地下水流动数值模拟的并行计算方法研究

Numerical modeling of groundwater is very important for understanding groundwater flow and solving hydrogeological problem. Today, groundwater studies require massive model cells and high calculation accuracy, which are beyond single-CPU computer’s capabilities. With the development of high performance parallel computing technologies, application of parallel computing method on numerical modeling of groundwater flow becomes necessary and important. Using parallel computing can improve the ability to resolve various hydro-geological and environmental problems. In this study, parallel computing method on two main types of modern parallel computer architecture, shared memory parallel systems and distributed shared memory parallel systems, are discussed. OpenMP and MPI (PETSc) are both used to parallelize the most widely used groundwater simulator, MODFLOW. Two parallel solvers, P-PCG and P-MODFLOW, were developed for MODFLOW. The parallelized MODFLOW was used to simulate regional groundwater flow in Beishan, Gansu Province, which is a potential high-level radioactive waste geological disposal area in China. 1. The OpenMP programming paradigm was used to parallelize the PCG (preconditioned conjugate-gradient method) solver, which is one of the main solver for MODFLOW. The parallel PCG solver, P-PCG, is verified using an 8-processor computer. Both the impact of compilers and different model domain sizes were considered in the numerical experiments. The largest test model has 1000 columns, 1000 rows and 1000 layers. Based on the timing results, execution times using the P-PCG solver are typically about 1.40 to 5.31 times faster than those using the serial one. In addition, the simulation results are the exact same as the original PCG solver, because the majority of serial codes were not changed. It is worth noting that this parallelizing approach reduces cost in terms of software maintenance because only a single source PCG solver code needs to be maintained in the MODFLOW source tree. 2. P-MODFLOW, a domain decomposition–based model implemented in a parallel computing environment is developed, which allows efficient simulation of a regional-scale groundwater flow. The basic approach partitions a large model domain into any number of sub-domains. Parallel processors are used to solve the model equations within each sub-domain. The use of domain decomposition method to achieve the MODFLOW program distributed shared memory parallel computing system will process the application of MODFLOW be extended to the fleet of the most popular systems, so that a large-scale simulation could take full advantage of hundreds or even thousands parallel processors. P-MODFLOW has a good parallel performance, with the maximum speedup of 18.32 (14 processors). Super linear speedups have been achieved in the parallel tests, indicating the efficiency and scalability of the code. Parallel program design, load balancing and full use of the PETSc were considered to achieve a highly efficient parallel program. 3. The characterization of regional ground water flow system is very important for high-level radioactive waste geological disposal. The Beishan area, located in northwestern Gansu Province, China, is selected as a potential site for disposal repository. The area includes about 80000 km2 and has complicated hydrogeological conditions, which greatly increase the computational effort of regional ground water flow models. In order to reduce computing time, parallel computing scheme was applied to regional ground water flow modeling. Models with over 10 million cells were used to simulate how the faults and different recharge conditions impact regional ground water flow pattern. The results of this study provide regional ground water flow information for the site characterization of the potential high-level radioactive waste disposal.

