Bertrand, Olivier

Mazaudou, Bernard

Sauvaget, Patrick

Schaguene, Julien

English

Hydraulic Engineering Repository

Article, Published VersionBertrand, Olivier; Schaguene, Julien; Mazaudou, Bernard; Sauvaget,PatrickNew trends in modeling applied to wastewater treatmentand potable waterHydrolinkVerfügbar unter/Available at: https://hdl.handle.net/20.500.11970/109326Vorgeschlagene Zitierweise/Suggested citation:Bertrand, Olivier; Schaguene, Julien; Mazaudou, Bernard; Sauvaget, Patrick (2016): Newtrends in modeling applied to wastewater treatment and potable water. In: Hydrolink 2016/2.Madrid: International Association for Hydro-Environment Engineering and Research (IAHR).S. 42-44. https://iahr.oss-accelerate.aliyuncs.com/library/HydroLink/HydroLink2016_02_Hydraulics_Wastewater_Treatment.pdf.Standardnutzungsbedingungen/Terms of Use:Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichendenNutzungsbedingungen getroffen wurden. Damit ist sowohl die kommerzielle Nutzung als auch das Teilen, dieWeiterbearbeitung und Speicherung erlaubt. Das Verwenden und das Bearbeiten stehen unter der Bedingung derNamensnennung. Im Einzelfall kann eine restriktivere Lizenz gelten; dann gelten abweichend von den obigenNutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte.Documents in HENRY are made available under the Creative Commons License CC BY 4.0, if no other license isapplicable. Under CC BY 4.0 commercial use and sharing, remixing, transforming, and building upon the materialof the work is permitted. In some cases a different, more restrictive license may apply; if applicable the terms ofthe restrictive license will be binding.42 hydrolink number 2/2016Figure 1. Simulation of water renewal within a circular/rectangular storage mega reservoirModern and environmentally developed citiesuse large sewage network systems to collectand transport all types of wastewater fromhomes to wastewater treatment facilities. At thetreatment plant, different processes are used toremove most of the pollutants from the waste-water. The efficiency of the treatment dependsnot only on the degree of purification applied towastewaters, but also on the ability of the facil-ities to treat the effluent homogeneously andwithout temporal variations.Artelia, as an independent engineering, projectmanagement and consulting group, operates innine markets including industry, water,environment and urban development, providingservices to private clients (industrial groups,developers, investors, building contractors, etc.)as well as to public clients (government depart-ments, local authorities, international fundingagencies, etc.). This article provides a briefoverview of Artelia’s use of modelling in supportof the design of water storage, transfer struc-tures, treatment installations and the devel-opment of solutions for decontaminatingwastewater.From simple to more complex modelMost of the structures involved in watertreatment or storage are large, but theirperformance is affected by small details in theirdesign (orifices, distribution weirs, baffles, etc.)and is highly sensitive to the definition of thewater surface, a few centimeters of watersurface variation having significant influence.This can be illustrated by the following project(Figure 1) the aim of which was to design analternative back-up system (reservoirs, pumpingstations and interconnection with the existingnetwork) in order to secure continuous watersupply. This involved a total storage capacity of17 Mm3 broken down into 5 storage sites. Thissystem was susceptible to be used in case ofsea water pollution or major power shortage fora country where water supply currently relies ondesalinated water source plants. MegaReservoirs structures were designed in order toachieve a 7-Day strategic water stock at anytime within the network system. The dimen-sioning of the reservoirs was one of the mainaspects of the project.This objective was achieved thanks to a 3Dnon-hydrostatic numerical model withadvection-diffusion of a conservative tracer toquantify the renewal time, elaborated on thebasis of open source TELEMAC modellingsystem. The flow was free surface only. Variousbaffle geometries and positions of orifices weresimulated and compared to minimize detentiontime in the water domain and to avoid recircu-lation or stagnant areas. Internal baffles wereplaced in the water storage tanks in order todirect and control the flow of water and toreduce water stagnation. Interacting physical and numericalmodelsPhysical and numerical modelling approachesare very complementary in the global study ofthe hydraulic structure of a water treatment plantand for many projects we performedcomparison of both tools.Physical scale models remain an incomparableresource when it comes to the analysis,communication and discussion of mostcomplex development projects. Their experi-mental and practical nature provides guidancefor engineers to understand various phenomenaand help them determine high-performancesolutions to manage projects in full compliancewith specific requirements. They make it easierto explain phenomena by presenting theexisting situation and changes to be expectedonce the project is implemented. PhysicalNEW TRENDS IN MODELING APPLIED TO WASTEWATER TREAT-MENT AND POTABLE WATERBY OLIVIER BERTRAND, JULIEN SCHAGUENE, BERNARD MAZAUDOU & PATRICK SAUVAGET43hydrolink number 2/2016IAHRAfter having obtained gen-eral training in fluid me-chanics and transfers,Olivier Bertrand developednumerous computationcodes in such varied fields as crystallogene-sis, compression of petroleum fluids, oceanicand river modelling, transport of oil slicks.As Project Manager/Director, he participatesin particular in expert appraisal and complexhydraulic. He provides his experience in hy-draulic development and its impact on theenvironment at different levels, from simpleadvisory services to design and innovativemodelling studies. In particular, he runs andcoordinates research and development proj-ects associated with these problems.In February 2015, he became Leader of theNumerical Hydraulic Modelling team andProject Director in the Maritime businessunit. Bernard Mazaudou partici-pated in the developmentand maintenance of theCAREDAS