Shantonu Roy | IIT Kharagpur (original) (raw)

Papers by Shantonu Roy

Elsevier eBooks, 2019

Abstract “Water and Energy” are the two most precious resources that would eventually shape the f... more Abstract “Water and Energy” are the two most precious resources that would eventually shape the future of the future generation. In recent times, the emphasis on development technology encompassing the use of alternative energy resources and “waste to energy” concept has gained importance globally. The microbial electrochemical systems (MESs) has emerged as one of the promising wastewater treatment technologies which could provide clean water as well as green energy. The MESs are bioelectrochemical reactors which can harvest energy from the biodegradable substances present in wastewater by using microbes. In MESs, migration of ions during generation of electricity can be utilized for valuable chemical production, water desalination, and resource recovery. Unlike, any chemical fuel cell, whose application is marred with high cost maintenance, MESs could provide a low cost and low maintenance solution for energy generation. The present chapter elaborates the existing researches on different microbial fuel cell–adapted systems and identifies a few key factors involved in efficiency optimization.

Microbial Electrochemical Technology, 2019

Abstract “Water and Energy” are the two most precious resources that would eventually shape the f... more Abstract “Water and Energy” are the two most precious resources that would eventually shape the future of the future generation. In recent times, the emphasis on development technology encompassing the use of alternative energy resources and “waste to energy” concept has gained importance globally. The microbial electrochemical systems (MESs) has emerged as one of the promising wastewater treatment technologies which could provide clean water as well as green energy. The MESs are bioelectrochemical reactors which can harvest energy from the biodegradable substances present in wastewater by using microbes. In MESs, migration of ions during generation of electricity can be utilized for valuable chemical production, water desalination, and resource recovery. Unlike, any chemical fuel cell, whose application is marred with high cost maintenance, MESs could provide a low cost and low maintenance solution for energy generation. The present chapter elaborates the existing researches on different microbial fuel cell–adapted systems and identifies a few key factors involved in efficiency optimization.

Bioresource Technology, 2019

Sustainable Biofuels Development in India, 2017

Hydrogen is a clean, renewable, and efficient source of energy. Being considered as a potential a... more Hydrogen is a clean, renewable, and efficient source of energy. Being considered as a potential alternative energy source, its economical production has gained attention in recent times. In the present study, a comprehensive insight into dark fermentative biohydrogen production process has been exemplified. This process is less energy intensive and environmentally benign and waste materials can be used as substrate. A plethora of H2-producing microorganisms have been identified in literature. Delineation of detailed microbial characteristics of these microbes shows the potentiality of thermophiles for high rate of H2 production. Process parameters such as pH, temperature, substrate concentration, HRT, and alkalinity play a vital role directly or indirectly on the metabolic activity of these organisms. Mathematical modeling and simulation of hydrogen production process help in better understanding of the process. Various logistic equations and unstructured models have been proposed for better understanding of H2 production process. Moreover, it might help in scaling up of the process. To make bioH2 production a renewable process, an improvisation in the use of feedstock is decidedly required. Organic wastes could be a potential feedstock for sustainable H2 production. For commercial production, the overall yield of H2 production process is still inferior. Major bottleneck for the commercialization of these processes is lower net utilizable energy product (NUEP) as hydrogen. Establishment of integrated two-stage processes might help in overall energy recovery. Widely studied second-stage processes were photofermentation, biomethanation, microbial fuel cell, microbial electrolysis cell, etc. Integration of bioH2 with biomethanation process can maximize the NUEP from the organic wastes. Future aspect of bioH2 relies on performance of scaled up reactors and their integration with fuel cells. This might help in decentralized energy generation in terms of electricity.

International Journal of Hydrogen Energy, 2016

Biohydrogen has been regarded as carbon neutral fuel. Thus it possesses tremendous potential in e... more Biohydrogen has been regarded as carbon neutral fuel. Thus it possesses tremendous potential in energy sector. The present study deals with the potentiality of bio-augmented facultative anaerobic bacteria with obligate anaerobe for the improvement of H 2 production. The co-culture strategy of Klebsellia pneumoniae and Clostridium acetobutylicum improved hydrogen yield by 37% and 18% respectively as compared to individual organism. COD removal efficiency was also observed higher in case of co-culture. Maximum H 2 yield by this augmented system using cane molasses, starchy wastewater and distillery effluent were 9.47, 8.72 and 7.78 mol H 2 kg À1 COD reduced respectively. The COD removal efficiency using different organic residues were in the range of 50e70%. Highest H 2 production rate of 1125, 642 and 790 mL L À1 h À1 were observed by using cane molasses, starchy wastewater and distillery effluent respectively in CSTR. So, bio-augmented system could be helpful in realizing the goal of "waste to energy" concept.

