The effect of the partition coefficient on the simulation of the operation of a biotrickling filt... more The effect of the partition coefficient on the simulation of the operation of a biotrickling filter treating a mixture of sulfur compounds was analyzed to evaluate the pertinence of using Henry’s law in determining its removal capacity. The analysis consisted of the simulation of a biotrickling filter that bio-oxides hydrogen sulfide (H2S), dimethyl sulfide (DMS), methyl mercaptan (MM) and dimethyl disulfide (DMDS) using different types of models for determining the partition coefficient: Henry’s law for pure water, Henry’s law adjusted from experimental data, a mixed model (Extended UNIQUAC) and a semi-empirical model of two-parameters. The simulations were compared with experimental data. It was observed that Henry’s law for pure water could produce significant deviations from empirical data due to the liquid phase not being pure water. The two-parameter model better fits with similar results compared to the extended UNIQUAC model, with a lower calculation cost and necessary param...
Trimethylamine (TMA) is the main responsible for the odor often associated with rotting fish and ... more Trimethylamine (TMA) is the main responsible for the odor often associated with rotting fish and is one of the major sources of annoying odors generated in many industrial activities, like composting facilities, fish-meal manufacturing plants, wastewater treatment plants, landfills and livestock farms. Traditionally amines can be removed by acid scrubbers that require the continuous supply of acid and generates large amounts of wastewater. Biofiltration has been proved to be an effective and sustainable technology treating many odorous compounds but the efficient removal of TMA using biofilters has not been completely shown. There are different microorganisms with the ability to use TMA as nutrient for their growth and presents different rates of TMA bio-degradation and biomass yields. Between those Hyphomicrobium vulgare and Aminobacter aminovorans are two bacteria known for their capability to use TMA as carbon and energy source.In order to select one of these bacteria as inoculum...
Currently the use of biofuels is a subject of great interest due to the pollution generated by th... more Currently the use of biofuels is a subject of great interest due to the pollution generated by the use of fossil fuels. Biofuels are generated by fermentation from agro-industrial waste generating a greater positive impact on the environment; these must have a pretreatment to obtain the fermentable sugars. Ethanol is undoubtedly the most studied compound as an alternative to traditional fuels, however in the last decades butanol has begun to be evaluated for its great advantages that it presents on ethanol. In this paper, plantainpeel for small-scale and Eucalyptus globulus for high-scale are evaluated as raw materials in the stand-alone ethanol and butanol production processes. For the plantain peel an acid pretreatment followed by an enzymatic hydrolysis is evaluated and for the Eucalyptus globulus an autohydrolysis before the enzymatic hydrolysis. As a result, it was demonstrated that the ethanol production is a more cost-effective process than the production of butanol. However,...
The yeast Scheffersomyces stipitis naturally produces ethanol from xylose, however reaching high ... more The yeast Scheffersomyces stipitis naturally produces ethanol from xylose, however reaching high ethanol yields is strongly dependent on aeration conditions. It has been reported that changes in the availability of NAD(H/+) cofactors can improve fermentation in some microorganisms. In this work genome-scale metabolic modeling and phenotypic phase plane analysis were used to characterize metabolic response on a range of uptake rates. Sensitivity analysis was used to assess the effect of ARC on ethanol production indicating that modifying ARC by inhibiting the respiratory chain ethanol production can be improved. It was shown experimentally in batch culture using Rotenone as an inhibitor of the mitochondrial NADH dehydrogenase complex I (CINADH), increasing ethanol yield by 18%. Furthermore, trajectories for uptakes rates, specific productivity and specific growth rate were determined by modeling the batch culture, to calculate ARC associated to the addition of CINADH inhibitor. Resul...
