In the recent past more and more attention has been given by sanitary engineers to the problem of nitrogen removal in sewage treatment. This attention is brought about by several problems associated with nitrogen. First, in some locations, such as our southwest United States, there is both an essentially constant supply of water and an increasing demand for water. This calls for water recycling. or reuse, as a means of meeting the demand for potable water. An accumulation of impurities, such as compounds of nitrogen, can limit the recycling of water. One such substance is nitrate nitrogen, which when in excess of ten parts per million can cause the disease methemo-globinemia in bottle-fed infants. / Master of Science

The microbial populations in the Hoechst-Celanese activated sludge were examined. Heterotrophs, denitrifiers, sulfate-reducers, protozoa and filamentous bacteria were enumerated. Variations in microbial populations were compared with influent and effluent constituent concentrations, and with aeration basin characteristics, such as dissolved oxygen and F/M ratio, to determine whether any microbial type could be used by plant operators to monitor process performance. Results indicated that filamentous bacteria may be useful to plant operators for monitoring process performance because an inverse relationship between filamentous bacteria, food-to-microorganism ratio and sludge volume index was suggested by this study. Protozoa may also be useful for operators, although more data is needed. Microthrix parvicella and Type 0041 were the most common filament types. Filament Type 1701 was most prevalent during a period of low dissolved oxygen. A strong relationship between stalked ciliates and effluent quality was mention in the literature, but was not found in this study. Enumeration methods were evaluated. / Master of Science

The performance of fibrous biomass support media (Ringlace) and porous spongelike biomass support media (Captor) was evaluated for enhanced nitrification and denitrification in a pilot-scale Virginia Initiative Project (VIP) biological nutrient removal (BNR) process. Four separate pilot-scale treatment trains were constructed and operated during this research. Three of the four treatment trains were operated with fixed film media (Ringlace/Captor) incorporated in the aerobic zone of the system and are referred to as the Integrated Fixed Film Activated Sludge (IFAS) systems. A fourth treatment train (Control train) was operated without any fixed film media. All experiments in this research were performed using domestic wastewater from Blacksburg, Virginia, and the Virginia Tech campus. Enhanced nitrification was observed in the IFAS system containing porous biomass support media (Captor) that was freely suspended in the mixed liquor of the aerobic zone. Near-complete nitrification was observed in the IFAS system containing Captor media even at total suspended growth MCRTs as low as 5.6 days and a 12°C liquid temperature. Significantly higher nitrification rates were observed in the IFAS system containing Captor media compared to both the IFAS system containing Ringlace media and the control train. However, there was less denitrification in the aerobic zone of the IFAS systems containing Captor media compared to the Ringlace media systems. Enhanced nitrification could not be statistically shown in the IFAS system containing Ringlace media. The overall nitrification rates in the Ringlace media system were about the same as the control train for the MCRTs and temperatures used during this research. However, a significantly greater amount of denitrification was observed in the aerobic zone of the IFAS system containing Ringlace media compared to both the IFAS system containing Captor media and the control system. Microscopic examination of the growth on the fixed film media (Ringlace and Captor) showed that red worms always grew on the Ringlace media, and were detrimental to performance on at least one occasion. Methods for controlling the worms were developed and applied successfully. During certain operating phases, lower sludge productions and observed sludge yields were measured in the IFAS system containing Ringlace media. However, a Statistical difference could not be calculated between the sludge production in the Ringlace media system and the control system. Lower sludge production and observed sludge yield were also observed in the IFAS system containing Captor media, but only two data points were available and a Statistical t-test analysis was not possible. / Master of Science

