Michel Perrier - Academia.edu (original) (raw)

Papers by Michel Perrier

Research paper thumbnail of Performance Improvement of Extremum Seeking Control using Recursive Least Square Estimation with Forgetting Factor

IFAC-PapersOnLine, 2016

The main limitation of perturbation based extremum seeking methods is the requirement of a multip... more The main limitation of perturbation based extremum seeking methods is the requirement of a multiple timescale separation between the system dynamics, the perturbation frequency, and the adaptation rate so as to avoid interactions and possible instabilities. This causes the convergence to be extremely slow. In the present work, we propose a simple modification to the perturbation-based extremum seeking control method that can be used when the system cannot be accurately approximated by a Wiener-Hammerstein model for which convergence rate acceleration schemes are available. The linear filtering used in the perturbation based extremum seeking control for estimating the objective function gradient is replaced by a recursive least square with forgetting factor estimation algorithm. It is shown that this simple modification can accelerate convergence to the optimum by removing one time scale separation. Recently, in (Guay and Dochain (2015); Ehsan and M.Guay (2014)) the authors reformulate the extremum seeking control problem as a time-varying estimation problem.

Research paper thumbnail of Staged Microbial Fuel Cells with Periodic Connection of External Resistance

IFAC-PapersOnLine, 2016

Reactor staging is widely used in wastewater treatment where treatment norms are achieved by conn... more Reactor staging is widely used in wastewater treatment where treatment norms are achieved by connecting two or more reactors in series. The first reactor operates at high carbon source loads and the last reactor performs the final polishing. Microbial Fuel Cells (MFCs) are bioelectrochemical devices designed for direct electricity production from organic matter. Periodic connection of the MFC external electrical resistance was demonstrated to increase performance. An engineering tool to understand this periodic mode of operation is developed. Effluent quality control can be ensured by developing control strategies able to reject variability in the influent concentration while tracking a desired set-point.

Research paper thumbnail of Modelling and control of a fluidized-bed reactor /

Research paper thumbnail of Automation of bioventing: a soil column study (5th Int'l Petroleum Environmental Conference, Albuquerque, New Mexico, October 20-23)

Research paper thumbnail of Global optimization of three-input systems using multi-unit extremum seeking control

Proceedings of the 2011 American Control Conference, 2011

An efficient global optimization method based on multi-unit extremum seeking has been proposed re... more An efficient global optimization method based on multi-unit extremum seeking has been proposed recently for scalar and two-input systems. For scalar systems, the global optimum is obtained by controlling the finite-difference gradient and reducing the offset used for calculating this gradient. With two inputs, the uni-variate method is repeated on the circumference of a circle of reducing radius. In this paper, the concept is extended to three-input systems where the circle of varying radius sits on a shrinking sphere. The theoretical concepts are illustrated on the global optimization of several examples. The results show the capability of the proposed technique in deterministic convergence to the global optimum of the three-input systems.

Research paper thumbnail of Parallel consecutive reactions in a fluidized catalyst bed

The Chemical Engineering Journal, 1984

The two-phase model of Werther is applied to a parallel consecutive triangular reaction scheme. A... more The two-phase model of Werther is applied to a parallel consecutive triangular reaction scheme. An analytical solution is obtained and used to predict the performance of a fluidized bed reactor producing maleic anhydride from benzene oxidation. The model predictions ...

Research paper thumbnail of Application of multi-wavelength fluorometry for monitoring wastewater treatment process dynamics

Water Research, 1996

Much of the methodology employed for characterizing wastewater and in modeling wastewater treatme... more Much of the methodology employed for characterizing wastewater and in modeling wastewater treatment processes employs off-line analysis. Off-line analysis is time consuming and not ideally suited to developing process control strategies. Clearly a rapid, inexpensive and reliable method suitable for following organic consumption and biomass production on-line would be very useful. In this study multiple excitation-multiple emission fluorometry was examined as a method for monitoring wastewater treatment processes. Results were first obtained for defined protein solutions and activated sludge to identify characteristic excitation and emission wavelength pairs. These results were then used to develop a rapid off-line assay for measurement of synthetic feeds consisting of protein substrates for batch aerobic and anoxic wastewater treatment processes and for on-line monitoring of cellular metabolic states in an anoxic process. Step-wise multiple regression and principal component analysis were employed for data analysis. The former was used to determine the most informative excitation and emission wavelength pairs while the latter was applied to reduce fluorescent spectra dimensions. Analysis of the batch kinetics suggests that this approach is valid and revealed some dynamic features of protein utilization and biomass accumulation under aerobic and anoxic conditions, A correlation was developed between COD-removal rates and the fluorescence signals in the two processes using fluorescent emission spectra rather than single signals. The data suggests that this multiple excitation-multiple emission fluorometry may be a suitable method for following wastewater and activated sludge dynamics and could be used as the basis for the development of expert system based biosensors.

