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Introduction
Current institution
Current position
- Director of Research
Additional affiliations
July 2001 - present
Publications
Publications (120)
Characterising bioflocculation and settling in activated sludge processes is mandatory to better understand and optimise organic matter removal and capture. Among the few indicators available, Threshold Of Flocculation (TOF) reflects the ability of activated sludge to settle following Stokesian settling mechanisms. In this work, the method original...
Pour traiter les eaux résiduaires, le procédé à boues activées conventionnel reste le plus utilisé dans les pays industrialisés. Ce procédé peut être intensifié en densifiant la biomasse épuratoire. L’installation d’hydrocyclones sur la boucle d’extraction des boues, créant une pression de sélection des particules les plus denses, est l’une des mét...
This review compiles information on sidestream characteristics that result from anaerobic digestion dewatering (conventional and preceded by a thermal hydrolysis process), biological and primary sludge thickening. The objective is to define a range of concentrations for the different characteristics found in literature and to confront them with the...
This book describes theory and approach for a comprehensive and applied physicochemical model for wastewater treatment. These are reactions which occur without a biological mediator, and are critical to both the biology of wastewater treatment, and stand-alone chemical treatment units. The book includes description of acid-base theory, solution ion...
In response to the growing global resource scarcity, wastewater is increasingly seen as a valuable resource to recover and valorise for the benefit of the society rather than another waste that needs treatment before disposal. Conventional wastewater treatment plants (WWTPs) oxidises most of the organic matter present in wastewater, instead of reco...
Les capteurs sont utilisés en continu ou ponctuellement dans la gestion des ouvrages d’assainissement, mais les coûts d’achat et de maintenance des sondes apparaissent fréquemment trop élevés d’après les collectivités et les exploitants dont les moyens financiers sont de plus en plus contraints. Dans ce contexte, de nombreux capteurs à bas coût arr...
The formation of hydrogen sulfide (H2S) during anaerobic digestion (AD) imposes constraints on the valorisation of biogas. So far, inorganic sulfur compounds -mainly sulfate - have been considered as the main contributors to H2S formation, while the contribution of organic sulfur compounds is mostly neglected. This study investigates the fate of or...
This study proposed to develop a model coupling hydrodynamics and mass transfer in order to gain an understanding of measurements taken on air-water bubble columns with low gas hold-up. Three experimental datasets with various operating conditions (water quality, liquid height, air flow range) were chosen. The model analyzes and interprets the sign...
To move today’s agricultural and urban systems towards tomorrow’s circular economy and respond to climate change, it is imperative to turn organic residues and wastewater into resourceful assets. This article discusses the changes that are needed in research to drive this paradigm shift and to go from a “losses and waste” situation to a “resource a...
La mission principale du groupe de travail Epnac est de mettre à disposition des informations techniques sur la conception, le dimensionnement et l’exploitation des ouvrages de traitement des eaux usées adaptés au contexte rural. Il s’adresse notamment aux maîtres d’oeuvre et maîtres d’ouvrage, qu’ils soient issus du domaine privé ou public. Le gro...
Even though sulfur compounds and their transformations may strongly affect wastewater treatment processes, their importance in water resource recovery facilities (WRRF) operation remains quite unexplored, notably when it comes to full-scale and plant-wide characterization. This contribution presents a first-of-a-kind, plant-wide quantification of t...
In conventional activated sludge (CAS) systems and membrane bioreactors (MBR), aeration, mixing and filtration are affected by various properties of activated sludge (AS) and especially viscosity and morphological properties of flocs.
The aim of the present study was to understand the relationship between hydrodynamic conditions and AS floc size pr...
The optimization of full-scale digesters requires the development of models able to describe the main process performances, due to the strategic role of anaerobic digestion in the sustainability of Water Resource Recovery Facilities (WRRF). In this study, an extended version of the Anaerobic Digestion Model No 1 (ADM1) was developed to simulate the...
The availability of mathematical models capable of accurately describing the operation of a Wastewater Treatment Plant (WWTP) is essential to support the transition of this industry towards a sustainable concept. Traditionally, the simulation of the processes involved in the sludge line of a WWTP has been performed using models based on constant ef...