Journal of Environmental Management, 2016

Renewable and Sustainable Energy Reviews, 2016

Algal Biorefinery: An Integrated Approach, 2015

Energy crisis is looming the global economy and environment. The rate at which fossil fuels are d... more Energy crisis is looming the global economy and environment. The rate at which fossil fuels are depleting, a necessity of alternate fuel has been gaining importance. The use of fossil fuels for energy is unsustainable and causes build up of greenhouse gases in the atmosphere leading to global warming. Biofuels store energy chemically that can be harnessed easily. It can also be used in existing combustion engines after blending with petroleum diesel to various degrees. No separate transportation infrastructures would be required for such fuels (Amaro et al., Appl Energy 88:3402–3410, 2011). In biorefinery concept, every component of the biomass material would be used to produce commercially important products. At present, first generation biofuels are produced using sucrose and starch crops. Second generation biofuels are produced using lignocellulosic biomass. Lignocellulosic biomass gained importance because of their abundant availability but need of pretreatment and saccharification processes has hindered their usage as feedstock. Moreover, bioenergy production using agricultural crops or agricultural wastes as feedstock is disadvantageous as resources for water and agriculture lands are limited (Li et al., Appl Microbiol Biotechnol 81:629–636, 2008). Algal biomass has been considered as third generation feedstock for biofuel production (Metzger and Largeau, Appl Microbiol Biotechnol 66:486–496, 2005). Many algal species having high lipid content thus could be explored for oleo-fuel generation. Similarly, algal species having high carbohydrate content can be exploited for bioethanol or biogas production.

Environmental Science and Pollution Research, 2015

The economy of an industrialized country is greatly dependent on fossil fuels. However, these non... more The economy of an industrialized country is greatly dependent on fossil fuels. However, these nonrenewable sources of energy are nearing the brink of extinction. Moreover, the reliance on these fuels has led to increased levels of pollution which have caused serious adverse impacts on the environment. Hydrogen has emerged as a promising alternative since it does not produce CO2 during combustion and also has the highest calorific value. The biohythane process comprises of biohydrogen production followed by biomethanation. Biological H2 production has an edge over its chemical counterpart mainly because it is environmentally benign. Maximization of gaseous energy recovery could be achieved by integrating dark fermentative hydrogen production followed by biomethanation. Intensive research work has already been carried out on the advancement of biohydrogen production processes, such as the development of suitable microbial consortium (mesophiles or thermophiles), genetically modified microorganism, improvement of the reactor designs, use of different solid matrices for the immobilization of whole cells, and development of two-stage process for higher rate of H2 production. Scale-up studies of the dark fermentation process was successfully carried out in 20- and 800-L reactors. However, the total gaseous energy recovery for two stage process was found to be 53.6 %. From single-stage H2 production, gaseous energy recovery was only 28 %. Thus, two-stage systems not only help in improving gaseous energy recovery but also can make biohythane (mixture of H2 and CH4) concept commercially feasible.

Bioresource Technology, 2015

Wastewater comprises of various carbon sources. So, the use of microbial consortium may improve t... more Wastewater comprises of various carbon sources. So, the use of microbial consortium may improve the hydrogen production and organic reduction. The present study deals with biohydrogen production by acidogenic mixed consortia (AMC), synthetic co-culture (Klebsiella pneumoniae IIT-BT 08 and Citrobacter freundii IIT-BT L139) and pure culture using distillery effluent (DE). Higher hydrogen yield was observed in case of AMC (9.17mol/kgCODreduced) as compared to the synthetic co-culture and pure culture. PCR-DGGE analysis indicated that the consortium was predominated by species closely affiliated to Clostridium sp. The average hydrogen production rate was 267mL/Lh. The maximum hydrogen production rate (Rm), hydrogen production potential (P) and lag time (λ) by AMC using DE were 507.2mL/Lh, 3729m/L and 2.04h, respectively. Maximum gaseous energy recovery by AMC was found to be higher by 21.9% and 45.4% than that of using co-culture and pure culture respectively.