水-岩土反应的力学与环境效应研究

The research on mechanical effects of water-rock and soil interaction on deformation and failure of rocks and soils involves three aspects of mechanics, physics and chemistry. It is the cross between geochemistry and rock mechanics and soil mechanics. To sum up, the mechanical effects of water-rock and soil interaction is related to many complex processes. Research in this respect has been being an important forward field and has broad prospects. In connection with the mechanism of the effects of the chemical action of water-rock on deformation and failure of rocks and soils, the research significance, the present state, the developments in this research domain are summarized. Author prospects the future of this research. The research of the subject should be possessed of important position in studying engineering geology and will lead directly to a new understand on geological hazard and control research. In order to investigation the macroscopic mechanics effects of chemical kinetics of water-rock interaction on the deformation and failure, calcic rock, red sandstone and grey granite reacting chemically with different aqueous solution at atmospheric temperature and atmospheric pressure are uniaxially compressed. The quantitative results concerning the changes of uniaxially compressive strength and elastic modulus under different conditions are obtained. It is found that the mechanical effects of water on rock is closely related to the chemical action of water-rock or the chemical damage in rock, and the intensity of chemical damage is direct ratio to the intensity of chemical action in water-rock system. It is also found that the hydrochemical action on rock is time-dependent through the test. The mechanism of permeation and hydrochemical action resulting in failure of loaded rock mass or propagation of fractures in rocks would be a key question in rock fracture mechanics. In this paper, the fracture mechanical effects of chemical action of water-rock and their time- and chemical environment-dependent behavior in grey granite, green granite, grey sandstone and red sandstone are analyzed by testing K_(IC) and COD of rock under different conditions. It is found that: ①the fracture mechanical effect of chemical action of water-rock is outstanding and time-dependent, and high differences exist in the influence of different aqueous solution, different rocks, different immersion ways and different velocity of cycle flow on the fracture mechanical effects in rock. ②the mechanical effects of water-rock interaction on propagation of fractures is consistent with the mechanical effects on the peak strength of rock. ③the intensity of the mechanical fracture effects increases as the intensity of chemical action of water-rock increases. ④iron and calcium ion bearing mineral or cement in rock are some key ion or chemical composition, and especially iron ion-bearing mineral resulting in chemical action of water-rock to be provided with both positive and negative mechanical effects on rock. Through the above two tests, we suggest that primary factors influencing chemical damage in rock consist of the chemical property of rock and aqueous solution, the structure or homogeneity of rocks, the flow velocity of aqueous solution passing through rock, and cause of formation or evolution of rock. The paper explores the mechanism on the mechanical effects of water-rock interaction on rock by using the theory of chemistry and rock fracture mechanics with chemical damage proposed by author, the modeling method and the energy point of view. In this paper, the concept of absorbed suction between soil grains caused by capillary response is given and expounded, and the relation and basic distinction among this absorbed suction, surface tension and capillary pressure of the soil are analyzed and established. The law of absorbed suction change and the primary factors affecting it are approached. We hold that the structure suction are changeable along with the change of the saturation state in unsaturated soils. In view of this, the concept of intrinsic structure suction and variable structure suction are given and expounded, and this paper points out: What we should study is variable structure suction when studying the effective stress. By IIIy κHH's theory of structure strength of soils, the computer method for variable structure suction is analyzed, the measure method for variable structure suction is discussed, and it reach the conclusions: ①Besides saturation state, variable structure suction is affected by grain composition and packing patter of grains. ②The internal relations are present between structure parameter N in computing structure suction and structure parameter D in computing absorbed suction. We think that some problems exit in available principle of effective stress and shear strength theory for unsaturated soil. Based on the variable structure suction and absorbed suction, the classification of saturation in soil and a principle of narrow sense effective stress are proposed for unsaturated soils. Based on generalized suction, the generalized effective stress formula and a principle of generalized effective stress are proposed for unsaturated soils. The experience parameter χ in Bishop's effective stress formula is defined, and the principal factors influencing effective stress or χ. The primary factor affecting the effective stress in unsaturated soils, and the principle classifying unsaturated soils and its mechanics methods analyzing unsaturated soils are discussed, and this paper points out: The theory on studying unsaturated soil mechanics should adopt the micromechanics method, then raise it to macromechanics and to applying. Researching the mechanical effects of chemical action of water-soil on soil is of great importance to geoenvironmental hazard control. The texture of soil and the fabric of soil mass are set forth. The tests on physical and mechanical property are performed to investigate the mechanism of the positive and negative mechanical effects of different chemical property of aqueous solution. The test results make clear that the plastic limit, liquid limit and plasticity index are changed, and there exists both positive and negative effects on specimens in this test. Based on analyzing the mechanism of the mechanical effects of water-soil interaction on soil, author thinks that hydrochemical actions being provided with mechanical effects on soil comprise three kinds of dissolution, sedimentation or crystallization. The significance of these tests lie in which it is recognized for us that we may improve, adjust and control the quality of soils, and may achieve the goal geological hazard control and prevention.The present and the significance of the research on environmental effects of water-rock and soil interaction. Various living example on geoenvironmental hazard in this field are enumerated. Following above thinking, we have approached such ideals that: ①changing the intensity and distribution of source and sink in groundwater flow system can be used to control the water-rock and soil interaction. ②the chemical action of water-rock and soil can be used to ameliorate the physical and mechanical property of rocks and soils. Lastly, the research thinking and the research methods on mechanical effects and environmental effects of water-rock and soil interaction are put forward and detailed.

