Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to o... more Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to optimize biofiltration systems performance. In this work, biological kinetics expressions were implemented into Computational Fluid Dynamics (CFD) model as transport equations, including convective and diffusive terms. Previously, activity within the biofilm of a flat plate bioreactor (FPB) was experimentally investigated measuring dissolved oxygen (DO) profiles by means of microsensors and under common operating conditions. Moreover, a mathematical model to describe mass transport and metabolic activity in the FPB was developed and their parameters were fitted from experimental results. Then, a CFD model, combining hydrodynamics and biochemical reactions, was developed and solved to simulate local transient flow and dynamic behaviors of biofilm growth and substrate (glucose) biodregradation in the FPB. The CFD simulation results were evaluated by studying hydrodynamics characterization i...
Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their su... more Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripple formation, and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex under such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here, we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high-speed imaging. The numerical model involved a two-phase flow of air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, she...
A novel sensing device for simultaneous dissolved oxygen (DO) and pH monitoring specially designe... more A novel sensing device for simultaneous dissolved oxygen (DO) and pH monitoring specially designed for biofilm profiling is presented in this work. This device enabled the recording of instantaneous DO and pH dynamic profiles within biofilms, improving the tools available for the study and the characterization of biological systems. The microsensor consisted of two parallel arrays of microelectrodes. Microelectrodes used for DO sensing were bare gold electrodes, while microelectrodes used for pH sensing were platinum-based electrodes modified using electrodeposited iridium oxide. The device was fabricated with a polyimide (Kapton®) film of 127 µm as a substrate for minimizing the damage caused on the biofilm structure during its insertion. The electrodes were covered with a Nafion® layer to increase sensor stability and repeatability and to avoid electrode surface fouling. DO microelectrodes showed a linear response in the range 0–8 mg L−1, a detection limit of 0.05 mg L−1, and a se...
The present study evaluates the technical and economical feasibility of the H2S elimination from ... more The present study evaluates the technical and economical feasibility of the H2S elimination from an energy-rich gas using a full-scale biotrickling filter installed in a municipal waste water treatment plant. The study analyzes the continuous operation of a 4.5 months period, treating 80 m3 h-1 of biogas with an average H2S concentration of 3000 ppmv. The bioreactor was operated at a gas contact time of 180 seconds and maximum elimination capacities of 170 g H2S m-3 h-1 were obtained without any occurrence of neither biological nor mass transfer limitation. Elemental sulfur and sulfate were the main detected byproducts of the H2S treatment. The main drawback observed during the studied period was related to the air flow supply. This caused a removal efficiency decrease and an excess of sulfur production. A comparative cost-benefit analysis of the more applied chemical oxidation processes with the biological treatment was performed. Savings chemicals indicated that the payback time o...
Respirometry was used to reveal the mechanisms involved in aerobic biological sulfide oxidation a... more Respirometry was used to reveal the mechanisms involved in aerobic biological sulfide oxidation and to characterize the kinetics and stoichiometry of a microbial culture obtained from a desulfurizing biotrickling filter. Physical-chemical processes such as stripping and chemical oxidation of hydrogen sulfide were characterized since they contributed significantly to the conversions observed in respirometric tests. Mass transfer coefficient for hydrogen sulfide and the kinetic parameters for chemical oxidation of sulfide with oxygen were estimated. The stoichiometry of the process was determined and the different steps in the sulfide oxidation process were identified. The conversion scheme proposed includes intermediate production of elemental sulfur and thiosulfate and the subsequent oxidation of both compounds to sulfate. A kinetic model describing each of the reactions observed during sulfide oxidation was calibrated and validated. The product selectivity was found to be independe...
The European Institutions have the challenge and the commitment to enhance plurilingual competenc... more The European Institutions have the challenge and the commitment to enhance plurilingual competence, and teaching curricular subjects in a foreign language is seen as one of the most promising alternatives. However, teaching in a foreign language doesn't mean just to translate contents, when the quality of the specific subject wants to be guaranteed. Some arrangements are necessary in order to balance the achievement of both, specific and linguistic competences. In that context, professors teaching different engineering subjects at the Campus of Manresa (EPSEM) at the UPC have been involved in projects to analyze the current situation and develop some on-line open access materials, as Class-talk and Multilingual Formulae, giving rise to the group Linguatech-Rima (Research group on Scientific and Technologic Multilingual Communication).
Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to o... more Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to optimize biofiltration systems performance. In this work, biological kinetics expressions were implemented into Computational Fluid Dynamics (CFD) model as transport equations, including convective and diffusive terms. Previously, activity within the biofilm of a flat plate bioreactor (FPB) was experimentally investigated measuring dissolved oxygen (DO) profiles by means of microsensors and under common operating conditions. Moreover, a mathematical model to describe mass transport and metabolic activity in the FPB was developed and their parameters were fitted from experimental results. Then, a CFD model, combining hydrodynamics and biochemical reactions, was developed and solved to simulate local transient flow and dynamic behaviors of biofilm growth and substrate (glucose) biodregradation in the FPB. The CFD simulation results were evaluated by studying hydrodynamics characterization i...
Biotechnology and Biochemical Engineering: Bioreactors Biological removal of hydrogen sulfide (H ... more Biotechnology and Biochemical Engineering: Bioreactors Biological removal of hydrogen sulfide (H 2 S) with biotrickling filters has become a good economic alternative to traditional physical-chemical methods used for treating air emissions (Kim and Deshusses, 2005). However, although the technology has been widely tested, there is a lack of knowledge in the degradation phenomena taking place within biofilms. Therefore it is essential to conduct studies to monitor biofilm and clarify its role in the process of biofiltration in order to optimize this technology. To carry out studies at laboratory-scale, biofilms growth in industrial reactors may be reproduced by constructing and operating suitable laboratory biofilm reactors. In the design of such experimental setups , it should be considered the type of reactor, the biological process to be developed and the necessary measurements in the study of biofilms (Lewandowski and Beyenal, 2007). In this work a gas-phase flat-plate (GPFP) bio...
The optimization of biofiltration technologies can be addressed improving the knowledge of the pr... more The optimization of biofiltration technologies can be addressed improving the knowledge of the process taking place within biofilms, mainly biokinetics and mass transport. Biokinetics are usually defined using different methodologies, such as respirometric and titrimetric tests. Mass transport within biofilms is usually described as diffusion through a homogeneous phase, despite it is accepted that biofilms are very heterogeneous. Thus, a quantitative understanding of how biofilm structure is linked to mass transport is essential to develop reliable models. For this purpose different works have collected the results of various diffusion studies, proposing correlations between biofilm density and mass transport. However the reliability of these correlations, widely used in modeling works, is under suspect because data used in their construction are highly dependent on the experimental conditions where they were obtained. The goal of this paper was to experimentally quantify the effec...
Journal of Chemical Technology & Biotechnology, 2015
A dynamic model has been developed to describe the performance of an anoxic biotrickling filter f... more A dynamic model has been developed to describe the performance of an anoxic biotrickling filter for biogas desulfurization. The model considers the most relevant phenomena involved in the biotrickling filter operation: convection, absorption, diffusion and biodegradation. The model also considers that a fraction of the liquid phase is stagnant-an assumption that increases the importance of diffusion phenomena for low liquid flow rates. The model was calibrated and validated using experimental data from a pilot-scale plant installed in a WWTP. In the calibration stage a set of periods with a wide range of operating conditions was used; i.e., biogas flow rate in the range 1-5 m 3 h −1 , recirculation flow rate in the range 1-3 m 3 h −1 , and nitrate concentration in the range 1-423 gN−NO3m −3. The predictions obtained on using the model were consistent with experimental data and the divergence was less than 2%. The model was subsequently validated using two faultless periods (recirculation flow rates of 1.5 and 3 m 3 h −1 , biogas flow rate in the range 1-5.2 m 3 h −1 , and inlet H2S concentration steps in the range 3600-5500 ppmV). An ANOVA study was carried out in order to quantify the suitability of the predictions. The results indicated that the differences between experimental and simulated outlet H2S concentrations were not statistically significant. The model was also able to predict simultaneously the dynamic concentrations of sulfide and nitrate in the liquid phase. Once the model had been validated, six control strategies were analyzed for different scenarios and purposes: i.e., to minimize the nitrate consumption and/or to maximize the H2S removal efficiency. The developed model is a potential tool to enhance and optimize the performance of biotrickling filters for the anoxic removal of H2S.