Journal of Hazardous Materials, 2015

External dosing of sweetmeat waste (SMW) dosing into exhausted upflow packed bed bioreactor (PBR)... more External dosing of sweetmeat waste (SMW) dosing into exhausted upflow packed bed bioreactor (PBR) resulted in prompt reactivation of SO4(2-) removal. Different SMW concentrations in terms of chemical oxygen demand (COD)/SO4(2-) ratios (1, 2, 4 and 8) were introduced into four identical PBR where process stability was found within 3 weeks of operation. SO4(2-) removal was proportional to COD/SO4(2-) ratios up to 4 at which maximum sulfate removal (99%) was achieved at a rate of 607mg/d. The value of COD consumption:SO4(2-)removal was much higher at ratio 4 than 8 whereas, ratio 2 was preferred over all. Net effluent acetate concentration profile and total microbial population attached to the reactor matrices were corresponding to COD/SO4(2-) ratio as 4>8>2>1. Sulfate reducing bacteria (SRB) population was found to be inversely proportional to COD/SO4(2-) ratio in which acetate oxidizing SRB and fermentative bacteria were the dominant.

International Journal of Hydrogen Energy, 2015

Abstract Facultative anaerobes play important roles in H 2 production by biological routes. In th... more Abstract Facultative anaerobes play important roles in H 2 production by biological routes. In the present study, a comprehensive insight on the importance of formate lyase in H 2 production by facultative microorganisms has been focused. Structural details of formate hydrogen lyase reveal the involvement of two enzymes, formate dehydrogenase H (FdhH) and hydrogenase (Hyd) along with electron carriers. The monocistronic fdhF gene codes for the functional formate dehydrogenase H. Functionality of these complexes are dependent on maturation system governed by FDH-D and FDH-E. The overall transcription of FHL complex is governed by protein encoded by fhl A gene. Under anaerobic condition, the pyruvate gets cleave into acetyl-CoA and formate by pyruvate-formate-lyase (PFL). The transporter proteins FocA and FocB helps in transporting formate. During dark fermentation, the physico–chemical parameters such as pH, HRTs, partial pressure play a crucial role in influencing formate degradation to molecular H 2 .

Water science and technology : a journal of the International Association on Water Pollution Research, 2015

An electrochemically active bacteria Pseudomonas aeruginosa IIT BT SS1 was isolated from a dark f... more An electrochemically active bacteria Pseudomonas aeruginosa IIT BT SS1 was isolated from a dark fermentative spent media fed anode, and a bioaugmentation technique using the isolated strain was used to improve the start-up time of a microbial fuel cell (MFC). Higher volumetric current density and lower start-up time were observed with the augmented system MFC-PM (13.7 A/m(3)) when compared with mixed culture MFC-M (8.72 A/m(3)) during the initial phase. This enhanced performance in MFC-PM was possibly due to the improvement in electron transfer ability by the augmented strain. However, pure culture MFC-P showed maximum volumetric current density (17 A/m(3)) due to the inherent electrogenic properties of Pseudomonas sp. An electrochemical impedance spectroscopic (EIS) study, along with matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) analysis, supported the influence of isolated species in improving the MFC performance. The present study indicates that the bioau...

International Journal of Hydrogen Energy, 2015

The present study demonstrated the feasibility of using an integrated approach of combining dark ... more The present study demonstrated the feasibility of using an integrated approach of combining dark fermentation with MFCs to maximize the energy recovery from cellulosic substrate. Thermophillic dark-H 2 fermentation exhibited maximum H 2 production yield of 2.92 mol mol À1 hexose equivalent with an energy recovery of 28% which was highest reported till date. The total cumulative hydrogen potential of 3799 mL L À1 with maximum rate of hydrogen production of 865 mL h À1 , and lag time of 1.84 h were determined by using modified Gompertz equation. Subsequent use of acid rich effluents in two chamber MFCs generated maximum power density of 85.05 mW m À2 with an energy recovery of 2.49%. Moreover, a 75% COD removal was also achieved with a coulombic efficiency of 13% illustrating its ability for wastewater treatment. By using this integrated approach, an overall energy recovery of 30.49% was achieved demonstrating both environmental and economic sustainability of the process.

