Colomer Cugat, M. Angeles

Fernández García, Belén

Flotats Ripoll, Xavier

Illa Alibes, Josep

Palatsi Civit, Jordi

UPCommons

Identintifying anaerobic digestion models using simultaneous batch experiments

UPCommons. Portal del coneixement obert de la UPC

Published by: Govern de les Illes BalearsConselleria d’Agricultura i PescaEusebio Estada, 145. Palma de Mallorca. Balearic Island. SPAINEdited by:Isabel Sastre Conde, Hervé Macarie, Gerardo López López, Ana Mª Ibáñez Burgos Carme Garau, Joana María Luna, Joan March, Antoni Martorell Margalida Colombas, Jaume Vadell, Jeroni Vera Jose Luis SanzMembers of the 3IMEBE OrganizationDesign of the Draws by: Macarena Moreno MorenoIII Campus Universitario. 28300 Aranjuez. Madrid. SPAINDesign and printing: Gràfiques TerrasaISBN: 978-84-692-4948-2Deposito Legal: PM-1549-20092151 IDENTIFYING ANAEROBIC DIGESTION MODELS USING SIMULTANEOUS BATCH EXPERIMENTSFlotats X.1*, Palatsi J.1, Fernández B.1, Colomer M.A.2, Illa J.31 GIRO Technological Centre, Rambla Pompeu Fabra 1, E-08100 Mollet del Vallès, Barcelona, Spain. Phone: +34935796780; Fax: +34935796785. 2 Dept. of Mathematics, University of Lleida,Avda. Rovira Roure 191, E-25198Lleida, Spain. 3 Dept. of Computing and Industrial Engineering, University of Lleida, Avda. Jaume II, 69-71, E-25001Lleida, SPAIN. * Contact and presenter: xavier.flotats@giroct.irta.esAs in other wastewater treatment processes, anaerobic digestion models have become a valuable tool to increase theunderstanding of complex biodegradation processes, to teach and to communicate using a common language, to opti-mize design plants and operating strategies and for trying operators and process engineers. Models require accurate andsignificant parameter values for being useful. Although the calibration problem is an issue of concern, often is neglect-ed. A method for calibration is the use of simultaneous batch experiments (SBE), which requires simple and usuallyavailable equipment, and is based on the analysis of replications and the responses obtained when starting from differ-ent initial conditions. The objective of the present work is to systematize the SBE method, illustrating and discussingthe applicable steps.The main steps of the method are: 1.) Set up the mathematical model and define the calibration problem. Namely,define exactly the problem to be solved; 2.) Preliminary experimental design approach. Set-up different SBE character-ized by different initial conditions, define the output function, characterized by the variables that can be measured dur-ing the experiments, and define variables which initial values can be known; 3.) Perform a structural identifiabilitystudy, consisting of a theoretical analysis to find out whether the designed experiment can lead to a unique set of param-eter values and unknown initial conditions (i.e., initial microorganisms concentrations); 4.) Perform the experimentaldesign leading to parameters and initial biomass identification, based on previous step results; 5.) Perform the practi-cal identification or estimation of the unknowns, as a result of optimizing an objective function, i.e. maximizing the sumof multiple determination coefficients for all measured variables and for all simultaneous experiments performed; 6.)Study the statistical characterization of estimated parameter values, calculating its confidence intervals, its statisticalsignificance and the correlation matrix; and 7.) Return to step 4) or 1) if step 6) provides low significance levels for thecalculated parameters or if the model structure cannot explain experimental behavior. Taking into account that appropriate experimental design depends on kinetic parameters values, which determinationis, actually, the objective of the work, results of previous experiments or results from literature are required to orientateinitial substrate and biomass concentrations to be used, in order to obtain an experimental design allowing unique andsignificant parameter values. The explanation of every step is done providing the theoretical basis, discussing applica-ble methods and equations, and illustrating with examples, some of them previously published*.Acknowledgements: This research was supported by the Spanish Ministerio de Educación y Ciencia (Project REN2004-00724).REFERENCES* Flotats, X., Ahring, B.K. and Angelidaki, I. (2003). Parameter identification of thermophilic anaerobic degradation of valerate. AppliedBiochemistry and Biotechnology, 109, 47-62.Flotats, X., Palatsi, J., Ahring, B.K., Angelidaki, I. (2006). Identifiability study of the proteins degradation model, based on ADM1, using simul-taneous batch experiments. Water Science and Technology, 54(4), 31-39.58 / 3IMEBEII WASTEWATER AND SOLID WASTE MANAGEMENT, TREATMENT AND REUSEWastewater Biological Treatments

Identintifying anaerobic digestion models using simultaneous batch experiments

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