computer modelfor simulating unsteadyflows in urban seweragenetworks, which constitutes the hydraulicsmodule of the CANOE system that has beenco-developed since 1992 by Artelia and INSA(engineering college in Lyons, France). Healso manages complex hydraulic studies formajor water and waste water transmissionschemes and pumping facilities, coveringboth steady and unsteady flow conditions.He is currently a project manager for waterand wastewater studies within the Water &Solid Waste - International Activities busi-ness unit of Artelia Ville & Transport.Following a general trainingin fluid mechanics, JulienSchaguene has specialisedin numerical modelling applied to the mechanics ofunconfined surface flows. Julien Schaguene isa hydraulic modelling project manager in thefields of maritime, river and structural engineering. In this framework he is develop-ing particular skills in the implementation ofthree-dimensional numerical models, notablyusing the CFD OpenFOAM computation code. Patrick Sauvaget has 36years of professional experi-ence in the field of numeri-cal modeling applied to thewater environment. After obtaining an engineering degree in Hydraulics(INPG, Grenoble, France), he passed a mas-ter’s thesis in civil and environmental engineer-ing (University of Iowa, USA) and a PhD thesisin fluid mechanics (INPG, Grenoble, France).He is presently head of the Hydraulics depart-ment of Artelia Eau & Environnement, Greno-ble, France. He acted as project leader or proj-ect director of water and environmental studiesin various domains: hydraulics and water qual-ity in rivers, coastal hydrodynamics, flood riskmanagement, water resources management,water distribution, etc.Contact:olivier.bertrand@arteliagroup.comblock the water flow along the upstream walls ofeach compartment, but the whole mass ofwater was in contact with the gas phase. Theozonated air transfer to water to be treated wasmore important for the diffusers positionedupstream of the compartments.models allow visualization and quantification offlow and solute transport by directly simulatingthese phenomena.On the other hand, mathematical modelsreplicate these physical processes throughmathematical governing equations, boundaryconditions, and initial conditions. Mathematicalmodels and computer simulations are alsoessential to describe, predict and control thecomplicated interactions of the processes. Thenumber of reactions and organism speciesinvolved in wastewater treatment may be verylarge. An accurate description of such systemscan therefore result in highly complex models,which may not be very useful from an opera-tional point of view. Numerical modelling has theadvantage of allowing flexibility in selectingproblem parameters, being this way bettersuited for predicting results under differentscenarios.As an example of numerical application, watertreatment plants are generally classified byimplemented processes. Treatments could bephysical (filters, settlers…) and/or chemical(coagulation, biological…). The use of ozone inwaste water as chemical treatment isexpanding. It is an accepted fact that drinkingwater is disinfected when a residual of ozonehas been maintained for few minutes. Thedesign of ozone generators and treatmentchambers can be improved with the use ofmodeling.In this application case (Figure 2), a model wasset up and used to assess the behaviour of theozonation tower. The entire tower was repre-sented in the model and ozonated air diffuserspositioned at the apron were included in themodel. Two-phase modeling thus allowedsimulating both the fluid phase and the gasphase. No exchange between the phases wasconsidered. The rise of gas bubbles tended toOpen source software and adistributed computer environmentWith the explosive growth of meshdiscretization there is a shift from the use ofsingle desktop computers to using computerclusters. At the same time the use of OpenSource software (as OpenFOAM) is gainingFigure 2. Analysisof the correctmixing in anozonation tower (left: plume ofwater/ozonatedair (99% water)and free surface;right: watervolume out ofcontact with theozonated airpopularity as it provides free access tocomputer programming codes allowing experi-enced users to modify equations, to programnew processes, or to optimize numericalsolvers. These choices allow in the end to buildnumerical models totally adapted to theengineering problem to be solved.These computational hardware and softwarefacilities made it possible for instance to studythe flow in a distribution chamber with weirswhich is used to avoid unequal distribution(Figure 3). This kind of geometry required thecomputation of a mixed free surface andconfined flow. The Volume Of Fluid (VOF)method that was used is simple, but it allowsvery complex free surface tracking. In this casethe mesh (spatial discretization) was refinednear the walls, at the free surface and in poten-tially highly turbulent areas.For all these studies, expertise on core businessand Computational Fluid Dynamics is extremelyimportant, as well as improvements in theFigure 3. Flow analysis of anupstream distri-bution chamberspeed of scientific computations. They facilitatethe use of more complex models, producebetter designs by the multiplication of tests,reduce the time of the development phase andat the end the costs of new projects. nReferencesBertrand O., Lavedrine A., Rebai A., David E., Pierrefeu G., RoumieuP. 2011 – Numerical modelling of the Vaugris reservoir on theRhône with Telemac 3D. Proceeding of the XVIIIth Telemac &Mascaret User Club, Chatou, France, October 19–21.Daou, M. P., Blayo, E., Rousseau, A., Bertrand, O., Tayachi, M.,Coulet, C., & Goutal, N. 2015. Coupling 3-D Navier Stokes and 1-D Shallow Water. La Houille Blanche, (6), 29-33.Loisel, P.E., Schaguene J., Bertrand O., Guilbaud C., 2015.Comparative study between numerical and physical hydraulicmodelling of flood spillway structures. ICOLD 25th Congress,Stavanger, Norway, June 17-19, 2015.

New trends in modeling applied to wastewater treatment and potable water

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New trends in modeling applied to wastewater treatment and potable water

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