essenciais para a sobrevivência dos organismos vivos e, embora abundante como gás (N₂), é em grande parte inacessível nesta forma à maioria dos organismos. O nitrogênio só se torna acessível quando convertido em, por exemplo, amônia, nitrito e nitrato. Substâncias essas que são encontradas em elevadas concentrações em efluentes, como os da suinocultura, gerando uma elevada concentração de nutrientes,que podem causar danos ao meio ambiente e à saúde pública. Para a remoção de elevadas cargas de nutrientes, os processos biológicos são amplamente utilizados. Assim, os processos anammox, nitritação parcial e seus sistemas combinados, como a desamonificação, estão sendo estudados para a remoção do nitrogênio. A desamonificação consiste na oxidação da amônia pela nitritação parcial (NP), gerando substrato para as bactérias com atividade anammox. Por isso, é necessário que ocorra controle rigoroso da NP a fim de evitar acúmulo de nitrito. O controle da produção de nitrito, a qual pode inibir as bactérias com atividade anammox,pode ser de várias formas, como, por exemplo, estratégias de aeração e configuração de reatores. Considerando estes aspectos, propõe-se estudar duas configurações de reatores, biomassa suspensa e biomassa expandida, com o intuito de avaliar a influência destas configurações em relação ao processo de desamonificação. Para isto, foram utilizados dois reatores de fluxo ascendente, com alimentação e aeração intermitente em ciclos de 30 min (sendo alimentação e aeração ligadas por 15 min e desligadas por 15 min), um com leito suspenso e outro expandido. Reatores com volume útil de 1L e 55 g (v/v) de meio suporte, temperatura mantida em 25 °C, TRH de 9 h, vazão de alimentação de 2,70 L.d⁻¹ e a de recirculação foi 2,5 vezes a de entrada. Os reatores foram alimentados com meio de cultura sintético contendo nitrogênio amoniacal total na faixa de 300 mgN.L⁻¹. A partir disso, foi possível estabelecer o processo de desamonificação nos dois reatores com vazões de ar de 20 e 30 mL.min⁻¹.L⁻¹, em três diferentes fases. As fases I e III foram instáveis (vazão de ar de 30 mL.min⁻¹.L⁻¹), ao passo que a fase II foi estável (vazão de ar de 20 mL.min⁻¹.L⁻¹). Dessa maneira, nas condições de processo testadas, inferiu-se que a vazão de ar de 20 mL.min⁻¹.L⁻¹ é a ideal. A configuração de reator de biomassa expandida obteve melhores resultados na remoção de nitrogênio, tendo 1,23 vezes maior eficiência do que o de biomassa suspensa. Assim sendo, o reator de leito expandido se mostrou a melhor opção para o processo estudado. Já na quantificação de biomassa anammox e nitrificante, não houve alterações significativas no reator de leito suspenso, somente crescimento de bactéria nitrificante na fase III. O reator de leito expandido, além disto, também apresentou crescimento de bactérias com atividade anammox na fase II. Os resultados evidenciaram que o reator de leito expandido teve um desempenho 23,06% superior ao de leito suspenso

Made available in DSpace on 2017-07-10T19:23:57Z (GMT). No. of bitstreams: 1 Angelica _Chini.pdf: 1719142 bytes, checksum: cacffbf4d6a7bd7dd87a559756ed1238 (MD5) Previous issue date: 2015-02-13 / Nitrogen is an essential nutrient for the survival of living organisms, and although abundant as a gas (N₂), it is largely inaccessible in this form to most beings. Nitrogen only becomes accessible when converted into, for example, ammonia, nitrite and nitrate. These substances can be found in high concentrations in effluents, such as swine wastewater, generating a high concentration of nutrients, which may cause damage to the environment and to public health. Biological processes are widely used to remove high nutrients loads. In this context, anammox, partial nitritation (PN) and their combination, as deammonification, are being studied for nitrogen removal. The deammonification consists in ammonia oxidation by PN and that generates substrate to anammox activity; therefore, it must have partial nitrification control to prevent nitrite accumulation. The nitrite concentration in the reactor can inhibit the anammox process, which can be controlled with different strategies, such as aeration and reactor configuration. Considering this, the present study aimed to evaluate two reactors configurations suspended and expanded sludge, for reactor configuration evaluation on deammonification process. For this, two up flow reactors were used with intermittent feeding and aeration at 30 min cycles (15 min on/ 15 min off), one with suspended and