Search

At the request of the French Ministry for Ecological and Inclusive Transition (MTES) and the French Biodiversity Agency (AFB), INRAE carried out a study focusing on the creation of a national asset knowledge base for drinking water networks, operating at Water Agency (WA) scale. Our study involved the creation of a number of statistical models. These models combine data relating to network characteristics (gathered from a sample of utilities) with geographical and demographical data collected from all municipalities in France. The SISPEA database, along with GIS data from a sample covering around half of the total French drinking water network, were used to configure multi-linear pipe models by diameter, installation period and type of material. On the basis of these models, the total length of drinking water pipes in mainland France was estimated to be 875,000 km. Networks are quite young (60% of the total length was laid after 1970), small diameter pipes are the majority (70% of the pipes have a diameter less than or equal to 100 mm) and the materials used are linked on geographic areas (pipes are mainly made of PVC in the west of France while cast iron pipes predominate in the other regions).

International audience; Drinking water supply networks are essential for the economic activity of territories, for their attractiveness and for the well-being of inhabitants. Maintaining a high performance of service over time requires taking into consideration many variables such as ageing infrastructures, demographic changes, socioeconomic dynamics and climate change consequences. In this context, Water Infrastructures Asset Management (WIAM) faces several challenges. This article presents the results of an original forecasting approach based on an interdisciplinary research carried out by a group of engineering and social scientists, and stakeholders. The main objective was to design various possible pathways for the future of a French territory and craft scenarios for WIAM strategies to 2070. The article describes first the main issues WIAM is facing in a global change context. Second we present the original forecasting method used. Third we expose the results and particularly the four prospective scenarios that describe the possible pathways of WIAM by 2070. Fourth scenarios are applied to four case studies in order to build prospective infrastructure needs scenarios. And finally we propose their implications for WIAM strategies and discuss the benefits and limits of such an approach to improve water management.

National audience; At the request of the French Ministry for Ecological and Inclusive Transition (MTES) and the French Biodiversity Agency (AFB), Inrae (Institut national de recherche pour l’agriculture, l’alimentation et l’environnement) carried out a study focusing on the creation of a national asset knowledge base for drinking water networks, operating at Water Agency (WA) scale. Our study involved the creation of a number of statistical models. These models combine data relating to network characteristics (gathered from a sample of utilities) with geographical and demographical data collected from all municipalities in France. The Sispea database (Système d’information des services publics d’eau et d’assainissement), along with GIS data from a sample covering around half of the total French drinking water network, were used to configure multi-linear pipe models by diameter, installation period, and type of material. On the basis of these models, the total length of drinking water pipes in mainland France was estimated to be 875,000 km. Of that figure, less than 40% were installed before 1970. Seventy percent of pipes are at least 100 mm in diameter. In the Loire-Bretagne and Adour-Garonne areas, the majority of pipes are made of PVC, while cast iron is more common in other areas.; À la demande du ministère français de la Transition écologique et solidaire (MTES) et de l’Agence française pour la biodiversité (AFB) pour contribuer à la conduite des politiques publiques de l’eau, l’Institut national de recherche pour l’agriculture, l’alimentation et l’environnement (Inrae) a mené une étude pour mettre en place un dispositif national de connaissance du patrimoine des réseaux d’eau potable à l’échelle des agences de l’eau. La méthode mise en oeuvre repose sur la construction de modèles statistiques qui relient les caractéristiques des réseaux, collectées pour un échantillon de services, à des données géographiques et démographiques disponibles à l’échelle communale de façon exhaustive sur le territoire français. La base de données Sispea (Système d’information des services publics d’eau et d’assainissement) et les données SIG (système d’information géographique) recueillies auprès d’un échantillon de services qui représentent environ la moitié du réseau français, ont été utilisées pour caler des modèles multilinéaires des longueurs de canalisation par diamètre, période de pose et matériau. Ils permettent d’estimer la longueur des canalisations d’eau potable de la France métropolitaine à 875000 km, dont moins de 40% ont été posées avant 1970. 70% des conduites sont d’un diamètre au plus égal à 100 mm et les canalisations en PVC sont très majoritaires dans les bassins Loire-Bretagne et Adour-Garonne tandis que celles en fonte dominent dans les autres bassins.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]GEUSI [Coll_IRSTEA]Programme 2016/2018 action n°70; La finalité de l'action est de construire un dispositif permanent d'évaluation du patrimoine des réseaux d'eau potable aux échelles nationale et de bassin, basé sur l'exploitation des descriptifs détaillés de services publics de l'eau et adapté aux besoins de l'Etat et des Agences de l'Eau pour orienter leur politiques publiques liées à la gestion patrimoniale des réseaux d'eau potable. Compte tenu de la lourdeur et de la difficulté de constituer une base de données nationale exhaustive (cf. les taux de remplissage de la base de données SISPEA), il apparait qu'une approche statistique est à privilégier. Afin d'adapter au mieux la connaissance du patrimoine (données, niveau de précision, mise à jour…) aux besoins des utilisateurs potentiels, il convient à la fois d'en effectuer une analyse préalable puis de valider l'adéquation à ces besoins du dispositif proposé. Enfin, une approche économique et financière est nécessaire pour évaluer in fine les coûts de la gestion patrimoniale, appréhender les éventuelles disparités territoriales et envisager les enjeux à moyen et long termes. Le présent rapport présente l'avancement des travaux fin 2017.

