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Multi-objective optimal control of small-size wastewater treatment plants

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journal contribution
posted on 2015-08-28, 08:43 authored by Hreiz Rainier, Nicolas Roche, Brahim BenyahiaBrahim Benyahia, M.A. Latifi
In this work, a multi-objective dynamic optimization of the operating strategy of a small-size wastewater treatment plant is carried out. In-situ incineration of the excess sludge produced for electricity production is investigated in order to reduce the operating costs. The trade-offs between the treatment quality and the operating costs are characterized. Compared to the literature, emphasis is put on a more rigorous formulation of the problem and an accurate modeling of the underlying phenomena so as to get physically relevant solutions. Thus, from a mathematical perspective, the problem is formulated so that the solution is less sensitive to the – arbitrarily chosen – plant initial conditions. Modeling of physical phenomena e.g. the detrimental effect of the concentration of suspended solids in the mixed liquor, on oxygen transfer rate, has been included in the model. Several constraints are added to the problem so as to maintain the optimal solutions within the limits of validity of the mathematical model. The results provided a clear picture about the trade-offs between the treatment quality and the exploitation costs. Sludge incineration was shown to be of a high energetic profit, but it does not allow the plant to be electrically autonomous


The authors want to thank the CARNOT Institutes of Nancy (ICEEL - Lorraine University) and Marseille (STAR - Aix-Marseille University) for the funding of the project oWWTP.



  • Aeronautical, Automotive, Chemical and Materials Engineering


  • Chemical Engineering

Published in

Chemical Engineering Research and Design




345 - 353


RAINIER, H. ...et al., 2015. Multi-objective optimal control of small-size wastewater treatment plants. Chemical Engineering Research and Design, 102 pp. 345 - 353


© Elsevier


  • AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date



This paper was accepted for publication in the journal Chemical Engineering Research and Design and the definitive published version is available at http://dx.doi.org/10.1016/j.cherd.2015.06.039




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