A partial nitritation-anammox continuous flow reactor (CFR) was operated for eight months demonstrating that a mixture of large anammox-supported aerobic granules (ASAGs) and small conventional aerobic granules (CAGs) can be maintained stably for extended periods of time. The influent NH4+ was kept at 50 - 60 mg N L-1 to verify that the upper range of total ammonia nitrogen (TAN) for domestic wastewater can supply an inhibitory level of free ammonia (FA) for nitrite oxidizing bacteria (NOB) suppression in CFRs at pH around 7.8. The ammonia oxidizing bacteria (AOB):NOB activity ratio was determined for a series of granule sizes to understand the impact of mass diffusion limitation on the FA inhibition of NOB. When dissolved oxygen (DO) limitation is the only mechanism for NOB suppression, the AOB:NOB ratio was usually found in previous studies to increase with the granule size. However, the trend is reversed when FA has an inhibitory effect on NOB, as was observed in this study. The decrease in AOB:NOB ratio indicates that the resistance to the diffusion of FA along the granule radius limited its ability to inhibit NOB. This means smaller granules, e.g. diameter < 150 microns, are preferred for nitrite accumulation when high FA is present, e.g. in the partial nitritation-anammox process. The trend was further verified by observing the increase in the apparent inhibition coefficient, KI,FAapp, as granule size increased. This study for the first time quantified the effect of diffusion limitation on the KI,FAapp of NOB in granules and biofilms. A mathematical model was then utilized to interpret the observed suppression of NOB. The model predicted that NOB suppression was only complete at the granule surface. The NOB that did survive in larger granules was forced to dwell within the granule interior, where the FA concentration was lower than that in the bulk solution. This means FA inhibition can be taken advantage of as an effective means for NOB suppression in small granules and thin biofilms. Further, FA and DO were found to be both required for the stratification of AOB and NOB in partial nitritation-anammox CFRs. The structural stratification commonly observed in granules is then concluded to be a consequence but not a cause of the NOB suppression. / MS / A partial nitritation-anammox continuous flow reactor (CFR) was operated for eight months demonstrating that granular sludge can be maintained stably for extended periods of time. In this approach, NH3 is only partially converted to NO2 - (partial nitritation), and the conversion to NO3 - is prevented by the suppression of nitrite oxidizing bacteria (NOB). NH3 and NO2 - are then utilized by anammox bacteria to create N2 gas. The influent NH4 + fed to the reactor was kept at 50 to 60 mg N L-1 to verify that the upper range of total ammonia nitrogen (TAN) for domestic wastewater can supply a sufficiently high level of free ammonia (FA) to inhibit NOB growth in CFRs at a pH around 7.8. It is expected that the penetration of a substrate into granule sludge will experience diffusional resistance as it moves from water to denser solid material and is consumed by bacteria. The ammonia oxidizing bacteria (AOB):NOB activity ratio was determined for a series of granule sizes to understand the impact of mass diffusion limitation on the FA inhibition of NOB. When dissolved oxygen (DO) limitation is the only mechanism for NOB suppression, the AOB:NOB ratio was usually found in previous studies to increase with the granule size. However, the trend is reversed when FA has an inhibitory effect on NOB, as was observed in this study. The decrease in AOB:NOB ratio indicates that the resistance to the diffusion of FA, which increases with increasing granule size, along the granule radius limited its ability to inhibit NOB. This means smaller granules, e.g. diameter < 150 µm, are preferred for NO2 - accumulation when high FA is present. The trend was further verified by observing the increase in the apparent inhibition coefficient, KI,FAapp, as granule size increased. This coefficient quantifies the effectiveness of an inhibitor, with larger values indicating weaker inhibition. This study for the first time quantified the effect of diffusion limitation on the KI,FAapp of NOB in granules and biofilms. A mathematical model was then utilized to interpret the observed suppression of NOB. The model predicted that NOB suppression was only complete at the granule surface. The NOB that did survive in larger granules was forced to dwell within the granule interior, where the FA concentration was lower than that in the bulk solution. This means FA inhibition can be taken advantage of as an effective means for NOB suppression in small granules and thin biofilms. Further, FA and DO were found to be both required for the stratification of a layer of AOB at the surface over a layer of NOB in partial nitritation-anammox CFRs. The structural stratification commonly observed in granules is then concluded to be a consequence but not a cause of the NOB suppression.