The excessive use of fossil fuels, industrialization, and growing populations have increased environmental pollution, global warming, and global energy demands (Dimitriadis & Bezergianni, 2017). Due to these problems, a new alternative energy source must be used. Biomass conversion to liquid transportation fuels is a major category of renewable energy, with various waste biomasses as leading candidates (Dimitriadis & Bezergianni, 2017). Multiple thermo-chemical conversion (TCC) technologies exist to convert biomass into fuels with one of the most promising methods being hydrothermal liquefaction (HTL). The main benefit of HTL is that it does not require that the biomass be dried before processing which would be a fuel- and cost-intensive process (Grande et al., 2021; SundarRajan et al., 2021). However, HTL produces toxic solid, gaseous, and aqueous byproducts. The hydrothermal liquefaction aqueous-phase byproduct (HTL-AP) is thought to be the factor limiting commercial viability of the HTL process, particularly because some of the constituents have inhibitory effects on nitrifying bacteria (Macêdo et al., 2023). There are existing treatment technologies for HTL-AP such as anaerobic digestion, wet air oxidation (WAO), and more. The simplest treatment method at a wastewater treatment plant (WWTP) using HTL for sludge disposal would be to return the HTL-AP to the v headworks to be treated alongside standard wastewater flow (MBE, 2019). However, the inhibitory effects may cause the WWTP to not meet ammonia regulations, if relevant. In this project, four 3.5-L bench-scale aerated reactors were built to simulate conventional activated sludge wastewater treatment to develop methods to determine the long-term effects of HTL-AP on nitrification. Two reactors were controls fed only synthetic wastewater, and two reactors were fed synthetic wastewater with a small dilution of HTL-AP, called AP reactors. Two different doses of hydrothermal liquefaction aqueous phase (HTL-AP) were tested on long-operated activated sludge systems. A 275x dilution factor (DF) of HTL-AP was tested for 132 days and a 2750x DF was tested for 23 days. The weekly nitrogen data (total ammonia nitrogen, nitrate, and nitrite) suggested that both doses inhibited nitrification in the bench-scale activated sludge systems. Additionally, the nitrifying bacteria did not adapt over time to be able to nitrify the wastewater with HTL-AP. During the first experiment with a 275x DF, no nitrate was detected in the AP reactors (/L NO3 - -N) and nitrite was sparsely detected. The control reactors had low concentrations of nitrate of around 3-8 mg/L NO3 - -N and high concentrations of nitrite, typically around 10-40 mg/L NO2 - -N. Therefore, the AP reactors were performing minimal nitrification, if any, while the control reactors were primarily performing partial nitrification. Before implementing the 2750x DF of HTL-AP, all reactors were emptied, cleaned, and restarted with nitrifying mixed liquor from the San Luis Obispo Water Resource Recovery Facility membrane bioreactor (SLO WRRF MBR). By the end of the 23 days of HTL-AP exposure at a 2750x DF, the treatment reactors had a sharper nitrate decline with final NO3 - -N concentrations around 1 mg/L compared to about 5-7 mg/L vi NO3 - -N in the control reactors. At this time, nitrite concentrations were not considerable in any reactor. Because nitrification was not ideal even in the control reactors, future work is advised, including stabilizing the solids retention time and changing the synthetic wastewater formula to support higher concentrations of treatment bacteria. Some methods for the specific oxygen uptake rate (SOUR) test that are not explicitly or extensively outlined in ISO 8192 (ISO, 2007) were examined. First, a 10- minute trial duration was deemed sufficient compared to 20 minutes (R 2>0.99 in either case and Preliminary SOUR tests using the correct methods found that raw HTL-AP doses of 50x, 125x, and 250x dilution factors (DF’s) inhibited nitrification by about 80 to 105% in nitrifying sludge from the SLO WRRF MBR. Raw HTL-AP doses of 500x and 1000x DF’s did not inhibit nitrification respiration rates. From a SOUR test on this same sludge but on a different day, HTL-AP pretreated by wet air oxidation (WAO) had near-zero vii (neg. 0.9%) inhibition on nitrification respiration rates at a 250x DF compared to the 66% nitrification inhibition found in raw HTL-AP at this 250x DF on this testing date.