Effect of fluid dynamics and device mechanism on biofluid behaviour in microchannel systems: modelling biofluids in a microchannel biochip separator

Biofluid behaviour in microchannel systems is investigated in this paper through the modelling of a microfluidic biochip developed for the separation of blood plasma. Based on particular assumptions, the effects of some mechanical features of the microchannels on behaviour of the biofluid are explored. These include microchannel, constriction, bending channel, bifurcation as well as channel length ratio between the main and side channels. The key characteristics and effects of the microfluidic dynamics are discussed in terms of separation efficiency of the red blood cells with respect to the rest of the medium. The effects include the Fahraeus and Fahraeus-Lindqvist effects, the Zweifach-Fung bifurcation law, the cell-free layer phenomenon. The characteristics of the microfluid dynamics include the properties of the laminar flow as well as particle lateral or spinning trajectories. In this paper the fluid is modelled as a single-phase flow assuming either Newtonian or Non-Newtonian behaviours to investigate the effect of the viscosity on flow and separation efficiency. It is found that, for a flow rate controlled Newtonian flow system, viscosity and outlet pressure have little effect on velocity distribution. When the fluid is assumed to be Non-Newtonian more fluid is separated than observed in the Newtonian case, leading to reduction of the flow rate ratio between the main and side channels as well as the system pressure as a whole.

Absorption Measurements in Liquid Core Waveguides Using Cavity

Short liquid core waveguides (LCWs) were included into a fiber-loop cavity ring-down absorption spectrometer to reduce the detection limit over, both, single pass absorption in a LCW and cavityenhanced absorption using a conventional fiber-loop cavity. LCWs of 5 and 10 cm length were interfaced with a pressure-flow system and a multimode fiber-loop cavity using concave fiber lenses with matching numerical apertures and diameters. Two red dyes, Allura Red AC and Congo Red, were detected with a 532 nm pulsed laser at a 5 nM limit of detection in a detection volume of less than 1 μL, corresponding to a minimal detectable absorbance of less than 4 × 10−4 cm−1 and a minimal detectable change in absorption cross section, σmin = Vdet × ε × CLOD, of about 14 μm2 (Allura Red AC) and 37 μm2 (Congo Red).

A comparison of nitogen fate and transport in catchments underlain by high and low permeability aquifers using chemical and isotopic tools.

