Landfilling is the most common approach to dispose of municipal solid wastes but inevitably leads to leachate formation. Persistent UV quenching substances (UVQS) in landfill leachate can affect the effectiveness of UV disinfection in municipal wastewater treatment systems when leachate co-treatment is applied. Membrane electrochemical reactor (MER) treatment was investigated to reduce the UV quenching capability and simultaneously recover resources in the leachate as an effective onsite pre-treatment. Ion-selective membranes were used in this MER to create two different conditions: a low-pH anolyte for organic oxidation and a high-pH catholyte for ammonia recovery. The MER achieved significantly higher removals of both dissolved organic carbon and UV254nm absorbance than membrane-less electrochemical treatment. The MER was able to remove a large percentage of total nitrogen from the leachate while recovering about half of the influent ammonia in the catholyte with less specific energy consumption. The second study coupled MER with Fenton oxidation through providing synergistic benefits with the low solution pH, reduced organics, and ammonia removal. This two-stage coupled system reduced the more leachate COD than the standalone Fenton process treating raw leachate. Also, the usage of chemicals as Fenton reagents has been greatly reduced: FeSO4 and H2O2 by 39%, H2SO4 by 100%, and NaOH by 55%. Consequently, the sludge production was reduced by 51% in weight and 12% in volume. Despite electricity consumption by the MER, the coupled system cost $4.76 per m3 leachate less than the standalone Fenton treatment. More notably, direct Fenton oxidation removed only 21% of ammonia; in comparison, the MER-Fenton system removed ammonia by 98% with the possibility for recovery at a rate of 30.6 -55.2 kg N m-3 reactor d-1. Those results demonstrated that coupling MER with the Fenton process could mitigate some inherent drawbacks of Fenton oxidation such as ineffective ammonia removal, high acid and chemical reagents dose requirements, and a large amount of sludge generation. The third study investigated the formation of total halogenated organics (DBP) and the associated toxicity as the side effect of leachate treatment in the MER. Compared to the 4538±100 µg L-1 from the control membrane-less electrochemical oxidation reactor, the amount of DBP generated in the MER only accounted for 19.1±4.5 % after the same treatment period. The total toxicity value (26.6 ×10-3 ) was low for MER effluent, only 15.1% of that in the control group. Both high pH and high ammonia concentration introduced more DBP mass and toxicity production after MER treatment. DBP concentrations were shown to increase with applied current density and possible temperature raise. With 67.5% of DBP mass concentration and 74.4% of the additive toxicity removal, the granular activated carbon (GAC) electrode system was shown more effective than GAC adsorption alone in remediating DBP harmful effects. This dissertation introduced MER as a promising technology for the treatment of leachate through performance demonstration, process integration and by-product remediation. / Doctor of Philosophy / Municipal solid waste is often disposed of in landfills because of the most economics and convenience. However, one of the most challenging problems is the leachate formation and treatment. In the US, leachate is currently often diluted in domestic wastewater treatment systems; meanwhile, the persistent contaminants in landfill leachate can lower the effectiveness of UV disinfection and result in high cost and permit violation. In this study, the membrane electrochemical reactor (MER) using electricity as the driving force was applied to solve the issue and simultaneously recover valuable resources in the leachate. Membranes as a barrier for selective ions were used in this MER to create two different conditions with different purposes: a low-pH anolyte for organic oxidation and a high-pH catholyte for ammonia recovery. The MER achieved significantly higher contaminants removals than membrane-less electrochemical treatment. The second study coupled MER with one of the established advanced oxidation processes, also known as Fenton oxidation through providing mutual benefits with the low solution pH, reduced organics, and ammonia removal/recovery. This two-stage coupled system reduced the leachate contaminants effectively towards the direct discharge standard. In addition, the usage of chemical reagents, as well as the amount of process residual, has significantly been reduced. The third study investigated the formation of by-products as the side effect of leachate treatment in the MER. Compared to the membrane-less reactor, the undesirable by-products generated in the MER only accounted for one fifth after the same treatment period. A granular activated carbon electrode system was shown effective in remediating the harmful effects. This dissertation introduced MER as a promising technology for the treatment of leachate as one of the toughest wastewaters.