Submitted in complete fulfillment for the degree of Doctor of Philosophy (Biotechnology), Durban University of Technology, Durban, South Africa, 2016. / Seasonal nitrification breakdown is a major problem in wastewater treatment plants which makes it difficult for the plant operators to meet discharge limits. The present study focused on understanding the seasonal impact of environmental and operational parameters on nitrifiers and nitrification, in a biological nutrient removal wastewater treatment works situated in the midlands of KwaZulu Natal. Composite sludge samples (from the aeration tank), influent and effluent water samples were collected twice a month for 237 days. A combination of fluorescent in-situ hybridization, polymerase chain reaction (PCR)-clone library, quantitative polymerase chain reaction (qPCR) were employed for characterizing and quantifying the dominant nitrifiers in the plant. In order to have more insight into the activated sludge community structure, pyrosequencing was used in profiling the amoA locus of ammonia oxidizing bacteria (AOB) community whilst Illumina sequencing was used in characterising the plant’s total bacterial community. The nonlinear effect of operating parameters and environmental conditions on nitrification was also investigated using an adaptive neuro-fuzzy inference system (ANFIS), Pearson’s correlation coefficient and quadratic models. The plant operated with higher MLSS of 6157±783 mg/L during the first phase (winter) whilst it was 4728±1282 mg/L in summer. The temperature recorded in the aeration tanks ranged from 14.2oC to 25.1oC during the period. The average ammonia removal during winter was 60.0±18% whereas it was 83±13% during summer and this was found to correlate with temperature (r = 0.7671; P = 0.0008). A significant correlation was also found between the AOB (amoA gene) copy numbers and temperature in the reactors (α= 0.05; P=0.05), with the lowest AOB abundance recorded during winter. Sanger sequencing analysis indicated that the dominant nitrifiers were Nitrosomonas spp. Nitrobacter spp. and Nitrospira spp. Pyrosequencing revealed significant differences in the AOB population which was 6 times higher during summer compared to winter. The AOB sequences related to uncultured bacterium and uncultured AOB also showed an increase of 133% and 360% respectively when the season changed from winter to summer. This study suggests that vast population of novel, ecologically significant AOB species, which remain unexploited, still inhabit the complex activated sludge communities. Based on ANFIS model, AOB increased during summer season, when temperature was 1.4-fold higher than winter (r 0.517, p 0.048), and HRT decreased by 31% as a result of rainfall (r - 0.741, p 0.002). Food: microorganism ratio (F/M) and HRT formed the optimal combination of two inputs affecting the plant’s specific nitrification (qN), and their quadratic equation showed r2-value of 0.50. This study has significantly contributed towards understanding the complex relationship between the microbial population dynamics, wastewater composition and nitrification performance in a full-scale treatment plant situated in the subtropical region. This is the first study applying ANFIS technique to describe the nitrification performance at a full-scale WWTP, subjected to dynamic operational parameters. The study also demonstrated the successful application of ANFIS for determining and ranking the impact of various operating parameters on plant’s nitrification performance, which could not be achieved by the conventional spearman correlation due to the non-linearity of the interactions during wastewater treatment. Moreover, this study also represents the first-time amoA gene targeted pyrosequencing of AOB in a full-scale activated sludge is being done. / D

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-15T11:55:55Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO LAÍSE ALVES CANDIDO.pdf: 1717138 bytes, checksum: 7884517a24d4674909faeecc260c672f (MD5) / Made available in DSpace on 2016-07-15T11:55:55Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO LAÍSE ALVES CANDIDO.pdf: 1717138 bytes, checksum: 7884517a24d4674909faeecc260c672f (MD5) Previous issue date: 2015-12-21 / O objetivo deste estudo foi avaliar a capacidade de previsão do algoritmo ASM2d modificado, utilizando o programa AQUASIM 2.0® após sua calibração para um reator de bateladas sequenciais com adição de fonte externa de carbono para tratamento de esgoto doméstico objetivando a remoção de matéria orgânica, fósforo e nitrogênio. O sistema piloto está instalado na área experimental da UFPE localizada na Estação de Tratamento de Esgotos da Mangueira que recebe os esgotos de uma comunidade de baixa renda da cidade de Recife-PE. O reator tem volume útil de 160 L (cento e sessenta litros) e opera em batelada com ciclos de 08h (oito horas) dividas em: enchimento e fase anaeróbia (120 min), fase aeróbia (260 min), fase anóxica (50 min), sedimentação (45 min) e esvaziamento (5 min). Os comportamentos previstos pelo modelo para as frações de