Results of a study on the influence of process parameters such as impeller speed, granulation time and binder viscosity on granule strength and properties are reported. A high shear granulator (Cyclomix manufactured by Hosokawa Micron B.V., The Netherlands) has been used to produce granules. Calcium carbonate (Durcal) was used as feed powder and aqueous polyethylene glycol (PEG) as the binder. The dried granules have been analysed for their strength, density and size distribution. The results show that increasing the granulation time has a great affect on granules strength, until an optimum time has been reached. The underlying cause is an increase in granule density. Granules are consolidated more at higher impeller speeds. Moreover, the granule size distribution seems not to be affected significantly by an increase in impeller speed. Granules produced with high binder viscosity have a considerably lower strength, wide strength distribution due to poor dispersion of binder on the powder bed. Binder addition methods have showed no considerable effect on granule strength or on granule size distribution.

Yes / The effect of screw configuration on granule size distribution (GSD) using gPROMS FormulatedProduct (gFP) software to perform optimization, estimation of complex processes, and analyses is evaluated. Twin-screw granulation modeling was used to investigate the contribution of screw configuration and liquid-to-solid (L/S) ratio on GSD. Lactose and Avicel were the granulating materials. Twelve different configurations were investigated under three feed rates as consistent with literature and at various L/S ratios. Results indicate that kneading elements promote the recovery of 100–1000 µm granules while reducing the production of oversized granules. Higher feed rates support the production of fines and agglomerates, while a low feed rate produces 100–1000 µm granules. / Ghana Scholarship Secretariat

Made available in DSpace on 2014-12-17T15:42:04Z (GMT). No. of bitstreams: 1 KeilaROM.pdf: 1106532 bytes, checksum: 919e086ca601ac57108653607838c88e (MD5) Previous issue date: 2008-11-10 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Leather tanneries generate effluents with high content of heavy metals, especially chromium, which is used in the mineral tanning process. Microemulsions have been studied in the extraction of heavy metals from aqueous solutions. Considering the problems related with the sediment resulting from the tanning process, due to its high content in chromium, in this work this sediment was characterized and microemulsion systems were applied for chromium removal. The extraction process consists in the removal of heavy metal ions present in an aqueous feeding solution (acid digestion solution) by a microemulsion system. First three different solid sludge digestion methods were evaluated, being chosen the method with higher digestion capacity. For this digestion method, seeking its optimization, was evaluated the influence of granule size, temperature and digestion time. Experimental results showed that the method proposed by USEPA (Method A) was the most efficient one, being obtained 95.77% of sample digestion. Regarding to the evaluated parameters, the best results were achieved at 95?C, 14 Mesh granule size, and 60 minutes digestion time. For chromium removal, three microemulsion extraction methods were evaluated: Method 1, in a Winsor II region, using as aqueous phase the acid digestion solution; Method 2, in a Winsor IV region, being obtained by the addition of the acid digestion solution to a microemulsion phase, whose aqueous phase is distilled water, until the formation of Winsor II system; and Method 3, in a Winsor III region, consisting in the formation of a Winsor III region using as aqueous phase the acid digestion solution, diluted in NaOH 0.01N. Seeking to optimize the extraction process only Method 1 (Systems I, II, and VIII) and Method 2 (System IX) were evaluated, being chosen points inside the interest regions (studied domains) to study the influence of contact time and pH in the extraction percentiles. The studied systems present the following compositions: