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Marcelo Zaiat - One of the best experts on this subject based on the ideXlab platform.
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feasibility of a sequencing reactor operated in batch and fed batch Mode applied to nitrification and denitrification processes
Afinidad, 2009Co-Authors: Roberta Albanez, Suzana Maria Ratusznei, José Alberto Domingues Rodrigues, Marcelo Zaiat, Catarina Simone Andrade Do Canto, Eugenio ForestiAbstract:The objective of this work was to study the operational feasibility of nitrification and denitrification processes in a mechanically stirred sequencing batch reactor (SBR) operated in batch and Fed-Batch Mode. The reactor was equipped with a draft-tube to improve mass transfer and contained dispersed (aerobic) and granulated (anaerobic) biomass. The following reactor variables were adjusted: aeration time during the nitrification step; dissolved oxygen concentration, feed time defining batch and fedbatch phases, concentration of external carbon source used as electron donor during the denitrification stage and volumetric ammonium nitrogen load in the influent. The reactor (5 L volume) was maintained at 30±1oC and treated either 1.0 or 1.5 L wastewater in 8-h cycles. Ammonium nitrogen concentrations assessed were: 50 (condition 1) and 100 mgN-NH4 +·L–1 (condition 2), resulting in 29 and 67 mgN-NH4 +·L-1·d–1, respectively. A synthetic medium and ethanol were used as external carbon sources (ECS). Total nitrogen removal efficiencies were 94.4 and 95.9% when the reactor was operated under conditions 1 and 2, respectively. Low nitrite (0.2 and 0.3 mgN-NO2 –·L–1, respectively) and nitrate (0.01 and 0.3 mgN-NO3 –·L–1, respectively) concentrations were detected in the effluent and ammonium nitrogen removal efficiencies were 97.6% and 99.6% under conditions 1 and 2, respectively.
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fed batch and batch operating Mode analysis of a stirred anaerobic sequencing reactor with self immobilized biomass treating low strength wastewater
Journal of Environmental Management, 2003Co-Authors: José Alberto Domingues Rodrigues, Suzana M. Ratusznei, Marcelo ZaiatAbstract:This work presents an analysis of a stirred anaerobic sequencing discontinuous reactor with different substrate feeding strategies resulting in batch, Fed-Batch/batch and Fed-Batch operating Modes. The reactor, containing granulated biomass, was fed with approximately 2.0L of synthetic domestic wastewater with Chemical Oxygen Demand of nearly 500 mg/L per cycle and operated at 30 degrees C and 50 rpm. Three feeding strategies with a total cycle time of 6 h, including 30-min settling, were adopted: batch Mode with a fill cycle of 6 min, a Fed-Batch/batch Mode with fill cycles of 60, 120 and 240 min and Fed-Batch Mode with a fill cycle of 320 min. The system attained average non-filtered and filtered substrate removal efficiency of 78 and 84%, respectively, for all operating conditions, presenting good stability, solid retention and no granule break-up. A first order kinetic Model with a residual organic matter concentration was proposed to analyze the influence of the feeding strategy on the performance during a cycle and bicarbonate alkalinity and total volatile acids concentration profiles were also quantified in order to verify the transient stability behavior.
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Effect of feeding strategy on a stirred anaerobic sequencing Fed-Batch reactor containing immobilized biomass.
Bioresource technology, 2003Co-Authors: Suzana Maria Ratusznei, José Alberto Domingues Rodrigues, Eduardo Freitas Moraes De Camargo, R. Ribeiro, Marcelo ZaiatAbstract:Abstract The present work reports on the influence of feeding strategy on the stability and performance of a stirred anaerobic sequencing Fed-Batch reactor containing biomass immobilized on polyurethane foam. The reactor treated low-strength wastewater and was operated at 30 °C with an agitation rate of 200 rpm. A 180-min cycle was used to treat approximately 0.5 l of synthetic substrate with a chemical oxygen demand concentration of nearly 500 mg/l. The reactor was operated in batch Mode with a 3-min feeding step and in constant rate Fed-Batch Mode with feeding steps of 30, 60 and 180 min. During batch operation, the system attained stability and had a removal efficiency of 86% based on non-filtered substrate concentration. However, during Fed-Batch operation stability and efficiency were impaired and formation of suspended material was identified. Stability was achieved only for the 30-min feeding step. The poor performance and instability observed in the Fed-Batch experiments were credited to the formation of considerable quantities of extracellular polymers, which impeded contact between substrate and biomass with consequent negative effect on the mass transfer fluxes. The biopolymer formation was very likely a result of the Fed-Batch operational Mode, in which part of the bioparticles were deprived of contact with the liquid medium for a relatively long period of time.
