Miguel Mussati - Academia.edu (original) (raw)

Papers by Miguel Mussati

Clean Technologies and Environmental Policy, 2002

ABSTRACT The cleaning performance of an activated sludge wastewater treatment plant for biologica... more ABSTRACT The cleaning performance of an activated sludge wastewater treatment plant for biological nitrogen removal was evaluated based on the Activated Sludge Models No. 1 (ASM1) and No. 3 (ASM3). The COST predenitrification benchmark plant was considered as a case study. Several treatment plant performance indexes were defined based on performance indicators and operating cost factors. Plant operation was evaluated for three dynamic disturbance scenarios corresponding to dry, rain, and storm weather conditions. The aeration rate was seen to be the most sensitive process parameter for this case study, and the nitrate recycle flow rate ratio was the least sensitive of all parameters analyzed. Different qualitative predictions were obtained from the two models, as a result of different model structures. For all three weather scenarios, the sludge production predicted by the ASM1 model increases slightly as the oxygen transfer rate increases; in contrast, the sludge production decreases for the ASM3 model. However, the resulting difference in the sludge treatment cost does not qualitatively modify the cost performance index profile. For all control handles considered the rain weather scenario showed the highest cost performance index and the lowest global cleaning efficiency.

International Journal of Hydrogen Energy, 2010

Journal of Power Sources, Nov 1, 2007

Industrial Engineering Chemistry Research, May 12, 2009

ABSTRACT Wood impregnation is crucial in any pulping process. The impregnation of chips of eucaly... more ABSTRACT Wood impregnation is crucial in any pulping process. The impregnation of chips of eucalyptus wood by a liquor of constant alkali concentration is here analyzed. A mass balance that considers kinetics of the main reactions and a dynamic diffusion coefficient is applied for the six chemical species analyzed. The diffusion rate is assumed dependent on temperature, alkali concentration, and the advance degree of reactions. The predicted concentration profiles are in acceptable agreement with the experimental results for hidroxyl and sodium ions, as well as for acetyl groups. For each set of impregnation conditions and chip thickness, characteristic impregnation times or impregnation levels can be predicted by the model.

Proceedings of the 15th IFAC World Congress, 2002, 2002

Iberoamerican Journal of Industrial Engineering, 2013

Computer Aided Chemical Engineering, 2012

Industrial & Engineering Chemistry Research, 2014

ABSTRACT Real-time optimization (RTO) is widely used in industry to improve the steady-state perf... more ABSTRACT Real-time optimization (RTO) is widely used in industry to improve the steady-state performance of a process using the available measurements, reacting to changing prices and demands scenarios and respecting operating, contractual, and environmental constraints. Traditionally, RTO has used nonlinear continuous formulations to model the process. Mixed-integer formulations have not been used in RTO, because of the need of a fast solution (on the order of seconds or a few minutes), and because many discrete decisions, such as startups or shutdowns, are taken with less frequency in a scheduling layer. This work proposes the use of disjunctions in RTO models, listing a series of examples of discrete decisions (different to startups or shutdowns) that can be addressed by RTO. Two model adaptation approaches (the two-step approach and the modifier adaptation strategy) are revised and modified to make them suitable for RTO with discrete decisions. Some common techniques used in RTO (such as filtering the optimal inputs) are also analyzed and adapted for a formulation with disjunctions. The performance of RTO with disjunctions is shown by a case study in which a generic process is optimized. The results show that the performance of a process can be improved by RTO with discrete decisions. The system converges to the vicinity of the real plant optimum when constraints gradients are corrected, even under structural and parametric mismatch.

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

The predenitrification, postdenitrification and combined pre-postdentrification are the most used... more The predenitrification, postdenitrification and combined pre-postdentrification are the most used basic activated sludge wastewater treatment plant configurations for biological nitrogen removal from municipal and industrial wastewaters. In general, the denitrification schemes may require an external carbon source dosage since the influent easily biodegradable COD is consumed by aerobic microorganisms, resulting in a shortage of easily biodegradable COD for denitrification. This is even worse when the fresh wastewater has low COD/nitrogen ratios. However, the excess of external carbon added may result in a deteriorated effluent quality causing increased fines and/or operation costs for the excess carbon that is not used for denitrification, the higher cost for treating an increased amount of sludge for disposal and energy demand for aeration to remove the excess COD. The problem addressed in this paper is the simultaneous optimization of the system structure (process configuration) ...

