Know more

Research activities

The simultaneous treatment of nitrogen and carbon content of the polluted effluents requires the implementation of complementary ecosystems functioning in aerobiosis (in the presence of oxygen) and anaerobiose (in the absence of oxygen). The work of Djalel Mazouni(1) yielded to the developement of a hybrid optimal control strategy of the sequencing batch reactor under interest.

The objective of my thesis is to revisit the proposed strategy in taking into account the fact that nitrogen and carbon removal may be realized simultaneously according to the oxygen concentration. Then, we will evaluate whether (i) this strategy allows an improvement in the treatment time needed to reach a target and (ii) if we can decrease the total oxygen quantity needed to do so or not.

The model suggested in the thesis of D. Mazouni being too complex to solve the complete problem, I decided first to study a degraged version oàf the problem involving two species in competition on two distinct substrates.  More precisely, I considered a model with two biological reactions involving the degradation of two types of slowly biodegradable substrates by two types of biomass. One of the reactions is aerobic while the other reaction is anaerobic. I solved two specific optimal control problems. One is a problem of minimal time and the other is the minimization of a compromise between the time and the energy of the oxygen consumed in the biological reaction.

 1. Mazouni, D, PhD – Optimization ofdiscontinuous sequential bioréacteurs, Universityof Montpellier II, (2005).

Publications

• W. Bouhafs–Mélange et biodégradation,  Actes de la  5ème conférence sur les tendances des Applications  Mathématiques en  Tunisie, Algérie, Maroc, Sousse, 23-26 Avril 2011,  Tunisie, M. Hassine and M. Moakher (Editeurs), Centre de Publication  Universitaire (2011) , 427-433.

• MED 2012, 20th Mediterranean Conference on Control and Automation, July 3-6, 2012, Barcelona, Spain (Invited session). Titre : Commande optimale en temps minimal d’un procédé biologique d’épuration de l’eau. Auteurs: W. Bouhafs, N. Abdellatif, F. Jean, J. Harmand.