Jochen Buchs - One of the best experts on this subject based on the ideXlab platform.
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validation of the transferability of membrane based fed batch shake flask cultivations to stirred tank reactor using three different protease producing bacillus strains
Journal of Bioscience and Bioengineering, 2019Co-Authors: Janina Muller, Tobias Habicher, Anne Hutterott, Nina Musmann, Jochen BuchsAbstract:Most industrial fermentation processes are operated in Fed-Batch Mode to overcome catabolite repression, undesired by-product formation and oxygen limitation. To maintain comparable process conditions during screening of optimal production strains, the implementation of a Fed-Batch Mode at small scale is crucial. In this study, three different protease producing Bacillus species, Bacillus aeolius, B. licheniformis and B. pumilus, were cultivated using the previously described membrane-based Fed-Batch shake flasks. Under carbon-limited conditions, catabolite repression was avoided, so that proteases were produced in all strains. Protease yields of B. aeolius and B. licheniformis increased 1.5-fold relative to batch cultivations. To validate process scalability between shake flasks and stirred tank reactors, membrane-based Fed-Batch shake flask cultivations were transferred to laboratory-scale stirred tank reactors with equal feeding rates. Despite inevitable differences between the scales such as pH control, feed supply and feed start, comparable results were achieved. Oxygen transfer rates of B. licheniformis and B. pumilus measured with the respiration activity monitoring system (RAMOS) in shake flasks and in stirred tank reactor with an off-gas analyzer were almost identical in both cultivation systems. The protease activities referring to the total consumed glucose were also mostly comparable. A slight decrease from shake flask to stirred tank reactor could be observed, which is presumably due to differences in pH control. This study successfully demonstrates the transferability of membrane-based Fed-Batch shake flask cultivations to laboratory-scale stirred tank reactors.
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high cell density processes in batch Mode of a genetically engineered escherichia coli strain with minimized overflow metabolism using a pressurized bioreactor
Journal of Biotechnology, 2010Co-Authors: Ingo Knabben, Lars Regestein, Frank Marquering, Sven Steinbusch, Alvaro R Lara, Jochen BuchsAbstract:A common method to minimize overflow metabolism and to enable high cell-density is to operate microbial processes in Fed-Batch Mode under carbon-limiting conditions. This requires sophisticated process control schemes with expensive hardware equipment and software and well-characterized processes parameters. To generate high-cell density, a more simplified strategy would be beneficial. Therefore, a genetically engineered Escherichia coli strain with a modified glucose uptake system was cultivated in batch Mode. In the applied strain, the usual phosphotransferase system of a K12-derived strain was inactivated, while the galactose permease system was amplified. Upon cultivating this E. coli strain in pure minimal media, the acetate concentration did not exceed values of 0.35 g L(-1), even when the batch fermentation was started with a glucose concentration of 130 g L(-1). Finally, maximum biomass concentrations of 48 g L(-1) dry cell weight and maximum space-time yields of 2.10 g L(-1) h(-1) were reached. To provide an unlimited growth under fully aerobic conditions (DOT>30%) at comparatively low values for specific power input (3-4 kW m(-3)), a pressurized bioreactor was used. Consequentially, to our knowledge, this study using a bioreactor with elevated headspace pressure generate the highest oxygen transfer rate (451 mmol L(-1) h(-1)) ever reached in batch cultivations.
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high throughput screening of hansenula polymorpha clones in the batch compared with the controlled release fed batch Mode on a small scale
Fems Yeast Research, 2010Co-Authors: Marco Scheidle, Markus Jeude, Barbara Dittrich, Sylvia Denter, Frank Kensy, Manfred Suckow, Doris Klee, Jochen BuchsAbstract:Most large-scale production processes in biotechnology are performed in Fed-Batch operational Mode. In contrast, the screenings for microbial production strains are run in batch Mode, which results in the microorganisms being subjected to different physiological conditions. This significantly affects strain selection. To demonstrate differences in ranking during strain selection depending on the operational Mode, screenings were performed in batch and Fed-Batch Modes. Two Model populations of the methylotrophic yeast Hansenula polymorpha RB11 with vector pC10-FMD (PFMD-GFP) (220 clones) and vector pC10-MOX (PMOX-GFP) (224 clones) were applied. For Fed-Batch cultivations in deep-well microtiter plates, a controlled-release system made of silicone elastomer discs containing glucose was used. Three experimental set-ups were investigated: batch cultivation with (1) glucose as a substrate, which catabolite represses product formation, and (2) glycerol as a carbon source, which is partially repressing, respectively, and (3) Fed-Batch cultivation with glucose as a limiting substrate using the controlled-release system. These three experimental set-ups showed significant variations in green fluorescent protein (GFP) yield. Interestingly, screenings in Fed-Batch Mode with glucose as a substrate resulted in the selection of yeast strains different from those cultivated in batch Mode with glycerol or glucose. Ultimately, Fed-Batch screening is considerably better than screening in batch Mode for Fed-Batch production processes with glucose as a carbon source.
