A multivariable adaptive feedback control for highly uncertain continuous anaerobic digestion pro... more A multivariable adaptive feedback control for highly uncertain continuous anaerobic digestion processes is proposed to regulate the volatile fatty acids (VFA) concentration, the strong ions concentrations, and the total and intermediate alkalinities. The multivariable control scheme includes a Luenberger observer to estimate both the unmeasured variables (i.e., VFA) and unknown microbial growth kinetics. The control approach is designed using an exponential Lyapunov function to resemble the typical exponential biological growth of the involved microbial consortia. Taking into account physicochemical equilibrium, alkalinities are represented as a function of the state variables. As a result, the control problem becomes a regulation problem on alkalinities, and in turn, a tracking control problem on the state variables, with two manipulated variables—the dilution rate and the feed rate of a strong alkali solution—while the state variables’ set-points are given as a function of pH. The...
Anaerobic digestion (AD) is an efficient wastewater bioprocess, suitable for treating agroindustr... more Anaerobic digestion (AD) is an efficient wastewater bioprocess, suitable for treating agroindustrial residues with high organic loads and characterized by both a low environmental impact and energy generation. This process is conformed by several chemical and biological reactions in an oxygen free atmosphere, that degrades high molecular weight organic compounds into carbon dioxide and methane mainly but also into traces of hydrogen and ammonia. This process is potentially unstable to volatile fatty acids (VFA), and the alkalinity. variations and is satisfactorily described by the non-linear AM2 model. In this contribution, the AM2 model is modified to include a more general expression for the pH, a cheap and continuous measurement, and also to add more detail in the interactions of the VFA, bicarbonates, and the alkalinity, key factors in the process stability. The stability of the AM2 modified model is explored through a rigorous bifurcation analysis that identifies unstable operation zones and viability of operation trajectories as a function of the dilution rate. Finally, an experimental validation is carried out to show the feasibility and accuracy of the proposed modifications.
The aim of this work is to propose a methodology to obtain an effectiveness factor for biofilm in... more The aim of this work is to propose a methodology to obtain an effectiveness factor for biofilm in a microbial electrolysis cell (MEC) system and use it to reduce a partial differential equation (PDE) biofilm MEC model to an ordinary differential equation (ODE) MEC model. The biofilm mass balances of the different species are considered. In addition, it is considered that all the involved microorganisms are attached to the anodic biological film. Three effectiveness factors are obtained from partial differential equations describing the spatial distributions of potential and substrate in the biofilm. Then, a model reduction is carried out using the global mass balances of the different species in the system. The reduced model with three uncertain but bounded effectiveness factors is evaluated numerically and analyzed in the sense of stability and parametric sensibility to demonstrate its applicability. The reduced ODE model is compared with a validated model taken from the literature...
In this work, the design of the hardware architecture to implement an algorithm for optimizing th... more In this work, the design of the hardware architecture to implement an algorithm for optimizing the Hydrogen Productivity Rate (HPR) in a Microbial Electrolysis Cell (MEC) is presented. The HPR in the MEC is maximized by the golden section search algorithm in conjunction with a super-twisting controller. The development of the digital architecture in the implementation step of the optimization algorithm was developed in the Very High Description Language (VHDL) and synthesized in a Field Programmable Gate Array (FPGA). Numerical simulations demonstrated the feasibility of the proposed optimization strategy embedded in an FPGA Cyclone II. Results showed that only 21% of the total logic elements, 5.19% of dedicated logic registers, and 64% of the total eight-bits multipliers of the FPGA were used. On the other hand, the estimated power consumption required by the FPGA-embedded optimization algorithm was only 146 mW.
In this paper, an experimental study upon alkalinity and hydrodynamic behavior in an anaerobic up... more In this paper, an experimental study upon alkalinity and hydrodynamic behavior in an anaerobic up-flow fixed bed reactor for the treatment of tequila vinasses is presented. Measurements of volatile fatty acids, pH, alkalinity and bicarbonate were obtained at three sampling points in the reactor in the axial axis. Then, the spatial distribution of alkalinity is studied and discussed. Moreover, for further control process purposes, a hydrodynamic model based on the use of two interconnected two-steps reduced AM2 type models is proposed and its parameters are identified using experimental data.