the other with expanded bed. These possess working volume of 1 L, 55 g (w/v) of biofilm plastic carrier, the temperature was maintained at 25 °C, HRT 9 h, circulation input flow rate of 2.70 L.d⁻¹ and recirculation flow rate was 2.5 times the input and it was fed with synthetic medium. It was possible to establish deammonification process in the two reactors and the experiments were carried out: phase I and III were unstable (air flow rate of 30 mL.min⁻¹.L⁻¹) and phase II was stable (air flow rate of 20 mL.min⁻¹.L⁻¹). Thus, in the tested process conditions, it was inferred that the ideal air flow rate was of 20 mL.min⁻¹.L⁻¹. The expanded biomass reactor configuration achieved better nitrogen removal efficiencies, being 1.23 more efficient than suspended bed, thus being considered the best option for the process under study. In the anammox and nitrifying quantification, there were no significant changes in the suspended bed reactor, only nitrifying growth in phase III. For the expanded bed reactor, anammox bacteria increased in phase II. The results showed that the expanded bed reactor presented a performance 23.06% more efficient than the suspended bed reactor. / O nitrogênio é um dos nutrientes essenciais para a sobrevivência dos organismos vivos e, embora abundante como gás (N₂), é em grande parte inacessível nesta forma à maioria dos organismos. O nitrogênio só se torna acessível quando convertido em, por exemplo, amônia, nitrito e nitrato. Substâncias essas que são encontradas em elevadas concentrações em efluentes, como os da suinocultura, gerando uma elevada concentração de nutrientes,que podem causar danos ao meio ambiente e à saúde pública. Para a remoção de elevadas cargas de nutrientes, os processos biológicos são amplamente utilizados. Assim, os processos anammox, nitritação parcial e seus sistemas combinados, como a desamonificação, estão sendo estudados para a remoção do nitrogênio. A desamonificação consiste na oxidação da amônia pela nitritação parcial (NP), gerando substrato para as bactérias com atividade anammox. Por isso, é necessário que ocorra controle rigoroso da NP a fim de evitar acúmulo de nitrito. O controle da produção de nitrito, a qual pode inibir as bactérias com atividade anammox,pode ser de várias formas, como, por exemplo, estratégias de aeração e configuração de reatores. Considerando estes aspectos, propõe-se estudar duas configurações de reatores, biomassa suspensa e biomassa expandida, com o intuito de avaliar a influência destas configurações em relação ao processo de desamonificação. Para isto, foram utilizados dois reatores de fluxo ascendente, com alimentação e aeração intermitente em ciclos de 30 min (sendo alimentação e aeração ligadas por 15 min e desligadas por 15 min), um com leito suspenso e outro expandido. Reatores com volume útil de 1L e 55 g (v/v) de meio suporte, temperatura mantida em 25 °C, TRH de 9 h, vazão de alimentação de 2,70 L.d⁻¹ e a de recirculação foi 2,5 vezes a de entrada. Os reatores foram alimentados com meio de cultura sintético contendo nitrogênio amoniacal total na faixa de 300 mgN.L⁻¹. A partir disso, foi possível estabelecer o processo de desamonificação nos dois reatores com vazões de ar de 20 e 30 mL.min⁻¹.L⁻¹, em três diferentes fases. As fases I e III foram instáveis (vazão de ar de 30 mL.min⁻¹.L⁻¹), ao passo que a fase II foi estável (vazão de ar de 20 mL.min⁻¹.L⁻¹). Dessa maneira, nas condições de processo testadas, inferiu-se que a vazão de ar de 20 mL.min⁻¹.L⁻¹ é a ideal. A configuração de reator de biomassa expandida obteve melhores resultados na remoção de nitrogênio, tendo 1,23 vezes maior eficiência do que o de biomassa suspensa. Assim sendo, o reator de leito expandido se mostrou a melhor opção para o processo estudado. Já na quantificação de biomassa anammox e nitrificante, não houve alterações significativas no reator de leito suspenso, somente crescimento de bactéria nitrificante na fase III. O reator de leito expandido, além disto, também apresentou crescimento de bactérias com atividade anammox na fase II. Os resultados evidenciaram que o reator de leito expandido teve um desempenho 23,06% superior ao de leito suspenso

