ABSTRACT Comparative study of established test methods for aggregate strength and durabilityof Archean rocks from Botswana In the current situation, river sand is used for building of roads and as raw material forconcrete in Botswana. River sand is a finite resource and important to preserve as itacts as natural water purification, groundwater aquifer and protection against soil erosion.Mining of bedrock may be a good alternative to replace the river sand with crushed rock(aggregates) in concrete and as road materials.The main purpose of this thesis was to determine if the rock grain size can be usedas a parameter to indicate durability and rock strength. It was also of interest to find outif the grain size correlates with established technical analysis and strength test methods.This knowledge can be used as a prospecting tool when searching for new quarry sites inthe future.In this master’s thesis, rock samples from the Gaborone granite complex have beenanalysed to examine how established test methods and the mineral grain size correspondswith the rock strength. By comparing technical properties (Los Angeles (LA) value ,aggregate crushing value (ACV), aggregate impact value (AIV) and 10 percent fines aggregatecrushing test (10 % FACT)) with quantitative analysis (mineral grain size andmineral grain size distribution), it is possible to determine the mineral grain size correspondenceto rock strength. Generally the result show that more fine-grained granitesshow better technical properties than more coarse-grained granites. The calculated meangrain size show weak negative correlation to ACV value, and a positive correlation to LA-, AIV- and 10 % FACT values. Best correlation can be seen between mean grain size andLA values (R2= 0.61) and AIV values (R2= 0.58). Low mean grain size tend to give bettertechnical properties in form of lower LA- and AIV values. The cumulative distributioncurve show that a high concentration of very fine material or fine material tend to contributeto a lower LA value. The results indicate that equigranular rocks with low meangrain size contributes to good technical properties, but when it comes to uneven grainedrock more factors must be taken into account to estimate technical properties.

The use of coarse-grained fill materials has grown significantly in recent years especially on account of their use in dams and transportation networks. This study investigates compressibility of various coarse-grained fill materials in dry and wet loading conditions in oedometer test. Four materials were used in the experiments, which falls into GP, GW, GM and GC categories respectively. GP material is a weathered rock obtained from Eymir Lake region. This material was chosen especially to be able to investigate degradation and particle breakage due to compaction and compression. GW, GM and GC materials were obtained by using the material called &lsquo / bypass&rsquo / which is a fill material used in the construction of metro of Eryaman. Using these four materials, large-scale double oedometer tests were carried out to investigate compressibility in both dry and wet conditions. The double oedometer testing technique is used to investigate the effect of soaking on compressibility behaviour of compacted fill materials. Various compactive efforts were used in the compaction stage to investigate the effect of compactive effort on compressibility and degradation of the four gravelly materials. Gradations of the post-test samples were obtained and particle breakage due to compaction using various compactive efforts and particle breakage due to compression were determined. It is found that amount of compression does not necessarily depend on the dry density of the material and fine fraction is also a dominating property regarding the compressibility in coarse-grained fill materials. The vertical strains induced by soaking are on the order of 12% - 20% of the compression measured in dry loading case for the well-graded coarse-grained fill materials tested. Besides, there is significant particle breakage in the compaction process and no further particle breakage in the oedometer test for GP material.

