samir gadow - Academia.edu (original) (raw)
Papers by samir gadow
The purpose of this study was to contribute to improvements in the hydrogen production technologi... more The purpose of this study was to contribute to improvements in the hydrogen production technologies from renewable sources. The effect of temperature and temperature shock on the hydrogen fermentation of cellulose was evaluated by continuous and batch experiments using anaerobic mixed microflora (digested sludge), and to evaluate the long-term stability of fermentation performance under steady state condition. The continuous experiments were conducted at four different temperatures, which were mesophilic (37±1 o C), thermophilic (55±1 o C) and hyper-thermophilic (80±1 and 70±1 o C), with an influent concentration of cellulose of 5 and 10 g/l and a hydraulic retention time (HRT) of 10 days. At 5 g/l, a stable hydrogen production was observed at each condition. At 37±1 o C, the maximum hydrogen yield was 0.6 mmol H 2 /g cellulose. However, at 55±1 o C and 80±1 o C, the maximum hydrogen yields were 15.2 and 19.02 mmol H 2 /g cellulose, respectively. While 26% of the biogas was methane under the mesophilic temperature, no methane gas was detected under both the thermophilic and hyper-thermophilic temperatures. At 10 g/l, during steady state condition, the sudden decreases in the fermentation temperature occurred twice in each condition for 24 h. The results show that the 55±1 and 80±1 o C presented stable hydrogen yields of 12.28 and 9.72 mmol /g cellulose, respectively. However, the 37±1 o C presented low hydrogen yield of 3.56 mmol/g cellulose and methane yield of 5.4 mmol/g cellulose. The reactor performance under 55±1 o C or 80±1 o C appeared to be more resilient to the sudden decreases in the fermentation temperature than 37±1 o C. For long-term operation, the thermophilic (55±1 o C) cellulosic-hydrogen Bio-hydrogen Production from Cellulosic Biomass by Continuous Dark Fermentation
Bioresource Technology Reports, 2022
Fullerenes, Nanotubes and Carbon Nanostructures, 2020
Abstract The rise in fuel demand and lack of petroleum products helped to find diesel oil replace... more Abstract The rise in fuel demand and lack of petroleum products helped to find diesel oil replacement. Therefore, in this study, we evaluated the corn biodiesel and its combustion characteristics improvements by the carbon-nanotube additive. The biodiesel (methyl-ester) was produced by transesterification process, as it was mixed with crude diesel (B20) to enhance the engine performance and emissions reductions of a diesel engine. The effect of blending three different carbon nanotube (CNTs) concentrations of 25, 50 and 100 ppm with biodiesel was also studied. The experimental results showed that the B20CNT100 improved the thermal efficiency by up to 15% compared to B20, B20CNT25 and B20CNT50 fuels. Furthermore, the CO, HC and smoke emissions were significantly decreased to 10, 16 and 22% respectively at the B20CNT100 blend. The maximum peak cylinder pressure, heat release, ignition delay and cylinder combustion temperature were decreased to 1.5%, 4%, 31% and 2.5% at full load, respectively. Consequently, in light of the findings of this study, the blended biodiesel with CNTs improved the diesel engine performance, combustion characteristics and reduction in emissions and the B20CNT100 produced the best performance and environmental impact.
Bulletin of the National Research Centre, 2020
Environmental pollution from varied sources is now deemed as one of the most serious problems eve... more Environmental pollution from varied sources is now deemed as one of the most serious problems everywhere. Several pollutants, however, could be perceived by certain biological indicators, each one is used to identify assured single or a category of pollutants. The current review presents the use of biotas, i.e., plants, microorganisms, and animals, to perceive ecosystems pollutants. The most significant biological indicators are presented. The plant indicators described belong to higher plants; the microbial indicators were represented by bacteria, fungi, algae, planktons, lichens, helminthes eggs and enzymes and the animal ones were earthworms, macro-invertebrates, frogs & toads, insects and animal toxins.
Current Science International, 2019
A series of standardized batch experiments were carried out to optimize the biogas production fro... more A series of standardized batch experiments were carried out to optimize the biogas production from cellulosic-rich wastewater treatment. The experimental results showed that the best result was produced under C/N ration of 20 with 80.94 % COD removal and cumulative biogas production reached 44.55 ml/g COD added. The maximum cellulose degradation was achieved at 10 g/L with a cumulative biogas production of 6.13 L/L. Based on the response surface model, the most significant operational parameter was cellulose concentration and C/N ratio with Log Worth values reached 2.112 and1.131, respectively. As for biological pretreatment, the experimental results showed that the pretreatment under shaking cultural conditions produced better results in COD removal efficiency however, the biogas production was negatively affected as well as the soluble by-products concentrations were significantly decreased. The experimental results showed that the changing in the soluble by-product concentrations could explain the effect of operational factors and the best condition was reported.