An alternative design of the membrane aerated biofilm reactor (MABR) was developed to overcome some of the current technical and economical limitations preventing full scale applications of the process. The ZeeLung system uses a new dense hollow-fibre membrane with an unprecedented thin diameter. Two pilot units treating a synthetic high-strength industrial wastewater (4700 mgCOD/L, 145 mgTKN/L) operated successfully for 16 months. They performed simultaneous COD removal, nitrification and denitrification. The very high specific surface area (810 m2/m3) allowed the surface loading rate to be kept low enough (3.6 gCOD/(m2.d)) to maintain a relatively thin biofilm (200 to 350 microm) and use low-pressure air (41 kPa) instead of high-pressure pure oxygen. Intermittent air and liquid mixing at high frequency and low shear were compared: they were equally effective in enhancing substrate transfer, but failed to stabilize biofilm accumulation. Air sparging additionally prevented the acidification of the bulk by stripping CO2.

A full-scale demonstration of an integrated fixed-film activated sludge (IFFAS) process with floating carriers has been conducted in Ontario, Canada, since August 2003. In this study, data collected on-site from July 2005 to December 2006 are analyzed and compared with the performance of a conventional activated sludge train operated in parallel. Both trains received similar loadings and maintained comparable mixed liquor concentrations; however, the IFFAS had 50% more biomass when the attached growth was considered. In the winter, the conventional train operated at the critical solids retention time (SRT) and had fluctuating partial nitrification. The IFFAS nitrified more consistently and had a doubled average capacity. In the summer, the suspended SRT was less limiting, and the benefit of IFFAS for nitrification was marginal. The lessons learned from the operational requirements and challenges of the IFFAS process (air flow, carrier management, and seasonal foaming) are discussed, and design recommendations are proposed for whole plant retrofit.

An integrated fixed-film activated sludge (IFFAS) process with four media cells is operating in parallel with a conventional activated sludge (CAS) train at Lakeview Wastewater Treatment Plant (Ontario, Canada). During winter 2007, an intensive sampling campaign was conducted to monitor the temporal and spatial variations of the nitrification capacity within the two plug-flow reactors. At the beginning of the six-week study, the CAS train was partially nitrifying, whereas the IFFAS train was nitrifying completely using the first two IFFAS cells only. Within one week, the CAS train lost nitrification because of a drop in solids retention time and pH caused by the onset of iron overdosing. When the IFFAS train received an iron spike, the carriers at the injection point (first cell) became iron-coated and lost 80% of their nitrification capacity. However, this train maintained its total nitrification capacity using the reserve capacity in the three remaining cells.