Research paper thumbnail of A systems approach to plant bioprocess optimization

Plant Biotechnology Journal, 2009

A dynamic model for plant cell metabolism was used as a basis for a rational analysis of plant pr... more A dynamic model for plant cell metabolism was used as a basis for a rational analysis of plant production potential in in vitro cultures. The model was calibrated with data from 3-L bioreactor cultures. A dynamic sensitivity analysis framework was developed to analyse the response curves of secondary metabolite production to metabolic and medium perturbations. Simulation results suggest that a straightforward engineering of cell metabolism or medium composition might only have a limited effect on productivity. To circumvent the problem of the dynamic allocation of resources between growth and production pathways, the sensitivity analysis framework was used to assess the effect of stabilizing intracellular nutrient concentrations. Simulations showed that a stabilization of intracellular glucose and nitrogen reserves could lead to a 116% increase in the specific production of secondary metabolites compared with standard culture protocol. This culture strategy was implemented experimentally using a perfusion bioreactor. To stabilize intracellular concentrations, adaptive medium feeding was performed using model mass balances and estimations. This allowed for a completely automated culture, with controlled conditions and predefined decision making algorithm. The proposed culture strategy leads to a 73% increase in specific production and a 129% increase in total production, as compared with a standard batch culture protocol. The sensitivity analysis on a mathematical model of plant metabolism thus allowed producing new insights on the links between intracellular nutritional management and cell productivity. The experimental implementation was also a significant improvement on current plant bioprocess strategies.

Research paper thumbnail of An efficient process for the purification of helper-dependent adenoviral vector and removal of helper virus by iodixanol ultracentrifugation

Journal of Virological Methods, 2010

The preparation of large amount of purified helper-dependent adenoviral vector material is hamper... more The preparation of large amount of purified helper-dependent adenoviral vector material is hampered by the lack of development of downstream processes with proven records on separation and recovery efficiencies. In order to facilitate the use of clinical-grade helper-dependent virus material for large-scale in vivo studies, a three-step purification scheme consisting of (1) an anion-exchange chromatography for initial capturing of virus, (2) a shallow iodixanol density gradient ultracentrifugation for the removal of helper virus from helper-dependent virus, and (3) a size-exclusion chromatography for the removal of iodixanol and residual protein contaminants as a polishing step was developed. The use of a fast iodixanol density ultracentrifugation step was highly effective in separating infectious helper-dependent virus from contaminating helper virus. The overall downstream processing scheme gave 80% infectious particle yield. The contamination ratio of helper virus in the helper-dependent virus preparation are reduced from 2.57 to 0.03% corresponding to a reduction of helper virus by factors of 85 by two iodixanol purification steps. It was also demonstrated that size-exclusion chromatography is an excellent step for the removal of iodixanol and polishing of the final helper-dependent virus preparation.

Research paper thumbnail of Paper machine controllability: effect of disturbances on basis weight and first-pass retention

Journal of Process Control, 2001

A controllability analysis of a paper machine forming zone in a newsprint mill was performed to d... more A controllability analysis of a paper machine forming zone in a newsprint mill was performed to determine the maximum allowable variability of the pulp furnished to the process. The goal was to keep the output variables, basis weight and ®rst-pass retention between certain limits in spite of disturbances and paper grade changes. The results indicate that the process is more disturbed at high frequencies, and that the two output variables may be maintained within the interval 1% of their nominal values if the maximum variability in the consistency and ®nes content of the thick-stock is kept lower than 1 and 2%, respectively.

Research paper thumbnail of Extremum-seeking algorithm design for fed-batch cultures of microorganisms with overflow metabolism

Journal of Process Control, 2011

ABSTRACT: Overflow metabolism characterizes cell strains that are likely to produce inhibiting me... more ABSTRACT: Overflow metabolism characterizes cell strains that are likely to produce inhibiting metabolites as a result of an excess of substrate feeding and a saturated respiratory capacity. In this study, extremum seeking is used to assess the actual critical substrate level, which is a function of the cell respiratory capacity. The latter is modelled as a function representing the existence of two different metabolic modes, namely the respirative mode and the respiro-fermentative mode, as well as modulation factors taking account of ...