This doctoral thesis reports analytical and numerical results for the electrostatic response of a dusty plasma to a moving test charge. Two important physical aspects of dusty plasmas, namely grain size distribution and grain charging dynamics were taken into account. In the first case, a dusty plasma in thermal equilibrium and with a distribution of grain sizes is considered. A size distribution is assumed which decreases exponentially with the grain mass for large sizes and gives a simple smooth reduction for small sizes. The electrostatic response to a slowly moving test charge, using a second order approximation is found and the effects of collisions are also investigated. It turns out that for this particular size distribution, there is a remarkably simple result that the resulting effective distribution for the electrostatic response is a kappa (generalized Lorentzian) distribution. In the second case, we present an analytical model for the shielding of a slowly moving test charge in a dusty plasma with dynamical grain charging for cases both with and without the collision effects. The response potential is treated as a power series in test charge velocity. Analytical expressions for the response potential are found up to second order in test charge velocity. The first-order dynamical charging term is shown to be the consequence of the delay in the shielding due to the dynamics of the charging process. It is concluded that the dynamical charging of the grains in a dusty plasma enhances the shielding of a test charge. To clarify the physics, a separate study is made where the charging is approximated by using a time delay. The resulting potential shows the delayed shielding effect explicitly. The terms in the potential that depend on the charging dynamics involve a spatial shift given by the test charge velocity and the charging time. The wake potential of a fast moving test charge in the case of grain charging dynamics was also found. It was observed that the grain charging dynamics leads to a spatial damping and a phase shift in the potential response. Finally, combining these two physical aspects, generalized results for the electrostatic potential were found incorporating the terms from both grain size distribution and grain charging dynamics. The generalized results contain the previous work where these two effects were studied separately and which can now be found as special limiting cases. This kind of work has relevance both in space and astrophysical plasmas. / QC 20100920

Development of the advanced, real-time methods for monitoring of bioaerosols is becoming increasingly important. At present, the Ultraviolet Aerodynamic Particle Sizer (UVAPS, Model 3312, TSI, St. Paul., MN) is the only commercially available method for in-situ, continuous measurements of viable airborne microorganisms. Research included in this thesis aimed towards comprehensive evaluation of the method over a wide range of operating conditions, linking the experimental results to the theoretical basis of its design and operation, and to developing a scientific basis for its application to real-time monitoring of bioaerosols. Specifically, due to a growing concern in the general community about the environmental and health aspects of biological aerosols originated from various types of agricultural operations including animal farming, this research was focussed on developing a research methodology/strategy for applying the method to the investigation of bioaerosols in the swine confinement buildings (SCB). Investigations under controlled laboratory conditions were primarily concerned with selectivity, sensitivity, counting efficiency, and detection limits of the spectrometer. This study also examined the effect of physiological state (metabolic activity) of bacteria on the performance characteristics of the method. The practical implications of the research findings are discussed in this thesis. Further field investigations undertaken on a pig farm advanced understanding of the UVAPS performance in the real-life environmental settings. The research also provided a new insight on the particle size distribution and the effect of on-farm-activities on aerosol load inside the SCBs, for both biological and non-biological aerosols. This study has proved that the UVAPS is a powerful tool for investigation of viable bioaerosols in the environment. However, this method is limited to detection of active metabolising bacteria that excludes dormant bacterial spores. In addition, the method is very sensitive to physiological state of bacteria and to the effect of adverse environmental conditions on metabolic activity of airborne bacteria, which may decrease the amount of the intrinsic fluorophores in the cells below sensitivity level iv of the monitor. Possible limitations of this technology include also the lack of selectivity and thus interferences from the non-microbial organic components of airborne particles. In addition, the sensitivity of the method is insufficient for monitoring viable bacteria in the environments with relatively low concentrations of bioaerosols. In order to increase sensitivity of the method, it would be desirable to concentrate the bioaerosols into a smaller volume with the aim of high-volume virtual impactors (aerosol concentrators) prior to the monitoring. Therefore, in the indoor environments where an application of the concentrator is not feasible, the utilisation of the UVAPS may be problematic. Due to the intrinsic limitations, the method is not recommended for the direct measurements of viable bioaerosols and should be used in conjunction with the conventional biosamplers for obtaining more realistic insights into the microbial air quality. Nevertheless, the UVAPS has been found to be an adequate method for the investigation of the dynamics of biological aerosols in real-time. Overall, this thesis contributes to the advancing of the understanding of the method and may assist in developing new, more advanced technologies for the real-time monitoring of viable bioaerosols, as well as in developing sampling strategies for the application of the method to various bioaerosol studies.