La digestion des boues de station d’épuration suscite de plus en plus d’intérêt auprès des collectivités. Ce procédé biologique permet en effet de réduire de façon importante le volume des boues produites, de les stabiliser et de générer du biogaz. Ce biogaz peut être valorisé sous forme d’énergie thermique et/ou électrique, être utilisé comme bioc...
La digestion des boues de station d’épuration suscite de plus en plus d’intérêt auprès des collectivités. Ce procédé biologique permet en effet de réduire de façon importante le volume des boues produites, de les stabiliser et de générer du biogaz. Ce biogaz peut être valorisé sous forme d’énergie thermique et/ou électrique, être utilisé comme bioc...
Les bioréacteurs à membranes se sont largement développés ces dernières années en assainissement des eaux résiduaires urbaines. Malgré les avantages du procédé, le colmatage des membranes engendre des contraintes économiques liées aux coûts énergétiques et au remplacement prématuré des membranes. Différentes stratégies de limitation du colmatage so...
Gas-liquid mass transfer in wastewater treatment processes has received considerable attention over the last decades both from academia and industry. Indeed, improvements in modelling gas-liquid-mass transfer can bring huge benefits in terms of reaction rates, plant energy expenditure, acid-base equilibria and greenhouse gas emissions. Despite thes...
powerful greenhouse gas contributing to ozone layer depletion. While recent models have greatly
improved our understanding of the triggers of N2O emissions from suspended-growth processes, less is
known about N2O emissions from full-scale biofilm processes.
Tertiary nitrifying BAFs have been modeled at some occasions but considering strong simplifi...
Membrane bioreactors (MBRs) are widely used in wastewater treatment processes. However, membrane fouling mitigation remains challenging. Several strategies have been developed industrially to enhance MBR productivity, including coarse bubble aeration. The way such aeration participates in hydrodynamic patterns is an important research topic given i...
Experimental laboratory methods and techniques have matured to the degree that they have become accepted as reliable tools in wastewater treatment research and practice. For sector professionals, especially the new generation of young scientists and engineers entering the wastewater treatment profession, the quantity, complexity and diversity of th...
Le contrôle des émissions de gaz à effet de serre, en particulier celles du protoxyde d'azote (N2O), constitue un enjeu émergent du secteur du traitement des eaux usées. Aujourd'hui, la compréhension des mécanismes de production de N2O dans les procédés à biomasse fixée, potentiellement très émetteurs, est moins avancée que pour les procédés conven...
Des mesures d'émission de protoxyde d'azote (N2O, puissant gaz à effet de serre) ont été réalisées sur les unités de biofiltration de la station de Seine Aval au cours de l'année 2014 (période estivale) et 2015 (période hivernale). Ces travaux s'inscrivent dans le cadre de l'axe n°1 du programme Mocopée « Métrologie et traitement du signal » et vis...
Les bioréacteurs à membranes se sont largement développés ces dernières années en assainissement domestique urbain. A ce jour, deux installations du Siaap sont équipées de ce procédé (Seine Aval, Seine Morée). Cependant, le colmatage des membranes reste une problématique industrielle importante pouvant entrainer des coûts énergétiques et de remplac...
In the last few years, the emission of nitrous oxide (N2O) from constructed wetlands has become a topic of
increased interest. Most N2O emission measurements made so far are based on limited grab-samples, leading to
sparse temporal resolution in the data. Using a high sampling frequency strategy, gaseous and dissolved N2O
emissions from a two-stage...
Mathematical models for the sludge line of a full-scale WWTP were developed with the aim of being integrated in a whole-plant model. A model describing the primary clarifier was also included. Reconciled data from plant routine sampling over a 2-year period together with data from dedicated campaigns were used to develop and calibrate the models. D...
Les politiques européennes des trente dernières années, impulsées par la Directive Eaux Résiduaires Urbaines de 1991 (91/271/CEE) et plus récemment par la directive cadre sur l’eau (2000/60/CE), ont conduit à la mise en conformité des stations d’épuration dans la plupart des pays de l’UE, comme le montre notamment le récent rapport au parlement eur...
Aeration is an essential component of aerobic biological wastewater treatment and is the largest energy consumer at most water resource recovery facilities. Most modelling studies neglect the inherent complexity of the aeration systems used. Typically, the blowers, air piping, and diffusers are not modelled in detail, completely mixed reactors in a...