The main objective of this study is to evaluate qualitatively and quantitatively the effect of st... more The main objective of this study is to evaluate qualitatively and quantitatively the effect of starvation periods in the biodegradation capacity of microorganisms when the support media is a material with high sorption capacity. Pollutant sorption and biodegradation, which occur simultaneously in the biofilter, describe the overall behavior of the air treatment system during normal operation and during starvation periods. Results obtained in the present study demonstrate that sorption capacity of the material not only plays an important role during the start-up of operation, but it is also important during steady operation. Simultaneously, as biomass grows on the support, biodegradation becomes more decisive in the performance. It was found that zones of packing material with low moisture content are controlled by the sorption mechanism, at the expense of biodegradation, and they are essential as a pollutant reservoir during starvation periods. In the present study a significant decrease in the biodegradation capacity of microorganisms immobilized on activated carbon was not observed as a consequence of continuous load interruptions.
A mathematical dynamic model describing biological removal of high loads of H2S from biogas strea... more A mathematical dynamic model describing biological removal of high loads of H2S from biogas streams through a biotrickling filter (BTF) was developed, calibrated and validated to a range of specific experimental conditions of a lab-scale BTF. This model takes into account the main processes occurring in the three phases of the desulfurizing BTF (gas, liquid and biofilm phase) in a co-current configuration flow mode. This model attempts to describe accurately intermediate products obtained from H2S oxidation using kinetic models, previously developed using respirometric techniques with biomass samples obtained from the same BTF set up used here. Previous to the model parameters calibration, a sensitivity analysis was performed in order to focus the parameters estimation on those parameters that showed a highest influence on modelling results over the main process variables. To calibrate the model, an objective function considering the difference between the experimental and the predi...
The aim of this work was to evaluate different operational modes in an anoxic biotrickling filter... more The aim of this work was to evaluate different operational modes in an anoxic biotrickling filter (BTF) by means of a dynamic model. The model was calibrated and validated satisfactorily with experimental data from a pilot-scale anoxic biotrickling filter plant for biogas sweetening. Model simulations allowed to find the optimal mode operation and predicting the biotrickling filter behavior.
Particle size, pH and Fe(III) ions affect the process of bioleaching of copper from chalcopyrite ... more Particle size, pH and Fe(III) ions affect the process of bioleaching of copper from chalcopyrite ores. In the study presented herein a copper sulfide ore was subjected to bioleaching process using a mixed microbial consortium obtained from a biotrickling filter treating high loads of H 2 S at different mineral particle size, distinct medium pH and various additional Fe(III) ion concentrations as leaching agent. After 1300 hours of operation, the total copper recovery achieved a value of 50 % in the most acidic conditions. A decrease of 2.5 units of pH implied an increase in the efficiency of 35%. It was also observed an optimal particle size (between 2 and 3 mm), considerably higher than previous reported studies, meaning a decrease in operational cost to mill material. Finally, results indicate that there is a threshold concentration of ferric ion from which the system is not sensitive (500 ppm).