Applied biochemistry and biotechnology, Jan 19, 2015

Algal biomass is gaining importance for biofuel production as it is rich in lipids. It becomes mo... more Algal biomass is gaining importance for biofuel production as it is rich in lipids. It becomes more significant when biomass is produced by capturing atmospheric greenhouse gas, CO2. In the present study, the effect of different physicochemical parameters were studied on the biomass and lipid productivity in Chlorella sp. MJ 11/11. The different parameters viz. initial pH, nitrate concentration, and phosphate concentration were optimized using single-parameter studies. The interactions between the parameters were determined statistically using the Box-Behnken design of optimization. The optimal values were decided by analyzing them with response surface methodology. The optimum levels of the parameters (pH 6.5, nitrate concentration 0.375 g L(-1), and phosphate concentration 0.375 mL L(-1)) yielded a maximum biomass concentration of 1.26 g L(-1) at a constant light intensity of 100 μmol m(-2) s(-1) and temperature of 30 °C. The effect of CO2 concentration on the biomass production w...

Bioresource Technology, 2013

h i g h l i g h t s " Operating continuous mode of operation for CO 2 sequestration using C. soro... more h i g h l i g h t s " Operating continuous mode of operation for CO 2 sequestration using C. sorokiniana. " Modeling and simulation of continuous culture of algae. " Utilizing algal biomass as substrate for H 2 production using E. cloacae IIT-BT 08. " Better H 2 energy using algal biomass as substrate over its use in biophotolysis.

Elsevier eBooks, 2019

Abstract “Water and Energy” are the two most precious resources that would eventually shape the f... more Abstract “Water and Energy” are the two most precious resources that would eventually shape the future of the future generation. In recent times, the emphasis on development technology encompassing the use of alternative energy resources and “waste to energy” concept has gained importance globally. The microbial electrochemical systems (MESs) has emerged as one of the promising wastewater treatment technologies which could provide clean water as well as green energy. The MESs are bioelectrochemical reactors which can harvest energy from the biodegradable substances present in wastewater by using microbes. In MESs, migration of ions during generation of electricity can be utilized for valuable chemical production, water desalination, and resource recovery. Unlike, any chemical fuel cell, whose application is marred with high cost maintenance, MESs could provide a low cost and low maintenance solution for energy generation. The present chapter elaborates the existing researches on different microbial fuel cell–adapted systems and identifies a few key factors involved in efficiency optimization.

Microbial Electrochemical Technology, 2019

Abstract “Water and Energy” are the two most precious resources that would eventually shape the f... more Abstract “Water and Energy” are the two most precious resources that would eventually shape the future of the future generation. In recent times, the emphasis on development technology encompassing the use of alternative energy resources and “waste to energy” concept has gained importance globally. The microbial electrochemical systems (MESs) has emerged as one of the promising wastewater treatment technologies which could provide clean water as well as green energy. The MESs are bioelectrochemical reactors which can harvest energy from the biodegradable substances present in wastewater by using microbes. In MESs, migration of ions during generation of electricity can be utilized for valuable chemical production, water desalination, and resource recovery. Unlike, any chemical fuel cell, whose application is marred with high cost maintenance, MESs could provide a low cost and low maintenance solution for energy generation. The present chapter elaborates the existing researches on different microbial fuel cell–adapted systems and identifies a few key factors involved in efficiency optimization.

Bioresource Technology, 2019

Sustainable Biofuels Development in India, 2017

Hydrogen is a clean, renewable, and efficient source of energy. Being considered as a potential a... more Hydrogen is a clean, renewable, and efficient source of energy. Being considered as a potential alternative energy source, its economical production has gained attention in recent times. In the present study, a comprehensive insight into dark fermentative biohydrogen production process has been exemplified. This process is less energy intensive and environmentally benign and waste materials can be used as substrate. A plethora of H2-producing microorganisms have been identified in literature. Delineation of detailed microbial characteristics of these microbes shows the potentiality of thermophiles for high rate of H2 production. Process parameters such as pH, temperature, substrate concentration, HRT, and alkalinity play a vital role directly or indirectly on the metabolic activity of these organisms. Mathematical modeling and simulation of hydrogen production process help in better understanding of the process. Various logistic equations and unstructured models have been proposed for better understanding of H2 production process. Moreover, it might help in scaling up of the process. To make bioH2 production a renewable process, an improvisation in the use of feedstock is decidedly required. Organic wastes could be a potential feedstock for sustainable H2 production. For commercial production, the overall yield of H2 production process is still inferior. Major bottleneck for the commercialization of these processes is lower net utilizable energy product (NUEP) as hydrogen. Establishment of integrated two-stage processes might help in overall energy recovery. Widely studied second-stage processes were photofermentation, biomethanation, microbial fuel cell, microbial electrolysis cell, etc. Integration of bioH2 with biomethanation process can maximize the NUEP from the organic wastes. Future aspect of bioH2 relies on performance of scaled up reactors and their integration with fuel cells. This might help in decentralized energy generation in terms of electricity.