Research paper thumbnail of A deposition efficiency model for fiber–filler flocculation by microparticle retention system

Journal of Industrial and Engineering Chemistry, 2009

Research paper thumbnail of Development of a two-step segregated model for the optimization of plant cell growth

Control Engineering Practice, 2000

ABSTRACT

Research paper thumbnail of Adaptive extremum-seeking control of convection-reaction distributed reactor with limited actuation

Computers & Chemical Engineering, 2008

ABSTRACT

Research paper thumbnail of A bridging model for the effects of a dual component flocculation system on the strength of fiber contacts in flocs of pulp fibers: Implications for control of paper uniformity

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006

Paper uniformity, commonly referred to as formation, depends to a large degree on the uniform dis... more Paper uniformity, commonly referred to as formation, depends to a large degree on the uniform distribution of pulp fibers in a sheet of paper. Fiber flocculation impairs paper formation. The size and strength of fiber flocs is determined mainly by two factors:(i) the ...

Research paper thumbnail of The process dynamics of filler retention in paper using a CPAM/bentonite retention aid system

The Canadian Journal of Chemical Engineering, 2010

ABSTRACT In an effort to develop robust control strategies for the wet-end of papermaking, an exp... more ABSTRACT In an effort to develop robust control strategies for the wet-end of papermaking, an experimental program was carried out to model the dynamic behaviour of the filler retention in paper using a Fourdrinier pilot paper machine and a cationic poly(acrylamide)/bentonite retention aid system. A dynamic simulation model of the pilot paper machine was developed from first-principles. To describe the wet-end chemistry effect, the first-pass retention was included in the model as a new independent variable. The important factors affecting the dynamics of the wet-end are first-pass retention and the parameters related to the white water circulation.Dans un effort pour développer des stratégies de contrôle robustes pour la partie humide de la fabrication du papier, on a mené un programme expérimental pour modéliser le comportement dynamique de la rétention d'agents de remplissage dans le papier à l'aide d'une machine à papier pilote Fourdrinier et d'un système d'aide à la rétention cationique poly(acrylamide)/bentonite. Un modèle de simulation dynamique du pilote a été mis au point à partir des principes fondamentaux. Pour décrire l'effet de la chimie de la partie humide, la rétention lors du premier passage a été incluse dans le modèle comme nouvelle variable indépendante. Les facteurs importants qui affectent la dynamique de la partie humide sont la rétention lors du premier passage et les paramètres reliés à la circulation des eaux blanches.

Research paper thumbnail of Expanded bed hydrodynamics The effects of scaling down

Research paper thumbnail of Adaptive extremum-seeking control of yeast fed-batch cultures

DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde l... more DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde la production scientifique de l'ULB.L'interface de recherche DI-fusion permet de consulter les publications des chercheurs de l'ULB et les thèses qui y ont été défendues.

Research paper thumbnail of Real-time optimization of a pulp and paper process by adaptive extremum seeking control

Research paper thumbnail of Optimization of Lignin Recovery from the Pre-Hydrolysate of Kraft-Based Dissolving Pulp Production Processes

Applied Sciences

A pre-hydrolysate is an aqueous stream obtained during the production of hardwood kraft dissolvin... more A pre-hydrolysate is an aqueous stream obtained during the production of hardwood kraft dissolving pulp. It is rich in sugars and contains dissolved organic matters. The purpose of this study is to investigate the optimization of lignin recovery from wood pre-hydrolysates and to characterize the extracted lignin. The optimal conditions for lignin extraction have been determined to be (a) a filtration temperature of 40 °C, (b) a sulfuric acid concentration of 8.5 kg·m−3, and (c) a coagulation time of 180 min. Using these conditions, high filtration rates have been obtained and the extracted lignin has a low content of impurities (8.3%), a low molecular weight (1270 Da), and a very low polydispersity (Mw/Mn = 1.22). Compared to kraft lignin, the pre-hydrolysate lignin has a much lower molecular weight and could be a potential candidate for niche applications. A high lignin recovery rate is possible (52% of the total lignin content in the pre-hydrolysate).