Proceedings of the 3rd International Congress on Biotechniques for Air Pollution Control. Delft, The Netherlands, September 28-30, 2009, 2010
Biofiltration employs the metabolic activity of microorganisms immobilized on a packing material ... more Biofiltration employs the metabolic activity of microorganisms immobilized on a packing material to degrade gas phase pollutants which are the energy source for microbial growth. However, biomass accumulation is one of the most critical parameters that need to be controlled along the operation of biofilters and biotrickling filters in order to achieve stable performance for long term operation. The excess of biomass inside the bioreactor
In this work the kinetics of a number of sulfide-oxidizing nitrate-reducing (SO-NR) cultures accl... more In this work the kinetics of a number of sulfide-oxidizing nitrate-reducing (SO-NR) cultures acclimated and not acclimated to nitrite were characterized. Anoxic respirometry coupled to kinetic modeling of respirometric profiles was the methodology used to study the two-step denitrification associated to thiosulfate oxidation. Autotrophic denitritation was initially studied in a non-acclimated SO-NR culture to confirm that nitrite reduction kinetics could be described through a Haldane-type equation. Afterwards, a kinetic model describing the two-step denitrification (NO 3-→ NO 2-→ N 2) was calibrated and validated through the estimation of several kinetic parameters from the fitting of experimental respirometric profiles obtained using either nitrate or nitrite as electron acceptors for both acclimated and non-acclimated biomass. The model proposed was a multi-substrate model that considered all the species implicated in the process as well as the stoichiometry associated particularly to the biomass studied in this work. A comparison between the kinetic parameters with the biomass acclimated and nonacclimated to nitrite revealed a 7-fold increase of the Haldane nitrite inhibition constant in the acclimated biomass with respect to the non-acclimated while the nitrite half-saturation constant and the maximum specific growth rate remained almost unchanged. The Fisher Information Matrix method was used to obtain the confidence intervals and also to evaluate the sensitivity and the identifiability in model calibration of each kinetic parameter estimated.
Biological removal of hydrogen sulfide with a biotrickling filter (BTF) has been widely tested. T... more Biological removal of hydrogen sulfide with a biotrickling filter (BTF) has been widely tested. The technology has proved to be a good alternative to the more expensive physical-chemical systems (Kim and Deshusses, 2005). However, the treatment of a high load of hydrogen sulfide (e.g. biogas from anaerobic digesters) has been less studied. The biological removal of hydrogen sulfide requires a large quantity of oxygen. When the oxygen supply is the stoichiometric, sulfates are generated continuously at the BTF, and they are removed from the BTF through the renovation of the liquid phase. When this requirement of dissolved oxygen is not accomplished, the elemental sulfur formation is enhanced. Elemental sulfur is accumulated in the packing material, increasing pressure drop and, thus, increasing the operational cost for equipment or even, causing the total clogging of the bed (Fortuny et al., 2008).
Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to o... more Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to optimize biofiltration systems performance. In this work, biological kinetics expressions were implemented into Computational Fluid Dynamics (CFD) model as transport equations, including convective and diffusive terms. Previously, activity within the biofilm of a flat plate bioreactor (FPB) was experimentally investigated measuring dissolved oxygen (DO) profiles by means of microsensors and under common operating conditions. Moreover, a mathematical model to describe mass transport and metabolic activity in the FPB was developed and their parameters were fitted from experimental results. Then, a CFD model, combining hydrodynamics and biochemical reactions, was developed and solved to simulate local transient flow and dynamic behaviors of biofilm growth and substrate (glucose) biodregradation in the FPB. The CFD simulation results were evaluated by studying hydrodynamics characterization i...
Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their su... more Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripple formation, and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex under such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here, we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high-speed imaging. The numerical model involved a two-phase flow of air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, she...
A novel sensing device for simultaneous dissolved oxygen (DO) and pH monitoring specially designe... more A novel sensing device for simultaneous dissolved oxygen (DO) and pH monitoring specially designed for biofilm profiling is presented in this work. This device enabled the recording of instantaneous DO and pH dynamic profiles within biofilms, improving the tools available for the study and the characterization of biological systems. The microsensor consisted of two parallel arrays of microelectrodes. Microelectrodes used for DO sensing were bare gold electrodes, while microelectrodes used for pH sensing were platinum-based electrodes modified using electrodeposited iridium oxide. The device was fabricated with a polyimide (Kapton®) film of 127 µm as a substrate for minimizing the damage caused on the biofilm structure during its insertion. The electrodes were covered with a Nafion® layer to increase sensor stability and repeatability and to avoid electrode surface fouling. DO microelectrodes showed a linear response in the range 0–8 mg L−1, a detection limit of 0.05 mg L−1, and a se...