Electronics Letters, 2021
Bioresource Technology Reports, 2020
The efficacy of combined continuous anaerobic-aerobic systems to treat 2-Naphthol Red dye-contain... more The efficacy of combined continuous anaerobic-aerobic systems to treat 2-Naphthol Red dye-containing industrial wastewater was investigated. A laboratory-scale of upflow anaerobic sludge bed (UASB) followed by an aerobic process was conducted at a hydraulic residence time (HRT) of 24, 12, 6, and 3 h. The integrated systems showed high performance on the COD removal and decolorization under an HRT of 6 h. The maximum chemical oxygen demand (COD) degradation reached 85.6% and 92.4% in the UASB and the aerobic reactor at organic loading rates (OLR) of 12.97 g COD L −1 d −1 , respectively with 98.4% colour removal. At 3 h HRT, the performance of the UASB reactor was deteriorated sharply, however it showed high resistance and rapidly full functions were recovered after stress removal. The maximum methane yield reached 13.3 mmol CH 4 g COD −1 d −1 at HRT 6 h and the proposed systems and operating conditions could be extended to full-scale applications.
Journal of Material Cycles and Waste Management, 2019
The industrial effluents recently have become more complex and a constant health hazard polluting... more The industrial effluents recently have become more complex and a constant health hazard polluting and contaminating water, soil and air. In this study, it is important to obtain high performance for the treatment of recalcitrant and toxic azo dyes being caused by textile industries and deal with inhibitory factors. For this aim, a continuous two-stage mesophilic anaerobic system has been employed to treat synthetic textile wastewater contained C. I. Acid Red 88 dye. A laboratory-scale of acidogenic continuous stirred tank reactor followed by methanogenic upflow anaerobic sludge bed reactor was operated at hydraulic retention time (HRT) of 48, 24 and 12 h. The acidogenic reactor was able to remove 50.3% of the total COD added and 90.3% of the color at HRT of 12 h. However, the maximum bio-hydrogen conversion as COD was 30.7% with acetate and butyrate as main by-products at HRT of 24 h. The second stage showed a total of 94.8% COD removal and 97.2% decolorization at HRT of 12 h with maximum methane production of 1.01 l/l/day. The experimental results showed that the changing in the soluble by-product could explain the effect of HRT and the maximum total hythane energy produced was 121.5 MJ/m 3 .
Waste and Biomass Valorization, 2019
Bioresource Technology, 2017
The two-stage hythane fermentation of cassava residue low in protein, rich in iron, and deficient... more The two-stage hythane fermentation of cassava residue low in protein, rich in iron, and deficient in nickel and cobalt, resulted in failure after long-term operation, showing a radical decrease in methane production along with an increase in volatile fatty acids (VFAs) accumulation in the second stage. Based on the gap between theoretical demand and existing content of nutrients, the effect of their additions on hythane fermentation was validated in the repeated batch experiment and continuous experiment. The proliferation of hydrolysis bacteria, acidic and hydrogen producing bacteria and methanogens was guaranteed by sufficient N (0.7 g /L), S (30 mg/L), Ni (1.0 mg/L) and Co (1.0 mg /L), and the metabolism of a sustainable hythane fermentation was recovered. In this optimal nutrient combination of above trace elements, the highest hythane yield (426 m 3 hythane with 27.7% of hydrogen from 1 ton of cassava residue) was obtained.
International Journal of Hydrogen Energy, 2017
The long-term performance of the thermophilic hydrogen fermentation of cassava residue was studie... more The long-term performance of the thermophilic hydrogen fermentation of cassava residue was studied in a continuous stirred tank reactor by mixed culture. The effect of different hydraulic retention times (30 days, 6 days and 3 days) on the three metabolic steps of hydrolysis, acidogenesis and hydrogen production was investigated. The highest hydrogen yield, 2.38 mmol H 2 /g dry cassava residue, was achieved at an HRT of 30 days, while acetic acid (2.14 g/L) and butyric acid (2.85 g/L) were the majority of liquid by-products. It was confirmed that the addition of a nitrogen supplement ensured the stable operation of the thermophilic dark fermentation of hydrogen. The energy recovery calculations indicated that it is possible to stably operate the hydrogen fermentation of cassava residue with positive energy recovery efficiency and the highest net energy was 540.5 MJ/ton at an HRT of 30 days.