Research paper thumbnail of Performance Improvement of Extremum Seeking Control using Recursive Least Square Estimation with Forgetting Factor

IFAC-PapersOnLine, 2016

The main limitation of perturbation based extremum seeking methods is the requirement of a multip... more The main limitation of perturbation based extremum seeking methods is the requirement of a multiple timescale separation between the system dynamics, the perturbation frequency, and the adaptation rate so as to avoid interactions and possible instabilities. This causes the convergence to be extremely slow. In the present work, we propose a simple modification to the perturbation-based extremum seeking control method that can be used when the system cannot be accurately approximated by a Wiener-Hammerstein model for which convergence rate acceleration schemes are available. The linear filtering used in the perturbation based extremum seeking control for estimating the objective function gradient is replaced by a recursive least square with forgetting factor estimation algorithm. It is shown that this simple modification can accelerate convergence to the optimum by removing one time scale separation. Recently, in (Guay and Dochain (2015); Ehsan and M.Guay (2014)) the authors reformulate the extremum seeking control problem as a time-varying estimation problem.

Research paper thumbnail of Staged Microbial Fuel Cells with Periodic Connection of External Resistance

IFAC-PapersOnLine, 2016

Reactor staging is widely used in wastewater treatment where treatment norms are achieved by conn... more Reactor staging is widely used in wastewater treatment where treatment norms are achieved by connecting two or more reactors in series. The first reactor operates at high carbon source loads and the last reactor performs the final polishing. Microbial Fuel Cells (MFCs) are bioelectrochemical devices designed for direct electricity production from organic matter. Periodic connection of the MFC external electrical resistance was demonstrated to increase performance. An engineering tool to understand this periodic mode of operation is developed. Effluent quality control can be ensured by developing control strategies able to reject variability in the influent concentration while tracking a desired set-point.

Research paper thumbnail of Modelling and control of a fluidized-bed reactor /

Research paper thumbnail of Automation of bioventing: a soil column study (5th Int'l Petroleum Environmental Conference, Albuquerque, New Mexico, October 20-23)

Research paper thumbnail of Global optimization of three-input systems using multi-unit extremum seeking control

Proceedings of the 2011 American Control Conference, 2011

An efficient global optimization method based on multi-unit extremum seeking has been proposed re... more An efficient global optimization method based on multi-unit extremum seeking has been proposed recently for scalar and two-input systems. For scalar systems, the global optimum is obtained by controlling the finite-difference gradient and reducing the offset used for calculating this gradient. With two inputs, the uni-variate method is repeated on the circumference of a circle of reducing radius. In this paper, the concept is extended to three-input systems where the circle of varying radius sits on a shrinking sphere. The theoretical concepts are illustrated on the global optimization of several examples. The results show the capability of the proposed technique in deterministic convergence to the global optimum of the three-input systems.

Research paper thumbnail of Parallel consecutive reactions in a fluidized catalyst bed

The Chemical Engineering Journal, 1984

The two-phase model of Werther is applied to a parallel consecutive triangular reaction scheme. A... more The two-phase model of Werther is applied to a parallel consecutive triangular reaction scheme. An analytical solution is obtained and used to predict the performance of a fluidized bed reactor producing maleic anhydride from benzene oxidation. The model predictions ...

Research paper thumbnail of Application of multi-wavelength fluorometry for monitoring wastewater treatment process dynamics

Water Research, 1996

Much of the methodology employed for characterizing wastewater and in modeling wastewater treatme... more Much of the methodology employed for characterizing wastewater and in modeling wastewater treatment processes employs off-line analysis. Off-line analysis is time consuming and not ideally suited to developing process control strategies. Clearly a rapid, inexpensive and reliable method suitable for following organic consumption and biomass production on-line would be very useful. In this study multiple excitation-multiple emission fluorometry was examined as a method for monitoring wastewater treatment processes. Results were first obtained for defined protein solutions and activated sludge to identify characteristic excitation and emission wavelength pairs. These results were then used to develop a rapid off-line assay for measurement of synthetic feeds consisting of protein substrates for batch aerobic and anoxic wastewater treatment processes and for on-line monitoring of cellular metabolic states in an anoxic process. Step-wise multiple regression and principal component analysis were employed for data analysis. The former was used to determine the most informative excitation and emission wavelength pairs while the latter was applied to reduce fluorescent spectra dimensions. Analysis of the batch kinetics suggests that this approach is valid and revealed some dynamic features of protein utilization and biomass accumulation under aerobic and anoxic conditions, A correlation was developed between COD-removal rates and the fluorescence signals in the two processes using fluorescent emission spectra rather than single signals. The data suggests that this multiple excitation-multiple emission fluorometry may be a suitable method for following wastewater and activated sludge dynamics and could be used as the basis for the development of expert system based biosensors.