The present study evaluates the technical and economical feasibility of the H2S elimination from ... more The present study evaluates the technical and economical feasibility of the H2S elimination from an energy-rich gas using a full-scale biotrickling filter installed in a municipal waste water treatment plant. The study analyzes the continuous operation of a 4.5 months period, treating 80 m3 h-1 of biogas with an average H2S concentration of 3000 ppmv. The bioreactor was operated at a gas contact time of 180 seconds and maximum elimination capacities of 170 g H2S m-3 h-1 were obtained without any occurrence of neither biological nor mass transfer limitation. Elemental sulfur and sulfate were the main detected byproducts of the H2S treatment. The main drawback observed during the studied period was related to the air flow supply. This caused a removal efficiency decrease and an excess of sulfur production. A comparative cost-benefit analysis of the more applied chemical oxidation processes with the biological treatment was performed. Savings chemicals indicated that the payback time o...
Respirometry was used to reveal the mechanisms involved in aerobic biological sulfide oxidation a... more Respirometry was used to reveal the mechanisms involved in aerobic biological sulfide oxidation and to characterize the kinetics and stoichiometry of a microbial culture obtained from a desulfurizing biotrickling filter. Physical-chemical processes such as stripping and chemical oxidation of hydrogen sulfide were characterized since they contributed significantly to the conversions observed in respirometric tests. Mass transfer coefficient for hydrogen sulfide and the kinetic parameters for chemical oxidation of sulfide with oxygen were estimated. The stoichiometry of the process was determined and the different steps in the sulfide oxidation process were identified. The conversion scheme proposed includes intermediate production of elemental sulfur and thiosulfate and the subsequent oxidation of both compounds to sulfate. A kinetic model describing each of the reactions observed during sulfide oxidation was calibrated and validated. The product selectivity was found to be independe...
The European Institutions have the challenge and the commitment to enhance plurilingual competenc... more The European Institutions have the challenge and the commitment to enhance plurilingual competence, and teaching curricular subjects in a foreign language is seen as one of the most promising alternatives. However, teaching in a foreign language doesn't mean just to translate contents, when the quality of the specific subject wants to be guaranteed. Some arrangements are necessary in order to balance the achievement of both, specific and linguistic competences. In that context, professors teaching different engineering subjects at the Campus of Manresa (EPSEM) at the UPC have been involved in projects to analyze the current situation and develop some on-line open access materials, as Class-talk and Multilingual Formulae, giving rise to the group Linguatech-Rima (Research group on Scientific and Technologic Multilingual Communication).
Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to o... more Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to optimize biofiltration systems performance. In this work, biological kinetics expressions were implemented into Computational Fluid Dynamics (CFD) model as transport equations, including convective and diffusive terms. Previously, activity within the biofilm of a flat plate bioreactor (FPB) was experimentally investigated measuring dissolved oxygen (DO) profiles by means of microsensors and under common operating conditions. Moreover, a mathematical model to describe mass transport and metabolic activity in the FPB was developed and their parameters were fitted from experimental results. Then, a CFD model, combining hydrodynamics and biochemical reactions, was developed and solved to simulate local transient flow and dynamic behaviors of biofilm growth and substrate (glucose) biodregradation in the FPB. The CFD simulation results were evaluated by studying hydrodynamics characterization i...
Biotechnology and Biochemical Engineering: Bioreactors Biological removal of hydrogen sulfide (H ... more Biotechnology and Biochemical Engineering: Bioreactors Biological removal of hydrogen sulfide (H 2 S) with biotrickling filters has become a good economic alternative to traditional physical-chemical methods used for treating air emissions (Kim and Deshusses, 2005). However, although the technology has been widely tested, there is a lack of knowledge in the degradation phenomena taking place within biofilms. Therefore it is essential to conduct studies to monitor biofilm and clarify its role in the process of biofiltration in order to optimize this technology. To carry out studies at laboratory-scale, biofilms growth in industrial reactors may be reproduced by constructing and operating suitable laboratory biofilm reactors. In the design of such experimental setups , it should be considered the type of reactor, the biological process to be developed and the necessary measurements in the study of biofilms (Lewandowski and Beyenal, 2007). In this work a gas-phase flat-plate (GPFP) bio...