High costs for aeration, greenhouse-gas emissions and excess sludge disposal have entailed a paradigm shift in the wastewater treatment. Microalgal-bacterial-based wastewater treatments have gained increasing attention because of their potential in energy demand reduction and biomass resource recovery. In particular, photosynthetic oxygenation is combined with bacterial activity to treat wastewater avoiding external artificial aeration. To optimize the technology in order to become more competitive than activated sludge, an in-depth investigation about the treatment performance and the microbiology interactions under real operational condition is needed. This work focused on the study of wastewater-borne microalgal-bacterial consortia treating real municipal wastewater. The main objectives were to: (i) Understand the removal mechanisms and the influence of operational conditions to optimize the process; (ii) Analyze the microbial community. At first, a photo-sequencing batch reactor (PSBR), called Pilot, was started up and continuously monitored for two years to analyze the evolution of the treatment performance and of the biomass composition. At the same time, other two lab-scale PSBRs were installed to evaluate if microalgal inoculation is essential to start up a consortium. Samples of these consortia were collected over a period of one year and analyzed through microscopic observations, flow cytometry and metagenomics, to investigate the microbial structure and diversity.A second part of the research focused on the optimization of the Pilot to explore its limit in view of the scale-up of the system. In addition, respirometry was adapted to test microalgal-bacterial consortia to estimate the removal kinetic parameters for future modelling. To conclude, the research project addressed many aspects and lay the foundation to apply a methodological research approach to scale-up this promising technology.

<p>The euthropthication of the Baltic Sea is a threat that is beginning to be taken seriously by the governments concerned. In Sweden, regulations concerning the allowed nitrogen (N) concentration in the effluent water from wastewater treatment plants are being tightened up. The Rimbo wastewater treatment plant has been imposed to reduce the annual mean concentration of total N in the effluent water to levels below 15 mg l-1. A more and more common way to reduce the nitrogen level in wastewater is to let the water pass through a wetland. This study investigates the possibility to build this kind of wetland at the outlet of the Rimbo wastewater treatment plant.</p><p>A prestudy of the topography, soil characteristics and groundwater flow indicates that the land area in question is well suited for the construction of a wetland. A proposal for the design has been made by using a physically based computer model developed in the PRIMROSE project (PRocess based Integrated Management of constructed and Riverine wetlands for Optimal control of wastewater at catchment ScalE), which is financed by the EU. Analysis of the residence time distribution (RTD) is a tool for understanding wetland design characteristics and can be used for wetland engineering such as optimizing design for best possibleefficiency in nitrogen removal. In order to characterize the performance of a wetland, it is useful to translate the RTD to a key figure representing the treatment efficiency. In this work, two types of such key figures have been used. Key figure 1 gives the hydraulic efficiency and Key figure 2 gives an estimation of the nitrogen retention by an integration of hydraulic characteristics and the chemical transformation of nitrogen.</p><p>The results of this study show that constructing a wetland in Rimbo probably would be an efficient way to reduce the nitrogen level at the effluent of the wastewater plant below the limits of the regulations. In addition, a wetland would form a nice place of recreation for the people in Rimbo and also make a good habitat for birds.</p> / <p>Övergödningen i Östersjön är ett problem som uppmärksammas alltmer. Ett led i att minska kvävebelastningen på Östersjön är ökade krav på rening i de svenska kommunala reningsverken. Rimbo avloppsreningsanläggning har blivit ålagd ett riktvärde för totalkväve på 15 mg l-1 i utgående vatten, vilket motsvarar en reningsgrad som inte uppnås idag. Ett alltmer vanligt sätt att minska föroreningshalterna är att anlägga våtmarker i anslutning till reningsverken för att efterpolera spillvattnet. Det här arbetet är en del av en förstudie till en sådan våtmark i Rimbo.</p><p>En förundersökning av topografi, jordart och grundvattenflöden indikerar att det område som föreslagits i anslutning till reningsverket i Rimbo lämpar sig väl för ett våtmarksbygge. Förslag till utformning har tagits fram med hjälp av en fysikaliskt baserad modell över vattenströmning, utvecklad inom det EU-finansierade projektet PRIMROSE (PRocess based Integrated Management of constructed and Riverine wetlands for Optimal control of wastewater at catchment ScalE). Analys av vattnets uppehållstidsfördelning ger förståelse för våtmarkens egenskaper och kan därför användas vid t ex optimering av våtmarksdesign med avseende på kväverening. För att på ett enkelt sätt kunna jämföra olika våtmarkers effektivitet är det praktiskt att översätta uppehållstidsfördelningen till ett nyckeltal för reningseffekten. I det här arbetet har två olika sådana nyckeltal beräknats. Det första ger den hydrauliska effektiviteten och det andra bygger på en metod där våtmarkens interna hydraulik integreras med den kemiska omvandlingen av kväve. Nyckeltal 1 ger ett mått på hur stor del av volymen i våtmarken som används för kväverening, medan Nyckeltal 2 ger ett mått på den procentuella kväveavskiljningen.</p><p>Den här förstudien visar att en våtmark sannolikt skulle vara ett utmärkt sätt att klara riktvärdet för kvävehalten vid reningsverket i Rimbo. Därutöver skulle en våtmark kunna utgöra ett positivt inslag i landskapet och öka den biologiska mångfalden, inte minst vad gäller fågelliv.</p>