Many industrial and agricultural wastewaters contain appreciable amounts of proteins. Under anaer... more Many industrial and agricultural wastewaters contain appreciable amounts of proteins. Under anaerobic conditions proteins are first hydrolyzed and degraded by proteolytic enzymes into peptides and individual amino acids. The peptides and amino acids are then acidified into volatile fatty acids (VFA), hydrogen, ammonium, and reduced sulfur. The VFA are further converted by acetogens into acetate and H2/CO 2, both of which are lastly converted to methane by methanogens. The aim of this work is to investigate the kinetics of protein hydrolysis for its further application in modeling of anaerobic degradation of complex substrates. A bacterial alkaline serine protease (EC 3.4.21.14, Sigma) from Bacillus Licheniformis , an anaerobic microorganism, is used. Gelatin, which is usually found in meat wastes; albumin, in whey effluents; and soy proteins, were chosen as characteristic molecules to represent the proteins commonly found in waste effluents. A glass stirred tank (batch) reactor (1.5...

A study of the anaerobic digestion of synthetic complex substrates, containing carbohydrates and ... more A study of the anaerobic digestion of synthetic complex substrates, containing carbohydrates and proteins, was carried out in two lab-scale, mesophilic fluidized-bed reactors, using sand as inert support for biofilm attachment. After start-up using a soluble substrate based on glucose and acetate, particulate substrates were fed to bioreactors. One reactor was fed with a mixture of sucrose and albumin (RAS ), and a second reactor with sucrose and gelatin (RGS ). Ninety-six percent of the chemical oxygen demand (COD) was removed up to 4 g COD L -1 d-1 of organic loading rate (OLR) for both reactors. A methane yield coefficient of 0.31 L CH 4 per gram of COD removed was obtained, regardless the OLR applied. Experimental data indicated that a concentration of 2.43 g L -1 as NaHCO 3 in the feed stream was sufficient to prevent a pH decrease below 6.6 for OLRs up to 6.24 and 4.16 g COD L -1 d-1 for RAS and RGS , respectively. The volatile fatty acid (VFA) levels and the VFA/alkalinity ra...

Fuel cell power systems for transportation applications have received increased attention in last... more Fuel cell power systems for transportation applications have received increased attention in last years because of their potential for high fuel efficiency and lower emissions. The operation conditions of automotive vehicles require short times of start-up, compact and lightweight equipment and efficient operation at different conditions. The reformer, the water gas shift (WGS) reactor and the preferential oxidation reactor (CO-PROX) constitute the nucleus of the processor, and are a significant fraction of the system volume and weight. In this work we approach the synthesis and design of a system processor of ethanol using conventional reactors. A model-based reactor optimization permits to obtain both designs for reducing volumes and optimal operation conditions as temperature and pressure profiles. These results can be useful for estimating the minimum and relative sizes of the component reactors that allows this technology. The reforming process is endothermic and requires an ex...

Fuel cells are being considered a promising alternative to the propulsors in transport vehicles i... more Fuel cells are being considered a promising alternative to the propulsors in transport vehicles in the next future since they operate at higher efficiencies and produce low environmental impact. The aim of this work is to investigate the synthesis and energy integration of a fuel processor for hydrogen production. Steam reforming of bioethanol and hydrogen purification process are coupled to a polymeric fuel cell (PEMFC). The hydrogen processors consist mainly of three fixed-bed catalytic reactors; the first is a fuel reformer and the other ones are used for reducing impurities, mainly CO, which affect the system operation and deteriorate the cell. A commercial simulator was used to solve the mass and energy balance, and to compute the operative conditions for the process units. The highest energy consumption is demanded by the reforming reactor, which operates at the highest thermal level. It is needed to preheat, evaporate and re-heat the feed stream, and to provide the reaction h...

UTN), Avellaneda 3657, (3000) Santa Fe, Argentina { a mfuentes; b nscenna; c paguir; d mmussati}@... more UTN), Avellaneda 3657, (3000) Santa Fe, Argentina { a mfuentes; b nscenna; c paguir; d mmussati}@ceride.gov.ar Abstract−− The present work is focused on evalu-ating the anaerobic digestion of complex substrates (proteins and carbohydrates) in anaerobic fluidized bed reactors (AFBRs). In a previous paper, an AFBR model was adjusted using only the experimen-tal data obtained during the acclimatization stage (glucose and acetate-based feeding) of two meso-philic bioreactors. Here, the sensitivity of that model to represent the digestion processes of proteins such as gelatin and albumin, and sucrose as a carbohy-drate, is analyzed. Some kinetic expressions and pa-rameters for the enzymatic hydrolysis processes need to be modified to represent the real behavior of bio-reactors. Under the analyzed operating conditions, a hydraulic retention time higher than 1 day is sug-gested to ensure good system efficiency. Keywords−− Anaerobic processes, biofilms, com-plex substrates, dynamic modeling...