In this paper we propose a multivariable robust feedback control for regulating the alkalinity an... more In this paper we propose a multivariable robust feedback control for regulating the alkalinity and the volatile fatty acid concentration in continuous anaerobic digestion processes used in wastewater treatment. The system exhibits a large lack of knowledge on kinetic parameters. Furthermore, key state variables, which cannot be measured, are estimated by using a Luemberger observer. Thus, even under this highly uncertain scenario, the proposed control law uses this partial information for regulating exponentially the control variables. The control objectives are firstly established upon physicochemical criteria based on normal operational conditions and then formally stated in terms of the concerned state variables. The resulting control law is tested experimentally in a 1 m3 pilot plant for the treatment of red wine vinasses under several uncertain situations in which the multivariable control law is able to recover the system stability around the pre-specified set points showing a...
The TELEMAC project brings new methodologies from the Information and Science Technologies field ... more The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem.
Reviews in Environmental Science and Bio/Technology, 2015
To enhance energy production from methane or resource recovery from digestate, anaerobic digestio... more To enhance energy production from methane or resource recovery from digestate, anaerobic digestion processes require advanced instrumentation and control tools. Over the years, research on these topics has evolved and followed the main fields of application of anaerobic digestion processes: from municipal sewage sludge to liquid -mainly industrial -then municipal organic fraction of solid waste and agricultural residues. Time constants of the processes have also changed with respect to the treated waste from minutes or hours to weeks or months. Since fast closed loop control is needed for short time constant processes, human operator is now included in the loop when taking decisions to optimize anaerobic digestion plants dealing with complex solid waste over a long retention time. Control objectives have also moved from the regulation of key variables -measured on-line -to the prediction of overall process performance -based on global off-line measurements -to optimize the feeding of the processes. Additionally, the need for more accurate prediction of methane production and organic matter biodegradation has impacted the complexity of instrumentation and should include a more detailed characterization of the waste (e.g., biochemical fractions like proteins, lipids and carbohydrates) and their bioaccessibility and biodegradability characteristics. However, even if in the literature several methodologies have been developed to determine biodegradability based on organic matter characterization, only a few papers deal with bioaccessibility assessment. In this review, we emphasize the high potential of some promising techniques, such as spectral analysis, and we discuss issues that could appear in the near future concerning control of AD processes.
The estimation of kinetic parameters and yield coefficients of a two-stage anaerobic digestion mo... more The estimation of kinetic parameters and yield coefficients of a two-stage anaerobic digestion model based on experimental data obtained from the treatment of tequila vinasses is considered in this paper. The proposed model is derived from mass balances of two fixed-bed up-flow bioreactors where the acidogenic phase takes place in the first bioreactor, whereas the second one contains a mixture of acidogenic and methanogenic biomass. The Marquardt method via a study of parametric sensitivity was implemented for estimating parameters and initial conditions using two sets of raw experimental data. The model and the estimated parameters were statistically analyzed to validate the results. Finally, the model was tested with a different set of raw experimental data showing satisfactory prediction capabilities. INTRODUCTION Modelling of Anaerobic Digestion (AD) is a complex task because this process exhibits nonlinear behavior, the presence of influent disturbances, uncertainties on biomas...
This paper deals with the control of the start-up phase in anaerobic digestion systems by using m... more This paper deals with the control of the start-up phase in anaerobic digestion systems by using monitoring parameters already implemented that have been coupled to the control law. Methane yield, as well as methane flow rate, and the ratio of intermediate over total alkalinity have been used as control parameters. These measurements have been included in a switching control strategy to drive the process toward a steady state in which biogas production is optimized avoiding accumulation of volatile fatty acids. Experimental validation of this control strategy has been performed from the results obtained using a 358 litter fixed bed anaerobic digester treating industrial winery wastewater.
In this paper a “virtually controlled observer” (VCO) is proposed to estimate simultaneously the ... more In this paper a “virtually controlled observer” (VCO) is proposed to estimate simultaneously the influent substrate concentration and unmeasured state variables in continuous anaerobic digestion processes. The hypothetical (unmeasured) influent substrate concentration is updated by a feedback control, which is regulated by the estimation error of a measured output. The proposed approach is firstly illustrated upon a simple continuous bioprocess. Then, the performance of the observer is tested via numerical simulations in a continuous anaerobic digestion model. Results showed that it is possible to estimate both, the influent substrate concentration and unmeasured states in the digester in the face of parametric uncertainties.