The aim of this study is to analyze the techno-economic performance of process configurations for... more The aim of this study is to analyze the techno-economic performance of process configurations for ethanol production involving solid-liquid separators and reactors in the saccharification and fermentation stage, a family of process configurations where few alternatives have been proposed. Since including these process alternatives creates a large number of possible process configurations, a framework for process synthesis and optimization is proposed. This approach is supported on kinetic models fed with experimental data and a plant-wide techno-economic model. Among 150 process configurations, 40 show an improved MESP compared to a well-documented base case (BC), almost all include solid separators and some show energy retrieved in products 32% higher compared to the BC. Moreover, 16 of them also show a lower capital investment per unit of ethanol produced per year. Several of the process configurations found in this work have not been reported in the literature.
Environmental science and pollution research international, 2016
The oxidation of methane (CH4) using biofilters has been proposed as an alternative to mitigate a... more The oxidation of methane (CH4) using biofilters has been proposed as an alternative to mitigate anthropogenic greenhouse gas emissions with a low concentration of CH4 that cannot be used as a source of energy. However, conventional biofilters utilize organic packing materials that have a short lifespan, clogging problems, and are commonly inoculated with non-specific microorganisms leading to unpredictable CH4 elimination capacities (EC) and removal efficiencies (RE). The main objective of this work was to characterize the oxidation of CH4 in two biotrickling filters (BTFs) packed with polyethylene rings and inoculated with two methanotrophic bacteria, Methylomicrobium album and Methylocystis sp., in order to determine EC and CO2 production (pCO2) when using a specific inoculum. The repeatability of the results in both BTFs was determined when they operated at the same inlet load of CH4. A dynamic mathematical model that describes the CH4 abatement in the BTFs was developed and vali...
ABSTRACT. Process synthesis for ethanol production from lignocellulosic materials has been primar... more ABSTRACT. Process synthesis for ethanol production from lignocellulosic materials has been primarily developed by applying heuristic rules for design and analysis of the obtained configurations. This work proposes a methodology for process synthesis based on optimization of a preestablished superstructure containing all selectable options. Processes characterization was carried out by considering a number of performance indexes, namely: technological availability, safety, cost and environmental impact, generated from the collection of available information in literature. The optimization problem was posed as the minimization of a weighted linear combination of the above mentio-ned indexes subject to a restriction on the minimum required yield of the optimal configuration. The selected process consists in treatment of wood chips with ethanol as solvent, simultaneous saccharification and fermentation of cellulose, pentose fermentation, distillation and dehydration by molecular sieves....
Uncertainty associated to the estimated values of the parameters in a model is a key piece of inf... more Uncertainty associated to the estimated values of the parameters in a model is a key piece of information for decision makers and model users. However, this information is typically not reported or the confidence intervals are too large to be useful. A semi-mechanistic model for the enzymatic saccharification of dilute acid pretreated corn stover is proposed in this work, the model is a modification of an existing one providing a statistically significant improved fit towards a set of experimental data that includes varying initial solid loadings (10-25% w/w) and the use of the pretreatment liquor and washed solids with or without supplementation of key inhibitors. A subset of 8 out of 17 parameters was identified, showing sufficiently tight confidence intervals to be used in uncertainty propagation and model analysis, without requiring interval truncation via expert judgment.
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. Additional...
Applied microbiology and biotechnology, Jan 6, 2017
Polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) are important indoo... more Polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) are important indoor contaminants. Their hydrophobic nature hinders the possibility of biological abatement using biofiltration. Our aim was to establish whether the use of a consortium of Fusarium solani and Rhodococcus erythropolis shows an improved performance (in terms of mineralization rate and extent) towards the degradation of formaldehyde, as a slightly polar VOC; toluene, as hydrophobic VOC; and benzo[α]pyrene (BaP) as PAH at low concentrations compared to a single-species biofilm in serum bottles with vermiculite as solid support to mimic a biofilter and to relate the possible improvements with the surface hydrophobicity and partition coefficient of the biomass at three different temperatures. Results showed that the hydrophobicity of the surface of the biofilms was affected by the hydrophobicity of the carbon source in F. solani but it did not change in R. erythropolis. Similarly, the partition ...
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.