The Vesilind settling velocity function forms the basis of flux theory used both in state point analysis (for design and capacity rating) and one-dimensional dynamic models (for dynamic process modelling). This paper proposes new methods to address known shortcomings of these methods, based on an extensive set of batch settling tests conducted at different scales. The experimental method to determine the Vesilind parameters from a series of bench scale settling tests is reviewed. It is confirmed that settling cylinders must be slowly stirred in order to represent settling performance of full scale plants for the whole range of solids concentrations. Two new methods to extract the Vesilind parameters from settling test series are proposed and tested against the traditional manual method. Finally, the same data set is used to propose an extension to one-dimensional (1-D) dynamic settler models to account for compression settling. Using the modified empirical function, the model is able to describe the batch settling interface independently of the number of layers.

The objective of this article is to compare the advantages and disadvantages of the sequencing batch reactor (SBR) versus the more conventional continuous flow reactor (CFR) setup for pilot plant studies. The SBR process can offer many superior features for research applications. The control of operational conditions is more reliable, precise and versatile. Data collection by sampling and on-line sensors is made easier, and results are more representative. Kinetic and settling tests that need to be conducted in a separate bench-scale reactor for a CFR can be carried out directly within an SBR pilot plant. Even routine data contains more information than obtained from a CFR, since each SBR cycle is equivalent to a batch treatment experiment. The drawbacks of an SBR pilot plant mainly concern the transferability of certain kinetic and settling results to (full scale) completely mixed flow-through reactors, and some experimental limitations due to the cyclic operation. It is expected that this comparison will support the decision of research teams intending to design a wastewater treatment pilot plant. If an SBR process is selected, some specific design recommendations are given at the end of this paper to make sure that its potential advantages are realized.

International audience; Présentation d'une étude de cas de réduction des consommations énergétiques liées à l'aération des boues activées.

Even if fouling in membrane bioreactors (MBRs) has been extensively studied during the last decade, its causes and mechanisms are not well understood yet. Furthermore, few full-scale and long-term experiments have been published, and their results do not always match with the models developed from lab-scale studies. A statistical approach linking long-term and short-term permeability evolution with operational variables in full-scale membrane bioreactors for domestic waste-water treatment is presented. Data originate from a 66,700 P.E. MBR plant monitored for more than one year. Permeability and several fouling indicators were calculated in each of the four hollow-fibre membrane tanks of the plant. The influence of SRT, temperature, MLSS, F:M ratio, iron dosing and membrane flux on daily permeability evolutions, instantaneous permeability evolution and hydraulic backwash efficiency was studied. In order to minimise the bias due to correlations between input variables, a statistical approach using principal component regression and partial least-square regression was tested. Flux, temperature, SRT and F:M ratio are the most influential input variables on long-term permeability evolutions. Iron dose and MLSS are less correlated with fouling indicators. The proposed approach may be improved by integrating the history of the membrane to better describe and predict the permeability evolution. (C) 2013 Elsevier B.V. All rights reserved.

Oxygen transfer in biological wastewater treatment processes with high sludge concentration, such as membrane bioreactor (MBR), is an important issue. The variation of α-factor versus mixed liquor suspended solids (MLSS) concentration was investigated in a full scale MBR plant under process conditions, using mass balances. Exhaustive data from the Supervisory Control And Data Acquisition (SCADA) and from additional online sensors (COD, DO, MLSS) were used to calculate the daily oxygen consumption (OC) using a non-steady state mass balance for COD and total N on a 24-h basis. To close the oxygen balance, OC has to match the total oxygen transfer rate (OTRtot) of the system, which is provided by fine bubble (FB) diffusers in the aeration tank and coarse bubbles (CB) in separate membrane tanks. First assessing OTRCB, then closing the balance OC=OTRtot allowed to calculate OTRFB and to fit an exponential relationship between OTRFB and MLSS. A comparison of the α-factor obtained by this balance method and by direct measurements with the off-gas method on the same plant is presented and discussed.