International Journal of Hydrogen Energy, 2016

Biohydrogen has been regarded as carbon neutral fuel. Thus it possesses tremendous potential in e... more Biohydrogen has been regarded as carbon neutral fuel. Thus it possesses tremendous potential in energy sector. The present study deals with the potentiality of bio-augmented facultative anaerobic bacteria with obligate anaerobe for the improvement of H 2 production. The co-culture strategy of Klebsellia pneumoniae and Clostridium acetobutylicum improved hydrogen yield by 37% and 18% respectively as compared to individual organism. COD removal efficiency was also observed higher in case of co-culture. Maximum H 2 yield by this augmented system using cane molasses, starchy wastewater and distillery effluent were 9.47, 8.72 and 7.78 mol H 2 kg À1 COD reduced respectively. The COD removal efficiency using different organic residues were in the range of 50e70%. Highest H 2 production rate of 1125, 642 and 790 mL L À1 h À1 were observed by using cane molasses, starchy wastewater and distillery effluent respectively in CSTR. So, bio-augmented system could be helpful in realizing the goal of "waste to energy" concept.

Journal of Environmental Management, 2016

Renewable and Sustainable Energy Reviews, 2016

Algal Biorefinery: An Integrated Approach, 2015

Energy crisis is looming the global economy and environment. The rate at which fossil fuels are d... more Energy crisis is looming the global economy and environment. The rate at which fossil fuels are depleting, a necessity of alternate fuel has been gaining importance. The use of fossil fuels for energy is unsustainable and causes build up of greenhouse gases in the atmosphere leading to global warming. Biofuels store energy chemically that can be harnessed easily. It can also be used in existing combustion engines after blending with petroleum diesel to various degrees. No separate transportation infrastructures would be required for such fuels (Amaro et al., Appl Energy 88:3402–3410, 2011). In biorefinery concept, every component of the biomass material would be used to produce commercially important products. At present, first generation biofuels are produced using sucrose and starch crops. Second generation biofuels are produced using lignocellulosic biomass. Lignocellulosic biomass gained importance because of their abundant availability but need of pretreatment and saccharification processes has hindered their usage as feedstock. Moreover, bioenergy production using agricultural crops or agricultural wastes as feedstock is disadvantageous as resources for water and agriculture lands are limited (Li et al., Appl Microbiol Biotechnol 81:629–636, 2008). Algal biomass has been considered as third generation feedstock for biofuel production (Metzger and Largeau, Appl Microbiol Biotechnol 66:486–496, 2005). Many algal species having high lipid content thus could be explored for oleo-fuel generation. Similarly, algal species having high carbohydrate content can be exploited for bioethanol or biogas production.

Environmental Science and Pollution Research, 2015

The economy of an industrialized country is greatly dependent on fossil fuels. However, these non... more The economy of an industrialized country is greatly dependent on fossil fuels. However, these nonrenewable sources of energy are nearing the brink of extinction. Moreover, the reliance on these fuels has led to increased levels of pollution which have caused serious adverse impacts on the environment. Hydrogen has emerged as a promising alternative since it does not produce CO2 during combustion and also has the highest calorific value. The biohythane process comprises of biohydrogen production followed by biomethanation. Biological H2 production has an edge over its chemical counterpart mainly because it is environmentally benign. Maximization of gaseous energy recovery could be achieved by integrating dark fermentative hydrogen production followed by biomethanation. Intensive research work has already been carried out on the advancement of biohydrogen production processes, such as the development of suitable microbial consortium (mesophiles or thermophiles), genetically modified microorganism, improvement of the reactor designs, use of different solid matrices for the immobilization of whole cells, and development of two-stage process for higher rate of H2 production. Scale-up studies of the dark fermentation process was successfully carried out in 20- and 800-L reactors. However, the total gaseous energy recovery for two stage process was found to be 53.6 %. From single-stage H2 production, gaseous energy recovery was only 28 %. Thus, two-stage systems not only help in improving gaseous energy recovery but also can make biohythane (mixture of H2 and CH4) concept commercially feasible.