The effect of the partition coefficient on the simulation of the operation of a biotrickling filt... more The effect of the partition coefficient on the simulation of the operation of a biotrickling filter treating a mixture of sulfur compounds was analyzed to evaluate the pertinence of using Henry’s law in determining its removal capacity. The analysis consisted of the simulation of a biotrickling filter that bio-oxides hydrogen sulfide (H2S), dimethyl sulfide (DMS), methyl mercaptan (MM) and dimethyl disulfide (DMDS) using different types of models for determining the partition coefficient: Henry’s law for pure water, Henry’s law adjusted from experimental data, a mixed model (Extended UNIQUAC) and a semi-empirical model of two-parameters. The simulations were compared with experimental data. It was observed that Henry’s law for pure water could produce significant deviations from empirical data due to the liquid phase not being pure water. The two-parameter model better fits with similar results compared to the extended UNIQUAC model, with a lower calculation cost and necessary param...
Trimethylamine (TMA) is the main responsible for the odor often associated with rotting fish and ... more Trimethylamine (TMA) is the main responsible for the odor often associated with rotting fish and is one of the major sources of annoying odors generated in many industrial activities, like composting facilities, fish-meal manufacturing plants, wastewater treatment plants, landfills and livestock farms. Traditionally amines can be removed by acid scrubbers that require the continuous supply of acid and generates large amounts of wastewater. Biofiltration has been proved to be an effective and sustainable technology treating many odorous compounds but the efficient removal of TMA using biofilters has not been completely shown. There are different microorganisms with the ability to use TMA as nutrient for their growth and presents different rates of TMA bio-degradation and biomass yields. Between those Hyphomicrobium vulgare and Aminobacter aminovorans are two bacteria known for their capability to use TMA as carbon and energy source.In order to select one of these bacteria as inoculum...
Currently the use of biofuels is a subject of great interest due to the pollution generated by th... more Currently the use of biofuels is a subject of great interest due to the pollution generated by the use of fossil fuels. Biofuels are generated by fermentation from agro-industrial waste generating a greater positive impact on the environment; these must have a pretreatment to obtain the fermentable sugars. Ethanol is undoubtedly the most studied compound as an alternative to traditional fuels, however in the last decades butanol has begun to be evaluated for its great advantages that it presents on ethanol. In this paper, plantainpeel for small-scale and Eucalyptus globulus for high-scale are evaluated as raw materials in the stand-alone ethanol and butanol production processes. For the plantain peel an acid pretreatment followed by an enzymatic hydrolysis is evaluated and for the Eucalyptus globulus an autohydrolysis before the enzymatic hydrolysis. As a result, it was demonstrated that the ethanol production is a more cost-effective process than the production of butanol. However,...
The yeast Scheffersomyces stipitis naturally produces ethanol from xylose, however reaching high ... more The yeast Scheffersomyces stipitis naturally produces ethanol from xylose, however reaching high ethanol yields is strongly dependent on aeration conditions. It has been reported that changes in the availability of NAD(H/+) cofactors can improve fermentation in some microorganisms. In this work genome-scale metabolic modeling and phenotypic phase plane analysis were used to characterize metabolic response on a range of uptake rates. Sensitivity analysis was used to assess the effect of ARC on ethanol production indicating that modifying ARC by inhibiting the respiratory chain ethanol production can be improved. It was shown experimentally in batch culture using Rotenone as an inhibitor of the mitochondrial NADH dehydrogenase complex I (CINADH), increasing ethanol yield by 18%. Furthermore, trajectories for uptakes rates, specific productivity and specific growth rate were determined by modeling the batch culture, to calculate ARC associated to the addition of CINADH inhibitor. Resul...