Bioresource technology, 2016
A series of standardized activity experiments were performed to characterize three different temp... more A series of standardized activity experiments were performed to characterize three different temperature ranges of hydrogen fermentation from different carbon sources. 16S rRNA sequences analysis showed that the bacteria were close to Enterobacter genus in the mesophilic mixed culture (MMC) and Thermoanaerobacterium genus in the thermophilic and hyper-thermophilic mixed cultures (TMC and HMC). The MMC was able to utilize the glucose and cellulose to produce methane gas within a temperature range between 25 and 45 °C and hydrogen gas from 35 to 60°C. While, the TMC and HMC produced only hydrogen gas at all temperature ranges and the highest activity of 521.4mlH2/gVSSd was obtained by TMC. The thermodynamic analysis showed that more energy is consumed by hydrogen production from cellulose than from glucose. The experimental results could help to improve the economic feasibility of cellulosic biomass energy using three-phase technology to produce hythane.
Biomass and Bioenergy, 2015
Thermophilic hydrogen fermentation of cellulose was evaluated by a long term continuous experimen... more Thermophilic hydrogen fermentation of cellulose was evaluated by a long term continuous experiment and batch experiments. The continuous experiment was conducted under 55 C using a continuously stirred tank reactor (CSTR) at a hydraulic retention time (HRT) of 10 day. A stable hydrogen yield of 15.4 ± 0.23 mol kg À1 of cellulose consumed was maintained for 190 days with acetate and butyrate as the main soluble byproducts. An analysis of the 16S rRNA sequences showed that the hydrogen-producing thermophilic cellulolytic microorganisms (HPTCM) were close to Thermoanaerobacterium thermosaccharolyticum, Clostridium sp. and Enterobacter cloacae. Batch experiment demonstrated that the highest H 2 producing activity was obtained at 55 C and the ultimate hydrogen yield and the metabolic by-products were influenced greatly by temperatures. The effect of temperature variation showed that the activation energy for cellulose and glucose were estimated at 103 and 98.8 kJ mol À1 , respectively.
Topical Themes in Energy and Resources, 2015
Biomass is playing an increasing role in renewable energy but has disadvantages where the biomass... more Biomass is playing an increasing role in renewable energy but has disadvantages where the biomass source competes with food supply, biodiversity and other essential components of a sustainable society. At Tohoku University, we are researching sources of alternative fuels such as bio-hydrogen and bio-methane from secondary sources such as wastewater treatment and reuse. In this chapter we present an overview of key concepts related to biomass energy production through various bacterial processes using single and two-phase fermentation technologies. Additionally, we also describe potential sources of biogas technology in Japan including cattle manure, chicken manure, sewage sludge and co-digestion in methane fermentation.
International Journal of Hydrogen Energy, 2012
The effect of temperature on the hydrogen fermentation of cellulose was evaluated by a continuous... more The effect of temperature on the hydrogen fermentation of cellulose was evaluated by a continuous experiment using a mixed culture without pretreatment. The experiments were conducted at three different temperatures, which were mesophilic [37 AE 2 C], thermophilic [55 AE 2 C] and hyper-thermophilic [80 AE 2 C], with an influent concentration of cellulose of 5 g/l and a hydraulic retention time [HRT] of 10 days. A stable hydrogen production was observed at each condition. At 37 AE 2 C, the maximum hydrogen yield was 0.6 mmol H 2 /g cellulose. However, at 55 AE 2 C and 80 AE 2 C, the maximum hydrogen yields were 15.2 and 19.02 mmol H 2 /g cellulose, respectively. While 26% of the biogas was methane under the mesophilic temperature, no methane gas was detected under both the thermophilic and hyper-thermophilic temperatures. The results show that operational temperature is a key to sustainable bio-hydrogen production and that the thermophilic and hyper-thermophilic conditions produced better results than mesophilic condition.