matéria orgânica, de nitrogênio e de fósforo e do oxigênio dissolvido (OD) e taxa de consumo de oxigênio são coerentes com o descrito pela literatura e concordam com os dados medidos durante a fase de operação do reator. No entanto, faz-se necessária sua validação com maiores séries temporais de dados para maximizar sua confiabilidade, assim como é imprescindível que sejam instalados equipamentos para medição do volume de oxigênio adicionado, monitoramento online do OD e da alcalinidade e controle rigoroso do volume e características do lodo descartado e das frações de sólidos em todas as fases da operação do reator. Embora o modelo não tenha tido sua capacidade de previsão dos parâmetros validada, foi possível verificar a aplicabilidade do ASM2d para a configuração de fases escolhida e com temperatura próxima à real. / The objective of this study was to evaluate the modified ASM2d algorithm foresight capacity using the AQUASIM 2.0® program after its calibration for sequencing batch reactor with the addition of external carbon source for domestic sewage treatment aiming at removal of organic matter, phosphorus and nitrogen. The pilot plant is installed at UFPE’s experimental area at the Wastewater Treatment Plant of Mangueira which receives influent from a low-income community in the city of Recife-PE. The reactor has an effective volume of 160 L (one hundred sixty liters) and operates in batch with cycles of 08h (eight hours) divided into: filling and anaerobic stage (120 min), aerobic phase (260 min), anoxic phase (50 min), sedimentation (45 minutes) and emptying (5 min). The behavior predicted by the model for fractions of organic matter, nitrogen and phosphorus, dissolved oxygen (DO) and oxygen uptake rate are consistent with that described in the literature and agree with the measured data during reactor operation phase. However, a validation with larger data time series is necessary to maximize its reliability, as it is indispensable to have installed equipment for measuring oxygen input, online monitoring of DO and alkalinity and strict control of the volume and characteristics of the excess sludge and solid fractions for all phases of reactor operation. Although the model has not had its predictive power validated, it was possible to verify the applicability of ASM2d for the chosen stage setting and at a temperature close to the operational.

<p>Slamsvällning orsakar stora problem i avloppsreningsverk med biologisk rening i aktivt slamprocesser. Slamsvällning orsakas av filamentösa (trådformiga) bakterier, som inverkar negativt på slammets sedimenteringsegenskaper.</p><p>Himmerfjärdens vattenreningsverk har drabbats av detta problem som leder till ett stabilt lager av slam på ytan av sedimenteringsbassängen som inte sedimenterar.</p><p>För att lösa detta problem behandlades returslammet från sedimenteringsbassängen med ozon för att minska mängden filamentösa bakterier i returslamflödet. Ozon är en starkt oxiderande gas, som är väl användbar för icke-specifik bekämpning av slamsvällning. När ozon kommer i kontakt med den filamentösa bakteriens cellvägg penetreras det in i cellen, varvid cellen lyserar.</p><p>Ozonbehandlingen resulterade i en förminskning av antalet filamentösa bakterier. Ozonbehandling av returslam förbättrade sedimenteringsegenskaperna hos svällande slam utan att påverka andra viktiga mikrobiologiska processer t.ex. nitrifikation.</p> / <p>Bulking sludge causes major problems in wastewater treatment plants that deal with biological nutrient removal in activated sludge processes. Bulking sludge is caused by filamentous bacteria, which have a negative impact on the sludge settling properties.</p><p>Himmerfjärden wastewater treatment plant suffers from this type of problem with bulking sludge which creates a stable layer at the surface that does not settle in the clarifier.</p><p>In order to solve this problem, on site generated ozone was used to decrease the amount of filamentous bacteria in the return activated sludge flow. Ozone is a strong oxidant is suitable for non-specific bulking control. It stresses the filamentous bacteria causing inactivation through cell wall disintegration.</p><p>The ozone treatment resulted in decreased abundance of filamentous bacteria. Ozone treatment of the recycled activated sludge improves the settling properties of bulking sludge, without interfering with other important microbiological processes e.g. nitrification.</p>