There is an urgent need to develop ammonia removal treatment systems for municipal and industrial wastewater treatment due to the increasingly stringent ammonia effluent discharge regulations implemented by Canada, the United States, and the European Union. The objective of this dissertation is to develop new understanding and advance the current design and operation of total ammonia nitrogen (TAN) removal via the moving bed biofilm reactor technology (MBBR) for municipal and industrial wastewaters. The first specific objective is to develop a passive, low operationally intensive, efficient and robust design strategy for municipal wastewater treatment to achieve partial nitritation (PN) as a pre-treatment to anammox treatment without using control strategies such as operating at low dissolved oxygen, or the use of inhibitors. This first objective includes developing new knowledge of the biofilm, biomass and microbiome of attached growth PN systems. The second specific objective is to investigate the impact of defining a maximum biofilm thickness, via bio-carrier design, to enhance the effects of free nitrous acid inhibition for PN of municipal wastewaters. The third objective is to investigate the effect of influent copper concentration on nitrifying MBBR systems over long-term operations, to demonstrate the feasibility of the nitrifying MBBR as a solution for TAN removal from gold mining wastewaters. The results pertaining to the first objective, achieved via a study investigating the operation of a nitrifying moving bed biofilm reactor at elevated TAN surface area loading rates (SALRs) of 3, 4, 5, and 6.5 g TAN/m²∙d with the aim of achieving passive PN, demonstrates that operating at a TAN SALR value of 6.5 g TAN/m²∙d can achieve PN without restricting dissolved oxygen or using inhibitors. Operating at a TAN SALR value of 6.5 g TAN/m²∙d achieves a TAN surface area removal rate (SARR) of 3.5 g TAN/m²∙d, and a nitrite accumulation of 99.8% of the oxidized TAN, demonstrating the suppression of nitrite oxidizing bacteria (NOB) activity, while achieving elevated TAN SARR values. At the molecular-scale, there is a statistically significant change in the ammonia oxidizing bacteria (AOB) to NOB ratio from 1:2.6 to 8.7:1 as the TAN SALR increases from 3 to 6.5 g TAN/m²∙d; however, even at a TAN SALR value of 6.5 g TAN/m²∙d there is an NOB abundance of approximately 2%; thus demonstrating that NOB remain present in the biofilm, while their activity is suppressed by operation at elevated TAN SALR values. Furthermore, this system was shown to achieve stable PN consistently for over a period of 10 months of operation, demonstrating a robust, passive, low operational strategy for attached growth PN. The second objective of this dissertation is addressed through a study that compared the carrier design of defined maximal biofilm thickness (z-prototype carrier) to undefined maximal biofilm thickness (chip-prototype carrier) for PN via free nitrous acid inhibition of tertiary, low carbon, municipal wastewaters. The study demonstrates that defined maximal biofilm thickness is a preferred design choice to achieve attached growth PN. The chip-prototype carrier shows biofilm thicknesses and biofilm mass values that are ten-fold higher than the z-prototype carrier, which is shown to contribute to the impact of free nitrous acid on AOB and NOB activities. The z-prototype carrier shows PN is achieved after 3 hours of exposure to free nitrous acid while the chip-prototype carrier does not achieve PN within this same time of exposure. Therefore, the defined maximal biofilm thickness carrier is identified in this research as the preferred design option to achieve attached growth PN for municipal, low carbon, tertiary wastewater treatment. The results of the third objective, achieved via a study investigating the effects of influent copper concentrations on nitrifying MBBR during long term operations to gold mining wastewaters, demonstrates that there is no AOB inhibition in attached growth systems exposed to 0.1, 0.3, 0.45, and 0.6 mg Cu/L for long exposure times. A trend of increasing nitrite accumulation with increasing influent copper concentrations is shown, indicating that NOB inhibition occurs at influent copper concentrations of 0.3 mg Cu/L and greater, with the greatest NOB inhibition observed with an influent copper concentration of 0.6 mg/L. There is no statistically significant difference in biofilm characteristics at the copper concentrations tested; however, there is a trend of increasing biofilm thickness and biofilm roughness with increasing copper concentrations. This study demonstrates the resilience of the nitrifying biofilm to copper inhibition and demonstrates that the nitrifying MBBR is a promising system for removing TAN in mining wastewater in the presence of copper.