The optimization of biofiltration technologies can be addressed improving the knowledge of the pr... more The optimization of biofiltration technologies can be addressed improving the knowledge of the process taking place within biofilms, mainly biokinetics and mass transport. Biokinetics are usually defined using different methodologies, such as respirometric and titrimetric tests. Mass transport within biofilms is usually described as diffusion through a homogeneous phase, despite it is accepted that biofilms are very heterogeneous. Thus, a quantitative understanding of how biofilm structure is linked to mass transport is essential to develop reliable models. For this purpose different works have collected the results of various diffusion studies, proposing correlations between biofilm density and mass transport. However the reliability of these correlations, widely used in modeling works, is under suspect because data used in their construction are highly dependent on the experimental conditions where they were obtained. The goal of this paper was to experimentally quantify the effec...
Journal of Chemical Technology & Biotechnology, 2015
A dynamic model has been developed to describe the performance of an anoxic biotrickling filter f... more A dynamic model has been developed to describe the performance of an anoxic biotrickling filter for biogas desulfurization. The model considers the most relevant phenomena involved in the biotrickling filter operation: convection, absorption, diffusion and biodegradation. The model also considers that a fraction of the liquid phase is stagnant-an assumption that increases the importance of diffusion phenomena for low liquid flow rates. The model was calibrated and validated using experimental data from a pilot-scale plant installed in a WWTP. In the calibration stage a set of periods with a wide range of operating conditions was used; i.e., biogas flow rate in the range 1-5 m 3 h −1 , recirculation flow rate in the range 1-3 m 3 h −1 , and nitrate concentration in the range 1-423 gN−NO3m −3. The predictions obtained on using the model were consistent with experimental data and the divergence was less than 2%. The model was subsequently validated using two faultless periods (recirculation flow rates of 1.5 and 3 m 3 h −1 , biogas flow rate in the range 1-5.2 m 3 h −1 , and inlet H2S concentration steps in the range 3600-5500 ppmV). An ANOVA study was carried out in order to quantify the suitability of the predictions. The results indicated that the differences between experimental and simulated outlet H2S concentrations were not statistically significant. The model was also able to predict simultaneously the dynamic concentrations of sulfide and nitrate in the liquid phase. Once the model had been validated, six control strategies were analyzed for different scenarios and purposes: i.e., to minimize the nitrate consumption and/or to maximize the H2S removal efficiency. The developed model is a potential tool to enhance and optimize the performance of biotrickling filters for the anoxic removal of H2S.
The main objective of this study is to evaluate qualitatively and quantitatively the effect of st... more The main objective of this study is to evaluate qualitatively and quantitatively the effect of starvation periods in the biodegradation capacity of microorganisms when the support media is a material with high sorption capacity. Pollutant sorption and biodegradation, which occur simultaneously in the biofilter, describe the overall behavior of the air treatment system during normal operation and during starvation periods. Results obtained in the present study demonstrate that sorption capacity of the material not only plays an important role during the start-up of operation, but it is also important during steady operation. Simultaneously, as biomass grows on the support, biodegradation becomes more decisive in the performance. It was found that zones of packing material with low moisture content are controlled by the sorption mechanism, at the expense of biodegradation, and they are essential as a pollutant reservoir during starvation periods. In the present study a significant decrease in the biodegradation capacity of microorganisms immobilized on activated carbon was not observed as a consequence of continuous load interruptions.
A mathematical dynamic model describing biological removal of high loads of H2S from biogas strea... more A mathematical dynamic model describing biological removal of high loads of H2S from biogas streams through a biotrickling filter (BTF) was developed, calibrated and validated to a range of specific experimental conditions of a lab-scale BTF. This model takes into account the main processes occurring in the three phases of the desulfurizing BTF (gas, liquid and biofilm phase) in a co-current configuration flow mode. This model attempts to describe accurately intermediate products obtained from H2S oxidation using kinetic models, previously developed using respirometric techniques with biomass samples obtained from the same BTF set up used here. Previous to the model parameters calibration, a sensitivity analysis was performed in order to focus the parameters estimation on those parameters that showed a highest influence on modelling results over the main process variables. To calibrate the model, an objective function considering the difference between the experimental and the predi...
