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Modeling and optimization of activated sludge bioreactors for wastewater treatment taking into account spatial inhomogeneities



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Crespo, M. and Ivorra, Benjamin and Ramos del Olmo, Ángel Manuel and Rapaport, Alain (2017) Modeling and optimization of activated sludge bioreactors for wastewater treatment taking into account spatial inhomogeneities. Journal of Process Control, 54 . pp. 118-128. ISSN 09591524


Official URL: http://www.sciencedirect.com/science/article/pii/S0959152417300720



In this work, we study optimal and suboptimal control strategies for the treatment of a polluted water resource by using aside a continuous bioreactor. The control consists in choosing the inlet volumetric flow rate for filling the bioreactor with contaminated water from a considered resource (lake, reservoir, water-table, …). The treated outflow returns to the resource. We tackle an optimization problem which aims to minimize the time needed to reach a prescribed minimal value of contamination in the resource by choosing the input flow. Next, we study the influence of inhomogeneities of concentrations in the bioreactor, considering a system based on partial differential equations which describe its dynamics. We show that applying the optimal feedback control derived for perfectly mixed bioreactor does not allow to reach the target with small diffusion parameters as it drives the bioreactor to washout (the bioreactor equilibrium with no biomass). In this case, a suboptimal feedback (which reaches the target in finite time) is obtained with the help of a Hybrid Genetic Algorithm. Furthermore, we consider that the fluid flow velocity of the water entering into the bioreactor follows either a uniform or a nonuniform profile, showing that the optimal volumetric flow rates obtained with the uniform profile are not optimal if the profile is nonuniform, even when high diffusion coefficients are considered in the model.

Item Type:Article
Uncontrolled Keywords:Advection diffusion reaction model; Bioreactor; Optimal control; Water treatment
Subjects:Sciences > Mathematics > Functions
ID Code:42835
Deposited On:22 May 2017 10:01
Last Modified:12 Dec 2018 15:06

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