Nitrogen removal from wastewater has been exstensively addressed by scientific literature in recent years; one of the most widely implemented technologies consists of the combination of partial nitritation and anaerobic ammonium oxidation (ANAMMOX). Compared to traditional nitrification and denitrification techniques such solution eliminates the requirement for an external carbon source and allows for a reduced production of excess sludge; furthermore, it brings down the costs associated to aeration by 60-90% and the emissions of CO2 by 90%. Similar techniques can turn out to be particularly interesting when stringent environmental regulations have to be met. At present, most of the dedicated research dwells on wastewater at high temperatures, high nitrogen loads and low organic content, as it is typical of sidestream effluents; this project, instead, is focused on mainstream wastewater, characterized by lower temperatures and nitrogen content, but higher COD values. At the center of the thesis is the application of a one-stage reactor treating synthetic mainstream municipal wastewater. The chosen approach consisted in maintaining low DO values, allowing for both for the establishment of a proper reaction environment and for the out-selection of nitrite oxidizers; granular biomass was employed for the experiment, aiming at effective biomass retention. The HRT value was gradually decreased, with a minimum at 6 hours. Resulting nitrogen removal rates proved to be satisfactory, with a maximum TN removal efficiency of 54%. Retention of biomass was also positively enhanced throughout the experiment, and yielded a final SRT value of 15.6 days. The whole process was then inserted into a more complete framework, accounting for possible energetic optimizations of similar treatment plants. Employing COD fractionation as a primary step paves the way for anaerobic digestion side processes, which can produce methane and ultimately provide energy for the main nitrogen removal step. Therefore, envisioning energy-sufficient water treatment processes seems a more and more feasible and realistic possibility.

Um reator de leito fixo, preenchido com biomassa imobilizada em espuma de poliuretano, foi operado em bateladas seqüenciais, alimentado com substrato sintético com concentração de nitrogênio amoniacal de 125, 250, 500 e 40 mg/L. O principal objetivo da pesquisa foi verificar a possibilidade de se promover a nitrificação curta no reator submetido à aeração intermitente, com a formação de nitrito como principal composto intermediário, seguida da desnitrificação. Para concentração de nitrogênio amoniacal de 125 e 250 mg/L o perfil temporal das concentrações de nitrogênio monitoradas evidenciou que tempo de ciclo de 24 horas foi excessivo. Durante a operação do reator submetido à concentração de nitrogênio amoniacal de 500 mg/L e de 40 mg/L, ficou evidente a influência do modo de operação, quanto à concentração de oxigênio e extensão dos períodos aeróbios e anóxicos, no tempo de ciclo necessário. Para todas as concentrações de nitrogênio amoniacal estudadas a duração do período de aeração foi suficiente para nitrificar uma fração do N-amoniacal afluente, de modo que as concentrações de nitrito e ácido nitroso não atingissem níveis tóxicos ao processo de oxidação de N-amoniacal. Ao longo do período de operação, o nitrogênio na forma de nitrito tornou-se a forma oxidada predominante e foi possível manter este acúmulo de nitrito em todas as etapas de operação do reator, mesmo alterando a concentração de oxigênio dissolvido, prolongando o período de aeração e, reduzindo a concentração de amônia livre. Constatou-se, portanto, ser possível obter-se processo estável de remoção de nitrogênio em reator operado em bateladas seqüenciais, submetido a etapas de aeração e não aeração em um mesmo ciclo. Esse modo de operação permitiu o estabelecimento do processo de nitrificação parcial a nitrito nas etapas aeradas e desnitrificação nas etapas anóxicas / A bench-scale sequencing batch reactor filled with polyurethane foam matrices was fed with synthetic substrate containing different influent ammonium nitrogen concentrations (120, 250, 500 and 40 mg/L) and subjected to different operating conditions. The main objective was to verify the possibility off promoting short nitrification in the reactor operated under intermittent aeration to obtain nitrite as the main intermediate compound to be denitrified during the anoxic periods. The profiles of the monitored nitrogen species along the cycles allowed verifying that the time cycle of 24 hours was excessive for ammonium nitrogen concentrations of 125 and 250 mg/L. The influence of the operating parameters relative to the dissolved oxygen concentration and extension of aerobic and anoxic periods on the cycle time was evident during the operation at ammonium nitrogen concentrations of 500 and 40 mg/L. The duration of the aeration periods was long enough to allow a fraction of the influent ammonium to be nitrified for all the ammonium nitrogen concentrations studied. The concentrations of nitrite and nitrous acid have never reached the toxic levels to affect ammonia oxidation. Nitrite was the predominant form of oxidized nitrogen along all the operating periods. Nitrite accumulation occurred during all the stages of reactor operation, even when the reactor was subjected to different dissolved oxygen concentrations, length of aeration period and free ammonia concentration. Therefore, stable process of nitrogen removal was achieved in the sequencing batch reactor containing immobilized biomass subjected to a wide range of ammonium nitrogen concentrations. The operation way consisting of intermittent aeration followed by non aeration periods in the same cycle allowed the establishment of the process of partial nitrification to nitrite in the aerated steps followed by denitrification in the anoxic steps