Anaerobic digestion (AD) is a highly nonlinear time-varying process commonly used for biological ... more Anaerobic digestion (AD) is a highly nonlinear time-varying process commonly used for biological wastewater treatment, which is subject to large disturbances of both influent concentrations, and flow rates that may lead the process to a breakdown. In order to compensate the effect of these disturbances, the dynamics of the main state variablesincluding biomass -must be closely monitored and used to improve the process performance. However, AD processes still suffer from a lack of reliable and cheap sensors of key process variables to insure the right process operation. This has led to the development of estimation schemes, which infer the information of such key variables from the available measurements. Nevertheless, reliable measurements are not always possible to get because these readings may be corrupted by noise or erroneous due to sensor failures and as a consequence, they may lead to deteriorated control efforts and the eventual crash of the AD process. In this article, we propose an integrated system for the detection, isolation, and analysis of faults in AD processes by using interval observers (IO). The proposed approach was experimentally implemented on a 1-m 3 pilot scale anaerobic digester. Based on the comparison between the measured outputs and their corresponding estimates, results show that this approach was able to detect sensor failures as well as faults in the basic hypotheses made during the design step.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2015
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
This paper presents a virtually controlled observer (VCO) used to estimate both, unmeasured state... more This paper presents a virtually controlled observer (VCO) used to estimate both, unmeasured states and unknown influent substrate concentrations in an anaerobic digestion process. This VCO is experimentally implemented in a pilot-scale AD process used for the treatment of wine distillery vinasses. This implementation was carried out under the complete ignorance of the process kinetics. Results indicate that the VCO is able to reconstruct the influent substrate concentration under moderate changes on the operating conditions, while showing also robustness and accuracy against model uncertainties and even sensor faults.
In this work, a classical linear control approach for the peroxide (H2O2) dosage in a photo-Fento... more In this work, a classical linear control approach for the peroxide (H2O2) dosage in a photo-Fenton process is presented as a suitable solution for improving the efficiency in the treatment of recalcitrant organic compounds that cannot be degraded by classical wastewater treatment processes like anaerobic digestion. Experiments were carried out to degrade Lignin, Melanoidin, and Gallic acid, which are typical recalcitrant organic compounds present in some kinds of effluents such as vinasses from the Tequila and Cachaça industries. Experiments were carried in Open-Loop mode for obtaining the degradation model for the three compounds in the form of a Transfer Function, and in Closed-Loop mode for controlling the concentration of each compound. First-order Transfer Functions were obtained using the reaction curve method, and then, based on these models, the parameters of Proportional Integral controllers were calculated using the direct synthesis method. In the Closed-Loop experiments, ...
The aim of this work is to evaluate biohydrogen production from agro-industrial wastewaters and b... more The aim of this work is to evaluate biohydrogen production from agro-industrial wastewaters and byproducts, by combining dark fermentation and microbial electrolysis in a two-step cascade process. Such coupling of both technologies constitutes a technological building block within a concept of environmental biorefinery where sustainable production of renewable energy is expected. Six different wastewaters and industrial by-products coming from cheese, fruit juice, paper, sugar, fruit processing and spirits factories were evaluated for the feasibility of hydrogen production in a two-step process. The overall hydrogen production when coupling dark fermentation and microbial electrolysis was increased up to 13 times when compared to fermentation alone, achieving a maximum overall hydrogen yield of 1608.6 ± 266.2 ml H 2 / gCOD consumed and a maximum of 78.5 ± 5.7% of COD removal. These results show that dark fermentation coupled with microbial electrolysis is a highly promising option to maximize the conversion of agro-industrial wastewaters and by-products into bio-hydrogen.
A nonlinear passive control approach is proposed for the steady state regulation of a twostages a... more A nonlinear passive control approach is proposed for the steady state regulation of a twostages anaerobic digestion process for the treatment of tequila vinasses. The model consists of two interconnected continuous bioreactors for the acidogenic phase and methanogenic phase respectively. Dilution rates, one for each bioreactor, are the manipulated variables. A classical choice of the Hamiltonian as the sum of square errors around the steady state shows that the conservation matrix and the dissipation matrix are a function only of the reaction terms and yield coefficients. Simulation results show robustness against set-point changes and input perturbations.
In this work, a mathematical description of a Microbial Electrolysis Cell (MEC) is proposed, taki... more In this work, a mathematical description of a Microbial Electrolysis Cell (MEC) is proposed, taking into account the global mass balances of the different species in the system and considering that all the involved microorganisms are attached to the anodic biological film. Three main biological reactions are introduced, which were obtained from the solution of partial differential equations describing the spatial distribution of potential and substrate in the biofilm. The simulation of the model was carried out using numerical methods, and the results are discussed.