Variability in nitrogen fate and transport in different catchments types is often not considered. This research considers the importance of such nitrogen processes within groundwater pathways in two agricultural catchments in Ireland; a well drained catchment, underlain by karstified Carboniferous limestone, and a poorly drained catchment, underlain by Silurian greywacke.
Depth specific low-flow groundwater sampling was used to evaluate the hydrochemical stratification in groundwater. Groundwater samples, as well as surface water samples, along river courses were analysed for nitrogen species (NO3, NH4 and NO2) and nitrate isotopes (d15N and d18O) as well as field parameters and major ions
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The dominant nitrate (NO3) groundwater pathway in the poorly drained greywacke catchment is through the shallow weathered bedrock, as indicated by transmissivity values and the ionic and isotopic signatures, and a clear reduction in NO3 concentration is observed with depth. A similar chloride trend would suggest dilution is a major factor, however d15N and d18O isotopic values producing an enrichment ratio of 1.8 indicate that denitrification is also an important process involved in the fate of the NO3 within the groundwater flow system. This consistent trend with depth is in contrast to the stratification pattern observed in the karstified catchment. NO3 was not detected in the shallow groundwater pathway; the dominant groundwater pathway is in the deeper groundwater where there is little change in the nitrate isotope values with depth (d15N values range between 4.1 and 4.6 ‰). This deeper groundwater contributes the dominant proportion of the river flow through a number of springs. As a result, the deeper groundwater, springs and river have a similar ionic signature and NO3 concentration range (23 ± 3 mg/l). Despite this pattern, the NO3 isotopes show a distinct difference in isotopic values between the deeper groundwater in the diffuse karst and the springs indicating some denitrification is occurring during groundwater discharge into the river. Furthermore the isotopes give an indication of the variability of the spatial extent of the springs and the complexities of the fissures through which they are fed. The results of this study clearly show the importance of the geology in the fate and transport of NO3 in agricultural catchments.

Effet de l’espèce de plante en marais filtrants artificiels selon la saison, le type de marais filtrant et la nature des polluants

Cette thèse a été codirigée par le Dr. Florent Chazarenc

Évaluation de l’effet des vagues de bateau sur les conditions hydrauliques près des berges en milieu fluvial

Les vagues de bateau ajoutent une pression supplémentaire sur les berges de rivières et doivent être considérées dans les modèles de prédiction des taux de recul des berges. L’objectif de cette étude est d’examiner le rôle des vagues de bateau sur l’écoulement et le transport en suspension le long des berges en milieu fluvial. Pour atteindre cet objectif, nous utilisons un transect perpendiculaire à la berge de quatre courantomètres électromagnétiques (ECMs) mesurant deux dimensions de l’écoulement et deux turbidimètres (OBSs) placés dos à dos, orientés vers la berge et le large pour mesurer les conditions moyennes et turbulentes de l’écoulement longitudinal et vertical ainsi que les flux de sédiments en suspension provoqués par les vagues. Une chaloupe à moteur de 16 pieds, équipée d’un moteur 40 hp, a été utilisée afin de générer des vagues. Nous avons mesuré l’effet de trois distances à partir de la berge (5, 10, 15 m) et trois vitesses de bateau (5, 15 et 25 km/h) et cinq répliques de chaque combinaison de distance et de vitesse ont été réalisées, totalisant 45 passages. Nous avons caractérisé la variabilité des conditions d’écoulement, de vagues et de transport de sédiments et nous avons réalisé des analyses spectrales afin de séparer les portions oscillatoire et turbulente de l’écoulement généré par les vagues de bateau. L’effet de la distance et de la vitesse du bateau sur le transport de sédiments est non-linéaire et la réponse sédimentaire induite par les passages de bateau montre une variabilité importante entre les répliques et les deux sondes OBS, ce qui suggère un changement morphologique induit par les vagues de bateau. Les corrélations entre les variables d’écoulement et de transport montrent l’importance des relations entre le cisaillement et la puissance de la portion turbulente de l’écoulement avec le transport de sédiments. Cette étude a permis de quantifier les relations entre la dynamique des vagues et les flux de concentrations de sédiments en suspension, ce qui représente une contribution importante au développement de mesures de mitigation dans les environnements fluviaux où les berges sont fragilisées par le trafic plaisancier.

The infrared spectrum, equilibrium structure and harmonic and anharmonic force field of thioborine, HBS

Infrared spectra of the two stretching fundamentals of both HBS and DBS have been observed, using a continuous flow system through a multiple reflection long path cell at a pressure around 1 Torr and a Nicolet Fourier Transform spectrometer with a resolution of about 0•1 cm-1. The v3 BS stretching fundamental of DBS, near 1140 cm-1, is observed in strong Fermi resonance with the overtone of the bend 2v2. The bending fundamental v2 has not been observed and must be a very weak band. The analysis of the results in conjunction with earlier work gives the equilibrium structure (re(BH) = 1•1698(12) , re(BS) = 1•5978(3) ) and the harmonic and anharmonic force field.