Um reator de leito fixo, preenchido com biomassa imobilizada em espuma de poliuretano, foi operado em bateladas seqüenciais, alimentado com substrato sintético com concentração de nitrogênio amoniacal de 125, 250, 500 e 40 mg/L. O principal objetivo da pesquisa foi verificar a possibilidade de se promover a nitrificação curta no reator submetido à aeração intermitente, com a formação de nitrito como principal composto intermediário, seguida da desnitrificação. Para concentração de nitrogênio amoniacal de 125 e 250 mg/L o perfil temporal das concentrações de nitrogênio monitoradas evidenciou que tempo de ciclo de 24 horas foi excessivo. Durante a operação do reator submetido à concentração de nitrogênio amoniacal de 500 mg/L e de 40 mg/L, ficou evidente a influência do modo de operação, quanto à concentração de oxigênio e extensão dos períodos aeróbios e anóxicos, no tempo de ciclo necessário. Para todas as concentrações de nitrogênio amoniacal estudadas a duração do período de aeração foi suficiente para nitrificar uma fração do N-amoniacal afluente, de modo que as concentrações de nitrito e ácido nitroso não atingissem níveis tóxicos ao processo de oxidação de N-amoniacal. Ao longo do período de operação, o nitrogênio na forma de nitrito tornou-se a forma oxidada predominante e foi possível manter este acúmulo de nitrito em todas as etapas de operação do reator, mesmo alterando a concentração de oxigênio dissolvido, prolongando o período de aeração e, reduzindo a concentração de amônia livre. Constatou-se, portanto, ser possível obter-se processo estável de remoção de nitrogênio em reator operado em bateladas seqüenciais, submetido a etapas de aeração e não aeração em um mesmo ciclo. Esse modo de operação permitiu o estabelecimento do processo de nitrificação parcial a nitrito nas etapas aeradas e desnitrificação nas etapas anóxicas / A bench-scale sequencing batch reactor filled with polyurethane foam matrices was fed with synthetic substrate containing different influent ammonium nitrogen concentrations (120, 250, 500 and 40 mg/L) and subjected to different operating conditions. The main objective was to verify the possibility off promoting short nitrification in the reactor operated under intermittent aeration to obtain nitrite as the main intermediate compound to be denitrified during the anoxic periods. The profiles of the monitored nitrogen species along the cycles allowed verifying that the time cycle of 24 hours was excessive for ammonium nitrogen concentrations of 125 and 250 mg/L. The influence of the operating parameters relative to the dissolved oxygen concentration and extension of aerobic and anoxic periods on the cycle time was evident during the operation at ammonium nitrogen concentrations of 500 and 40 mg/L. The duration of the aeration periods was long enough to allow a fraction of the influent ammonium to be nitrified for all the ammonium nitrogen concentrations studied. The concentrations of nitrite and nitrous acid have never reached the toxic levels to affect ammonia oxidation. Nitrite was the predominant form of oxidized nitrogen along all the operating periods. Nitrite accumulation occurred during all the stages of reactor operation, even when the reactor was subjected to different dissolved oxygen concentrations, length of aeration period and free ammonia concentration. Therefore, stable process of nitrogen removal was achieved in the sequencing batch reactor containing immobilized biomass subjected to a wide range of ammonium nitrogen concentrations. The operation way consisting of intermittent aeration followed by non aeration periods in the same cycle allowed the establishment of the process of partial nitrification to nitrite in the aerated steps followed by denitrification in the anoxic steps

Nitrogen is the major component of biosphere. Paradoxically, nitrogen pollution is the concern globally. Ammonia pollution is due to its unceasing rejection into nature such as groundwater, current water and the atmosphere. This phenomenon constitutes a threat for the humanity, land and aquatic flora, and consequently disturbs the balance of natural ecosystem. Recently, that situation has lead to develop various techniques and/or technologies for ammonia removal from municipal and industrial wastewaters. Particularly in the environmental biotechnology area, two main objectives were recently aimed in many research activities: the development of new configurations of competitive bioreactors and the monitoring of partial nitrification process, which are the fundamental basis of this thesis project. In