International Journal of Hydrogen Energy, 2013
A continuous stirred tank reactor was used for the dark hydrogen fermentation of cellulose by mix... more A continuous stirred tank reactor was used for the dark hydrogen fermentation of cellulose by mixed microflora at hyper-thermophilic temperature (70 AE 1 C) for 240 days. A total of twenty six batch experiments were conducted to investigate the effect of temperature on the activity of cellulosic-hydrogen producing bacteria. The results show that the system reached a steady state condition after 90 days. A stable hydrogen yield of 7.07 AE 0.23 mmol H 2 /g cellulose was maintained for 150 days with acetate, butyrate, ethanol and propionate as main soluble byproducts. Analysis of 16S rRNA sequences showed that the cellulolytic bacteria were close to Thermoanaerobacterium genus. The cellulosic-hydrogen producing bacteria were able to utilize the cellulose or glucose within a wide range of fermentation temperatures (45e80 C) to produce hydrogen. The activation energy for cellulose and glucose were estimated at 133.2 and 117.7 kJ/mol, respectively.
Bioresource Technology, 2013
The 55 ± 1 and 80 ± 1°C presented long-term stable cellulosic-hydrogen fermentation. The first st... more The 55 ± 1 and 80 ± 1°C presented long-term stable cellulosic-hydrogen fermentation. The first study on the effect of temperature shock on bioH 2 production of cellulose. The reactor under 55 or 80°C appeared to be more resilient to the shock than 37°C. The recovery period after the 2nd shock was shorter than after the 1st shock.
Water Research, 2022
[Bmim]FeCl4, or 1‑butyl‑3-methylimidazolium tetrachloroferrate, is a typical ionic liquid (IL). I... more [Bmim]FeCl4, or 1‑butyl‑3-methylimidazolium tetrachloroferrate, is a typical ionic liquid (IL). Its recyclable, magnetic, multicomponent, and solvent-free nature makes it a particularly attractive ionic liquid for use in industrial processes. Despite its widespread use, the potential hazards that [Bmim]FeCl4 might pose to the environment, including productive microorganisms, have not been explored. In this study, the dose-response of [Bmim]FeCl4 in anaerobic digestion (AD) was investigated to assess the potential toxification and biochar-dependent detoxification in microbial communities, including enzymatic activity and molecule docking dynamics. Our results showed that methane production (31.52 mLmax/gVS) was sharply inhibited following [Bmim]FeCl4 treatment. Moreover, increasing the dosage of [Bmim]FeCl4 caused more dissolved organic matter (DOM) to be generated. Interestingly, 0.4 g/L of [Bmim]FeCl4 could stimulate the high activity of microbial hydrolase and ATPase. However, a higher concentration of 2.65 g/L prevented these enzymatic processes from continuing. At the cellular level, higher concentration of [Bmim]FeCl4 (>0.4 g/L) increased malondialdehyde (MDA) levels, leading to a higher cell lethal rate and weakening of the secondary structures of protein (especially, the amide I region). At the molecular level, the competitive H-bonding in the active sites caused low activity and consummated more energy. At the community level, structural equation modeling (SEM) revealed that [Bmim]FeCl4 and biochar were the main drivers for microbial community succession. For instance, high [Bmim]FeCl4 (8 g/L) benefited the growth of Clostridium sensu_stricto (from ≤1% to 27%). It is worth mentioning that biochar reversed the inhibition with high α-diversity, which caused a resurgence in the activity of previously inhibited ATPase and hydrolase. H2-trophic methanogens (Methanolinea and Methaofastidisoum) were sensitive to [Bmim]FeCl4 and decreased linearly while acetoclastic methanogens (Methanosaeta) were unchanged. These findings were consistent with the short-term activity tests and further verified by functional analysis.