A presente pesquisa teve, por principal objetivo, avaliar a viabilidade da desnitrificação autotrófica, empregando sulfeto como doador de elétrons, aplicada a efluentes de reatores anaeróbios tratando esgoto sanitário. Estudos anteriores indicam que o sulfeto presente na fase líquida de efluentes e no biogás pode ser utilizado como doador de elétrons para a desnitrificação. Porém, há poucas informações sobre as interações entre os ciclos do carbono, nitrogênio e enxofre neste processo que permitam a utilização prática dos fundamentos já conhecidos sobre a desnitrificação na presença de sulfeto. Neste trabalho, realizaram-se ensaios de desnitrificação na presença de sulfeto, a fim de se avaliar o potencial de uso desse composto como doador de elétrons. Inicialmente, foram utilizados frascos de 1 L contendo biomassa imobilizada em espuma de poliuretano, alimentados com meio sintético nitrificado contendo sulfeto como doador e nitrito e nitrato como receptores de elétrons. Variou-se a concentração de sulfeto, obtendo-se diferentes relações N/S. Constatou-se desnitrificação completa de ambos os receptores estudados; entretanto, isto só ocorreu com estabilidade para relações N/S inferiores à relação estequiométrica baseada nas reações químicas correspondentes, isto é, quando foi aplicado sulfeto em excesso. Os resultados mostraram que a oxidação total ou parcial dos compostos de enxofre no processo depende da relação N/S, e a velocidade de consumo de nitrato foi maior que a de nitrito. Posteriormente, realizaram-se novos ensaios semelhantes ao anterior, porém, a alimentação consistiu na mistura do efluente sintético nitrificado a efluente de reator anaeróbio tratando água residuária de abatedouro de aves, e o único receptor de elétrons aplicado foi nitrato. Neste caso, foi constatada desnitrificação completa na relação N/S correspondente à estequiometria relativa a sulfeto e nitrato. A cinética de remoção de nitrogênio seguiu modelo de decaimento exponencial de primeira ordem; entretanto, houve limitação à transferência de massa intraparticular e na fase líquida, fato que caracterizou os modelos ajustados como sendo de primeira ordem. As velocidades específicas aparentes obtidas na primeira fase foram próximas de 15 mgN/gSSV.h, tanto com a aplicação de nitrato, quanto de nitrito como receptores de elétrons. Na segunda fase, a máxima velocidade específica aparente de remoção de nitrato foi da ordem de 6 mgN/gSSV.h. / The feasibility of autotrophic denitrification of effluent from anaerobic reactor treating domestic sewage using sulfide as electron donor was evaluated. Prior researches reveals sulfide into liquid phase of effluents and biogas can be utilized as electron donor for denitrification. However, information about the interaction between carbon, nitrogen and sulfur cycles in this process are few to permit practice utilization of known fundamentals about denitrification in presence of sulfide. In this work, laboratory tests of denitrification in the presence of sulfide were carried out to evaluate potential employ of this compound as electron donor. Initially, 1 L flasks with immobilized biomass in polyurethane foam was fed with synthetic nitrified wastewater containing sulfide as donor and nitrite e nitrate as electron acceptors. Sulfide concentration was diversified to obtain different N/S ratios. Complete denitrification occurred with nitrate and nitrite; nevertheless, it was observed in a stable way only for N/S ratios smaller than stoichiometric rate based in the corresponding chemistry reactions, that is, when applied excess of sulfide. The results showed that total or partial sulfur compounds oxidation depends on N/S ratio and the nitrate removal rate was bigger than nitrite removal rate. Afterward, new assays were carried out in the same way. However, the flasks were fed with synthetic nitrified wastewater mixed to effluent from anaerobic reactor treating bird slaughterhouse wastewater, and nitrate was the only electron acceptor applied. In this case, complete denitrification was evidenced for stoichiometric N/S ratio relating to sulfide and nitrate. Nitrogen removal kinetic followed exponential decay model of first order; however, this behavior was due to mass transfer limitation in the liquid phase and intraparticular. Apparent specific rates of nitrogen removal found in the first phase were nearby 15 mgN/gSSV.h, with nitrate as well as nitrite application. In the second phase, maxima apparent specific rate of nitrogen removal in nitrate form was about 6 mgN/gSSV.h.