In this study, nitrous oxide (N2O) emissions from a full-scale denitrifying biofilter plant were continuously monitored over two periods (summer campaign in September 2014 and winter campaign in February 2015). Results of the summer campaign showed that the major part (>99%) of N2O flux was found in the liquid phase and was discharged with the effl...
A full-scale nitrifying biofilter was continuously monitored during two measurement periods (September 2014; February 2015) during which both gaseous and liquid N2O fluxes were monitored on-line. The results showed diurnal and seasonal variations of N2O emissions. A statistical model was run to determine the main operational parameters governing N2...
Aluminium and iron chloride were added to a biological nutrient removal pilot plant (1,500 population equivalent) treating urban wastewater to investigate the control of Microthrix parvicella bulking and foaming by metallic salts. Monitoring plant performance over two 6-month periods showed a slight impact on the removal efficiencies. Addition of m...
L’analyse du fonctionnement des stations d’épuration, et a fortiori l’utilisation d’outils de modélisation dynamique de ce fonctionnement, s’appuient sur un ensemble de données issues de mesures pouvant être entachées d’erreurs. Ces données, acquises pour l’autosurveillance de l’installation ou pour son exploitation, doivent donc être validées de m...
Dans l’objectif de mieux comprendre l’impact des caractéristiques des boues activées sur leur comportement rhéologique et sur le transfert d’oxygène, un dispositif expérimental, constitué d'une colonne à fines bulles de 0,3 m3 alimentée en boues activées en continu et d'un rhéomètre capillaire, a été mis en oeuvre sur une station d’épuration à boue...
This work investigated the impact of aeration control strategy on energy consumption and nitrous oxide (N 2 O) emission in a full-scale wastewater treatment plant. Two identical activated sludge processes treating the same effluent but operated with different aeration control strategies were compared. Aeration tank 1 was operated with a new control...
This work investigated the impact of aeration control strategy on energy consumption and nitrous oxide (N2O) emission in a full-scale wastewater treatment plant. Two identical activated sludge processes treating the same effluent but operated with different aeration control strategies were compared. Aeration tank 1 was operated with a new control s...
Increasingly stringent effluent limits and an expanding scope of model system boundaries beyond activated sludge has led to new modelling objectives and consequently to new and often more detailed modelling concepts. Nearly three decades after the publication of Activated Sludge Model No1 (ASM1), the authors believe it is time to re-evaluate wastew...
This work critically reviews modelling concepts for standard activated sludge wastewater treatment processes (e.g. hydrolysis, growth and decay of organisms, etc.) for some of the most commonly used models. Based on a short overview on the theoretical biochemistry knowledge this review should help model users to better understand i) the model conce...
L'impact des paramètres géométriques et opératoires sur le transfert de masse dans un réacteur à lit fluidisé semi-industriel (d'un volume maximal de 2,8 m3) a été étudié. Le coefficient volumique de transfert d'oxygène (kLa20) a été mesuré en eau claire sur un ensemble de 39 conditions opératoires. Les résultats obtenus mettent en évidence l'impac...
Wastewater Treatment Process Modeling, Second Edition provides expert guidance to ensure that process models are developed, used, and documented correctly. This authoritative guide helps process engineers understand general modeling concepts and terminology and offers practical details on how to use process models for the design of small, medium, a...
Although mathematical modelling of activated sludge systems has become a widely accepted engineering tool, model results are only useful if the model predictions are reliable.
The level of detail and quality required for simulation studies varies greatly depending on the project objectives, the resources committed to the project and the available e...
RESUME Les dysfonctionnements biologiques dus au développement de bactéries filamenteuses posent de nombreux problèmes d'exploitation aux stations d'épuration du type boues activées. Le filament le plus souvent mis en cause dans ce type de dysfonctionnement en France est Microthrix parvicella. La solution curative la plus utilisée actuellement est...
Mathematical modelling of activated sludge systems is used widely for plant design,
optimisation, training, controller design and research. The quality of simulation
studies varies depending on the project objectives, finances and expertise available.
Consideration has to be given to the model accuracy and the amount of time required
to carry out a...