International audience; Nutrient assimilation was revisited using a steady state model developed from the activated sludge modeling concepts. While nitrogen assimilation is only related to organic particulate fractions, the role of inorganic complexes and precipitates was accounted for in phosphorus assimilation. It is shown that the influent aluminum background concentration may contribute significantly to phosphorus assimilation, and that in 3.6% of cases, calcium phosphate may precipitate in activated sludge. A global sensitivity analysis was conducted with the Monte Carlo method to identify the most sensitive model parameters and input variables. The nutrient content of the unbiodegradable mixed liquor fractions emerged as the most sensitive parameters and were calibrated using databases and some assumptions. Most of the remaining variability of nutrient assimilation then comes down to four variables (three influent concentration ratios and SRT), which were used to prepare charts to predict assimilation in design and operation. For an SRT of 20 days, it is proposed to update the typical empirical BOD5:N:P ratio from 100:5:1 to 100:5.7:1.4.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [Axe_IRSTEA]TED-EPURE; International audience; A full-scale membrane bioreactor (1600 m3.d-1) was monitored for modelling purposes during the summer of 2006. A complete calibration of the ASM1 model is presented, in which the key points were the wastewater characterisation, the oxygen transfer and the biomass kinetics. Total BOD tests were not able to correctly estimate the biodegradable fraction of the wastewater. Therefore the wastewater fractionation was identified by adjusting the simulated sludge production rate to the measured value. MLVSS and MLSS were accurately predicted during both calibration and validation periods (20 and 30 days). Because the membranes were immerged in the aeration tank, the coarse bubble and fine bubble diffusion systems coexisted in the same tank. This allowed five different aeration combinations, depending whether the 2 systems were operating separately or simultaneously, and at low speed or high speed. The aeration control maintained low DO concentrations, allowing simultaneous nitrification and denitrification. This made it difficult to calibrate the oxygen transfer. The nitrogen removal kinetics were determined using maximum nitrification rate tests and an 8-hour intensive sampling campaign. Despite the challenges encountered, a calibrated set of parameters was identified for ASM1 that gave very satisfactory results for the calibration period. Matching simulated and measured data became more difficult during the validation period, mainly because the dominant aeration configuration had changed. However, the merit of this study is to be the first effort to simulate a full-scale MBR plant.

International audience; The Activated Sludge Model n°1 (ASM1) is the main model used in simulation projects focusing on nitrogen removal. Recent laboratory-scale studies have found that the default values given 20 years ago for the decay rate of nitrifiers and for the heterotrophic biomass yield in anoxic conditions were inadequate. To verify the relevance of the revised parameter values at full scale, a series of simulations were carried out with ASM1 using the original and updated set of parameters at 20°C and 10°C. The simulation results were compared with data collected at 13 full-scale nitrifying-denitrifying municipal treatment plants. This work shows that simulations using the original ASM1 default parameters tend to overpredict the nitrification rate and underpredict the denitrification rate. The updated set of parameters allows more realistic predictions over a wide range of operating conditions.

The present study aims at optimising the nitrification and denitrification phases at intermittently aerated process (activated sludge) removing nitrogen from municipal wastewater. The nitrogen removal performance recorded at 22 intermittently aerated plants was compared to the results obtained from the simulations given by the widely used ASM1. It is shown that simulations with a single value for the heterotrophic yield with any electron acceptor over-predict the nitrate concentration in the effluent of treatment plants. The reduction of this coefficient by 20% for anoxic conditions reduces the nitrate concentration by 10 g N·m-3. It significantly improves the accuracy of the predictions of nitrate concentrations in treatedeffluents compare to real data. Simulations with dual values (aerobic and anoxic conditions) for heterotrophic yield (modified ASM1) were then used to determine the practical daily aerobic time interval to meet a given nitrogen discharge objective. Finally, to support design decisions, the relevance of a pre-denitrification configuration in front of an intermittently aerated tank was studied. It is shown that when the load of BOD5 is below the conventional design value, a small contribution of the anoxic zone to nitrate removal occurs, except for over-aerated plants. When plants receive a higher load of BOD5, the modified ASM1 suggests that the anoxic zone has a higher contribution to nitrogen removal, for both correctly and over-aerated plants.