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

Made available in DSpace on 2017-07-21T18:53:07Z (GMT). No. of bitstreams: 1 Joao Guilherme Baggio de Oliveira.pdf: 2058376 bytes, checksum: 82bb5fa9502e9c114bd0570d5ed85d62 (MD5) Previous issue date: 2016-06-21 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / The dumping of untreated effluents into water bodies can cause serious damage to the environment. Eutrophication, a phenomenon caused by the release of nutrients such as nitrogen and phosphorus, is one of those damages. Their occurrence promotes excessive growth of algae, decreased dissolved oxygen concentration. The conventional nitrogen removal processes employ two stages physically separated to nitrification and denitrification, which increases construction costs and operation of the process. Research has shown that some reactors models are efficient for simultaneous removal of chemical oxygen demand (COD) and total nitrogen (NT). In this sense, the objective of this study was to evaluate a bed reactor structured with intermittent aeration in the removal of COD and NT sewage untreated combined with effluent RALF. Worked with hydraulic retention time (HRT) fixed in 12 hours and recirculation flow (Qr) of the effluent 3, 2 and 1 to the input flow. Worked up with three times aeration: 33%, 50% and 100% of the time. The affluent used was composed of a fraction of 50% of sewage untreated and 50% of effluent from a reactor Anaerobic Fluidized Bed (RALF). The results indicated that there was no statistical difference between the COD removal rates, regardless of the value of Qr and the reactor aeration time. The COD value obtained for the reactor effluent ranged between 27 and 68 mg.L-1. Values of Total Kjeldahl Nitrogen (TKN) affluent ranged between 40 and 52 mg L-1. Obtained removal rate NT of 50 to 78%, effluent generated treated with N-NH4+ content between 0.7 and 7.1 mg.L-1. We observed the occurrence of nitrification and denitrification Simultaneous (NDS) as oxidized forms were detected (nitrite and nitrate) and reduced (N -NH4) nitrogen at all stages studied. It was concluded that the bed reactor structured with intermittent aeration is effective in joint COD removal and sewage nitrogen / O despejo de efluentes não tratados em corpos d’água pode causar sérios danos ao meio ambiente. A eutrofização, fenômeno causado pelo lançamento de nutrientes como o nitrogênio e fósforo, é um desses danos. A sua ocorrência promove o crescimento exagerado de algas, diminuição da concentração de oxigênio dissolvido. Os processos convencionais de remoção de nitrogênio utilizam duas etapas fisicamente separadas para a nitrificação e desnitrificação, o que aumenta custos com construção e operação do processo. Pesquisas têm mostrado que alguns modelos de reatores são eficientes para remoção concomitante de Demanda Química de Oxigênio (DQO) e nitrogênio total (NT). Neste sentido, o objetivo deste trabalho foi avaliar um reator de leito estruturado com aeração intermitente na remoção de DQO e NT de esgoto sanitário não tratado combinado com efluente de RALF. Trabalhou-se com Tempo de Detenção Hidráulica (TDH) fixo em 12 horas evazão de recirculação (Qr) do efluente de 3, 2 e 1 vez a vazão de entrada. Trabalhou-se com três tempos de aeração: 33%, 50% e 100% do tempo.O afluente utilizado foi composto por uma fração de 50% de esgoto sanitário não tratado e 50% de efluente de um Reator Anaeróbio de Leito Fluidizado (RALF). Os resultados indicaram que não houve diferença estatística entre as taxas de remoção de DQO, independentemente de Qr e tempo de aeração do reator. Os valores de DQO obtidos para o efluente do reator variaram entre 27 e 68 mg.L-1. Os valores de Nitrogênio Total Kjeldahl (NTK) afluente variaram entre 40 e 52 mg.L-1. Obteve-se taxas de remoção de NT de 50 a 78%, geraram efluente tratado com teor de N-NH4+ entre 0,7 e 7,1 mg.L-1. Observou-se a ocorrência de Nitrificação e Desnitrificação Simultâneas (NDS), pois foram detectadas formas oxidadas (nitrito e nitrato) e reduzidas (N-NH4+) de nitrogênio em todas as fases estudadas. Foi possível concluir que o reator de leito estruturado com aeração intermitente é eficiente na remoção conjunta de DQO e nitrogênio de esgoto doméstico.