A multivariable adaptive feedback control for highly uncertain continuous anaerobic digestion pro... more A multivariable adaptive feedback control for highly uncertain continuous anaerobic digestion processes is proposed to regulate the volatile fatty acids (VFA) concentration, the strong ions concentrations, and the total and intermediate alkalinities. The multivariable control scheme includes a Luenberger observer to estimate both the unmeasured variables (i.e., VFA) and unknown microbial growth kinetics. The control approach is designed using an exponential Lyapunov function to resemble the typical exponential biological growth of the involved microbial consortia. Taking into account physicochemical equilibrium, alkalinities are represented as a function of the state variables. As a result, the control problem becomes a regulation problem on alkalinities, and in turn, a tracking control problem on the state variables, with two manipulated variables—the dilution rate and the feed rate of a strong alkali solution—while the state variables’ set-points are given as a function of pH. The...
Anaerobic digestion (AD) is an efficient wastewater bioprocess, suitable for treating agroindustr... more Anaerobic digestion (AD) is an efficient wastewater bioprocess, suitable for treating agroindustrial residues with high organic loads and characterized by both a low environmental impact and energy generation. This process is conformed by several chemical and biological reactions in an oxygen free atmosphere, that degrades high molecular weight organic compounds into carbon dioxide and methane mainly but also into traces of hydrogen and ammonia. This process is potentially unstable to volatile fatty acids (VFA), and the alkalinity. variations and is satisfactorily described by the non-linear AM2 model. In this contribution, the AM2 model is modified to include a more general expression for the pH, a cheap and continuous measurement, and also to add more detail in the interactions of the VFA, bicarbonates, and the alkalinity, key factors in the process stability. The stability of the AM2 modified model is explored through a rigorous bifurcation analysis that identifies unstable operation zones and viability of operation trajectories as a function of the dilution rate. Finally, an experimental validation is carried out to show the feasibility and accuracy of the proposed modifications.
The aim of this work is to propose a methodology to obtain an effectiveness factor for biofilm in... more The aim of this work is to propose a methodology to obtain an effectiveness factor for biofilm in a microbial electrolysis cell (MEC) system and use it to reduce a partial differential equation (PDE) biofilm MEC model to an ordinary differential equation (ODE) MEC model. The biofilm mass balances of the different species are considered. In addition, it is considered that all the involved microorganisms are attached to the anodic biological film. Three effectiveness factors are obtained from partial differential equations describing the spatial distributions of potential and substrate in the biofilm. Then, a model reduction is carried out using the global mass balances of the different species in the system. The reduced model with three uncertain but bounded effectiveness factors is evaluated numerically and analyzed in the sense of stability and parametric sensibility to demonstrate its applicability. The reduced ODE model is compared with a validated model taken from the literature...
In this work, the design of the hardware architecture to implement an algorithm for optimizing th... more In this work, the design of the hardware architecture to implement an algorithm for optimizing the Hydrogen Productivity Rate (HPR) in a Microbial Electrolysis Cell (MEC) is presented. The HPR in the MEC is maximized by the golden section search algorithm in conjunction with a super-twisting controller. The development of the digital architecture in the implementation step of the optimization algorithm was developed in the Very High Description Language (VHDL) and synthesized in a Field Programmable Gate Array (FPGA). Numerical simulations demonstrated the feasibility of the proposed optimization strategy embedded in an FPGA Cyclone II. Results showed that only 21% of the total logic elements, 5.19% of dedicated logic registers, and 64% of the total eight-bits multipliers of the FPGA were used. On the other hand, the estimated power consumption required by the FPGA-embedded optimization algorithm was only 146 mW.
In this paper, an experimental study upon alkalinity and hydrodynamic behavior in an anaerobic up... more In this paper, an experimental study upon alkalinity and hydrodynamic behavior in an anaerobic up-flow fixed bed reactor for the treatment of tequila vinasses is presented. Measurements of volatile fatty acids, pH, alkalinity and bicarbonate were obtained at three sampling points in the reactor in the axial axis. Then, the spatial distribution of alkalinity is studied and discussed. Moreover, for further control process purposes, a hydrodynamic model based on the use of two interconnected two-steps reduced AM2 type models is proposed and its parameters are identified using experimental data.