Building an aeration system requires a major investment, with blowers typically being the single most costly piece of equipment at a WWTP. Aeration is also responsible for about 50-60 % of the total energy demand for an activated sludge plant. Moreover the DO concentration controls
which processes are active or kinetically limited. The investment a...
L’optimisation des dispositifs d’aération équipant les bassins aérobies des stations d’épuration est essentielle pour garantir la qualité du traitement des eaux résiduaires, mais aussi pour limiter les coûts de construction et énergétiques des installations. À l’aide de la mécanique des fluides numérique, Irstea développe des modèles pour améliorer...
Le groupe de travail Good Modelling Practice de l’IWA a analysé les pratiques et l’expérience en matière d’utilisation des outils de modélisation du fonctionnement des boues activées, et a élaboré une procédure afin de mener à bien un projet de modélisation, de manière systématique, et en concertation avec l’ensemble des partenaires du projet. Le p...
The IWA Task Group on Good Modelling Practice (GMP) has analysed current practice and experience on the use of activated sludge models. The group developed a framework to make modelling more straightforward and that helps structuring the interaction between modellers and the project stakeholders. The GMP protocol is a synthesis of existing procedur...
Over the past decades in Europe, man-made ecosystems such as constructed wetland systems have been successfully harnessed to treat sewage and other pollutants in waste waters. This work presents a comparative Life Cycle Assessment (LCA) study between (i) a 2-stage vertical Reed Bed Filter, and (ii) a conventional activated sludge system, both desig...
This study aims at synthesizing experiences in the practical application of ASM type models. The information is made easily accessible to model users by creating a database of modelling projects. This database includes answers to a questionnaire that was sent out to model users in 2008 to provide inputs for a Scientific and Technical Report of the...
Oxygen transfer in biological wastewater treatment processes with high sludge concentration, such as membrane bioreactor (MBR), is an important issue. The variation of alpha-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...
Mixing and aeration characteristics obtained on three full scale loop reactors for 28 configurations (different mixers' location and rotation speed, air flow rates and diffuser grids' location) were analyzed. The propellers' thrust was measured in situ. Observed values vary with the tank geometry, the location of the mixers and the induced axial ve...
Mathematical process modeling is used extensively in research, plant design, optimization, training, and model-supported design of process control strategies. The IWA Task Group on Good Modelling Practice (GMP, https://iwa-gmp-tg.cemagref.fr/)
has analyzed current practice and experience (Hauduc et al., 2009) and out of this evaluation developed a...
The first objective of this work was to evaluate the ability of the long-term BOD tests to provide the total biodegradable COD (BCOD) for domestic wastewaters. Results show that the method is repeatable (using two different volume samples, 97 and 164 mL) and that the fractions of BCOD determined were not statistically different from the one obtaine...
Les procédés biologiques sont largement utilisés pour le traitement des déchets liquides et solides contenant une fraction importante de matières biodégradables. Pour les optimiser, ils sont souvent étudiés à partir des outils de modélisation, dont l’utilisation implique de compartimenter la matière organique en plusieurs fractions plus ou moins ra...
The objective of this experimental study was to collect and to interpret data in order to better understand the oxygen mass transfer phenomena occurring in full-scale aeration tanks equipped with fine bubble diffusers and slow speed mixers (inducing horizontal liquid flows). Bubble size, local depth and oxygen mass transfer coefficient were measure...
The quality of simulation results can be significantly affected by errors in the published model (typing, inconsistencies, gaps or conceptual errors) and/or in the underlying numerical model description. Seven of the most commonly used activated sludge models have been investigated to point out the typing errors, inconsistencies and gaps in the mod...
One of the key parameters for membrane bioreactor (MBR) design and operation is the air supply and the related energy consumption. The objective of this work was to investigate how the alpha factor varies with MLSS for both fine and coarse aeration systems in full scale MBR plants. Oxygen transfer rates were determined in two MBR plants with large...
This paper serves as a problem statement of the issues surrounding uncertainty in wastewater treatment modelling. The paper proposes a structure for identifying the sources of uncertainty introduced during each step of an engineering project concerned with model-based design or optimisation of a wastewater treatment system. It briefly references th...