The measurement of submicrometre (< 1.0 m) and ultrafine particles (diameter < 0.1 m) number concentration have attracted attention since the last decade because the potential health impacts associated with exposure to these particles can be more significant than those due to exposure to larger particles. At present, ultrafine particles are not regularly monitored and they are yet to be incorporated into air quality monitoring programs. As a result, very few studies have analysed their long-term and spatial variations in ultrafine particle concentration, and none have been in Australia. To address this gap in scientific knowledge, the aim of this research was to investigate the long-term trends and seasonal variations in particle number concentrations in Brisbane, Australia. Data collected over a five-year period were analysed using weighted regression models. Monthly mean concentrations in the morning (6:00-10:00) and the afternoon (16:00-19:00) were plotted against time in months, using the monthly variance as the weights. During the five-year period, submicrometre and ultrafine particle concentrations increased in the morning by 105.7% and 81.5% respectively whereas in the afternoon there was no significant trend. The morning concentrations were associated with fresh traffic emissions and the afternoon concentrations with the background. The statistical tests applied to the seasonal models, on the other hand, indicated that there was no seasonal component. The spatial variation in size distribution in a large urban area was investigated using particle number size distribution data collected at nine different locations during different campaigns. The size distributions were represented by the modal structures and cumulative size distributions. Particle number peaked at around 30 nm, except at an isolated site dominated by diesel trucks, where the particle number peaked at around 60 nm. It was found that ultrafine particles contributed to 82%-90% of the total particle number. At the sites dominated by petrol vehicles, nanoparticles (< 50 nm) contributed 60%-70% of the total particle number, and at the site dominated by diesel trucks they contributed 50%. Although the sampling campaigns took place during different seasons and were of varying duration these variations did not have an effect on the particle size distributions. The results suggested that the distributions were rather affected by differences in traffic composition and distance to the road. To investigate the occurrence of nucleation events, that is, secondary particle formation from gaseous precursors, particle size distribution data collected over a 13 month period during 5 different campaigns were analysed. The study area was a complex urban environment influenced by anthropogenic and natural sources. The study introduced a new application of time series differencing for the identification of nucleation events. To evaluate the conditions favourable to nucleation, the meteorological conditions and gaseous concentrations prior to and during nucleation events were recorded. Gaseous concentrations did not exhibit a clear pattern of change in concentration. It was also found that nucleation was associated with sea breeze and long-range transport. The implications of this finding are that whilst vehicles are the most important source of ultrafine particles, sea breeze and aged gaseous emissions play a more important role in secondary particle formation in the study area.

Structure of submicrocrystalline materials was investigated by X-ray powder diffraction, mainly by modelling of widths and shapes of diffraction profiles. The diffraction method was applied to colloid gold nanoparticles, copper samples deformed by equal channel angular pressing and titanium dioxide nanoparticles prepared by various chemical routes. Dislocations and twin faults were identified in the metallic samples from characteristic broadening of diffraction lines. Densities of lattice defects were estimated from the diffraction data. Possibilities and limits of the diffraction method for characterisation of a crystallite size distribution were tested on the titanium dioxide samples. Crystallites of size in the range 3-25 nm could be well characterised. The problems were encountered only for samples with extremely broad size dispersion. Diffraction methods and a computer program were developed and tested, which can be applied also for the analysis of thin films.