O tratamento do lodo gerado em estações de tratamento de água para abastecimento (ETAs) é uma questão a ser equacionada em todo o território nacional. O tratamento desses lodos em estações de tratamento de esgoto (ETEs) é uma alternativa a ser estudada, pois pode levar a uma solução eficaz e de custos reduzidos se compararmos aos custos de implantação e operação de um sistema de tratamento de lodos nas próprias ETAs. O recebimento de lodo de ETAs em ETEs é feito em algumas ETEs dos Estados Unidos, porém no Brasil ainda são escassos estudos específicos para sanar as questões técnicas envolvidas tanto na etapa aeróbia quanto na anaeróbia. O sistema de tratamento de esgotos por lodos ativados utilizando mídia plástica como meio suporte ao crescimento microbiológico é outro atrativo ao recebimento de lodo de ETA em uma ETE, visto que estudos demonstram que este tipo de variante é capaz de tratar maior carga orgânica, sem sofrer qualquer inibição de processo. O presente estudo avaliou o recebimento de até 400 mg de SST de lodo de ETA por litro de esgoto em um sistema utilizando mídia plástica como meio suporte. O lodo de ETA utilizado foi proveniente de sistemas que utilizaram sais de Ferro e de Alumínio em seus processos. Não foi observada qualquer inibição no processo aeróbio quanto à remoção de matéria orgânica ou nitrogenada com o recebimento de lodo de ETA em qualquer concentração e operando um sistema com mídia plástica. A carga de DBO5,20 aplicada ao reator biológico ficou entre 1,7 a 15,3 gDBO5,20/m²/dia, e a concentração média da DBO 5,20 no efluente final esteve em todo o período do experimento em 34 mg/L. Com a utilização da mídia plástica o processo de nitrificação teve taxas de remoção passando de 0,9 gNKT/m²/dia para 1,7 gNKT/m²/dia, portanto aumento de 95%. A avaliação do lodo gerado no decantador primário da ETE Piloto demonstra que houve alteração em sua composição, principalmente na relação de SV/ST e o aumento na concentração de metais, principalmente o elemento Ferro. Estas características podem levar à inibição o processo anaeróbio. O teste de Atividade Metanogênica Especifica (AME) realizada com dosagens de 0,4 g e 0,8 g de ST de lodo de ETA demonstra que há inibição da metanogênese para concentrações acima de 0,4 g de ST. A concentração na qual não se observou efeito negativo corresponde a 10% da quantidade mássica que o digestor anaeróbio foi alimentado. Porém o teste de AME reproduz toxicidade aguda, não considerando a possível adaptação que pode ocorrer ou mesmo demonstrar que um esgoto que, em primeira análise é considerado biodegradável, tem na realidade toxicidade crônica. A operação do sistema utilizando mídia plástica levou a uma redução na produção de lodo na ordem de 57%. Antes da maturação do biofilme a produção era de 0,19 g SSV/g DQO removida e passou para 0,09 g SSV/g DQO removida. / An issue to be taken into account, regarding the continental size of the country is the sludge treatment generated in water treatment plants (WTPs). The treatment of the aforementioned sludge which is held in water treatment plant (WWTP) is a valid alternative considering its costs and efficacy as opposed to the budgetary considerations for the sludge treatment in the WTPs alone. The recipience of the sludge from WTP into WWTPs, is done by some North Americans WWTPs, in Brazil, nonetheless, such specific studies are of short supply to heal the technical questions regarding both the anaerobic and also the aerobic processes. The activated sludge operational swage system with plastic medium as means to aid the microbiologic development, also entices the reception of sludge from WTP into WWTPs, given the fact that some studies have demonstrated this variant type capable of treating a much bigger organic load not even suffering any inhibition over the process. This current study evaluated the reception of a sum up to 400 mg (milligrams) of sludge TSS by sewage liter in a plastic medium as means to aid such process. The sludge from WTP used in here came from systems which utilized Iron and aluminum salt in their processes. Any inhibition regarding the removal of organic or nitrogenated matter in the aerobic process operated with the plastic medium system with the reception of sludge from WTP was observed and/or noticed The BOD5,20 charge which was applied to the biological reactor ranked between 1,7 to 15,3 gDBO5,20/m²/day, and the BOD5,20 average concentration into the final effluent was all the time the experiment was going on in 34 mg/L. Regarding the usage of plastic medium over the nitrification process, removal which jumped from 0,9 gNKT/m²/day to 1,7 gNKT/m²/day, thus an increase of 95%. The evaluation of the sludge generated from the WWTPs primary settling tank demonstrates alteration in its composition, mainly related to VS/TS and the metal concentration augmentation, iron being the most present element in here. Such characteristics may lead to an inhibition regarding the anaerobic process. The specific methanogenic activity (SMA) taking into account the dosages: 0, 4 g and 0, 8 g of TS sludge from WTP shows methanogenesis inhibition for concentrations superior to 0, 4 g of TS. 10% of mass quantity is the amount which no negative effect was noticed when feeding the anaerobic digestor. The SMA test, however, reproduces acute toxicity, not taking into account the possible adaptation that may occur or even demonstrate that the sewage which at first instance could be considered biodegradable is in its real sense chronically toxic. The activated sludge operating with plastic medium has lead the sludge production to reduction of around 57%, before the biofilm maturation the production was 0,19 g VSS/g COD removed and it was upgraded to 0,09 g VSS/g COD removed.