The Good Modelling Practice Task Group (GMP-TG) of the International Water Association (IWA) is developing guidelines for the use of Activated Sludge Models (ASM). As part of this work the group created and sent out a questionnaire to current and potential activated sludge model users in 2007. The objectives of the questionnaire were (i) to better...
The Activated Sludge Model number 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 rev...
The past several years have seen a significant increase in the use of computer models to simulate wastewater treatment processes for plant design and optimization. The quality and level of detail of these models vary widely, depending on their purpose, availability of resources and the skill level of the modeler. Modelers use different approaches a...
The present study aims at optimizing 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...
The objective of this work was to analyse the impact of different geometric and operating parameters on the alpha factor value for fine bubble aeration systems equipped with EPDM membrane diffusers. Measurements have been performed on nitrifying plants operating under extended aeration and treating mainly domestic wastewater. Measurements performed...
The present study aims at determining most likely values for the maximum growth rate (µ A, max) and the endogenous decay rate (b A) 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...
This paper exemplifies the beneficial use of CFD models coupled to mass transfer equations to optimize fine bubble aeration systems in closed-loop reactors. The models, previously validated at different scales (Fayolle et al. 2007), allow assessing the impact of the design and operating parameters on the oxygenation performances. In this article, t...
The objective of this work was to analyse the impact of different geometric and operating parameters on the alpha factor value for fine bubble aeration systems equipped with EPDM membrane diffusers. Measurements have been performed on nitrifying plants operating under extended aeration and treating mainly domestic wastewater. Measurements performed...
In order to optimize aeration in the activated sludge processes, an experimentally validated numerical tool, based on computational fluid dynamics and able to predict flow and oxygen transfer characteristics in aeration tanks equipped with fine bubble diffusers and axial slow speed mixers, is proposed. For four different aeration tanks (1;1493;8191...
The Activated Sludge Model n°1 (ASM1) published in 1987 is still one of the main models used in simulation projects for design and optimization of processes. It was published with a set of default parameter values at 20°C and at 10°C that reflected the best knowledge twenty years ago. Several recent lab-scale studies using experiments conducted und...
Les procédés biologiques à biomasse en suspension, du type des boues activées, sont largement appliqués pour le traitement des eaux usées urbaines ou industrielles. Généralement, ces procédés sont dimensionnés sur la base d'équations de bilans « matières » établis à partir de l'hypothèse d'un régime permanent. Pourtant ces systèmes subissent contin...
MBRs necessitate two sources of aeration: one for scouring the membranes (coarse bubble, CB) and the other for the biomass requirements (usually fine bubble, FB). In the framework of a in-depth study of a full scale municipal MBR plant (10 000 p.e.) where CB and FB are in the same tank (Biosep®), mass balances were used to determine the OTR of the...
The European Directive 91/271/EEC related to domestic wastewater treatment, and the new
requirements of the European Water Framework Directive (WFD 2000/60/CE) have induced numbers
of new-built and upgraded wastewater treatment plants (WWTPs). As they are mainly dedicated
to nitrogen removal, even in non-sensible areas, these WWTPs often include ac...
Measurement methods to determine in situ local parameters were developed, in order to optimize design and operating parameters impacting oxygen transfer in aeration tanks equipped with EDPM membrane diffusers and slow speed mixers. New tools to measure bubble sizes and gas hold-ups were coupled with the traditional ones used to determine liquid vel...
To determine the oxygen mass transfer in clean water in biofilters, a method based on the follow up of the oxygen fraction in the off gas during the oxidation of sulphite in excess has been evaluated and applied to a pilot-scale unit (250 L, superficial gas velocity from 0 to , superficial liquid velocity from 0 to ). Tests performed on a two-phase...
The standard oxygenation performances of fine bubble diffused aeration systems in clean water, measured in 12 cylindrical tanks (water depth from 2.4 to 6.1m), were analysed using dimensional analysis. A relationship was established to estimate the scale-up factor for oxygen transfer, the transfer number (N(T)) The transfer number, which is written...
Since airing amounts to more than half the energy bill of activated sludge waste water treatment plants, this process needs to be optimized. This article gives a summary of the data and experiences linked to the installation and utilization of air injection systems in which fine bubbles are injected through EPDM membranes, which is the most widely...