Ho Nam Chang - One of the best experts on this subject based on the ideXlab platform.
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simultaneous saccharification and fermentation of lignocellulosic residues pretreated with phosphoric acid acetone for bioethanol production
Bioresource Technology, 2009Co-Authors: Hui Li, Min Jiang, Jong Won Kang, Ho Nam ChangAbstract:Abstract Bermudagrass, reed and rapeseed were pretreated with phosphoric acid–acetone and used for ethanol production by means of simultaneous saccharification and fermentation (SSF) with a batch and Fed-Batch Mode. When the batch SSF experiments were conducted in a 3% low effective cellulose, about 16 g/L of ethanol were obtained after 96 h of fermentation. When batch SSF experiments were conducted with a higher cellulose content (10% effective cellulose for reed and bermudagrass and 5% for rapeseed), higher ethanol concentrations and yields (of more than 93%) were obtained. The Fed-Batch SSF strategy was adopted to increase the ethanol concentration further. When a higher water-insoluble solid (up to 36%) was applied, the ethanol concentration reached 56 g/L of an inhibitory concentration of the yeast strain used in this study at 38 °C. The results show that the pretreated materials can be used as good feedstocks for bioethanol production, and that the phosphoric acid–acetone pretreatment can effectively yield a higher ethanol concentration.
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simultaneous saccharification and fermentation of lignocellulosic residues pretreated with phosphoric acid acetone for bioethanol production
Bioresource Technology, 2009Co-Authors: Nagjong Kim, Min Jiang, Jong Won Kang, Ho Nam ChangAbstract:Bermudagrass, reed and rapeseed were pretreated with phosphoric acid-acetone and used for ethanol production by means of simultaneous saccharification and fermentation (SSF) with a batch and Fed-Batch Mode. When the batch SSF experiments were conducted in a 3% low effective cellulose, about 16 g/L of ethanol were obtained after 96 h of fermentation. When batch SSF experiments were conducted with a higher cellulose content (10% effective cellulose for reed and bermudagrass and 5% for rapeseed), higher ethanol concentrations and yields (of more than 93%) were obtained. The Fed-Batch SSF strategy was adopted to increase the ethanol concentration further. When a higher water-insoluble solid (up to 36%) was applied, the ethanol concentration reached 56 g/L of an inhibitory concentration of the yeast strain used in this study at 38 degrees C. The results show that the pretreated materials can be used as good feedstocks for bioethanol production, and that the phosphoric acid-acetone pretreatment can effectively yield a higher ethanol concentration.
José Alberto Domingues Rodrigues - One of the best experts on this subject based on the ideXlab platform.
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feasibility of a sequencing reactor operated in batch and fed batch Mode applied to nitrification and denitrification processes
Afinidad, 2009Co-Authors: Roberta Albanez, Suzana Maria Ratusznei, José Alberto Domingues Rodrigues, Marcelo Zaiat, Catarina Simone Andrade Do Canto, Eugenio ForestiAbstract:The objective of this work was to study the operational feasibility of nitrification and denitrification processes in a mechanically stirred sequencing batch reactor (SBR) operated in batch and Fed-Batch Mode. The reactor was equipped with a draft-tube to improve mass transfer and contained dispersed (aerobic) and granulated (anaerobic) biomass. The following reactor variables were adjusted: aeration time during the nitrification step; dissolved oxygen concentration, feed time defining batch and fedbatch phases, concentration of external carbon source used as electron donor during the denitrification stage and volumetric ammonium nitrogen load in the influent. The reactor (5 L volume) was maintained at 30±1oC and treated either 1.0 or 1.5 L wastewater in 8-h cycles. Ammonium nitrogen concentrations assessed were: 50 (condition 1) and 100 mgN-NH4 +·L–1 (condition 2), resulting in 29 and 67 mgN-NH4 +·L-1·d–1, respectively. A synthetic medium and ethanol were used as external carbon sources (ECS). Total nitrogen removal efficiencies were 94.4 and 95.9% when the reactor was operated under conditions 1 and 2, respectively. Low nitrite (0.2 and 0.3 mgN-NO2 –·L–1, respectively) and nitrate (0.01 and 0.3 mgN-NO3 –·L–1, respectively) concentrations were detected in the effluent and ammonium nitrogen removal efficiencies were 97.6% and 99.6% under conditions 1 and 2, respectively.