Processos biológicos de tratamento de esgotos são largamente utilizados mundialmente e, apesar de serem eficientes na remoção de matéria orgânica, têm capacidades limitadas na remoção de poluentes orgânios emergentes, principalmente fármacos. Este trabalho avaliou a eficiência dos processos de tratamento de esgotos por lodos ativados com oxigênio puro, lagoas aeradas e reator anaeróbio de fluxo ascendente (RAFA) na remoção de seis fármacos selecionados - paracetamol, ibuprofeno, atenolol, sinvastatina, carbamazepina e clonazepam, com altos índices de utilização pela população. Para isto, foram analisadas amostras de esgoto bruto e de esgoto tratado oriundas de três estações de tratamento de esgotos em operação no Estado de São Paulo, sendo realizadas quatro campanhas de coleta, durante dois anos, em períodos hidrológicos de seca e chuva. A técnica analítica utilizada foi a cromatografia líquida de alta eficiência acoplada à espectrometria de massas (LC-MS/MS), através de método estabelecido e validado para a execução desta pesquisa. Ibuprofeno, sinvastatina e clonazepam não foram identificados em nenhuma das amostras analisadas. Atenolol, paracetamol e carbamazepina foram detectados em todas as estações estudadas, observando-se remoção e liberação deles durante todos os processos de tratamento. A estação que adota o processo por lagoas aeradas mostrou maior eficiência na remoção de paracetamol e atenolol, sendo que um elevado tempo de detenção hidráulica empregado nela parece ter influenciado positivamente na eficácia de remoção destas subtâncias. A estação que utiliza lodos ativados com oxigênio puro apresentou remoções inferiores e maiores taxas de liberação dos fármacos paracetamol e carbamazepina. Já a estação que adota RAFA apresentou discreta superioridade na remoção de carbamazepina, e eficiências intermediárias para paracetamol e atenolol. A carbamazepina mostrou resistência à degradaçào pelos processos avaliados, porém a desinfecção do efluente final, por cloração, aparentemente elevou a remoção deste composto. / Sewage biological treatment processes are the most used worldwide and, in general, they show organic matter removal high efficiency, however their pharmaceuticals removal capacity were quite limited. The aim of this study is verify the efficiency of sewage biological treatment processes per pure oxygen activated sludge, aerated basin and upflow anaerobic sludge blanket (UASB), in removal of six selected drugs acetaminophen, ibuprofen, atenolol, simvastatin, carbamazepine and clonazepam, most frequently used by population. For this purpose, it was analyzed raw sewage and treated sewage samples from three sewage treatment plants localized at Sao Paulo, Brazil, in four collection stages, during two years, at dry and wet periods. The analytical technique of choice was high performance liquid chromatography tandem mass spectrometry (LC-MS/MS), by developed and validated method for this study. Ibuprofen, simvastatin and clonazepam were not detected at any samples collected. Atenolol, acetaminophen and carbamazepine were identified at all plants investigated, with removal and production during all treatment processes here considered. Aerated basin plant was most efficient in acetaminophen and atenolol removal, and a high hydraulic detention time seem be better to remove these compounds. Pure oxygen activated sludge plant showed lower removal rates and higher production of acetaminophen and carbamazepine. Already the UASB plant revealed a little superiority in carbamazepine removal, and intermediary efficacy to acetaminophen and atenolol removal. Carbamazepine showed persistence in treatment processes evaluated, however final effluent disinfection, with chlorination, apparently raised this compound removal.