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

Computer Aided Chemical Engineering, 2008

An optimization model based on a superstructure embedding several activated sludge process config... more An optimization model based on a superstructure embedding several activated sludge process configurations for nutrient removal is formulated and solved. Simultaneous optimization of the process configuration (process synthesis) and operation conditions for given wastewater specifications and influent flow rate in steady state operation are investigated. The performance criteria selected is the total annual operation cost minimization while predicting compliance with the effluent permitted limits. As the piece of equipment is supposed given, investment costs are not considered. The Activated Sludge Model No. 3 extended with the Bio-P module for computing biological phosphorus removal are used to model the reaction compartments, and the Takács model for representing the secondary settler. The resulting mathematical model is a highly non-linear system, formulated as a Non-Linear-Programming Problem, specifically as a DNLP. The model is implemented and solved using GAMS and CONOPT, respectively. The optimal solution computed from the superstructure model provides cost improvements of around 10% with respect to conventional processes.

Computer Aided Chemical Engineering, 2009

ABSTRACT In the present work, a previous superstructure model developed for simultaneous optimiza... more ABSTRACT In the present work, a previous superstructure model developed for simultaneous optimization of the process configuration and equipment dimensions- i.e., process synthesis and design- and the operation conditions of activated sludge wastewater treatment plants (Alasino et al., 2007) will be extended to account for phosphorus as well as nitrogen removal. Continuous operation is supposed, and the influent wastewater flowrate and composition are assumed known. The performance criterion selected is to minimize the net present value including investment and operating costs while verifying compliance with the effluent permitted limits.The Activated Sludge Model No. 3 extended with the Bio-P module for computing biological phosphorus removal is used to model the reaction compartments, and the Takàcs model for representing the secondary settler. In the present work, new variables and equations for components accounting for phosphorus removal processes are incorporated and the superstructure is also enlarged to embed the most widely used combined N and P removal process configurations. Therefore, the complexity of the problem has been increased. The problem is posed as a NLP problem, specifically a nonlinear programming problem with discontinuous derivatives -DNLP-, as it results in a highly nonlinear system with non-smooth functions. The model is implemented and solved using General Algebraic Modelling System (GAMS), and proved to be robust and flexible. Results for case studies are presented and discussed.

Clean Technologies and Environmental Policy, 2002

ABSTRACT The cleaning performance of an activated sludge wastewater treatment plant for biologica... more ABSTRACT The cleaning performance of an activated sludge wastewater treatment plant for biological nitrogen removal was evaluated based on the Activated Sludge Models No. 1 (ASM1) and No. 3 (ASM3). The COST predenitrification benchmark plant was considered as a case study. Several treatment plant performance indexes were defined based on performance indicators and operating cost factors. Plant operation was evaluated for three dynamic disturbance scenarios corresponding to dry, rain, and storm weather conditions. The aeration rate was seen to be the most sensitive process parameter for this case study, and the nitrate recycle flow rate ratio was the least sensitive of all parameters analyzed. Different qualitative predictions were obtained from the two models, as a result of different model structures. For all three weather scenarios, the sludge production predicted by the ASM1 model increases slightly as the oxygen transfer rate increases; in contrast, the sludge production decreases for the ASM3 model. However, the resulting difference in the sludge treatment cost does not qualitatively modify the cost performance index profile. For all control handles considered the rain weather scenario showed the highest cost performance index and the lowest global cleaning efficiency.

International Journal of Hydrogen Energy, 2010

Journal of Power Sources, Nov 1, 2007

Industrial Engineering Chemistry Research, May 12, 2009

ABSTRACT Wood impregnation is crucial in any pulping process. The impregnation of chips of eucaly... more ABSTRACT Wood impregnation is crucial in any pulping process. The impregnation of chips of eucalyptus wood by a liquor of constant alkali concentration is here analyzed. A mass balance that considers kinetics of the main reactions and a dynamic diffusion coefficient is applied for the six chemical species analyzed. The diffusion rate is assumed dependent on temperature, alkali concentration, and the advance degree of reactions. The predicted concentration profiles are in acceptable agreement with the experimental results for hidroxyl and sodium ions, as well as for acetyl groups. For each set of impregnation conditions and chip thickness, characteristic impregnation times or impregnation levels can be predicted by the model.