this study, the partial ammonium oxidation process, also called nitrite route, was studied in a 60 litre jet-loop submerged membrane bioreactor pilot plant. The research was organized around six chapters. An exhaustive literature review of the state-of- art of the biological nitrification process and the membrane technologies was performed. The materials and measurement methods were presented. The colorimetric method, the chromatography analysis, the biomass estimation by the suspended solids (SS), the aggregates size measurement, the gas holdup, the gas-liquid mass transfer, the bubbles gas diameter determination, the medium rheology aspects, etc., and the complete equipment of the bioreactor were studied in detail. The plant automation functioning was also studied. Membrane module (Mitsubishi Sterapore-L) characterization was carried out and three characteristic parameters were estimated: the membrane intrinsic resistance Rm, the membrane permeability Lp and the membrane porosity εm. Estimations revealed good agreement between experimental results and theoretical methods based on the Darcys law and the Carman-Kozeny law applicable in microfiltration system. Hydrodynamics and aeration aspects were studied. The mixing in the jet-loop system was characterized by the mixing time (tmix) and the circulation time (tc), respectively. The results showed that the characteristic times (tmix and tc) decrease with an increase in input gas flowrate and the circulated liquid flowrate. A model correlation involving the air and the combined liquid effects was proposed to describe the circulation time evolution. The classical non-steady state clean water test was used to determine the gas-liquid mass transfer coefficient (kLa). It was found to be influenced by the combined action of air and recirculated-liquid flowrates and a correlation has been proposed to describe their influence. The interpretation of kLa results and the system mixing data showed that the developed reactor corresponds to a near perfect mixing tank. This criterion was satisfactorily verified by literature data. The gas holdup (εg) was directly measured by the volume expansion method. In the absence of liquid circulation, εg ranged between 1 and 4% for the investigated range of gas liquid superficial velocities. It was found to increase linearly with the air superficial velocity, which corresponds to the bubbly flow regime. However, in the presence of liquid flowrate, εg slightly increased (from 1 to 6%) with increase in the superficial liquid velocity. A model has been proposed to correlate εg and the air and the recirculated-liquid velocities. The average diameter of the bubbles gas (dB) in the system was also estimated by the Leibson theoretical model based on the Reynolds number at the orifice of the gas distributor. Finally, biological aspects were studied. Respirometry measurements were conducted to characterize the process medium. The mass transfer, the gas holdup and the medium viscosity were determined. The obtained data allowed estimating the α factor and the β factor, respectively. The interaction of the growth of microorganisms into the process and the membrane performance was also investigated and a correlation model was proposed to describe membrane fouling with time. The optimal conditions for ammonium partial oxidation were determined using process monitoring and simulation. Dissolved oxygen (DO), temperature (T) and hydraulic retention time (HRT) were selected to achieve a high nitrite accumulation in the system. The results obtained showed that the selected parameters should be fixed at DO ≈ 2 mgO2.l-1, HRT ≈ 6 7 h and T = 30°C, respectively. The partial nitrification was simulated by the use of the TwoPopNitrification model included into the BioWin 2.2 software. For these simulations, a sequencing ammonia oxidation assumption was adopted: the nitrozation followed by the nitration step, respectively. The corresponding kinetics and stoichiometric constants were estimated by combining literature data and experimental nitrification results. For these estimates, the ammonium oxidation was monitored on several process samples taken at different times. The estimates were also delivered by monitoring the ammonium oxidation on the process operated in the batch mode. The plotting of simulations and experimental results revealed good agreement. In order to investigate the process performance in terms of biological stability, a long time period (≈ 600 days) was simulated. The results showed that a high stable nitrite accumulation (> 95%) could be achieved when the above optimal conditions are imposed to the system. However, after a long time, the accumulated nitrite is converted into nitrate and then the system is disrupted. For the simulated experimental conditions, the process disruption period was located between 180 and 350 days. At this period, a corresponding theoretical purge flowrate was found to range between 0.15 10-3 m3.d-1 and 3.0 10-3 m3.d-1. Simulations also showed that increasing the purge flowrate decreases the sludge retention time and then favours nitrite accumulation into the process. That is an interesting strategy to increase the performance of the biological partial nitrification process.