System I: Surfactant Saponified coconut oil, Cosurfactant 1-Butanol, Oil phase Kerosene, Aqueous phase 2% NaCl solution; System II: Aqueous phase Acid digestion solution with pH adjusted using KOH (pH 3.5); System VIII: Aqueous phase - Acid digestion solution (pH 0.06); and System IX Aqueous phase Distilled water (pH 10.24), the other phases of Systems II, VIII and IX are similar to System I. Method 2 showed to be the more efficient one regarding chromium extraction percentile (up to 96.59% - pH 3.5). Considering that with Method 2 the microemulsion region only appears in the Winsor II region, it was studied Method 3 (System X) for the evaluation and characterization of a triphasic system, seeking to compare with a biphases system. System X is composed by: Surfactant Saponified coconut oil, Cosurfactant 1-Butanol, Oil phase Kerosene, Aqueous phase Acid digestion solution diluted with water and with its pH adjusted using 0.01N NaOH solution. The biphasic and triphasic microemulsion systems were analyzed regarding its viscosity, extraction efficiency and drop effective diameter. The experimental results showed that for viscosity studies the obtained values were low for all studied systems, the diameter of the drop is smaller in the Winsor II region, with 15.5 nm, reaching 46.0 nm in Winsor III region, being this difference attributed to variations in system compositions and micelle geometry. In chromium extraction, these points showed similar results, being achieved 99.76% for Winsor II system and 99.62% for Winsor III system. Winsor III system showed to be more efficient due to the obtaining of a icroemulsion with smaller volume, with the possibility to recover the oil phase in excess, and the use of a smaller proportion of surfactant and cosurfactant (C/S) / Os curtumes geram efluentes carregados em metais pesados, especialmente o cromo, utilizado no processo de curtimento. Microemuls?es t?m sido estudadas na remo??o de metais pesados. Considerando o problema encontrado no sedimento gerado no processo de curtimento, pelo elevado teor de cromo, no presente trabalho nos propomos a caracteriz?-lo e aplicar sistemas microemulsionados para remo??o do cromo. O processo de extra??o consiste em remover o metal de uma alimenta??o aquosa (solu??o ?cida digerida) para uma fase microemuls?o. Iniciou-se a pesquisa avaliando tr?s diferentes m?todos de digest?o de sedimentos, escolhendo-se o m?todo que apresentasse maior percentual de digest?o, sendo este m?todo otimizado atrav?s de mudan?as no di?metro das part?culas do sedimento, tempo e temperatura de digest?o. Nesse estudo, escolheu-se o m?todo proposto pelo EPA (M?todo A), que se mostrou mais eficiente, obtendo-se um percentual de 95,77% de digest?o da amostra. Com rela??o aos par?metros avaliados, os melhores resultados foram obtidos com a temperatura a 95?C, granulometria de 14 Mesh e tempo de opera??o de 60 minutos. Para os estudos da extra??o foram utilizados tr?s m?todos: o M?todo 1, que consiste na forma??o de uma regi?o de Winsor II, utilizando a solu??o ?cida digerida como fase aquosa; o M?todo 2, que consiste em utilizar uma microemuls?o cuja fase aquosa ? ?gua destilada e adicionar a solu??o ?cida digerida at? a obten??o de um sistema de Winsor II; e o M?todo 3, que consiste na forma??o de uma regi?o de Winsor III, utilizando a solu??o ?cida digerida, dilu?da em NaOH 0,01N, como fase aquosa. Para o estudo da otimiza??o da extra??o foram avaliados apenas os M?todos 1 (Sistemas I, II e VIII) e 2 (Sistema IX), escolhendo-se pontos dentro das regi?es de interesse (dom?nio estudado) para estudar a influ?ncia do tempo e do pH no percentual de extra??o. Os sistemas estudados apresentam as seguintes composi??es: Sistema I: Tensoativo ?leo de coco saponificado, Cotensoativo 1-Butanol, Fase oleosa Querosene, Fase aquosa NaCl 2,0%; Sistema II: Fase aquosa Solu??o ?cida digerida ajustada c/ KOH (pH 3,5); Sistema VIII: Fase aquosa Solu??o ?cida digerida (pH 0,06) e Sistema IX: Fase aquosa ?gua destilada (pH 10,24), as demais fases dos Sistemas II, VIII e IX s?o semelhantes ao Sistema I. Atrav?s desse estudo, observou-se que o M?todo 2 foi mais eficiente, com