Proceedings of the 15th IFAC World Congress, 2002, 2002

Iberoamerican Journal of Industrial Engineering, 2013

Computer Aided Chemical Engineering, 2012

Industrial & Engineering Chemistry Research, 2014

ABSTRACT Real-time optimization (RTO) is widely used in industry to improve the steady-state perf... more ABSTRACT Real-time optimization (RTO) is widely used in industry to improve the steady-state performance of a process using the available measurements, reacting to changing prices and demands scenarios and respecting operating, contractual, and environmental constraints. Traditionally, RTO has used nonlinear continuous formulations to model the process. Mixed-integer formulations have not been used in RTO, because of the need of a fast solution (on the order of seconds or a few minutes), and because many discrete decisions, such as startups or shutdowns, are taken with less frequency in a scheduling layer. This work proposes the use of disjunctions in RTO models, listing a series of examples of discrete decisions (different to startups or shutdowns) that can be addressed by RTO. Two model adaptation approaches (the two-step approach and the modifier adaptation strategy) are revised and modified to make them suitable for RTO with discrete decisions. Some common techniques used in RTO (such as filtering the optimal inputs) are also analyzed and adapted for a formulation with disjunctions. The performance of RTO with disjunctions is shown by a case study in which a generic process is optimized. The results show that the performance of a process can be improved by RTO with discrete decisions. The system converges to the vicinity of the real plant optimum when constraints gradients are corrected, even under structural and parametric mismatch.

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

The predenitrification, postdenitrification and combined pre-postdentrification are the most used... more The predenitrification, postdenitrification and combined pre-postdentrification are the most used basic activated sludge wastewater treatment plant configurations for biological nitrogen removal from municipal and industrial wastewaters. In general, the denitrification schemes may require an external carbon source dosage since the influent easily biodegradable COD is consumed by aerobic microorganisms, resulting in a shortage of easily biodegradable COD for denitrification. This is even worse when the fresh wastewater has low COD/nitrogen ratios. However, the excess of external carbon added may result in a deteriorated effluent quality causing increased fines and/or operation costs for the excess carbon that is not used for denitrification, the higher cost for treating an increased amount of sludge for disposal and energy demand for aeration to remove the excess COD. The problem addressed in this paper is the simultaneous optimization of the system structure (process configuration) ...

Many industrial and agricultural wastewaters contain appreciable amounts of proteins. Under anaer... more Many industrial and agricultural wastewaters contain appreciable amounts of proteins. Under anaerobic conditions proteins are first hydrolyzed and degraded by proteolytic enzymes into peptides and individual amino acids. The peptides and amino acids are then acidified into volatile fatty acids (VFA), hydrogen, ammonium, and reduced sulfur. The VFA are further converted by acetogens into acetate and H2/CO 2, both of which are lastly converted to methane by methanogens. The aim of this work is to investigate the kinetics of protein hydrolysis for its further application in modeling of anaerobic degradation of complex substrates. A bacterial alkaline serine protease (EC 3.4.21.14, Sigma) from Bacillus Licheniformis , an anaerobic microorganism, is used. Gelatin, which is usually found in meat wastes; albumin, in whey effluents; and soy proteins, were chosen as characteristic molecules to represent the proteins commonly found in waste effluents. A glass stirred tank (batch) reactor (1.5...

A study of the anaerobic digestion of synthetic complex substrates, containing carbohydrates and ... more A study of the anaerobic digestion of synthetic complex substrates, containing carbohydrates and proteins, was carried out in two lab-scale, mesophilic fluidized-bed reactors, using sand as inert support for biofilm attachment. After start-up using a soluble substrate based on glucose and acetate, particulate substrates were fed to bioreactors. One reactor was fed with a mixture of sucrose and albumin (RAS ), and a second reactor with sucrose and gelatin (RGS ). Ninety-six percent of the chemical oxygen demand (COD) was removed up to 4 g COD L -1 d-1 of organic loading rate (OLR) for both reactors. A methane yield coefficient of 0.31 L CH 4 per gram of COD removed was obtained, regardless the OLR applied. Experimental data indicated that a concentration of 2.43 g L -1 as NaHCO 3 in the feed stream was sufficient to prevent a pH decrease below 6.6 for OLRs up to 6.24 and 4.16 g COD L -1 d-1 for RAS and RGS , respectively. The volatile fatty acid (VFA) levels and the VFA/alkalinity ra...

Fuel cell power systems for transportation applications have received increased attention in last... more Fuel cell power systems for transportation applications have received increased attention in last years because of their potential for high fuel efficiency and lower emissions. The operation conditions of automotive vehicles require short times of start-up, compact and lightweight equipment and efficient operation at different conditions. The reformer, the water gas shift (WGS) reactor and the preferential oxidation reactor (CO-PROX) constitute the nucleus of the processor, and are a significant fraction of the system volume and weight. In this work we approach the synthesis and design of a system processor of ethanol using conventional reactors. A model-based reactor optimization permits to obtain both designs for reducing volumes and optimal operation conditions as temperature and pressure profiles. These results can be useful for estimating the minimum and relative sizes of the component reactors that allows this technology. The reforming process is endothermic and requires an ex...