L’accident de Fukushima a démontré qu’aujourd’hui encore, malgré les progrès déjà réalisésdans le domaine de la sûreté nucléaire, une interruption prolongée du circuit de refroidissement primaire du réacteur (plusieurs semaines ici) était possible. La France s’est par conséquent vue contrainte de réévaluer le niveau de sûreté de ses centrales. Plus spécifiquement, le cas le plus défavorable qu’EDF considérait jusqu’alors, qui consistait en un arrêt total du système de refroidissement primaire de 24h, a été réévalué à deux semaines. Ce changement d’échelle temporelle a introduit des problématiques de fluage, d’évolution hygrométrique du béton ainsi que de flux de vapeur – celle-ci transportant les radionucléides – jusque-là laissées de côté. De ces considérations est né le projet ANR/RSNR MACENA (MAîtrise du Confinement d’une ENceinte en Accident), qui vise à évaluer le confinement d’une enceinte soumise à une température de 180°C et à une pression de 5 bar pendant deux semaines. Ce travail s’inscrit dans la lignée de celui entamé par Khaddour [2014] dans le but de parvenir à une meilleure prédiction des propriétés de transport des milieux poreux en se basant uniquement sur une caractérisation indirecte, la distribution des tailles de pore obtenue grâce à la technique de porosimétrie par intrusion de mercure. Si l’aptitude du modèle initial à estimer correctement les perméabilités intrinsèques a été confirmée sur des matériaux représentant une large gamme de perméabilités, il n’était pas, en l’état, capable de prédire les perméabilités relatives au gaz et au liquide. C’est pourquoi une approche dite redistributive a été développée, laquelle a montré de bons résultats sur diverses PSD. Enfin, un nouveau modèle a été développé pour essayer de s’affranchir de cette approche tout en améliorant la capacité à déterminer les perméabilités relatives. Bien qu’efficace sur des PSD monomodales, étroites ou larges, il a montré ses limites sur une PSD réelle bimodale. En parallèle, une étude de faisabilité a exhibé la possibilité de suivre un front de saturation à l’intérieur d’un matériau poreux, ce qui permettrait à terme de valider l’inclusion d’autres phénomènes dans le modèle, liés notamment à la pression de perçage. / The Fukushima catastrophe that struck Japan in 2011 demonstrated that despite significant progress in the field of nuclear safety a prolonged reactor primary cooling circuit breakdown was possible (several weeks in this specific case). With 4 nuclear power plants located on its shoreline, France therefore needed to reassess the safety level of its facilities. More specifically, the worst case scenario considered up until that point by EdF — which consisted in a 24h breakdown of the primary cooling system — was revised up to two weeks. This time-scale shift induced creep, drying and vapour flow problems previously left aside. Thus came to be the ANR/RSNR MACENA (MAîtrise du Confinement d’une ENceinte en Accident) project, which aims at bettering the tightness assessment of a nuclear containment vessel submitted to a temperature of 180°C and to a pressure of 5 bar for two weeks. This work falls in line with that initiated by Khaddour [2014], who set out to better predict porous materials’ transport properties based solely on an indirect characterisation of their topology, namely Pore Size Distribution (PSD) which is obtained via an experimental technique called Mercury Intrusion Porosimetry (MIP). The initial model’s ability to correctly estimate intrinsic permeabilities was confirmed on several different materials whose intrinsic permeabilities span several orders of magnitude. However, it was not fit to accurately account for gas and liquid relative permeabilities. This led to the introduction of a so-called redistributive approach, which yielded better results on various PSD and corresponding experimental datasets. Finally, a new model was developed to try and avoid said approach while bettering relative permeability predictions. Although it behaved well with monomodal pore size distributions, be they wide or narrow, it fell short when applied to a real bimodal PSD. In parallel, an experimental feasibility study demonstrated the possibility of tracking a saturation front within a porous material, which should ultimately allow for the implementation of several other phenomena into the model, linked among others to breakthrough capillary pressure.