Research paper thumbnail of A systems approach to plant bioprocess optimization

Plant Biotechnology Journal, 2009

A dynamic model for plant cell metabolism was used as a basis for a rational analysis of plant pr... more A dynamic model for plant cell metabolism was used as a basis for a rational analysis of plant production potential in in vitro cultures. The model was calibrated with data from 3-L bioreactor cultures. A dynamic sensitivity analysis framework was developed to analyse the response curves of secondary metabolite production to metabolic and medium perturbations. Simulation results suggest that a straightforward engineering of cell metabolism or medium composition might only have a limited effect on productivity. To circumvent the problem of the dynamic allocation of resources between growth and production pathways, the sensitivity analysis framework was used to assess the effect of stabilizing intracellular nutrient concentrations. Simulations showed that a stabilization of intracellular glucose and nitrogen reserves could lead to a 116% increase in the specific production of secondary metabolites compared with standard culture protocol. This culture strategy was implemented experimentally using a perfusion bioreactor. To stabilize intracellular concentrations, adaptive medium feeding was performed using model mass balances and estimations. This allowed for a completely automated culture, with controlled conditions and predefined decision making algorithm. The proposed culture strategy leads to a 73% increase in specific production and a 129% increase in total production, as compared with a standard batch culture protocol. The sensitivity analysis on a mathematical model of plant metabolism thus allowed producing new insights on the links between intracellular nutritional management and cell productivity. The experimental implementation was also a significant improvement on current plant bioprocess strategies.

Research paper thumbnail of An efficient process for the purification of helper-dependent adenoviral vector and removal of helper virus by iodixanol ultracentrifugation

Journal of Virological Methods, 2010

The preparation of large amount of purified helper-dependent adenoviral vector material is hamper... more The preparation of large amount of purified helper-dependent adenoviral vector material is hampered by the lack of development of downstream processes with proven records on separation and recovery efficiencies. In order to facilitate the use of clinical-grade helper-dependent virus material for large-scale in vivo studies, a three-step purification scheme consisting of (1) an anion-exchange chromatography for initial capturing of virus, (2) a shallow iodixanol density gradient ultracentrifugation for the removal of helper virus from helper-dependent virus, and (3) a size-exclusion chromatography for the removal of iodixanol and residual protein contaminants as a polishing step was developed. The use of a fast iodixanol density ultracentrifugation step was highly effective in separating infectious helper-dependent virus from contaminating helper virus. The overall downstream processing scheme gave 80% infectious particle yield. The contamination ratio of helper virus in the helper-dependent virus preparation are reduced from 2.57 to 0.03% corresponding to a reduction of helper virus by factors of 85 by two iodixanol purification steps. It was also demonstrated that size-exclusion chromatography is an excellent step for the removal of iodixanol and polishing of the final helper-dependent virus preparation.

Research paper thumbnail of Paper machine controllability: effect of disturbances on basis weight and first-pass retention

Journal of Process Control, 2001

A controllability analysis of a paper machine forming zone in a newsprint mill was performed to d... more A controllability analysis of a paper machine forming zone in a newsprint mill was performed to determine the maximum allowable variability of the pulp furnished to the process. The goal was to keep the output variables, basis weight and ®rst-pass retention between certain limits in spite of disturbances and paper grade changes. The results indicate that the process is more disturbed at high frequencies, and that the two output variables may be maintained within the interval 1% of their nominal values if the maximum variability in the consistency and ®nes content of the thick-stock is kept lower than 1 and 2%, respectively.

Research paper thumbnail of Extremum-seeking algorithm design for fed-batch cultures of microorganisms with overflow metabolism

Journal of Process Control, 2011

ABSTRACT: Overflow metabolism characterizes cell strains that are likely to produce inhibiting me... more ABSTRACT: Overflow metabolism characterizes cell strains that are likely to produce inhibiting metabolites as a result of an excess of substrate feeding and a saturated respiratory capacity. In this study, extremum seeking is used to assess the actual critical substrate level, which is a function of the cell respiratory capacity. The latter is modelled as a function representing the existence of two different metabolic modes, namely the respirative mode and the respiro-fermentative mode, as well as modulation factors taking account of ...

