Background: Despite its semi-commercial status, ethanol production from lignocellulosics presents... more Background: Despite its semi-commercial status, ethanol production from lignocellulosics presents many complexities not yet fully solved. Since the pretreatment stage has been recognized as a complex and yield-determining step, it has been extensively studied. However, economic success of the production process also requires optimization of the biochemical conversion stage. This work addresses the search of bioreactor configurations with improved residence times for continuous enzymatic saccharification and fermentation operations. Instead of analyzing each possible configuration through simulation, we apply graphical methods to optimize the residence time of reactor networks composed of steady-state reactors. Although this can be easily made for processes described by a single kinetic expression, reactions under analysis do not exhibit this feature. Hence, the attainable region method, able to handle multiple species and its reactions, was applied for continuous reactors. Additionally, the effects of the sugars contained in the pretreatment liquor over the enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) were assessed. Results: We obtained candidate attainable regions for separate enzymatic hydrolysis and fermentation (SHF) and SSF operations, both fed with pretreated corn stover. Results show that, despite the complexity of the reaction networks and underlying kinetics, the reactor networks that minimize the residence time can be constructed by using plug flow reactors and continuous stirred tank reactors. Regarding the effect of soluble solids in the feed stream to the reactor network, for SHF higher glucose concentration and yield are achieved for enzymatic hydrolysis with washed solids. Similarly, for SSF, higher yields and bioethanol titers are obtained using this substrate. Conclusions: In this work, we demonstrated the capabilities of the attainable region analysis as a tool to assess the optimal reactor network with minimum residence time applied to the SHF and SSF operations for lignocellulosic ethanol production. The methodology can be readily modified to evaluate other kinetic models of different substrates, enzymes and microorganisms when available. From the obtained results, the most suitable reactor configuration considering residence time and rheological aspects is a continuous stirred tank reactor followed by a plug flow reactor (both in SSF mode) using washed solids as substrate.
Background: Bioethanol is produced mainly from sugar cane and corn. In the last years it has been... more Background: Bioethanol is produced mainly from sugar cane and corn. In the last years it has been subject of debate due to the effects in food prices and land use change. The use of lignocellulosic materials for bioethanol production, such as agroindustry, forestry and municipal residues, wood or dendroenergetic species, has been proposed as a sustainable way for producing this biofuel. The design of a sustainable process for producing bioethanol requires a methodological approach whereby economical, environmental and social criteria are systematically integrated from the early stages of process design.
Results: Until now a methodology for guiding the design of a sustainable process for bioethanol production is not available, and there are just a few studies on this subject. Moreover, with the recent global concerns on climate change, developed technologies have been confronted with additional requirements to validate their sustainability. In this sense, the inclusion of sustainability criteria on process design becomes necessary for defining a systematic methodology to select the most appropriate operations in the process stages to achieve a sustainable bioethanol production.
Conclusions: A description of the stages for the production of bioethanol from lignocellulosic materials is provided in this review and the main findings in relation to the more important sustainability indicators are presented.
Background: Despite its semi-commercial status, ethanol production from lignocellulosics presents... more Background: Despite its semi-commercial status, ethanol production from lignocellulosics presents many complexities not yet fully solved. Since the pretreatment stage has been recognized as a complex and yield-determining step, it has been extensively studied. However, economic success of the production process also requires optimization of the biochemical conversion stage. This work addresses the search of bioreactor configurations with improved residence times for continuous enzymatic saccharification and fermentation operations. Instead of analyzing each possible configuration through simulation, we apply graphical methods to optimize the residence time of reactor networks composed of steady-state reactors. Although this can be easily made for processes described by a single kinetic expression, reactions under analysis do not exhibit this feature. Hence, the attainable region method, able to handle multiple species and its reactions, was applied for continuous reactors. Additionally, the effects of the sugars contained in the pretreatment liquor over the enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) were assessed. Results: We obtained candidate attainable regions for separate enzymatic hydrolysis and fermentation (SHF) and SSF operations, both fed with pretreated corn stover. Results show that, despite the complexity of the reaction networks and underlying kinetics, the reactor networks that minimize the residence time can be constructed by using plug flow reactors and continuous stirred tank reactors. Regarding the effect of soluble solids in the feed stream to the reactor network, for SHF higher glucose concentration and yield are achieved for enzymatic hydrolysis with washed solids. Similarly, for SSF, higher yields and bioethanol titers are obtained using this substrate. Conclusions: In this work, we demonstrated the capabilities of the attainable region analysis as a tool to assess the optimal reactor network with minimum residence time applied to the SHF and SSF operations for lignocellulosic ethanol production. The methodology can be readily modified to evaluate other kinetic models of different substrates, enzymes and microorganisms when available. From the obtained results, the most suitable reactor configuration considering residence time and rheological aspects is a continuous stirred tank reactor followed by a plug flow reactor (both in SSF mode) using washed solids as substrate.
Background: Bioethanol is produced mainly from sugar cane and corn. In the last years it has been... more Background: Bioethanol is produced mainly from sugar cane and corn. In the last years it has been subject of debate due to the effects in food prices and land use change. The use of lignocellulosic materials for bioethanol production, such as agroindustry, forestry and municipal residues, wood or dendroenergetic species, has been proposed as a sustainable way for producing this biofuel. The design of a sustainable process for producing bioethanol requires a methodological approach whereby economical, environmental and social criteria are systematically integrated from the early stages of process design.