The sediment movement system in a river basin consists of sediment production process in the mountainous region, sediment supply process to the torrents and sediment deposition process in the lower reach and coastal area. There are human impacts as well as natural impacts in the system. These impacts affect the topographical feature and ecosystem in the basin including the coastal area. Bed variation model is one of the tools for assessing the topographical feature of river. In previous riverbed variation calculations, engineers or researchers conventionally assumed that the porosity in riverbed material is a constant, regardless of whether the grain sizes of the riverbed material was uniform. Since there is no doubt that the porosity depends on the grain sizes distribution, fixing the porosity at a constant value is inadequate for simulating practical sediment movements, such as the removal of fine materials out of the riverbed material or the deposition of fine material into voids between the coarse material. Voids in a riverbed themselves are also important as habitat for aquatic biota. Not only natural sediment transport phenomena, such as floods and debris flows induced by heavy rainstorms, but also artificial impacts, such as the construction of dams or sediment flushing from reservoirs, seriously affect the voids in the riverbed. So far no bed variation model has been available for the analysis of the change in porosity. As the void of bed material plays an important role in fluvial geomorphology, infiltration system in riverbeds and river ecosystem, a structural change of the void with bed variation is one of the concerned issues in river management. Thus, a bed-porosity variation model is strongly required and it is expected that the model contributes the analysis of those problems as a tool for integrated sediment management. The objectives of this work are: 1) to point out recent problems in a volcanic river basin, as well as the impacts on riverbed variation and ecosystem; the problems in Merapi volcano area and Progo River, Indonesia were chosen as case studies; 2) to develop a method for identifying the type of grain size distribution and two methods for obtaining the porosity for the different type of grain size distribution; 3) to develop a framework and a bed variation model available for the analysis of the change in porosity of bed material as well as the bed variation. The report consists of four subjects and organized into six chapters as shown in the diagram below (Figure 1). The following diagram shows the framework of proposed bed-porosity variation model and the correspondence of each chapter of this report. In Chapter 2, the sediment-related problems in volcanic area, particularly in Mt. Merapi and Progo River, Indonesia and the impacts on bed variation and ecosystem were pointed out. The sediment-related problems persist in the upper reach, middle reach, also in lower reach. Some problems are triggered by natural activities such as volcanic activity of Mt. Merapi and heavy rainfall, and many others are occurred due to the human interfere such as deforestation, construction of sabo dam and sand mining. Uncontrolled sand mining is the serious problem in this area. Those problems are increasing the susceptibility in the downstream and deteriorating the watershed. A flume experiment was conducted to realize the impact of mining pit on bed variation. Countermeasures of sediment problems, which have been done in Mt. Merapi area and Progo River, were also presented. Finally, the necessity of a tool for integrated sediment management in consideration of the ecosystem in river was indicated. In Chapter 3, the method for classifying and geometrically identifying the type of grain size distribution was presented. First, grain size distribution was classified into some typical types and those characteristic parameters were found out. Then a method for geometrically identifying the type of grain size distribution by using geometric indices .. and .. was presented. Based on the geometrical analysis of typical grain size distributions, a diagram on classification of grain size distribution type was indicated. The presented identification method was then applied to the natural grain size distribution data and the validity of the method was verified. In Chapter 4, two methods for estimating the porosity of sediment mixtures were presented. One was based on a particle packing simulation model and the other was based on a measurement method. The porosity of particle mixtures depends on not only the grain size distribution but also the compaction degree. However, the compaction degree could not be intentionally controlled in the model. Both of the methods were applied to estimate the porosity of three typical grain size distributions, namely lognormal distribution, modified-Talbot distribution and bimodal distribution. Particularly in the measurement, it was very difficult to mix the sediment evenly. Consequently, the coarser particle lies at higher position than the finer particle. This grading process made the porosity larger, while in the simulation the particles were mixed evenly. Thus, the particles packing in the simulation might be denser than the packing of particles in the measurement. The results showed that the relationship between grain size distribution and porosity could be determined by using the characteristic parameters of typical grain size distribution. This relation could be introduced into the bed variation model. In Chapter 5, a one dimensional bed-porosity variation model was developed for simulating the changes in porosity of bed material as well as the bed variation. Analytical model for binary mixtures with much different grain sizes and the relationship between the characteristic parameters of grain size distribution and porosity presented in Chapter 4 were introduced into the bed variation model. Two numerical methods were employed to solve the governing