Research paper thumbnail of A deposition efficiency model for fiber–filler flocculation by microparticle retention system

Journal of Industrial and Engineering Chemistry, 2009

Research paper thumbnail of Development of a two-step segregated model for the optimization of plant cell growth

Control Engineering Practice, 2000

ABSTRACT

Research paper thumbnail of Adaptive extremum-seeking control of convection-reaction distributed reactor with limited actuation

Computers & Chemical Engineering, 2008

ABSTRACT

Research paper thumbnail of A bridging model for the effects of a dual component flocculation system on the strength of fiber contacts in flocs of pulp fibers: Implications for control of paper uniformity

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006

Paper uniformity, commonly referred to as formation, depends to a large degree on the uniform dis... more Paper uniformity, commonly referred to as formation, depends to a large degree on the uniform distribution of pulp fibers in a sheet of paper. Fiber flocculation impairs paper formation. The size and strength of fiber flocs is determined mainly by two factors:(i) the ...

Research paper thumbnail of The process dynamics of filler retention in paper using a CPAM/bentonite retention aid system

The Canadian Journal of Chemical Engineering, 2010

ABSTRACT In an effort to develop robust control strategies for the wet-end of papermaking, an exp... more ABSTRACT In an effort to develop robust control strategies for the wet-end of papermaking, an experimental program was carried out to model the dynamic behaviour of the filler retention in paper using a Fourdrinier pilot paper machine and a cationic poly(acrylamide)/bentonite retention aid system. A dynamic simulation model of the pilot paper machine was developed from first-principles. To describe the wet-end chemistry effect, the first-pass retention was included in the model as a new independent variable. The important factors affecting the dynamics of the wet-end are first-pass retention and the parameters related to the white water circulation.Dans un effort pour développer des stratégies de contrôle robustes pour la partie humide de la fabrication du papier, on a mené un programme expérimental pour modéliser le comportement dynamique de la rétention d'agents de remplissage dans le papier à l'aide d'une machine à papier pilote Fourdrinier et d'un système d'aide à la rétention cationique poly(acrylamide)/bentonite. Un modèle de simulation dynamique du pilote a été mis au point à partir des principes fondamentaux. Pour décrire l'effet de la chimie de la partie humide, la rétention lors du premier passage a été incluse dans le modèle comme nouvelle variable indépendante. Les facteurs importants qui affectent la dynamique de la partie humide sont la rétention lors du premier passage et les paramètres reliés à la circulation des eaux blanches.

Research paper thumbnail of Expanded bed hydrodynamics The effects of scaling down

Research paper thumbnail of Adaptive extremum-seeking control of yeast fed-batch cultures

DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde l... more DI-fusion, le Dépôt institutionnel numérique de l'ULB, est l'outil de référencementde la production scientifique de l'ULB.L'interface de recherche DI-fusion permet de consulter les publications des chercheurs de l'ULB et les thèses qui y ont été défendues.

Research paper thumbnail of Real-time optimization of a pulp and paper process by adaptive extremum seeking control

Research paper thumbnail of Optimization of Lignin Recovery from the Pre-Hydrolysate of Kraft-Based Dissolving Pulp Production Processes

Applied Sciences

A pre-hydrolysate is an aqueous stream obtained during the production of hardwood kraft dissolvin... more A pre-hydrolysate is an aqueous stream obtained during the production of hardwood kraft dissolving pulp. It is rich in sugars and contains dissolved organic matters. The purpose of this study is to investigate the optimization of lignin recovery from wood pre-hydrolysates and to characterize the extracted lignin. The optimal conditions for lignin extraction have been determined to be (a) a filtration temperature of 40 °C, (b) a sulfuric acid concentration of 8.5 kg·m−3, and (c) a coagulation time of 180 min. Using these conditions, high filtration rates have been obtained and the extracted lignin has a low content of impurities (8.3%), a low molecular weight (1270 Da), and a very low polydispersity (Mw/Mn = 1.22). Compared to kraft lignin, the pre-hydrolysate lignin has a much lower molecular weight and could be a potential candidate for niche applications. A high lignin recovery rate is possible (52% of the total lignin content in the pre-hydrolysate).