The aim of this study is to analyze the techno-economic performance of process configurations for... more The aim of this study is to analyze the techno-economic performance of process configurations for ethanol production involving solid-liquid separators and reactors in the saccharification and fermentation stage, a family of process configurations where few alternatives have been proposed. Since including these process alternatives creates a large number of possible process configurations, a framework for process synthesis and optimization is proposed. This approach is supported on kinetic models fed with experimental data and a plant-wide techno-economic model. Among 150 process configurations, 40 show an improved MESP compared to a well-documented base case (BC), almost all include solid separators and some show energy retrieved in products 32% higher compared to the BC. Moreover, 16 of them also show a lower capital investment per unit of ethanol produced per year. Several of the process configurations found in this work have not been reported in the literature.
Environmental science and pollution research international, 2016
The oxidation of methane (CH4) using biofilters has been proposed as an alternative to mitigate a... more The oxidation of methane (CH4) using biofilters has been proposed as an alternative to mitigate anthropogenic greenhouse gas emissions with a low concentration of CH4 that cannot be used as a source of energy. However, conventional biofilters utilize organic packing materials that have a short lifespan, clogging problems, and are commonly inoculated with non-specific microorganisms leading to unpredictable CH4 elimination capacities (EC) and removal efficiencies (RE). The main objective of this work was to characterize the oxidation of CH4 in two biotrickling filters (BTFs) packed with polyethylene rings and inoculated with two methanotrophic bacteria, Methylomicrobium album and Methylocystis sp., in order to determine EC and CO2 production (pCO2) when using a specific inoculum. The repeatability of the results in both BTFs was determined when they operated at the same inlet load of CH4. A dynamic mathematical model that describes the CH4 abatement in the BTFs was developed and vali...
ABSTRACT. Process synthesis for ethanol production from lignocellulosic materials has been primar... more ABSTRACT. Process synthesis for ethanol production from lignocellulosic materials has been primarily developed by applying heuristic rules for design and analysis of the obtained configurations. This work proposes a methodology for process synthesis based on optimization of a preestablished superstructure containing all selectable options. Processes characterization was carried out by considering a number of performance indexes, namely: technological availability, safety, cost and environmental impact, generated from the collection of available information in literature. The optimization problem was posed as the minimization of a weighted linear combination of the above mentio-ned indexes subject to a restriction on the minimum required yield of the optimal configuration. The selected process consists in treatment of wood chips with ethanol as solvent, simultaneous saccharification and fermentation of cellulose, pentose fermentation, distillation and dehydration by molecular sieves....
Uncertainty associated to the estimated values of the parameters in a model is a key piece of inf... more Uncertainty associated to the estimated values of the parameters in a model is a key piece of information for decision makers and model users. However, this information is typically not reported or the confidence intervals are too large to be useful. A semi-mechanistic model for the enzymatic saccharification of dilute acid pretreated corn stover is proposed in this work, the model is a modification of an existing one providing a statistically significant improved fit towards a set of experimental data that includes varying initial solid loadings (10-25% w/w) and the use of the pretreatment liquor and washed solids with or without supplementation of key inhibitors. A subset of 8 out of 17 parameters was identified, showing sufficiently tight confidence intervals to be used in uncertainty propagation and model analysis, without requiring interval truncation via expert judgment.
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. Additional...
Applied microbiology and biotechnology, Jan 6, 2017
Polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) are important indoo... more Polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) are important indoor contaminants. Their hydrophobic nature hinders the possibility of biological abatement using biofiltration. Our aim was to establish whether the use of a consortium of Fusarium solani and Rhodococcus erythropolis shows an improved performance (in terms of mineralization rate and extent) towards the degradation of formaldehyde, as a slightly polar VOC; toluene, as hydrophobic VOC; and benzo[α]pyrene (BaP) as PAH at low concentrations compared to a single-species biofilm in serum bottles with vermiculite as solid support to mimic a biofilter and to relate the possible improvements with the surface hydrophobicity and partition coefficient of the biomass at three different temperatures. Results showed that the hydrophobicity of the surface of the biofilms was affected by the hydrophobicity of the carbon source in F. solani but it did not change in R. erythropolis. Similarly, the partition ...
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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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.
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.