In this paper we propose a multivariable robust feedback control for regulating the alkalinity an... more In this paper we propose a multivariable robust feedback control for regulating the alkalinity and the volatile fatty acid concentration in continuous anaerobic digestion processes used in wastewater treatment. The system exhibits a large lack of knowledge on kinetic parameters. Furthermore, key state variables, which cannot be measured, are estimated by using a Luemberger observer. Thus, even under this highly uncertain scenario, the proposed control law uses this partial information for regulating exponentially the control variables. The control objectives are firstly established upon physicochemical criteria based on normal operational conditions and then formally stated in terms of the concerned state variables. The resulting control law is tested experimentally in a 1 m3 pilot plant for the treatment of red wine vinasses under several uncertain situations in which the multivariable control law is able to recover the system stability around the pre-specified set points showing a...
The TELEMAC project brings new methodologies from the Information and Science Technologies field ... more The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem.
Reviews in Environmental Science and Bio/Technology, 2015
To enhance energy production from methane or resource recovery from digestate, anaerobic digestio... more To enhance energy production from methane or resource recovery from digestate, anaerobic digestion processes require advanced instrumentation and control tools. Over the years, research on these topics has evolved and followed the main fields of application of anaerobic digestion processes: from municipal sewage sludge to liquid -mainly industrial -then municipal organic fraction of solid waste and agricultural residues. Time constants of the processes have also changed with respect to the treated waste from minutes or hours to weeks or months. Since fast closed loop control is needed for short time constant processes, human operator is now included in the loop when taking decisions to optimize anaerobic digestion plants dealing with complex solid waste over a long retention time. Control objectives have also moved from the regulation of key variables -measured on-line -to the prediction of overall process performance -based on global off-line measurements -to optimize the feeding of the processes. Additionally, the need for more accurate prediction of methane production and organic matter biodegradation has impacted the complexity of instrumentation and should include a more detailed characterization of the waste (e.g., biochemical fractions like proteins, lipids and carbohydrates) and their bioaccessibility and biodegradability characteristics. However, even if in the literature several methodologies have been developed to determine biodegradability based on organic matter characterization, only a few papers deal with bioaccessibility assessment. In this review, we emphasize the high potential of some promising techniques, such as spectral analysis, and we discuss issues that could appear in the near future concerning control of AD processes.
The estimation of kinetic parameters and yield coefficients of a two-stage anaerobic digestion mo... more The estimation of kinetic parameters and yield coefficients of a two-stage anaerobic digestion model based on experimental data obtained from the treatment of tequila vinasses is considered in this paper. The proposed model is derived from mass balances of two fixed-bed up-flow bioreactors where the acidogenic phase takes place in the first bioreactor, whereas the second one contains a mixture of acidogenic and methanogenic biomass. The Marquardt method via a study of parametric sensitivity was implemented for estimating parameters and initial conditions using two sets of raw experimental data. The model and the estimated parameters were statistically analyzed to validate the results. Finally, the model was tested with a different set of raw experimental data showing satisfactory prediction capabilities. INTRODUCTION Modelling of Anaerobic Digestion (AD) is a complex task because this process exhibits nonlinear behavior, the presence of influent disturbances, uncertainties on biomas...
This paper deals with the control of the start-up phase in anaerobic digestion systems by using m... more This paper deals with the control of the start-up phase in anaerobic digestion systems by using monitoring parameters already implemented that have been coupled to the control law. Methane yield, as well as methane flow rate, and the ratio of intermediate over total alkalinity have been used as control parameters. These measurements have been included in a switching control strategy to drive the process toward a steady state in which biogas production is optimized avoiding accumulation of volatile fatty acids. Experimental validation of this control strategy has been performed from the results obtained using a 358 litter fixed bed anaerobic digester treating industrial winery wastewater.
In this paper a “virtually controlled observer” (VCO) is proposed to estimate simultaneously the ... more In this paper a “virtually controlled observer” (VCO) is proposed to estimate simultaneously the influent substrate concentration and unmeasured state variables in continuous anaerobic digestion processes. The hypothetical (unmeasured) influent substrate concentration is updated by a feedback control, which is regulated by the estimation error of a measured output. The proposed approach is firstly illustrated upon a simple continuous bioprocess. Then, the performance of the observer is tested via numerical simulations in a continuous anaerobic digestion model. Results showed that it is possible to estimate both, the influent substrate concentration and unmeasured states in the digester in the face of parametric uncertainties.