Bioresource Technology, 2015

Wastewater comprises of various carbon sources. So, the use of microbial consortium may improve t... more Wastewater comprises of various carbon sources. So, the use of microbial consortium may improve the hydrogen production and organic reduction. The present study deals with biohydrogen production by acidogenic mixed consortia (AMC), synthetic co-culture (Klebsiella pneumoniae IIT-BT 08 and Citrobacter freundii IIT-BT L139) and pure culture using distillery effluent (DE). Higher hydrogen yield was observed in case of AMC (9.17mol/kgCODreduced) as compared to the synthetic co-culture and pure culture. PCR-DGGE analysis indicated that the consortium was predominated by species closely affiliated to Clostridium sp. The average hydrogen production rate was 267mL/Lh. The maximum hydrogen production rate (Rm), hydrogen production potential (P) and lag time (λ) by AMC using DE were 507.2mL/Lh, 3729m/L and 2.04h, respectively. Maximum gaseous energy recovery by AMC was found to be higher by 21.9% and 45.4% than that of using co-culture and pure culture respectively.

Journal of Hazardous Materials, 2015

External dosing of sweetmeat waste (SMW) dosing into exhausted upflow packed bed bioreactor (PBR)... more External dosing of sweetmeat waste (SMW) dosing into exhausted upflow packed bed bioreactor (PBR) resulted in prompt reactivation of SO4(2-) removal. Different SMW concentrations in terms of chemical oxygen demand (COD)/SO4(2-) ratios (1, 2, 4 and 8) were introduced into four identical PBR where process stability was found within 3 weeks of operation. SO4(2-) removal was proportional to COD/SO4(2-) ratios up to 4 at which maximum sulfate removal (99%) was achieved at a rate of 607mg/d. The value of COD consumption:SO4(2-)removal was much higher at ratio 4 than 8 whereas, ratio 2 was preferred over all. Net effluent acetate concentration profile and total microbial population attached to the reactor matrices were corresponding to COD/SO4(2-) ratio as 4>8>2>1. Sulfate reducing bacteria (SRB) population was found to be inversely proportional to COD/SO4(2-) ratio in which acetate oxidizing SRB and fermentative bacteria were the dominant.

International Journal of Hydrogen Energy, 2015

Abstract Facultative anaerobes play important roles in H 2 production by biological routes. In th... more Abstract Facultative anaerobes play important roles in H 2 production by biological routes. In the present study, a comprehensive insight on the importance of formate lyase in H 2 production by facultative microorganisms has been focused. Structural details of formate hydrogen lyase reveal the involvement of two enzymes, formate dehydrogenase H (FdhH) and hydrogenase (Hyd) along with electron carriers. The monocistronic fdhF gene codes for the functional formate dehydrogenase H. Functionality of these complexes are dependent on maturation system governed by FDH-D and FDH-E. The overall transcription of FHL complex is governed by protein encoded by fhl A gene. Under anaerobic condition, the pyruvate gets cleave into acetyl-CoA and formate by pyruvate-formate-lyase (PFL). The transporter proteins FocA and FocB helps in transporting formate. During dark fermentation, the physico–chemical parameters such as pH, HRTs, partial pressure play a crucial role in influencing formate degradation to molecular H 2 .

Water science and technology : a journal of the International Association on Water Pollution Research, 2015

An electrochemically active bacteria Pseudomonas aeruginosa IIT BT SS1 was isolated from a dark f... more An electrochemically active bacteria Pseudomonas aeruginosa IIT BT SS1 was isolated from a dark fermentative spent media fed anode, and a bioaugmentation technique using the isolated strain was used to improve the start-up time of a microbial fuel cell (MFC). Higher volumetric current density and lower start-up time were observed with the augmented system MFC-PM (13.7 A/m(3)) when compared with mixed culture MFC-M (8.72 A/m(3)) during the initial phase. This enhanced performance in MFC-PM was possibly due to the improvement in electron transfer ability by the augmented strain. However, pure culture MFC-P showed maximum volumetric current density (17 A/m(3)) due to the inherent electrogenic properties of Pseudomonas sp. An electrochemical impedance spectroscopic (EIS) study, along with matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) analysis, supported the influence of isolated species in improving the MFC performance. The present study indicates that the bioau...