Gas-solid reactions of single crystals: a study of reactions of NH3 and NO2 with single crystalline organic substrates by infrared microspectroscopy

Reaction of single crystals of benzoic and trans-cinnamic acids with 200 Torr pressure of ammonia gas in a sealed glass bulb at 20 degrees C generates the corresponding ammonium salts; there is no sign of any 1:2 adduct as has been reported previously for related systems. Isotopic substitution using ND3 has been used to aid identification of the products. Adipic acid likewise reacts with NH3 gas to form a product in which ammonium salts are formed at both carboxylic acid groups. Reaction of 0.5 Torr pressure of NO2 gas with single crystals of 9-methylanthracene and 9-anthracenemethanol in a flow system generates nitrated products where the nitro group appears to be attached at the 10-position, i.e. the position trans to the methyl or methoxy substituent on the central ring. Isotopic substitution using (NO2)-N-15 has been used to confirm the identity of the bands arising from the coordinated NO2 group. The products formed when single crystals of hydantoin are reacted with NO2 gas under similar conditions depend on the temperature of the reaction. At 20 degrees C, a nitrated product is formed, but at 65 degrees C this gives way to a product containing no nitro groups. The findings show the general applicability of infrared microspectroscopy to a study of gas-solid reactions of organic single crystals. (c) 2005 Elsevier B.V. All rights reserved.

Experimental determination of layer cloud edge charging from cosmic ray ionisation

The cloud-air transition zone at stratiform cloud edges is an electrically active region where droplet charging has been predicted. Cloud edge droplet charging is expected from vertical flow of cosmic ray generated atmospheric ions in the global electric circuit. Experimental confirmation of stratiform cloud edge electrification is presented here, through charge and droplet measurements made within an extensive layer of supercooled stratiform cloud, using a specially designed electrostatic sensor. Negative space charge up to 35 pC m−3 was found in a thin (<100 m) layer at the lower cloud boundary associated with the clear air-cloud conductivity gradient, agreeing closely with space charge predicted from the measured droplet concentration using ion-aerosol theory. Such charge levels carried by droplets are sufficient to influence collision processes between cloud droplets.

Kinetic studies of reactions of the nitrate radical (NO3) with peroxy radicals (RO2): an indirect source of OH at night?

A discharge-flow system, coupled to cavity-enhanced absorption spectroscopy (CEAS) detection systems for NO3 at lambda = 662 nm and NO2 at lambda = 404 nm, was used to investigate the kinetics of the reactions of NO3 with eight peroxy radicals at P similar to 5 Torr and T similar to 295 K. Values of the rate constants obtained were (k/10(-12) cm(3) molecule(-1) s(-1)): CH3O2 (1.1 +/- 0.5), C2H5O2 (2.3 +/- 0.7), CH2FO2 (1.4 +/- 0.9), CH2ClO2 (3.8(-2.6)(+1.4)), c-C5H9O2 (1.2(-0.5)(+1.1)), c-C6H11O2 (1.9 +/- 0.7), CF3O2 (0.62 +/- 0.17) and CF3CFO2CF3 (0.24 +/- 0.13). We explore possible relationships between k and the orbital energies of the reactants. We also provide a brief discussion of the potential impact of the reactions of NO3 with RO2 on the chemistry of the night-time atmosphere.

VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way

We describe the public ESO near-IR variability survey (VVV) scanning the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high. The survey will take 1929 h of observations with the 4-m VISTA telescope during 5 years (2010-2014), covering similar to 10(9) point sources across an area of 520 deg(2), including 33 known globular clusters and similar to 350 open clusters. The final product will be a deep near-IR atlas in five passbands (0.9-2.5 mu m) and a catalogue of more than 106 variable point sources. Unlike single-epoch surveys that, in most cases, only produce 2-D maps, the VVV variable star survey will enable the construction of a 3-D map of the surveyed region using well-understood distance indicators such as RR Lyrae stars, and Cepheids. It will yield important information on the ages of the populations. The observations will be combined with data from MACHO, OGLE, EROS, VST, Spitzer, HST, Chandra, INTEGRAL, WISE, Fermi LAT, XMM-Newton, GAIA and ALMA for a complete understanding of the variable sources in the inner Milky Way. This public survey will provide data available to the whole community and therefore will enable further studies of the history of the Milky Way, its globular cluster evolution, and the population census of the Galactic Bulge and center, as well as the investigations of the star forming regions in the disk. The combined variable star catalogues will have important implications for theoretical investigations of pulsation properties of stars. (C) 2009 Elsevier B.V. All rights reserved.

Well-preserved Late Paleoproterozoic volcanic centers in the Sao Felix do Xingu region, Amazonian Craton, Brazil

The Amazonian craton in the Sao Felix do Xingu city, southeast region of the Para state, north of Brazil, hosts exceptionally well-preserved Paleoproterozoic bimodal magmatic units grouped in the Sobreiro and Santa Rosa formations. These formations are correlated to the Uatuma magmatic event, which is largely distributed in the Amazonian craton occupying more than 1,500,000 km(2). Geological mapping and petrographical observations reveal distinct spectra of volcanic facies in both formations. The basal calc-alkaline Sobreiro Formation is composed mainly of andesitic and dacitic lava flows and associated volcaniclastic facies of autoclastic origin, with subordinate pyroclastic flow deposits. This formation shows inferred eruption style that is similar to those in Flood Basalt Provinces, with rare scutulum-type lava shields. The upper A-type Santa Rosa Formation was generated by multicyclic explosive and effusive episodes predominantly associated with large fissures and is materialized by voluminous ignimbrites with subordinated ash-fall tuff, crystal tuff, lapilli-tuff, co-ignimbritic breccias, rhyolitic dikes and domes, and associated granitic porphyries and equigranular granitic intrusions. Ignimbrite and rhyolite dikes reveal conspicuous vertical flow pattern pointing to a fissure-controlled eruption, similar to Sierra Madre Occidental ignimbrite province. The proposed evolutionary model for the Sao Felix do Xingu units differs from those of other occurrences related to the Uatuma magmatic event in the Amazonian craton, characterized by predominance of A-type volcanism and contemporaneous granites. (C) 2010 Elsevier B.V. All rights reserved.

Temperature (over) compensation in an oscillatory surface reaction

Biological rhythms are regulated by homeostatic mechanisms that assure that physiological clocks function reliably independent of temperature changes in the environment. Temperature compensation, the independence of the oscillatory period on temperature, is known to play a central role in many biological rhythms, but it is rather rare in chemical oscillators. We study the influence of temperature on the oscillatory dynamics during the catalytic oxidation of formic acid on a polycrystalline platinum electrode. The experiments are performed at five temperatures from 5 to 25 degrees C, and the oscillations are studied under galvanostatic control. Under oscillatory conditions, only non-Arrhenius behavior is observed. Overcompensation with temperature coefficient (q(10), defined as the ratio between the rate constants at temperature T + 10 degrees C and at T) < I is found in most cases, except that temperature compensation with q(10) approximate to I predominates at high applied currents. The behavior of the period and the amplitude result from a complex interplay between temperature and applied current or, equivalently, the distance from thermodynamic equilibrium. High, positive apparent activation energies were obtained under voltammetric, nonoscillatory conditions, which implies that the non-Arrhenius behavior observed under oscillatory conditions results from the interplay among reaction steps rather than, from a weak temperature dependence of the individual steps.