The aim of this work was to evaluate different operational modes in an anoxic biotrickling filter... more The aim of this work was to evaluate different operational modes in an anoxic biotrickling filter (BTF) by means of a dynamic model. The model was calibrated and validated satisfactorily with experimental data from a pilot-scale anoxic biotrickling filter plant for biogas sweetening. Model simulations allowed to find the optimal mode operation and predicting the biotrickling filter behavior.
Particle size, pH and Fe(III) ions affect the process of bioleaching of copper from chalcopyrite ... more Particle size, pH and Fe(III) ions affect the process of bioleaching of copper from chalcopyrite ores. In the study presented herein a copper sulfide ore was subjected to bioleaching process using a mixed microbial consortium obtained from a biotrickling filter treating high loads of H 2 S at different mineral particle size, distinct medium pH and various additional Fe(III) ion concentrations as leaching agent. After 1300 hours of operation, the total copper recovery achieved a value of 50 % in the most acidic conditions. A decrease of 2.5 units of pH implied an increase in the efficiency of 35%. It was also observed an optimal particle size (between 2 and 3 mm), considerably higher than previous reported studies, meaning a decrease in operational cost to mill material. Finally, results indicate that there is a threshold concentration of ferric ion from which the system is not sensitive (500 ppm).
Proceedings of the 3rd International Congress on Biotechniques for Air Pollution Control. Delft, The Netherlands, September 28-30, 2009, 2010
Biofiltration employs the metabolic activity of microorganisms immobilized on a packing material ... more Biofiltration employs the metabolic activity of microorganisms immobilized on a packing material to degrade gas phase pollutants which are the energy source for microbial growth. However, biomass accumulation is one of the most critical parameters that need to be controlled along the operation of biofilters and biotrickling filters in order to achieve stable performance for long term operation. The excess of biomass inside the bioreactor
In this work the kinetics of a number of sulfide-oxidizing nitrate-reducing (SO-NR) cultures accl... more In this work the kinetics of a number of sulfide-oxidizing nitrate-reducing (SO-NR) cultures acclimated and not acclimated to nitrite were characterized. Anoxic respirometry coupled to kinetic modeling of respirometric profiles was the methodology used to study the two-step denitrification associated to thiosulfate oxidation. Autotrophic denitritation was initially studied in a non-acclimated SO-NR culture to confirm that nitrite reduction kinetics could be described through a Haldane-type equation. Afterwards, a kinetic model describing the two-step denitrification (NO 3-→ NO 2-→ N 2) was calibrated and validated through the estimation of several kinetic parameters from the fitting of experimental respirometric profiles obtained using either nitrate or nitrite as electron acceptors for both acclimated and non-acclimated biomass. The model proposed was a multi-substrate model that considered all the species implicated in the process as well as the stoichiometry associated particularly to the biomass studied in this work. A comparison between the kinetic parameters with the biomass acclimated and nonacclimated to nitrite revealed a 7-fold increase of the Haldane nitrite inhibition constant in the acclimated biomass with respect to the non-acclimated while the nitrite half-saturation constant and the maximum specific growth rate remained almost unchanged. The Fisher Information Matrix method was used to obtain the confidence intervals and also to evaluate the sensitivity and the identifiability in model calibration of each kinetic parameter estimated.
Biological removal of hydrogen sulfide with a biotrickling filter (BTF) has been widely tested. T... more Biological removal of hydrogen sulfide with a biotrickling filter (BTF) has been widely tested. The technology has proved to be a good alternative to the more expensive physical-chemical systems (Kim and Deshusses, 2005). However, the treatment of a high load of hydrogen sulfide (e.g. biogas from anaerobic digesters) has been less studied. The biological removal of hydrogen sulfide requires a large quantity of oxygen. When the oxygen supply is the stoichiometric, sulfates are generated continuously at the BTF, and they are removed from the BTF through the renovation of the liquid phase. When this requirement of dissolved oxygen is not accomplished, the elemental sulfur formation is enhanced. Elemental sulfur is accumulated in the packing material, increasing pressure drop and, thus, increasing the operational cost for equipment or even, causing the total clogging of the bed (Fortuny et al., 2008).
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