The present study aims at determining most likely values for the maximum growth rate (μA, max) and the endogenous decay rate (bA) of nitrifiers for activated sludge processes treating municipal wastewater operated at low temperature (10°C). The work used nitrification rate data measured on 10 full-scale plants and 2 pilot plants fed with domestic sewage. This set of data was combined with a modelling and a theoretical approach. The unified values (μA, max = 0.45·d-1 and bA = 0.13·d-1) were obtained at 10°C for the kinetic parameters of the autotrophic biomass in the SRT range 10 to 50 d. In addition, the factors affecting the expected nitrification rate (rv, nit) were established by a theoretical approach and confirmed by experimental results. For a given SRT, a linear relationship with the nitrogen volumetric loading rate was shown. The COD/TKN ratio of the influent on the nitrification rate was demonstrated. Finally, an operational tool for the verification of the nitrification rate in the design procedure of activated sludge processes is proposed.Keywords: nitrification; kinetics; low temperature; autotrophic biomass, maximum growth rate; decay rate

The measured volatile suspended solids (VSS) fraction of activated sludge is assumed to represent the organic fraction of suspended solids. However, mineral suspended solids can also lose some mass at 550C. Experiments were performed on iron phosphate and hydroxide precipitates, which form upon ferric addition into the secondary stage for phosphorus removal. They showed that the precipitates lose 6 to 18% of their mass during VSS measurement. Suggested explanations are loss of bound water and partial chemical decomposition involving gas formation. Experiments showed that the extent of mass loss will depend on actual temperature and duration of heat exposure during the VSS measurement, as well as implementation of a washing step to remove dissolved solids from the mass retained on the filter. VSS thus overestimate the truly organic fraction of sludge. The error will increase with the mineral content of the sludge, which depends on influent characteristics, chemical doses and sludge retention time (SRT). Two case studies show that if several of these factors occur in combination on the plant, the error will be significant compared to the VSS measurement error. If the measured sludge VSS fraction is used in calculations, the actual F/M ratio and SRT will be underestimated and the actual sludge wastage rate will be overestimated.

International audience; This study deals with wastewater treatment plant (WWTP) loading and performance when receiving combined sewage. A yearly data set from an activated sludge plant operating at very low food-to-mass ratio (F/M) and being intermittently aerated was analyzed statistically to compare loading and discharge during dry and wet weather. The results show that despite some loading increase, the nitrogen removal performance is only slightly affected by rain, whereas higher soluble COD load discharge is observed. This approach was supplemented with dynamic simulations with the Activated Sludge Model No 1 (ASM1). It was first calibrated on data from an intensive 48-h dry weather sampling campaign at 20 °C. A good fit between simulated and measured variables was obtained after adjusting five parameters of the ASM1. This parameter set was then validated on a wet weather sampling campaign. Once the confidence in the simulations' results was established, several wet-weather scenarios were simulated, with maximum flow and variable pollutant loading. They show that the higher COD load discharge is due to a hydraulic flush of soluble inert compounds, and how the biological potential can be used to treat almost any realistically possible carbon and nitrogen overload.; Cette étude traite du comportement d'une station d'épuration en temps de pluie. Dans un premier temps, les données routinières d'une station par boues activées faible charge aérée de façon intermittente ont été analysées statistiquement pour comparer les affluents et effluents temps sec et temps de pluie. Il ressort de cette analyse que, malgré une hausse des charges entrantes à la station en temps de pluie, la performance au niveau de l'enlèvement de l'azote n'est que peu affectée, alors qu'on observe une augmentation de la charge de DCO soluble rejetée. En deuxième lieu, pour compléter cette analyse, une simulation dynamique du comportement de la station en temps de pluie a été effectuée à l'aide du modèle ASM1. Le modèle a tout d'abord été calé à l'aide de données récoltées lors d'une campagne intensive d'échantillonnage de temps sec de 48 h. Une bonne représentation du comportement de la station a été obtenue en ajustant 5 paramètres du modèle. Le calage a ensuite été validé avec des données récoltées en temps de pluie. Par la suite, plusieurs scénarios de temps de pluie, avec le débit nominal maximal et des charges variables, ont été simulés pour vérifier et expliquer le comportement de la station en temps de pluie. Les résultats montrent que l'augmentation de la charge de DCO soluble dans l'effluent de la station est due à un lessivage hydraulique de la DCO soluble inerte, et que le potentiel biologique peut être utilisé pour traiter toute charge supplémentaire d'azote ou de carbone susceptible d'arriver en temps de pluie.