Made available in DSpace on 2017-07-21T18:53:21Z (GMT). No. of bitstreams: 1 Priscila Arcoverde Wosiack.pdf: 2005192 bytes, checksum: 49fa05e9e5f72b1ae4d6f70637a69779 (MD5) Previous issue date: 2014-06-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The treatment of wastewater generated in the pet food industries, characterized by the high organic carbon and nitrogen content, becomes necessary to meet the standards required by the legislation and minimize environmental impacts on water bodies. Biological treatment is an effective way to treat potentially polluting wastes from agroindustries processes. However, conventional systems for treating industrial wastewater do not allow the simultaneous removal of organic carbon and nutrients. Thus, the present study aimed to evaluate the performance of a structured bed reactor with continuous flow, for the simultaneous removal of carbon organic, expressed as Chemical Oxygen Demand (COD), and nitrogen from wastewater of a pet food industry, under conditions of intermittent aeration. The system was composed by a structured bed reactor under 30oC of temperature, and recirculation ratio of 5 times the flow. The reactor was initially operated in differents Hydraulic Retention Times (HRT) of seven, five, three and one day under continuous aeration. In such conditions were verified removal of COD above 80% and Total Nitrogen (TN) above 60%. The best results were obtained with HRT of three days (91.8% of COD removal and 93.3 % of TN). The response surface methodology was used to evaluate the effect of aeration and load of TKN (Total Kjeldahl Nitrogen) in the removal of COD and TN, with HRT fixed in 1 day. It was observed that the parameter aeration was the most important for the results. The removal of COD reached levels of 85% when the reactor was aerated on 100% of the time. Aeration also was positive for nitrification and negative for denitrification. The best responses obtained for the removal of COD and TN, nitrification and denitrification were 80.03%, 88.16%, 99.13% and 88.92%, respectively, and were obtained with 158.2 minutes of aeration in a cycle of 180 minutes, and 255.1 mg.L-1 of the TKN affluent. In view these results, it was concluded that this new system was effective in simultaneous removal of nitrogen and carbon organic matter. / O tratamento das águas residuárias geradas nas indústrias de ração animal, caracterizadas por elevada carga orgânica e conteúdo nitrogenado, torna-se absolutamente necessário para atender aos padrões exigidos pela legislação e minimizar impactos ambientais em corpos de água. O tratamento biológico é uma maneira eficaz de se tratar resíduos potencialmente poluidores originados de processos agroalimentares. Porém, sistemas convencionais de tratamento de águas residuárias industriais, não possibilitam a remoção simultânea de matéria orgânica e nutrientes. Assim, o presente trabalho teve como objetivo avaliar o desempenho de um reator de leito estruturado e fluxo contínuo, na remoção simultânea da matéria orgânica carbonácea, expressa em Demanda Química de Oxigênio (DQO), e nitrogenada, das águas residuárias de uma indústria de ração animal, sob condições de aeração intermitente. O sistema foi composto por um reator de leito estruturado mantido à temperatura de 30oC e taxa de recirculação de 5 vezes a vazão. O reator foi inicialmente operado em diferentes Tempos de Detenção Hidráulica (TDH), de sete, cinco, três e um dia, sob aeração contínua. Nestas condições foram verificadas remoções de DQO acima de 80% e de Nitrogênio Total (NT) acima de 60%. Os melhores resultados foram obtidos com TDH de três dias (91,8% de remoção de DQO e 93,3% de NT). A metodologia de superfície de resposta foi utilizada para avaliar o efeito da aeração e da carga de NTK (Nitrogênio Total Kjeldahl) na remoção de DQO e NT, com TDH fixo em um dia. Foi verificado que o parâmetro aeração foi o que mais influenciou os resultados. A remoção de DQO chegou a 85% quando o reator foi aerado em 100% do tempo. A aeração também apresentou efeito positivo para a nitrificação, mas negativo para a desnitrificação. As melhores respostas para remoção de DQO, NT, nitrificação e desnitrificação, de 80,03%, 88,16% 99,13% e 88,92%, respectivamente, foram obtidas com o reator operando com 158,2 minutos de aeração a cada ciclo de 180 minutos e 255,1 mg.L-1 de NTK afluente. Diante destes resultados, conclui-se que este novo sistema foi eficiente na remoção simultânea de matéria orgânica e nitrogenada.