A viabilidade técnica de um sistema termofílico combinado de reatores anaeróbio-aeróbio foi avaliada para tratamento de efluente sintético da indústria de pasta de celulose não branqueada. Estas indústrias apresentam efluente com temperatura superior a 40ºC e o tratamento termofílico pode eliminar a necessidade do resfriamento, necessário para a faixa mesofílica de tratamento, reduzindo custos. Os reatores foram inoculados com lodo mesofílico com gradual adaptação para a condição termofílica. Na faixa mesofílica (37,5 a 42,5ºC) a eficiência do sistema foi de (69±3)%, com maior eficiência do reator anaeróbio (56±7)%. Depois que os reatores apresentaram equilíbrio dinâmico aparente, a temperatura foi gradualmente aumentada de 45,0 para 52ºC. As eficiências de remoção de DQO do sistema variaram de 57% a 88%. A porcentagem de metano no biogás foi decrescendo com o aumento de temperatura, de 77% para valores abaixo do limite de detecção do método cromatográfico utilizado. A eficiência do reator anaeróbio foi baixa e houve acúmulo de ácidos, principalmente acético. O reator aeróbio apresentou maior eficiência de remoção de DQO porém a concentração no licor misto foi baixa. Após a alteração no tempo de detenção hidráulica dos reatores UASB e de lodos ativados para 24 horas e 8 horas, respectivamente, os reatores operaram em faixa de temperatura de 52 a 57ºC por 85 dias. As eficiências de remoção de DQO do sistema variaram de 54% a 70%. A eficiência do reator UASB continuou baixa enquanto o reator aeróbio apresentou bom desempenho, com eficiências variando de 3% a 35% e de 43% a 75%, respectivamente. As concentrações de SSV no licor misto aumentaram, variando de 122 mg/L a 2940 mg/L. Em faixa de temperatura termofílica houve predomínio de Methanosaetas sp e bacilos no reator anaeróbio, não havendo diferenciação significativa de morfologias comparando com a fase mesofílica. No reator aeróbio houve diferenciação a partir da temperatura de 42,5ºC e predominaram bacilos, cocos e filamentos em temperatura termofílica. Os resultados demonstram a viabilidade do tratamento termofílico, mas outros experimentos são necessários antes da aplicação industrial do processo. / The technical feasibility of a combined thermophilic anaerobic-aerobic biological reactors configuration was evaluated in this work using a synthetic unbleached pulp mill effluent. These industries introduce effluent with temperature greater 40ºC and the treatment would eliminate the need of cooling that is required for the mesophilic range, reducing the costs. The reactors were inoculated with mesophilic sludge with gradual adaptation to the termophilic condition. In the mesophilic range (37.5 to 42.5ºC) the efficiency of the combined system was (69±3)%, with the higher efficiency in the anaerobic reactor (56±7)%. After the reactors reached apparent steady state regime the temperature was gradually increased from 42.5 to 52ºC. The system efficiency ranged from 57% to 88%. The percentage of methane in the biogas decreased with the increase in temperature, from 77% to values below the detection limit of the chromatographic measurement used in this work. The anaerobic efficiency was low and the reactor accumulated fatty acid, mostly acetic. The aerobic reactor presented higher efficiency removal of COD but the mixed liquor concentration was lower. After adjustment in the hydraulic retention time of both reactors, with the UASB operating with 24 hours HRT and the aerobic with 8 hours HRT, the reactors operated in the temperature range of 52 to 57ºC during 85 days. The overall removal efficiency ranged from 54% to 70%. The efficiency of the UASB reactor remained lower while the aerobic reactor presented good performance, with COD removal efficiency in the range of 3% to 35%, respectively. The mixed liquor VSS concentration increased with the increase in temperature from 122 mg/L to 2940 mg/L. In thermophilic temperature there was predominance of Methanosaetas sp and baccilus in the anaerobic reactor, without significant differentiation of morphology in comparison with the mesophilic temperature. In the aerobic reactor there was differentiation in temperature of 42.5ºC and baccilus, cocus and filamentous predominated in the thermophilic temperature. These results indicated the feasibility of the thermophilic treatment but other experiments are needed before industrial application of this process.