International Journal of Hydrogen Energy, 2015

The present study demonstrated the feasibility of using an integrated approach of combining dark ... more The present study demonstrated the feasibility of using an integrated approach of combining dark fermentation with MFCs to maximize the energy recovery from cellulosic substrate. Thermophillic dark-H 2 fermentation exhibited maximum H 2 production yield of 2.92 mol mol À1 hexose equivalent with an energy recovery of 28% which was highest reported till date. The total cumulative hydrogen potential of 3799 mL L À1 with maximum rate of hydrogen production of 865 mL h À1 , and lag time of 1.84 h were determined by using modified Gompertz equation. Subsequent use of acid rich effluents in two chamber MFCs generated maximum power density of 85.05 mW m À2 with an energy recovery of 2.49%. Moreover, a 75% COD removal was also achieved with a coulombic efficiency of 13% illustrating its ability for wastewater treatment. By using this integrated approach, an overall energy recovery of 30.49% was achieved demonstrating both environmental and economic sustainability of the process.

Applied biochemistry and biotechnology, Jan 19, 2015

Algal biomass is gaining importance for biofuel production as it is rich in lipids. It becomes mo... more Algal biomass is gaining importance for biofuel production as it is rich in lipids. It becomes more significant when biomass is produced by capturing atmospheric greenhouse gas, CO2. In the present study, the effect of different physicochemical parameters were studied on the biomass and lipid productivity in Chlorella sp. MJ 11/11. The different parameters viz. initial pH, nitrate concentration, and phosphate concentration were optimized using single-parameter studies. The interactions between the parameters were determined statistically using the Box-Behnken design of optimization. The optimal values were decided by analyzing them with response surface methodology. The optimum levels of the parameters (pH 6.5, nitrate concentration 0.375 g L(-1), and phosphate concentration 0.375 mL L(-1)) yielded a maximum biomass concentration of 1.26 g L(-1) at a constant light intensity of 100 μmol m(-2) s(-1) and temperature of 30 °C. The effect of CO2 concentration on the biomass production w...

Bioresource Technology, 2013

h i g h l i g h t s " Operating continuous mode of operation for CO 2 sequestration using C. soro... more h i g h l i g h t s " Operating continuous mode of operation for CO 2 sequestration using C. sorokiniana. " Modeling and simulation of continuous culture of algae. " Utilizing algal biomass as substrate for H 2 production using E. cloacae IIT-BT 08. " Better H 2 energy using algal biomass as substrate over its use in biophotolysis.

Hydrogen has been mooted as future fuel on the basis of its carbon neutrality, renewable nature, ... more Hydrogen has been mooted as future fuel on the basis of its carbon neutrality, renewable nature, and highest energy density. In the recent times, its economical production has gained attention. The present chapter deals with a comprehensive insight on dark-fermentative biohydrogen production process. This process is less energy intensive and environmentally benign, and waste materials can be used as substrate. Biochemical insight on hydrogen production via dark fermentation exemplifies the complexity of the process. The maximum H 2 yield of 4 mol H 2 per mol of glucose has been observed when fermentation followed a solely acetate pathway. The potential H 2-producing microorganisms are present in various natural and man-made habitats such as sewage sludge, anaerobically digested sludge, animal waste, compost, hot springs, oceanic sediments, and soil. There are many advantages of working with mixed consortia, viz., presence of different hydrolytic enzymes, better oxygen tolerance, etc. Various pretreatment processes have been explored to enrich H 2-producing microbes. A detailed pretreatment processes, viz., chemical, physical, combined treatments, etc., creates a selection pressure, which could effectively alter the microbial dynamics of the mixed culture. Molecular techniques like polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), terminal restriction fragment length polymorphism (T-RFLP), ribosomal intergenic spacer analysis (RISA), quantitative PCR (qPCR), single-strand conformation polymorphism (SSCP), fluorescence in situ hybridization (FISH), and fluorescence-activated cell sorting (FACS) could be used for advanced and rapid microbial characterization. Use of cheap, renewable, and easily available raw materials could bring down the production cost of bioH 2 .