Fuel cells are being considered a promising alternative to the propulsors in transport vehicles i... more Fuel cells are being considered a promising alternative to the propulsors in transport vehicles in the next future since they operate at higher efficiencies and produce low environmental impact. The aim of this work is to investigate the synthesis and energy integration of a fuel processor for hydrogen production. Steam reforming of bioethanol and hydrogen purification process are coupled to a polymeric fuel cell (PEMFC). The hydrogen processors consist mainly of three fixed-bed catalytic reactors; the first is a fuel reformer and the other ones are used for reducing impurities, mainly CO, which affect the system operation and deteriorate the cell. A commercial simulator was used to solve the mass and energy balance, and to compute the operative conditions for the process units. The highest energy consumption is demanded by the reforming reactor, which operates at the highest thermal level. It is needed to preheat, evaporate and re-heat the feed stream, and to provide the reaction h...

UTN), Avellaneda 3657, (3000) Santa Fe, Argentina { a mfuentes; b nscenna; c paguir; d mmussati}@... more UTN), Avellaneda 3657, (3000) Santa Fe, Argentina { a mfuentes; b nscenna; c paguir; d mmussati}@ceride.gov.ar Abstract−− The present work is focused on evalu-ating the anaerobic digestion of complex substrates (proteins and carbohydrates) in anaerobic fluidized bed reactors (AFBRs). In a previous paper, an AFBR model was adjusted using only the experimen-tal data obtained during the acclimatization stage (glucose and acetate-based feeding) of two meso-philic bioreactors. Here, the sensitivity of that model to represent the digestion processes of proteins such as gelatin and albumin, and sucrose as a carbohy-drate, is analyzed. Some kinetic expressions and pa-rameters for the enzymatic hydrolysis processes need to be modified to represent the real behavior of bio-reactors. Under the analyzed operating conditions, a hydraulic retention time higher than 1 day is sug-gested to ensure good system efficiency. Keywords−− Anaerobic processes, biofilms, com-plex substrates, dynamic modeling...

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

Computer Aided Chemical Engineering, 2008

An optimization model based on a superstructure embedding several activated sludge process config... more An optimization model based on a superstructure embedding several activated sludge process configurations for nutrient removal is formulated and solved. Simultaneous optimization of the process configuration (process synthesis) and operation conditions for given wastewater specifications and influent flow rate in steady state operation are investigated. The performance criteria selected is the total annual operation cost minimization while predicting compliance with the effluent permitted limits. As the piece of equipment is supposed given, investment costs are not considered. The Activated Sludge Model No. 3 extended with the Bio-P module for computing biological phosphorus removal are used to model the reaction compartments, and the Takács model for representing the secondary settler. The resulting mathematical model is a highly non-linear system, formulated as a Non-Linear-Programming Problem, specifically as a DNLP. The model is implemented and solved using GAMS and CONOPT, respectively. The optimal solution computed from the superstructure model provides cost improvements of around 10% with respect to conventional processes.

Computer Aided Chemical Engineering, 2009

ABSTRACT In the present work, a previous superstructure model developed for simultaneous optimiza... more ABSTRACT In the present work, a previous superstructure model developed for simultaneous optimization of the process configuration and equipment dimensions- i.e., process synthesis and design- and the operation conditions of activated sludge wastewater treatment plants (Alasino et al., 2007) will be extended to account for phosphorus as well as nitrogen removal. Continuous operation is supposed, and the influent wastewater flowrate and composition are assumed known. The performance criterion selected is to minimize the net present value including investment and operating costs while verifying compliance with the effluent permitted limits.The Activated Sludge Model No. 3 extended with the Bio-P module for computing biological phosphorus removal is used to model the reaction compartments, and the Takàcs model for representing the secondary settler. In the present work, new variables and equations for components accounting for phosphorus removal processes are incorporated and the superstructure is also enlarged to embed the most widely used combined N and P removal process configurations. Therefore, the complexity of the problem has been increased. The problem is posed as a NLP problem, specifically a nonlinear programming problem with discontinuous derivatives -DNLP-, as it results in a highly nonlinear system with non-smooth functions. The model is implemented and solved using General Algebraic Modelling System (GAMS), and proved to be robust and flexible. Results for case studies are presented and discussed.