A remoção de nitrogênio acoplada à oxidação de sulfeto pode ser uma opção adequada para o pós-tratamento de efluentes de reatores anaeróbios, os quais contêm nitrogênio amoniacal, que deve ser nitrificado, e sulfeto, que poderia ser utilizado como doador de elétrons endógeno para a desnitrificação autotrófica. Com base nessa constatação, esta pesquisa propôs a aplicação da nitrificação e desnitrificação autotrófica acoplada à oxidação de sulfeto, em um único reator, para a remoção de nitrogênio de efluentes de reatores anaeróbios tratando esgoto sanitário. Visto que existem lacunas na literatura referente ao processo desnitrificante autotrófico citado, as bases teóricas para a determinação das condições operacionais partiram da caracterização cinética e de aspectos fundamentais da desnitrificação autotrófica com uso de sulfeto como doador de elétrons. Numa primeira etapa, avaliou-se o efeito da concentração de sulfeto na desnitrificação, com uso de nitrato e nitrito como receptores de elétrons, em reatores verticais de leito fixo. Os resultados revelaram que compostos intermediários de enxofre foram principalmente formados quando se aplicou excesso de sulfeto, fato que foi mais evidente com o uso de nitrato. Evidências visuais sugeriram que enxofre elementar foi o principal intermediário formado, o qual também estava sendo utilizado quando aplicadas concentrações estequiométricas de sulfeto relativas a nitrato/nitrito. De modo geral, a desnitrificação autotrófica não foi afetada pela desnitrificação heterotrófica residual via atividade endogênica. Numa segunda etapa, determinou-se a cinética intrínseca da desnitrificação autotrófica via nitrato e nitrito com uso de diferentes concentrações de sulfeto em reatores diferenciais de leito fixo. Este bioprocesso pôde ser descrito por modelo cinético de ordem ½ para biofilmes. As constantes cinéticas variaram entre 0,425-0,658 mg N1/2 / L1/2 h para desnitrificação via nitrito e entre 0,190-0,609 mg N1/2 / L1/2 h para desnitrificação via nitrato. Neste último, o menor valor foi devido ao uso de elétrons doados a partir de compostos intermediários de enxofre formados. Numa terceira etapa, utilizou-se um reator de leito fixo operado em batelada alimentada seqüencial, com ciclos de 8 horas, submetido à aeração intermitente e empregando a desnitrificação autotrófica com uso de sulfeto presente no efluente sanitário, pré-tratado anaerobiamente, como doador de elétrons. O prévio estabelecimento da nitrificação com posterior aplicação de baixas concentrações de sulfeto foi a melhor estratégia de partida do reator. A alimentação em batelada alimentada com aplicação de sulfeto em excesso apenas nos períodos anóxicos foi a melhor estratégia de alimentação, proporcionando eficiência média de 85,7% e 53,0% para nitrificação e desnitrificação, respectivamente. O acúmulo de nitrito foi observado após aplicação de carga de choque de sulfeto, que inibiu as bactérias oxidadoras de nitrito. No entanto, houve dificuldade em se estabelecer a desnitrificação via nitrito em função da toxicidade deste composto aos organismos desnitrificantes instalados no reator. A baixa eficiência global de remoção de nitrogênio e algumas restrições operacionais indicaram que a desnitrificação autotrófica usando sulfeto em um único reator operado em bateladas seqüenciais não foi adequada para a proposta desta pesquisa. / Nitrogen removal coupled with sulfide oxidation may be suitable for the post treatment of effluents from anaerobic reactors. These effluents contain ammonium, which must be nitrified, and sulfide, which could be used as an endogenous electron donor for autotrophic denitrification. Since there are gaps in literature regarding the mentioned autotrophic denitrifying process, the theoretical basis for determination of operating conditions came from the characterization of kinetics and fundamentals aspects of autotrophic denitrification using sulfide as electron donor. In a first step, the effect of sulfide concentration on this bioprocess using nitrate and nitrite as electron acceptors in vertical fixed-bed reactors was evaluated. The results showed that intermediary sulfur compounds were mainly produced when excess of electron donor was applied, which was more evident when nitrate was used. Visual evidences suggested that elemental sulfur was the intermediary compound produced. There was also evidence that the elemental sulfur previously formed was being used when