percentuais de 96,59% de extra??o, em pH 3,5. Tendo em vista que com a aplica??o do M?todo 2 s? se obt?m os sistemas de Winsor II, estudou-se um sistema capaz de fornecer a regi?o de Winsor III (tr?s fases) para efeito de compara??o da efici?ncia na extra??o do cromo, com um sistema de duas fases (Winsor II) e, assim, constituiu-se o M?todo 3, utilizando o Sistema X. O sistema X apresenta a seguinte composi??o: Tensoativo ?leo de coco saponificado, Cotensoativo 1-Butanol, Fase oleosa Querosene, Fase aquosa Solu??o ?cida digerida dilu?da em ?gua e ajustado com NaOH 0,01N. As microemuls?es nas regi?es bif?sicas e trif?sicas foram analisadas com rela??o ? viscosidade, extra??o e di?metro efetivo da gota. Os resultados obtidos nas regi?es de W II e WIII foram os seguintes: a viscosidade ? baixa em todos os pontos estudados e o comportamento dos fluidos ? do tipo Newtoniano; o di?metro da gota ? menor na regi?o de Winsor II, com di?metro de 15,5 nm, atingindo 46 nm em Winsor III, sendo essa varia??o atribu?da ?s composi??es estudadas e ? geometria da micela; os resultados obtidos na extra??o com os dois sistemas foram semelhantes, com 99,76% de extra??o em WII e 99,62 % em WIII. O sistema utilizando WIII mostrou-se mais eficiente na extra??o do cromo devido a obten??o de uma microemuls?o com menor volume, a possibilidade de recuperar o ?leo em excesso e a utiliza??o de uma menor propor??o de cotensoativo e tensoativo (C/T)

Os sistemas de esgotos urbanos são classificados em separador absoluto, separador parcial e unitário, conforme o grau de separação que existe no recolhimento dos esgotos sanitários e das águas de drenagem pluviais. Embora a diretriz das cidades brasileiras seja a adoção do sistema separador, na prática ocorre uma importante contribuição das águas de chuvas nas vazões afluentes às estações de tratamento de esgotos como produto das interconexões existentes, clandestinas ou não, entre as redes de esgotos sanitários e pluviais. Esta pesquisa investigou os impactos causados pelos choques de carga orgânica e hidráulica provocados pela contribuição das águas pluviais no desempenho de reatores UASB e seu tempo de recuperação depois de sofrer estes choques. Três reatores de acrílico de 17 litros foram construídos no Laboratório de Saneamento Ambiental do IPH. Os reatores trataram esgoto sintético simulando a concentração de DQO de esgotos domésticos a uma temperatura de 30 ± 2 °C. Um dos reatores serviu de controle enquanto os outros dois receberam choques de carga hidráulica (aumento de vazão) e diluição de matéria orgânica, simultaneamente. A operação dos reatores foi dividida em três fases: 1°) aclimatação, 2°) choques individuais de carga hidráulica e diluição de matéria orgânica 3°) simulação de uma temporada de chuva. Os choques tiveram um efeito deletério na qualidade do efluente, ocasionando quedas na eficiência de remoção de DQO total de até quase 600% e de 200% na eficiência de remoção de DQO dissolvida nos choques mais severos. Também constatou-se perda de parte da biomassa presente nos reatores devido ao aumento excessivo na velocidade ascensional do fluxo. Esta perda tornou-se menor com o tempo devido à pressão de seleção exercida pelos sucessivos choques. O pH dentro dos reatores manteve-se sempre perto da faixa neutra, porém apresentou-se um consumo de alcalinidade que se prolongou por até três vezes o tempo de detenção hidráulica após o início dos choques, devido provavelmente ao aumento na concentração de ácidos graxos voláteis no efluente. A produção de biogás também diminuiu como conseqüência da diluição da carga orgânica afluente. Os efeitos e o tempo de recuperação após os choques dependeram da sua duração e magnitude, sendo que os choques mais severos (menor concentração de matéria orgânica afluente e TDH) causaram maior deterioração na qualidade do efluente e requereram maior tempo de recuperação.Já no que diz respeito às características físico-químicas e biológicas do lodo, verificou-se que os choques causaram diminuição no tamanho médio dos grânulos do lodo e na sua velocidade de sedimentação, provavelmente devido ao aumento das forças abrasivas v provocado