Imperial College London

DrBenoitChachuat

Faculty of EngineeringDepartment of Chemical Engineering

Reader in Process Systems Engineering
 
 
 
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b.chachuat Website

 
 
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609Roderic Hill BuildingSouth Kensington Campus

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Summary

 

Publications

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160 results found

Fikar M, Chachuat B, Latifi MA, 2004, Dynamic optimisation of the aeration in a small-size alternating activated sludge process, Pages: 589-594, ISSN: 1474-6670

Copyright © IFAC Computer Applications in Biotechnology, Nancy, France, 2004. This simulation study presents dynamic optimisation of a small size single basin wastewater treatment plant. The objectives are to determine an optimal sequence of aeration/non-aeration times and the corresponding periodical steady state subject to minimisation of energy consumption. Based on the optimal trajectories, two simple feedback rules are proposed that follow from properties of the optimal solution. Simulation results with these simple rules show very satisfactory control performance.

Conference paper

Chachuat B, Bernard O, 2004, Design and practical use of probabilistic observers for mass-balance based bioprocess models, Pages: 359-364, ISSN: 1474-6670

Copyright © IFAC Dynamics and Control of Process Systems, Cambridge, Massachusetts, USA, 2004 In this paper, the design of probabilistic observers for mass-balance based bio-process models is investigated. It is assumed that the probability density function of every uncertain parameter, input and/or initial state is known a priori. Then, the probability density functions of the state variables are obtained, at any time, by considering the image of this initial probability density function by the flow of the dynamical system. In comparison to classical open-loop interval observers, the method provides information on the confidence level of the estimates rather than simple upper and lower bounds. The numerical implementation of the method is closely considered and an application to an industrial anaerobic digester is detailed.

Conference paper

Fikar M, Chachuat B, Latifi MA, 2003, Dynamic optimisation of alternating activated sludge processes, Pages: 3189-3193

© 2003 EUCA. The study presents dynamic optimisation of a small size single basin wastewater treatment plant. The objectives are to determine an optimal sequence of aeration/non-aeration times and the corresponding periodical steady state subject to minimisation of energy consumption. Based on the optimal trajectories, two simple feedback rules are proposed that follow from properties of the optimal solution. Simulation results with these simple rules show very satisfactory control performance.

Conference paper

Chachuat B, Latifi MA, 2003, A new approach in deterministic global optimisation of problems with ordinary differential equations, 4th International Conference on Frontiers in Global Optimization, Publisher: KLUWER ACADEMIC PUBLISHERS, Pages: 83-108

Conference paper

Chachuat B, Roche N, Latifi MA, 2003, Reduction of the ASM 1 model for optimal control of small-size activated sludge treatment plants, Revue des Sciences de l'Eau, Vol: 16, Pages: 5-26, ISSN: 0992-7158

In order to meet the stricter wastewater effluent guidelines adopted by the European Union, wastewater treatment plants require better management strategies. Wastewater treatment process models have become a major tool to design closed-loop control schemes. However, the dynamic models that are currently used in the simulation of activated sludge treatment plants (ASM 1, ASM 2 and, more recently, ASM 3 models) are highly dimensional and are not appropriate for on-line implementation (e.g., for model predictive control or optimal control). It is therefore important to develop reduced models that could be used for this purpose. A reduced model was developed to describe the behaviour of alternating activated sludge treatment plants, with the aim of applying it to the optimal control of an aeration system. The reduction scheme was based on appropriate simplifications to the ASM 1 model (which is more appropriate for open-loop control). The objective was to verify if accurate predictions could be made time periods of several hours (about 8 h). The present results are related to an existing small-size wastewater treatment plant. This plant was designed for 15000 population-equivalents (p.e.) and consists of a primary treatment stage (screening, grit removal, primary sedimentation), followed by a secondary treatment stage (biological treatment). The latter consists of a single aeration tank of about 2050 m3 equipped with 3 turbines which are operated cyclically to create alternating aerobic and anoxic conditions. Ammonia is converted into nitrate during air-on periods (nitrification step) and nitrate is subsequently removed during air-off periods (denitrification step). It is important to note that a dynamic model, based on the ASM 1 model and calibrated from a set of input/output measurements over a one-day period (CHACHUAT, 2001), was used here as a reference to perform model reduction. The following two-level simplification procedure was applied: • A homotopy method

Journal article

Fikar M, Chachuat B, Latifi MA, 2003, Dynamic optimisation of alternating activated sludge processes, Pages: 3189-3193

© 2003 EUCA. The study presents dynamic optimisation of a small size single basin wastewater treatment plant. The objectives are to determine an optimal sequence of aeration/non-aeration times and the corresponding periodical steady state subject to minimisation of energy consumption. Based on the optimal trajectories, two simple feedback rules are proposed that follow from properties of the optimal solution. Simulation results with these simple rules show very satisfactory control performance.

Conference paper

Chachuat B, Roche N, Aberentz P, 2001, A new approch for the optimum management of aeration in a small activated sludge treatment plants, Eau, l'INDUSTRIE, les Nuisances, Pages: 53-59, ISSN: 0755-5016

Most of small size wastewater treatment plants use simple control strategies based on dissolved oxygen concentration, redox potential or ammonia concentrations. Dynamic optimisation methods are here applied to improve both economic and reliability performances of small size wastewater treatment plants equipped with mechanical surface aerators. The aeration policy which minimises the energy consumption and satisfies discharge requirements under specified constraints (process and physical constraints) is then determined. The comparison between rule-based control policies and optimised aeration strategies showed that the optimised aeration profiles lead to reductions of energy consumption of about 40%.

Journal article

Chachuat B, Roche N, Latifi MA, 2001, Dynamic optimisation of small size wastewater treatment plants including nitrification and denitrification processes, COMPUTERS & CHEMICAL ENGINEERING, Vol: 25, Pages: 585-593, ISSN: 0098-1354

Journal article

Chachuat B, Roche N, Latifi MA, 2000, Dynamic optimisation of small size wastewater treatment plants including nitrification and denitrification processes, Computer Aided Chemical Engineering, Vol: 8, Pages: 853-858, ISSN: 1570-7946

In this paper, dynamic optimisation of small size wastewater treatment plants is studied. The problem is stated as a hybrid dynamic optimisation problem which is solved using a gradient-based method. The aeration policy which minimises the energy consumption and satisfies discharge requirements under specified constraints (process and physical constraints) is then determined. The comparison between usual rule-based control policies and optimised aeration strategies showed that the optimised aeration profiles lead, to reductions of energy consumption of at least 30%. © 2000 Elsevier B.V. All rights reserved.

Journal article

Nikolaou A, Bernardi A, Bezzo F, Morosinotto T, Chachuat Bet al., Dynamic Model of Photoproduction, Photoregulation and Photoinhibition in Microalgae using Chlorophyll Fluorescence., IFAC WC, Publisher: Elsevier

Conference paper

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