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fed batch and batch operating Mode analysis of a stirred anaerobic sequencing reactor with self immobilized biomass treating low strength wastewater
Journal of Environmental Management, 2003Co-Authors: José Alberto Domingues Rodrigues, Suzana M. Ratusznei, Marcelo ZaiatAbstract:This work presents an analysis of a stirred anaerobic sequencing discontinuous reactor with different substrate feeding strategies resulting in batch, Fed-Batch/batch and Fed-Batch operating Modes. The reactor, containing granulated biomass, was fed with approximately 2.0L of synthetic domestic wastewater with Chemical Oxygen Demand of nearly 500 mg/L per cycle and operated at 30 degrees C and 50 rpm. Three feeding strategies with a total cycle time of 6 h, including 30-min settling, were adopted: batch Mode with a fill cycle of 6 min, a Fed-Batch/batch Mode with fill cycles of 60, 120 and 240 min and Fed-Batch Mode with a fill cycle of 320 min. The system attained average non-filtered and filtered substrate removal efficiency of 78 and 84%, respectively, for all operating conditions, presenting good stability, solid retention and no granule break-up. A first order kinetic Model with a residual organic matter concentration was proposed to analyze the influence of the feeding strategy on the performance during a cycle and bicarbonate alkalinity and total volatile acids concentration profiles were also quantified in order to verify the transient stability behavior.
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Effect of feeding strategy on a stirred anaerobic sequencing Fed-Batch reactor containing immobilized biomass.
Bioresource technology, 2003Co-Authors: Suzana Maria Ratusznei, José Alberto Domingues Rodrigues, Eduardo Freitas Moraes De Camargo, R. Ribeiro, Marcelo ZaiatAbstract:Abstract The present work reports on the influence of feeding strategy on the stability and performance of a stirred anaerobic sequencing Fed-Batch reactor containing biomass immobilized on polyurethane foam. The reactor treated low-strength wastewater and was operated at 30 °C with an agitation rate of 200 rpm. A 180-min cycle was used to treat approximately 0.5 l of synthetic substrate with a chemical oxygen demand concentration of nearly 500 mg/l. The reactor was operated in batch Mode with a 3-min feeding step and in constant rate Fed-Batch Mode with feeding steps of 30, 60 and 180 min. During batch operation, the system attained stability and had a removal efficiency of 86% based on non-filtered substrate concentration. However, during Fed-Batch operation stability and efficiency were impaired and formation of suspended material was identified. Stability was achieved only for the 30-min feeding step. The poor performance and instability observed in the Fed-Batch experiments were credited to the formation of considerable quantities of extracellular polymers, which impeded contact between substrate and biomass with consequent negative effect on the mass transfer fluxes. The biopolymer formation was very likely a result of the Fed-Batch operational Mode, in which part of the bioparticles were deprived of contact with the liquid medium for a relatively long period of time.
Hong Liu - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Coulombic efficiency and power density of air-cathode microbial fuel cells with an improved cell configuration
Journal of Power Sources, 2007Co-Authors: Yanzhen Fan, Hongqiang Hu, Hong LiuAbstract:Single chamber air-cathode microbial fuel cells (MFCs) that lack a proton exchange membrane (PEM) hold a great promise for many practical applications due to their low operational cost, simple configuration and relative high power density. One of the great challenges for PEM-less MFC is that the Coulombic efficiency is much lower than those containing PEM. In this study, single-chamber PEM-less MFCs were adapted by applying a J-Cloth layer on the water-facing side of air cathode. Due to the significant reduction of oxygen diffusion by the J-Cloth, the MFCs with two-layers of J-Cloth demonstrated an over 100% increase in Coulombic efficiency in comparison with those without J-Cloth (71% versus 35%) at the same current density of 0.6 mA cm-2. A new cell configuration, cloth electrode assembly (CEA), therefore, was designed by sandwiching the cloth between the anode and the cathode. Such an MFC configuration greatly reduced the internal resistance, resulting in a power density of 627 W m-3when operated in Fed-Batch Mode and 1010 W m-3in continuous-flow Mode, which is the highest reported power density for MFCs and more than 15 times higher than those reported for air-cathode MFCs using similar electrode materials. This study indicates that the Coulombic efficiency and power density of air-cathode MFCs can be improved significantly using an inexpensive cloth layer, which greatly increases the feasibility for the practical applications of MFCs.