pelo incremento na velocidade ascensional do fluxo. De igual modo, a atividade metanogênica específica também apresentou quedas devidas, provavelmente, à diluição da carga orgânica afluente e à diminuição do tamanho das partículas do lodo. / Sewerage systems are classified as separate, partially separated, or combined, according to the degree of separation that exists in the collection of municipal wastewater and stormwater runoff. Although the official policy of brazilian cities is for adoption of the separate system, the actual scenario shows that there are significant contributions of stormwater to the flows that are transported to the wastewater treatment plants, partly because of the inappropriate interconnections that exist between the systems. This research investigated the impacts that organic and hydraulic shock loads brought by stormwater contributions have on the efficiency of UASB reactors, as well as the recovery time after the ending of the shocks. Three 17-liters acrylic reactors were built in the Environmental Technology Laboratory at IPH. The reactors were fed with synthetic wastewater prepared to resemble the organic content of wastewater. All reactors were operated at a temperature of 30 ± 2ºC. One of the reactors was used as control while the other two received hydraulic shocks with organic matter dilution, simultaneously. Reactor’s operation was divided in three phases: 1º) star-up, 2º) single organic and hydraulic shocks, and 3º) rain season simulation, with multiple shocks.Shocks have a deleterious effect on the reactor effluent quality. In the most severe cases, drops in removal efficiencies reached up to 200% and 600% for dissolved and total DQO, respectively. Reactor biomass washout occurred due to the increasing upflow velocity. This loss was dampened by the selective pressure exerted by successive shocks. pH in the reactors remained in the neutral range, although alkalinity was consumed for as long as three detention times, probably due to an increase in the concentration of volatile fatty acids in the liquid. Dilution also caused a decrease in biogas production. Recovery time depended on the duration and intensity of the shock, with more severe shocks demanding more time for recovery. The impacts of the shocks on the treatment efficiency depended on duration, organic dilution rate and flowrate increase. Longer shocks, with higher flowrates and dilution rate resulted in the worst conditions for the reactor. Shocks loads caused a decrease in the mean size of the sludge granule, as well as in their sedimentation velocities, probably because of an increase in the abrasive forces acting on the granules brought by the upflow velocity. The specific methanogenic activity also decreased with higher dilution and smaller sized sludge granules.

Os sistemas de esgotos urbanos são classificados em separador absoluto, separador parcial e unitário, conforme o grau de separação que existe no recolhimento dos esgotos sanitários e das águas de drenagem pluviais. Embora a diretriz das cidades brasileiras seja a adoção do sistema separador, na prática ocorre uma importante contribuição das águas de chuvas nas vazões afluentes às estações de tratamento de esgotos como produto das interconexões existentes, clandestinas ou não, entre as redes de esgotos sanitários e pluviais. Esta pesquisa investigou os impactos causados pelos choques de carga orgânica e hidráulica provocados pela contribuição das águas pluviais no desempenho de reatores UASB e seu tempo de recuperação depois de sofrer estes choques. Três reatores de acrílico de 17 litros foram construídos no Laboratório de Saneamento Ambiental do IPH. Os reatores trataram esgoto sintético simulando a concentração de DQO de esgotos domésticos a uma temperatura de 30 ± 2 °C. Um dos reatores serviu de controle enquanto os outros dois receberam choques de carga hidráulica (aumento de vazão) e diluição de matéria orgânica, simultaneamente. A operação dos reatores foi dividida em três fases: 1°) aclimatação, 2°) choques individuais de carga hidráulica e diluição de matéria orgânica 3°) simulação de uma temporada de chuva. Os choques tiveram um