sulfide was applied in stoichiometric concentration relative to nitrate/nitrite. For all conditions assayed, autotrophic denitrification was not affected by residual heterotrophic denitrification via endogenic activity, occurring as a minor additional nitrogen removal process. In a second step, the intrinsic kinetics of sulfide-oxidizing autotrophic denitrification via nitrate and nitrite in systems containing attached cells was determined. Differential reactors were fed with nitrified synthetic domestic sewage and different sulfide concentrations. This bioprocess could be described by a half-order kinetic model for biofilms. The half-order kinetic coefficients ranged from 0.425 to 0.658 mg N1/2 / L1/2 h for denitrification via nitrite and from 0.190 to 0.609 mg N1/2 / L1/2 h for denitrification via nitrate. In this latter, the lower value was due to the use of electrons donated from intermediary sulfur compounds formed. In a third step, a sequencing fed-batch biofilm reactor of 8-h cycles was operated under intermittent aeration, applying autotrophic denitrification using sulfide present in the sanitary effluent, anaerobically pre-treated, as electron donor. The effect of the start-up period and the feeding strategy were evaluated. The previous establishment of nitrification process with subsequent application of sulfide in low concentrations was the best start-up strategy. The fed-batch mode with sulfide application in excess only in the anoxic periods was the best feeding strategy, providing average efficiencies of 85.7% and 53.0% for nitrification and denitrification, respectively. Nitrite accumulation was observed after application of shock loading of sulfide, which inhibited nitrite-oxidizing bacteria. However, it was difficult to establish denitrification via nitrite due to the toxicity of this compound to denitrifying organisms developed inside the reactor. The low overall efficiency of nitrogen removal and some operational constraints indicated that autotrophic denitrification using sulfide in a single sequencing fed-batch reactor was not suitable for the purpose of this research.

Embora em alguns países como os europeus, o aterro sanitário como forma de disposição final de Resíduos Sólidos venha perdendo espaço, entre nós essa técnica é ainda largamente empregada. O lixiviado gerado nos aterros sanitários apresenta grande potencial poluidor, devido à presença de matéria orgânica, rica em substâncias húmicas e matéria inorgânica, representada especialmente pelos cloretos, nitrogênio amoniacal, entre outras substâncias. O presente trabalho visou, em linhas gerais, avaliar três proporções de mistura de lixiviado/efluente anaeróbio e as influências sobre o processo aeróbio (lodos ativados) em escala de bancada. Nessa pesquisa foram realizados ensaios de tratabilidade utilizando as proporções de 0% (controle), 2,5%, 10% e 20 % de lixiviado em relação ao efluente anaeróbio em diferentes condições experimentais. Os resultados mostraram que as proporções de 10% e 20% de lixiviado nas condições experimentais foram prejudiciais ao sistema aeróbio de tratamento. Foram obtidos os melhores resultados em termos de eficiência de remoção de matéria orgânica e nitrogênio amoniacal no reator alimentado com a proporção de 2,5% de lixiviado bruto, alcançando eficiência de remoção de DQO e nitrogênio amoniacal total (NAT) de 57% e 100%, respectivamente. / The use of landfill as a disposal of solid waste has been avoided in some countries, especially in Europe. Nevertheless this technique is still widely used in Brazil. Leachate generated in landfills has great potential as pollutant due to presence of organic matter, humic substances in high concentrations and inorganic matter such as chlorides and ammonia nitrogen. This study aims to broadly assess effects of three levels of mixing of leachate/anaerobic effluent on aerobic process (activated sludge) in bench scale. Treatability tests were performed using proportions of 0% (control), 2.5%, 10% and 20% leachate added to anaerobic effluent under different experimental conditions. Results showed that proportions of 10% and 20% of leached were unfavorable to aerobic system treatment. The higher removal efficiency of organic matter and ammonia nitrogen was obtained in reactor fed with 2.5% of leachate (removal efficiency of COD and total ammonia nitrogen (TAN) were 57% and 100%, respectively).

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