The purpose of this study was to contribute to improvements in the hydrogen production technologi... more The purpose of this study was to contribute to improvements in the hydrogen production technologies from renewable sources. The effect of temperature and temperature shock on the hydrogen fermentation of cellulose was evaluated by continuous and batch experiments using anaerobic mixed microflora (digested sludge), and to evaluate the long-term stability of fermentation performance under steady state condition. The continuous experiments were conducted at four different temperatures, which were mesophilic (37±1 o C), thermophilic (55±1 o C) and hyper-thermophilic (80±1 and 70±1 o C), with an influent concentration of cellulose of 5 and 10 g/l and a hydraulic retention time (HRT) of 10 days. At 5 g/l, a stable hydrogen production was observed at each condition. At 37±1 o C, the maximum hydrogen yield was 0.6 mmol H 2 /g cellulose. However, at 55±1 o C and 80±1 o C, the maximum hydrogen yields were 15.2 and 19.02 mmol H 2 /g cellulose, respectively. While 26% of the biogas was methane under the mesophilic temperature, no methane gas was detected under both the thermophilic and hyper-thermophilic temperatures. At 10 g/l, during steady state condition, the sudden decreases in the fermentation temperature occurred twice in each condition for 24 h. The results show that the 55±1 and 80±1 o C presented stable hydrogen yields of 12.28 and 9.72 mmol /g cellulose, respectively. However, the 37±1 o C presented low hydrogen yield of 3.56 mmol/g cellulose and methane yield of 5.4 mmol/g cellulose. The reactor performance under 55±1 o C or 80±1 o C appeared to be more resilient to the sudden decreases in the fermentation temperature than 37±1 o C. For long-term operation, the thermophilic (55±1 o C) cellulosic-hydrogen Bio-hydrogen Production from Cellulosic Biomass by Continuous Dark Fermentation
Bioresource Technology Reports, 2022
Fullerenes, Nanotubes and Carbon Nanostructures, 2020
Abstract The rise in fuel demand and lack of petroleum products helped to find diesel oil replace... more Abstract The rise in fuel demand and lack of petroleum products helped to find diesel oil replacement. Therefore, in this study, we evaluated the corn biodiesel and its combustion characteristics improvements by the carbon-nanotube additive. The biodiesel (methyl-ester) was produced by transesterification process, as it was mixed with crude diesel (B20) to enhance the engine performance and emissions reductions of a diesel engine. The effect of blending three different carbon nanotube (CNTs) concentrations of 25, 50 and 100 ppm with biodiesel was also studied. The experimental results showed that the B20CNT100 improved the thermal efficiency by up to 15% compared to B20, B20CNT25 and B20CNT50 fuels. Furthermore, the CO, HC and smoke emissions were significantly decreased to 10, 16 and 22% respectively at the B20CNT100 blend. The maximum peak cylinder pressure, heat release, ignition delay and cylinder combustion temperature were decreased to 1.5%, 4%, 31% and 2.5% at full load, respectively. Consequently, in light of the findings of this study, the blended biodiesel with CNTs improved the diesel engine performance, combustion characteristics and reduction in emissions and the B20CNT100 produced the best performance and environmental impact.
Bulletin of the National Research Centre, 2020
Environmental pollution from varied sources is now deemed as one of the most serious problems eve... more Environmental pollution from varied sources is now deemed as one of the most serious problems everywhere. Several pollutants, however, could be perceived by certain biological indicators, each one is used to identify assured single or a category of pollutants. The current review presents the use of biotas, i.e., plants, microorganisms, and animals, to perceive ecosystems pollutants. The most significant biological indicators are presented. The plant indicators described belong to higher plants; the microbial indicators were represented by bacteria, fungi, algae, planktons, lichens, helminthes eggs and enzymes and the animal ones were earthworms, macro-invertebrates, frogs & toads, insects and animal toxins.
Current Science International, 2019
A series of standardized batch experiments were carried out to optimize the biogas production fro... more A series of standardized batch experiments were carried out to optimize the biogas production from cellulosic-rich wastewater treatment. The experimental results showed that the best result was produced under C/N ration of 20 with 80.94 % COD removal and cumulative biogas production reached 44.55 ml/g COD added. The maximum cellulose degradation was achieved at 10 g/L with a cumulative biogas production of 6.13 L/L. Based on the response surface model, the most significant operational parameter was cellulose concentration and C/N ratio with Log Worth values reached 2.112 and1.131, respectively. As for biological pretreatment, the experimental results showed that the pretreatment under shaking cultural conditions produced better results in COD removal efficiency however, the biogas production was negatively affected as well as the soluble by-products concentrations were significantly decreased. The experimental results showed that the changing in the soluble by-product concentrations could explain the effect of operational factors and the best condition was reported.