efeito deletério na qualidade do efluente, ocasionando quedas na eficiência de remoção de DQO total de até quase 600% e de 200% na eficiência de remoção de DQO dissolvida nos choques mais severos. Também constatou-se perda de parte da biomassa presente nos reatores devido ao aumento excessivo na velocidade ascensional do fluxo. Esta perda tornou-se menor com o tempo devido à pressão de seleção exercida pelos sucessivos choques. O pH dentro dos reatores manteve-se sempre perto da faixa neutra, porém apresentou-se um consumo de alcalinidade que se prolongou por até três vezes o tempo de detenção hidráulica após o início dos choques, devido provavelmente ao aumento na concentração de ácidos graxos voláteis no efluente. A produção de biogás também diminuiu como conseqüência da diluição da carga orgânica afluente. Os efeitos e o tempo de recuperação após os choques dependeram da sua duração e magnitude, sendo que os choques mais severos (menor concentração de matéria orgânica afluente e TDH) causaram maior deterioração na qualidade do efluente e requereram maior tempo de recuperação.Já no que diz respeito às características físico-químicas e biológicas do lodo, verificou-se que os choques causaram diminuição no tamanho médio dos grânulos do lodo e na sua velocidade de sedimentação, provavelmente devido ao aumento das forças abrasivas v provocado pelo incremento na velocidade ascensional do fluxo. De igual modo, a atividade metanogênica específica também apresentou quedas devidas, provavelmente, à diluição da carga orgânica afluente e à diminuição do tamanho das partículas do lodo. / Sewerage systems are classified as separate, partially separated, or combined, according to the degree of separation that exists in the collection of municipal wastewater and stormwater runoff. Although the official policy of brazilian cities is for adoption of the separate system, the actual scenario shows that there are significant contributions of stormwater to the flows that are transported to the wastewater treatment plants, partly because of the inappropriate interconnections that exist between the systems. This research investigated the impacts that organic and hydraulic shock loads brought by stormwater contributions have on the efficiency of UASB reactors, as well as the recovery time after the ending of the shocks. Three 17-liters acrylic reactors were built in the Environmental Technology Laboratory at IPH. The reactors were fed with synthetic wastewater prepared to resemble the organic content of wastewater. All reactors were operated at a temperature of 30 ± 2ºC. One of the reactors was used as control while the other two received hydraulic shocks with organic matter dilution, simultaneously. Reactor’s operation was divided in three phases: 1º) star-up, 2º) single organic and hydraulic shocks, and 3º) rain season simulation, with multiple shocks.Shocks have a deleterious effect on the reactor effluent quality. In the most severe cases, drops in removal efficiencies reached up to 200% and 600% for dissolved and total DQO, respectively. Reactor biomass washout occurred due to the increasing upflow velocity. This loss was dampened by the selective pressure exerted by successive shocks. pH in the reactors remained in the neutral range, although alkalinity was consumed for as long as three detention times, probably due to an increase in the concentration of volatile fatty acids in the liquid. Dilution also caused a decrease in biogas production. Recovery time depended on the duration and intensity of the shock, with more severe shocks demanding more time for recovery. The impacts of the shocks on the treatment efficiency depended on duration, organic dilution rate and flowrate increase. Longer shocks, with higher flowrates and dilution rate resulted in the worst conditions for the reactor. Shocks loads caused a decrease in the mean size of the sludge granule, as well as in their sedimentation velocities, probably because of an increase in the abrasive forces acting on the granules brought by the upflow velocity. The specific methanogenic activity also decreased with higher dilution and smaller sized sludge granules.