A methodology that is specific of the effluent to be treated is necessary to chose the solution in function of constraints. The problematic is presented by developing the functioning specificities of biologic treatments when they are applied to viniculture effluents. Stress is on half-continue processes that are adapted to little units of wine transformation., Une large gamme de procédés de traitement est désormais applicable aux effluents vinicoles et une méthodologie spécifique à ce type d'effluent est nécessaire pour choisir la solution la plus adaptée en fonction des contraintes (caractéristiques des rejets, qualité requise pour les des eaux traitées, environnement, capacités de stockage, .). La problématique est présentée en développant les spécificités de fonctionnement des traitements biologiques lorsqu'ils sont appliqués aux effluents vinicoles. Une large place est donnée aux procédés semi-continus adaptés aux petites unités de vinification, en particulier aux différentes techniques couplant stockage aéré et techniques de séparation de la biomasse formée.

Les caractéristiques du réseau public d’alimentation en eau potable (hors branchements particuliers) sont évaluer aux échelles nationale et par grand bassin. Ainsi la longueur totale des réseaux de France métropolitaine ( évaluée à 875 000 km et environ 890 000 km avec les DROM) est déclinée par matériaux, diamètres et périodes de pose pour l'année 2017,A l’échelle nationale, un peu moins de 40% des réseaux encore en service (38.2%) ont été posés avant 1970. 70% des conduites ont un diamètre inférieur ou égal à 100 mm. Les canalisations en PVC totalisent près de la moitié du linéaire (47%) tandis que 41% des conduites sont en fonte.D’importantes disparités territoriales ont été constatées. Par exemple, près de 70% des conduites du bassin Loire-Bretagne sont en PVC tandis que ce matériau ne concerne que 14% du linéaire du bassin Artois-Picardie. Dans ce dernier, la proportion du linéaire de canalisations en Amiante Ciment est de 18,4% alors qu’elle est de 4% en moyenne nationale.

Une large gamme de procédés de traitement est désormais applicable aux effluents vinicoles et une méthodologie propre à ce type d'effluents est nécessaire pour choisir la solution la plus adaptée en fonction des contraintes (caractéristiques des rejets, qualité requise pour les eaux traitées, environnement, capacités de stockage in situ...). Les spécificités de fonctionnement des traitements biologiques appliqués aux effluents vinicoles sont rappelées ainsi que les performances possibles. Une large place est donnée aux procédés semi-continus adaptés aux petites unités de vinification, en particulier aux différents systèmes couplant stockage aéré et traitement complémentaire de finition. / A wide range of processes is now applicable to the treatment of winery effluents and a specific methodology should be applied to choose the solution the most adapted according to the constraints (characteristics of effluents, quality required for treated waters, environment, storage capacity). The specificity of biological treatment applied to winery effluents is reminded as well as the possible performances. A wide development is given to the partial batch processes adapted to the small units of wine making, especially to the various systems associating aerated storage and various techniques of additional finishing treatment.