equations, i.e., standard successive approximation and MacCormack scheme. A flume experiment was conducted to realize the transformation processes of void structure for two conditions; one was the only fine sediment was removed from a sediment mixture and another was the fine sediment deposited into a coarser bed material. After the validity of the presented model was verified using a data set provided by the experiment, the model was applied to the bed and porosity variation process for bed material with binary mixtures and continuous grain size distribution. Its performance was examined in detail for two conditions; (1) no sediment supply condition and (2) sediment supply condition. The simulation results showed the model could produce a reasonable distribution of porosity of the riverbed material in the longitudinal and vertical directions for both conditions. A one-dimensional bed-porosity variation model proposed in this study is different from the previous model from a viewpoint of considering the porosity of bed material. Hence, the proposed model is available for the analysis of the change in porosity of bed material as well as the bed variation. The model contributes in two aspects; from the hydraulics point of view, the model provides an improvement of the accuracy in the riverbed variation calculation and from ecological point of view, the model provides the changes in porosity with the bed variation. In the case of binary mixtures, the validity of the model has been verified using a data set provided by the experiment and the simulation result showed that the model produced a reasonable result on the change in porosity as well as the bed variation. In the case of sediment mixtures with continuous grain size distribution, although the validity of the model has not been verified yet, the simulation result showed the model available for analysis of bed and porosity variation. / Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13795号 / 工博第2899号 / 新制||工||1428(附属図書館) / 26011 / UT51-2008-C711 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 藤田 正治, 教授 中川 一, 教授 戸田 圭一 / 学位規則第4条第1項該当

Les objectifs principaux des travaux de recherche réalisés sont de caractériser, quantifier et corréler les changements induits lors du recyclage sur les fibres, la pâte et le papier. Pour ce faire, des techniques de caractérisation spécifique ont été utilisées telles que la chromatographie inverse d'exclusion stérique (ISEC), l'analyse mécanique dynamique (DMA), la microscopie électronique à balayage environnementale (ESEM), la microscopie à force atomique (AFM) et la tomographie à rayons X. Le racornissement des fibres à elle seule ne peut pas expliquer totalement la perte de résistance des fibres. Lors du recyclage la largeur des fibres, l'épaisseur des parois fibreuses, la courbure, le nombre de coudes et d'irrégularité diminuent. Les points faibles à l'intérieur de la paroi augmentent dans les premiers et les derniers cycles de recyclage. Les fibres deviennent plus dures et cassantes à l'état sec. Les forces capillaires et la friction de surface augmentent à l'état humide. La surface de liaison entre fibres dans le réseau fibreux diminue initialement à cause de la perte de la flexibilité des fibres à l'état humide et des éléments fins alors que l'augmentation qui suit peut être reliée au collapse du lumen. Comme la solidité des fibres de diminue pas, la baisse des caractéristiques mécaniques du papier pourrait être attribuée à la dégradation de la qualité des liaisons et plus particulièrement à une délamination partielle de la couche P/S1. / Incorporation of recycled fibres in high value paper products can reduce costand environmental loads. Papermaking potential of cellulosic fibres decreaseswith recycling. The phenomenon of fibre hornification during pressing anddrying is normally held responsible for the loss in strength. To study the impactsof recycling on pulp, fibre and paper properties some non conventionalcharacterisation techniques like fibre saturation point, X-rays microtomography,environmental scanning electron microscopic observations, atomic forcemicroscope (PeakForce QNM mode) and inverse size exclusion chromatography(ISEC) were used. In order to achieve good reproducibility of ISEC measurements,a semi-automatic column fabrication pilot system was built. Thetechniques were first validated on refining process before being applied to therecycling process. In this study, it was found that fibre hornification alone cannot fully explain loss in strength during recycling. The loss in strength is muchmore complex and it is required to understand the morphological and ultrastructural changes associated with recycling. Fibre width, cell wall thickness,curl, kink, irregularities decreased during recycling. Fibre became hard andbrittle in dry state. Number of weak points in the fibre wall were increasedinitially and in the later recyclings. The increase in wet breaking length indicatesincreased surface friction and capillary forces with recycling. Decreasein bonded area during first recycle may be caused by the loss of fines and fibreflexibility whereas the increase afterwards may be linked to the lumen collapse.The strength of fibres did not decrease with recycling as shown by zero-spanbreaking lengths therefore the quality of bond may be deteriorated. It wasthought that the partially delaminated P/S1 layers may be responsible for theloss of paper strength. It is suggested since the significant change is associatedwith the pressing and drying of never dried pulp therefore the drying processneeds to be revisited. The delaminated layer should be restored so as to increasethe recyclability of the recovered fibres for high value paper. Influenceof recycled pulp blends on physical properties of paper was also studied. It wasrevealed that small quantity of recycled pulp can be used without significantlyaffecting the mechanical strength properties.

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.