Anaerobic digestion (AD) is a highly nonlinear time-varying process commonly used for biological ... more Anaerobic digestion (AD) is a highly nonlinear time-varying process commonly used for biological wastewater treatment, which is subject to large disturbances of both influent concentrations, and flow rates that may lead the process to a breakdown. In order to compensate the effect of these disturbances, the dynamics of the main state variablesincluding biomass -must be closely monitored and used to improve the process performance. However, AD processes still suffer from a lack of reliable and cheap sensors of key process variables to insure the right process operation. This has led to the development of estimation schemes, which infer the information of such key variables from the available measurements. Nevertheless, reliable measurements are not always possible to get because these readings may be corrupted by noise or erroneous due to sensor failures and as a consequence, they may lead to deteriorated control efforts and the eventual crash of the AD process. In this article, we propose an integrated system for the detection, isolation, and analysis of faults in AD processes by using interval observers (IO). The proposed approach was experimentally implemented on a 1-m 3 pilot scale anaerobic digester. Based on the comparison between the measured outputs and their corresponding estimates, results show that this approach was able to detect sensor failures as well as faults in the basic hypotheses made during the design step.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2015
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
This paper presents a virtually controlled observer (VCO) used to estimate both, unmeasured state... more This paper presents a virtually controlled observer (VCO) used to estimate both, unmeasured states and unknown influent substrate concentrations in an anaerobic digestion process. This VCO is experimentally implemented in a pilot-scale AD process used for the treatment of wine distillery vinasses. This implementation was carried out under the complete ignorance of the process kinetics. Results indicate that the VCO is able to reconstruct the influent substrate concentration under moderate changes on the operating conditions, while showing also robustness and accuracy against model uncertainties and even sensor faults.
In this work, a classical linear control approach for the peroxide (H2O2) dosage in a photo-Fento... more In this work, a classical linear control approach for the peroxide (H2O2) dosage in a photo-Fenton process is presented as a suitable solution for improving the efficiency in the treatment of recalcitrant organic compounds that cannot be degraded by classical wastewater treatment processes like anaerobic digestion. Experiments were carried out to degrade Lignin, Melanoidin, and Gallic acid, which are typical recalcitrant organic compounds present in some kinds of effluents such as vinasses from the Tequila and Cachaça industries. Experiments were carried in Open-Loop mode for obtaining the degradation model for the three compounds in the form of a Transfer Function, and in Closed-Loop mode for controlling the concentration of each compound. First-order Transfer Functions were obtained using the reaction curve method, and then, based on these models, the parameters of Proportional Integral controllers were calculated using the direct synthesis method. In the Closed-Loop experiments, ...
The aim of this work is to evaluate biohydrogen production from agro-industrial wastewaters and b... more The aim of this work is to evaluate biohydrogen production from agro-industrial wastewaters and byproducts, by combining dark fermentation and microbial electrolysis in a two-step cascade process. Such coupling of both technologies constitutes a technological building block within a concept of environmental biorefinery where sustainable production of renewable energy is expected. Six different wastewaters and industrial by-products coming from cheese, fruit juice, paper, sugar, fruit processing and spirits factories were evaluated for the feasibility of hydrogen production in a two-step process. The overall hydrogen production when coupling dark fermentation and microbial electrolysis was increased up to 13 times when compared to fermentation alone, achieving a maximum overall hydrogen yield of 1608.6 ± 266.2 ml H 2 / gCOD consumed and a maximum of 78.5 ± 5.7% of COD removal. These results show that dark fermentation coupled with microbial electrolysis is a highly promising option to maximize the conversion of agro-industrial wastewaters and by-products into bio-hydrogen.
A nonlinear passive control approach is proposed for the steady state regulation of a twostages a... more A nonlinear passive control approach is proposed for the steady state regulation of a twostages anaerobic digestion process for the treatment of tequila vinasses. The model consists of two interconnected continuous bioreactors for the acidogenic phase and methanogenic phase respectively. Dilution rates, one for each bioreactor, are the manipulated variables. A classical choice of the Hamiltonian as the sum of square errors around the steady state shows that the conservation matrix and the dissipation matrix are a function only of the reaction terms and yield coefficients. Simulation results show robustness against set-point changes and input perturbations.
In this work, a mathematical description of a Microbial Electrolysis Cell (MEC) is proposed, taki... more In this work, a mathematical description of a Microbial Electrolysis Cell (MEC) is proposed, taking into account the global mass balances of the different species in the system and considering that all the involved microorganisms are attached to the anodic biological film. Three main biological reactions are introduced, which were obtained from the solution of partial differential equations describing the spatial distribution of potential and substrate in the biofilm. The simulation of the model was carried out using numerical methods, and the results are discussed.
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