Electronics Letters, 2021
Bioresource Technology Reports, 2020
The efficacy of combined continuous anaerobic-aerobic systems to treat 2-Naphthol Red dye-contain... more The efficacy of combined continuous anaerobic-aerobic systems to treat 2-Naphthol Red dye-containing industrial wastewater was investigated. A laboratory-scale of upflow anaerobic sludge bed (UASB) followed by an aerobic process was conducted at a hydraulic residence time (HRT) of 24, 12, 6, and 3 h. The integrated systems showed high performance on the COD removal and decolorization under an HRT of 6 h. The maximum chemical oxygen demand (COD) degradation reached 85.6% and 92.4% in the UASB and the aerobic reactor at organic loading rates (OLR) of 12.97 g COD L −1 d −1 , respectively with 98.4% colour removal. At 3 h HRT, the performance of the UASB reactor was deteriorated sharply, however it showed high resistance and rapidly full functions were recovered after stress removal. The maximum methane yield reached 13.3 mmol CH 4 g COD −1 d −1 at HRT 6 h and the proposed systems and operating conditions could be extended to full-scale applications.
Journal of Material Cycles and Waste Management, 2019
The industrial effluents recently have become more complex and a constant health hazard polluting... more The industrial effluents recently have become more complex and a constant health hazard polluting and contaminating water, soil and air. In this study, it is important to obtain high performance for the treatment of recalcitrant and toxic azo dyes being caused by textile industries and deal with inhibitory factors. For this aim, a continuous two-stage mesophilic anaerobic system has been employed to treat synthetic textile wastewater contained C. I. Acid Red 88 dye. A laboratory-scale of acidogenic continuous stirred tank reactor followed by methanogenic upflow anaerobic sludge bed reactor was operated at hydraulic retention time (HRT) of 48, 24 and 12 h. The acidogenic reactor was able to remove 50.3% of the total COD added and 90.3% of the color at HRT of 12 h. However, the maximum bio-hydrogen conversion as COD was 30.7% with acetate and butyrate as main by-products at HRT of 24 h. The second stage showed a total of 94.8% COD removal and 97.2% decolorization at HRT of 12 h with maximum methane production of 1.01 l/l/day. The experimental results showed that the changing in the soluble by-product could explain the effect of HRT and the maximum total hythane energy produced was 121.5 MJ/m 3 .
Waste and Biomass Valorization, 2019
Bioresource Technology, 2017
The two-stage hythane fermentation of cassava residue low in protein, rich in iron, and deficient... more The two-stage hythane fermentation of cassava residue low in protein, rich in iron, and deficient in nickel and cobalt, resulted in failure after long-term operation, showing a radical decrease in methane production along with an increase in volatile fatty acids (VFAs) accumulation in the second stage. Based on the gap between theoretical demand and existing content of nutrients, the effect of their additions on hythane fermentation was validated in the repeated batch experiment and continuous experiment. The proliferation of hydrolysis bacteria, acidic and hydrogen producing bacteria and methanogens was guaranteed by sufficient N (0.7 g /L), S (30 mg/L), Ni (1.0 mg/L) and Co (1.0 mg /L), and the metabolism of a sustainable hythane fermentation was recovered. In this optimal nutrient combination of above trace elements, the highest hythane yield (426 m 3 hythane with 27.7% of hydrogen from 1 ton of cassava residue) was obtained.
International Journal of Hydrogen Energy, 2017
The long-term performance of the thermophilic hydrogen fermentation of cassava residue was studie... more The long-term performance of the thermophilic hydrogen fermentation of cassava residue was studied in a continuous stirred tank reactor by mixed culture. The effect of different hydraulic retention times (30 days, 6 days and 3 days) on the three metabolic steps of hydrolysis, acidogenesis and hydrogen production was investigated. The highest hydrogen yield, 2.38 mmol H 2 /g dry cassava residue, was achieved at an HRT of 30 days, while acetic acid (2.14 g/L) and butyric acid (2.85 g/L) were the majority of liquid by-products. It was confirmed that the addition of a nitrogen supplement ensured the stable operation of the thermophilic dark fermentation of hydrogen. The energy recovery calculations indicated that it is possible to stably operate the hydrogen fermentation of cassava residue with positive energy recovery efficiency and the highest net energy was 540.5 MJ/ton at an HRT of 30 days.
Bioresource technology, 2016
A series of standardized activity experiments were performed to characterize three different temp... more A series of standardized activity experiments were performed to characterize three different temperature ranges of hydrogen fermentation from different carbon sources. 16S rRNA sequences analysis showed that the bacteria were close to Enterobacter genus in the mesophilic mixed culture (MMC) and Thermoanaerobacterium genus in the thermophilic and hyper-thermophilic mixed cultures (TMC and HMC). The MMC was able to utilize the glucose and cellulose to produce methane gas within a temperature range between 25 and 45 °C and hydrogen gas from 35 to 60°C. While, the TMC and HMC produced only hydrogen gas at all temperature ranges and the highest activity of 521.4mlH2/gVSSd was obtained by TMC. The thermodynamic analysis showed that more energy is consumed by hydrogen production from cellulose than from glucose. The experimental results could help to improve the economic feasibility of cellulosic biomass energy using three-phase technology to produce hythane.