Os sistemas de esgotos urbanos são classificados em separador absoluto, separador parcial e unitário, conforme o grau de separação que existe no recolhimento dos esgotos sanitários e das águas de drenagem pluviais. Embora a diretriz das cidades brasileiras seja a adoção do sistema separador, na prática ocorre uma importante contribuição das águas de chuvas nas vazões afluentes às estações de tratamento de esgotos como produto das interconexões existentes, clandestinas ou não, entre as redes de esgotos sanitários e pluviais. Esta pesquisa investigou os impactos causados pelos choques de carga orgânica e hidráulica provocados pela contribuição das águas pluviais no desempenho de reatores UASB e seu tempo de recuperação depois de sofrer estes choques. Três reatores de acrílico de 17 litros foram construídos no Laboratório de Saneamento Ambiental do IPH. Os reatores trataram esgoto sintético simulando a concentração de DQO de esgotos domésticos a uma temperatura de 30 ± 2 °C. Um dos reatores serviu de controle enquanto os outros dois receberam choques de carga hidráulica (aumento de vazão) e diluição de matéria orgânica, simultaneamente. A operação dos reatores foi dividida em três fases: 1°) aclimatação, 2°) choques individuais de carga hidráulica e diluição de matéria orgânica 3°) simulação de uma temporada de chuva. Os choques tiveram um efeito deletério na qualidade do efluente, ocasionando quedas na eficiência de remoção de DQO total de até quase 600% e de 200% na eficiência de remoção de DQO dissolvida nos choques mais severos. Também constatou-se perda de parte da biomassa presente nos reatores devido ao aumento excessivo na velocidade ascensional do fluxo. Esta perda tornou-se menor com o tempo devido à pressão de seleção exercida pelos sucessivos choques. O pH dentro dos reatores manteve-se sempre perto da faixa neutra, porém apresentou-se um consumo de alcalinidade que se prolongou por até três vezes o tempo de detenção hidráulica após o início dos choques, devido provavelmente ao aumento na concentração de ácidos graxos voláteis no efluente. A produção de biogás também diminuiu como conseqüência da diluição da carga orgânica afluente. Os efeitos e o tempo de recuperação após os choques dependeram da sua duração e magnitude, sendo que os choques mais severos (menor concentração de matéria orgânica afluente e TDH) causaram maior deterioração na qualidade do efluente e requereram maior tempo de recuperação.Já no que diz respeito às características físico-químicas e biológicas do lodo, verificou-se que os choques causaram diminuição no tamanho médio dos grânulos do lodo e na sua velocidade de sedimentação, provavelmente devido ao aumento das forças abrasivas v provocado pelo incremento na velocidade ascensional do fluxo. De igual modo, a atividade metanogênica específica também apresentou quedas devidas, provavelmente, à diluição da carga orgânica afluente e à diminuição do tamanho das partículas do lodo. / Sewerage systems are classified as separate, partially separated, or combined, according to the degree of separation that exists in the collection of municipal wastewater and stormwater runoff. Although the official policy of brazilian cities is for adoption of the separate system, the actual scenario shows that there are significant contributions of stormwater to the flows that are transported to the wastewater treatment plants, partly because of the inappropriate interconnections that exist between the systems. This research investigated the impacts that organic and hydraulic shock loads brought by stormwater contributions have on the efficiency of UASB reactors, as well as the recovery time after the ending of the shocks. Three 17-liters acrylic reactors were built in the Environmental Technology Laboratory at IPH. The reactors were fed with synthetic wastewater prepared to resemble the organic content of wastewater. All reactors were operated at a temperature of 30 ± 2ºC. One of the reactors was used as control while the other two received hydraulic shocks with organic matter dilution, simultaneously. Reactor’s operation was divided in three phases: 1º) star-up, 2º) single organic and hydraulic shocks, and 3º) rain season simulation, with multiple shocks.Shocks have a deleterious effect on the reactor effluent quality. In the most severe cases, drops in removal efficiencies reached up to 200% and 600% for dissolved and total DQO, respectively. Reactor biomass washout occurred due to the increasing upflow velocity. This loss was dampened by the selective pressure exerted by successive shocks. pH in the reactors remained in the neutral range, although alkalinity was consumed for as long as three detention times, probably due to an increase in the concentration of volatile fatty acids in the liquid. Dilution also caused a decrease in biogas production. Recovery time depended on the duration and intensity of the shock, with more severe shocks demanding more time for recovery. The impacts of the shocks on the treatment efficiency depended on duration, organic dilution rate and flowrate increase. Longer shocks, with higher flowrates and dilution rate resulted in the worst conditions for the reactor. Shocks loads caused a decrease in the mean size of the sludge granule, as well as in their sedimentation velocities, probably because of an increase in the abrasive forces acting on the granules brought by the upflow velocity. The specific methanogenic activity also decreased with higher dilution and smaller sized sludge granules.