Comportamento do reator seqüencial em batelada (RSB) sob estado estacionário dinâmico utilizando idade do lodo como parâmetro de controle operacional

O reator seqüencial em batelada (RSB) é uma variante de lodos ativados capaz de promover a remoção da matéria orgânica, a remoção dos nutrientes e a separação da fase sólida da líquida em uma unidade. A valorização das áreas urbanas, a carência de tratamento terciário e a crescente necessidade de redução nas dimensões de estações de tratamento de esgoto devem impulsionar o desenvolvimento de pesquisas sobre RSB em curto espaço de tempo. A partir deste cenário, o presente trabalho teve como objetivo modelar o comportamento do reator seqüencial em batelada a partir da teoria desenvolvida por Marais e colaboradores. Dentro deste contexto, a cinética de oxidação dos compostos orgânicos e do nitrogênio na forma amoniacal foi descrita e modelada. O trabalho experimental foi realizado em duas escalas: bancada e piloto. O experimento em escala de bancada foi dividido em duas fases. Foram utilizados dois RSBs e um sistema de fluxo contínuo. Um reator seqüencial em batelada (RSB1) foi operado com idade de lodo. O outro reator em batelada (RSB2) foi operado em função da relação F/M e o sistema de fluxo contínuo (FC1) por idade de lodo. Estes reatores foram utilizados como controle no monitoramento do RSB1 Na primeira fase, os três sistemas removeram apenas matéria orgânica. Na fase seguinte, removeram matéria orgânica e nitrogênio. A partir dos resultados obtidos em escala de bancada, foi possível concluir que o modelo desenvolvido pode ser aplicado ao reator seqüencial em batelada operando com idade de lodo, permitindo determinar a qualidade do efluente, a produção de lodo e o consumo de oxidante. Além disso, foi possível descrever o comportamento da taxa de consumo de oxigênio em função da oxidação da matéria orgânica biodegradável e da oxidação do nitrogênio na forma amoniacal. O reator seqüencial em batelada operado com idade de lodo (RSB1) alcançou remoção média de matéria orgânica de 90 % nas idades de lodo de 30, 20, 10 e 5 dias. A remoção média de nitrogênio mais elevada foi obtida na idade de lodo de 20 dias e atingiu 87 %. Nas demais idades de lodo a remoção média de nitrogênio variou entre 79 e 42 %. A modelagem do comportamento do reator seqüencial em batelada resultou numa proposta de metodologia para o dimensionamento que tem como finalidade abolir critérios obsoletos e inadequados para o dimensionamento de lodos ativados em batelada No experimento em escala piloto, foram utilizados um reator seqüencial em batelada, denominado RSB, e um sistema de fluxo contínuo com a configuração Bardenpho, denominado FC. Os sistemas de lodos ativados sob investigação foram monitorados em duas idades de lodo: 30 e 10 dias. Os dados do experimento em escala piloto mostraram que os processos físico-químicos e biológicos envolvidos na remoção de matéria orgânica e nitrogênio no RSB foram mais eficientes do que no Bardenpho quando trataram o mesmo esgoto doméstico e foram submetidos às mesmas condições operacionais. No RSB, obteve-se 88 e 89 % de remoção de matéria orgânica nas idades de lodo de 10 e 30 dias, respectivamente. Nesta seqüência das idades de lodo, a eficiência do Bardenpho caiu de 87 para 76 %. O sistema de fluxo contínuo removeu 66 e 52 % do nitrogênio total afluente nas idades de lodo de 10 e 30 dias, respectivamente. A eficiência do RSB na remoção de nitrogênio foi determinada apenas na idade de lodo de 10 dias e alcançou 69 %. A partir dos resultados obtidos em escala de bancada e piloto, constata-se que o reator seqüencial em batelada operando com idade de lodo pode ser utilizado no tratamento de esgoto doméstico e obter eficiência na remoção de matéria orgânica e nitrogênio igual ou superior ao sistema de fluxo contínuo.