Results: Until now a methodology for guiding the design of a sustainable process for bioethanol production is not available, and there are just a few studies on this subject. Moreover, with the recent global concerns on climate change, developed technologies have been confronted with additional requirements to validate their sustainability. In this sense, the inclusion of sustainability criteria on process design becomes necessary for defining a systematic methodology to select the most appropriate operations in the process stages to achieve a sustainable bioethanol production.
Conclusions: A description of the stages for the production of bioethanol from lignocellulosic materials is provided in this review and the main findings in relation to the more important sustainability indicators are presented.
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Papers by Felipe Scott
complexities not yet fully solved. Since the pretreatment stage has been recognized as a complex and
yield-determining step, it has been extensively studied. However, economic success of the production process
also requires optimization of the biochemical conversion stage. This work addresses the search of bioreactor
configurations with improved residence times for continuous enzymatic saccharification and fermentation
operations. Instead of analyzing each possible configuration through simulation, we apply graphical methods to
optimize the residence time of reactor networks composed of steady-state reactors. Although this can be easily
made for processes described by a single kinetic expression, reactions under analysis do not exhibit this feature.
Hence, the attainable region method, able to handle multiple species and its reactions, was applied for continuous
reactors. Additionally, the effects of the sugars contained in the pretreatment liquor over the enzymatic hydrolysis
and simultaneous saccharification and fermentation (SSF) were assessed.
Results: We obtained candidate attainable regions for separate enzymatic hydrolysis and fermentation (SHF) and
SSF operations, both fed with pretreated corn stover. Results show that, despite the complexity of the reaction
networks and underlying kinetics, the reactor networks that minimize the residence time can be constructed by
using plug flow reactors and continuous stirred tank reactors. Regarding the effect of soluble solids in the feed
stream to the reactor network, for SHF higher glucose concentration and yield are achieved for enzymatic
hydrolysis with washed solids. Similarly, for SSF, higher yields and bioethanol titers are obtained using this substrate.
Conclusions: In this work, we demonstrated the capabilities of the attainable region analysis as a tool to assess the
optimal reactor network with minimum residence time applied to the SHF and SSF operations for lignocellulosic
ethanol production. The methodology can be readily modified to evaluate other kinetic models of different
substrates, enzymes and microorganisms when available. From the obtained results, the most suitable reactor
configuration considering residence time and rheological aspects is a continuous stirred tank reactor followed by a
plug flow reactor (both in SSF mode) using washed solids as substrate.
Results: Until now a methodology for guiding the design of a sustainable process for bioethanol production is not available, and there are just a few studies on this subject. Moreover, with the recent global concerns on climate change, developed technologies have been confronted with additional requirements to validate their sustainability. In this sense, the inclusion of sustainability criteria on process design becomes necessary for defining a systematic methodology to select the most appropriate operations in the process stages to achieve a sustainable bioethanol production.
Conclusions: A description of the stages for the production of bioethanol from lignocellulosic materials is provided in this review and the main findings in relation to the more important sustainability indicators are presented.
complexities not yet fully solved. Since the pretreatment stage has been recognized as a complex and
yield-determining step, it has been extensively studied. However, economic success of the production process
also requires optimization of the biochemical conversion stage. This work addresses the search of bioreactor
configurations with improved residence times for continuous enzymatic saccharification and fermentation
operations. Instead of analyzing each possible configuration through simulation, we apply graphical methods to
optimize the residence time of reactor networks composed of steady-state reactors. Although this can be easily
made for processes described by a single kinetic expression, reactions under analysis do not exhibit this feature.
Hence, the attainable region method, able to handle multiple species and its reactions, was applied for continuous
reactors. Additionally, the effects of the sugars contained in the pretreatment liquor over the enzymatic hydrolysis
and simultaneous saccharification and fermentation (SSF) were assessed.
Results: We obtained candidate attainable regions for separate enzymatic hydrolysis and fermentation (SHF) and
SSF operations, both fed with pretreated corn stover. Results show that, despite the complexity of the reaction
networks and underlying kinetics, the reactor networks that minimize the residence time can be constructed by
using plug flow reactors and continuous stirred tank reactors. Regarding the effect of soluble solids in the feed
stream to the reactor network, for SHF higher glucose concentration and yield are achieved for enzymatic
hydrolysis with washed solids. Similarly, for SSF, higher yields and bioethanol titers are obtained using this substrate.
Conclusions: In this work, we demonstrated the capabilities of the attainable region analysis as a tool to assess the
optimal reactor network with minimum residence time applied to the SHF and SSF operations for lignocellulosic
ethanol production. The methodology can be readily modified to evaluate other kinetic models of different
substrates, enzymes and microorganisms when available. From the obtained results, the most suitable reactor
configuration considering residence time and rheological aspects is a continuous stirred tank reactor followed by a
plug flow reactor (both in SSF mode) using washed solids as substrate.
Results: Until now a methodology for guiding the design of a sustainable process for bioethanol production is not available, and there are just a few studies on this subject. Moreover, with the recent global concerns on climate change, developed technologies have been confronted with additional requirements to validate their sustainability. In this sense, the inclusion of sustainability criteria on process design becomes necessary for defining a systematic methodology to select the most appropriate operations in the process stages to achieve a sustainable bioethanol production.
Conclusions: A description of the stages for the production of bioethanol from lignocellulosic materials is provided in this review and the main findings in relation to the more important sustainability indicators are presented.