Biomass and Bioenergy, 2015
Thermophilic hydrogen fermentation of cellulose was evaluated by a long term continuous experimen... more Thermophilic hydrogen fermentation of cellulose was evaluated by a long term continuous experiment and batch experiments. The continuous experiment was conducted under 55 C using a continuously stirred tank reactor (CSTR) at a hydraulic retention time (HRT) of 10 day. A stable hydrogen yield of 15.4 ± 0.23 mol kg À1 of cellulose consumed was maintained for 190 days with acetate and butyrate as the main soluble byproducts. An analysis of the 16S rRNA sequences showed that the hydrogen-producing thermophilic cellulolytic microorganisms (HPTCM) were close to Thermoanaerobacterium thermosaccharolyticum, Clostridium sp. and Enterobacter cloacae. Batch experiment demonstrated that the highest H 2 producing activity was obtained at 55 C and the ultimate hydrogen yield and the metabolic by-products were influenced greatly by temperatures. The effect of temperature variation showed that the activation energy for cellulose and glucose were estimated at 103 and 98.8 kJ mol À1 , respectively.
Topical Themes in Energy and Resources, 2015
Biomass is playing an increasing role in renewable energy but has disadvantages where the biomass... more Biomass is playing an increasing role in renewable energy but has disadvantages where the biomass source competes with food supply, biodiversity and other essential components of a sustainable society. At Tohoku University, we are researching sources of alternative fuels such as bio-hydrogen and bio-methane from secondary sources such as wastewater treatment and reuse. In this chapter we present an overview of key concepts related to biomass energy production through various bacterial processes using single and two-phase fermentation technologies. Additionally, we also describe potential sources of biogas technology in Japan including cattle manure, chicken manure, sewage sludge and co-digestion in methane fermentation.
International Journal of Hydrogen Energy, 2012
The effect of temperature on the hydrogen fermentation of cellulose was evaluated by a continuous... more The effect of temperature on the hydrogen fermentation of cellulose was evaluated by a continuous experiment using a mixed culture without pretreatment. The experiments were conducted at three different temperatures, which were mesophilic [37 AE 2 C], thermophilic [55 AE 2 C] and hyper-thermophilic [80 AE 2 C], with an influent concentration of cellulose of 5 g/l and a hydraulic retention time [HRT] of 10 days. A stable hydrogen production was observed at each condition. At 37 AE 2 C, the maximum hydrogen yield was 0.6 mmol H 2 /g cellulose. However, at 55 AE 2 C and 80 AE 2 C, the maximum hydrogen yields were 15.2 and 19.02 mmol H 2 /g cellulose, respectively. While 26% of the biogas was methane under the mesophilic temperature, no methane gas was detected under both the thermophilic and hyper-thermophilic temperatures. The results show that operational temperature is a key to sustainable bio-hydrogen production and that the thermophilic and hyper-thermophilic conditions produced better results than mesophilic condition.
International Journal of Hydrogen Energy, 2013
A continuous stirred tank reactor was used for the dark hydrogen fermentation of cellulose by mix... more A continuous stirred tank reactor was used for the dark hydrogen fermentation of cellulose by mixed microflora at hyper-thermophilic temperature (70 AE 1 C) for 240 days. A total of twenty six batch experiments were conducted to investigate the effect of temperature on the activity of cellulosic-hydrogen producing bacteria. The results show that the system reached a steady state condition after 90 days. A stable hydrogen yield of 7.07 AE 0.23 mmol H 2 /g cellulose was maintained for 150 days with acetate, butyrate, ethanol and propionate as main soluble byproducts. Analysis of 16S rRNA sequences showed that the cellulolytic bacteria were close to Thermoanaerobacterium genus. The cellulosic-hydrogen producing bacteria were able to utilize the cellulose or glucose within a wide range of fermentation temperatures (45e80 C) to produce hydrogen. The activation energy for cellulose and glucose were estimated at 133.2 and 117.7 kJ/mol, respectively.
Bioresource Technology, 2013
The 55 ± 1 and 80 ± 1°C presented long-term stable cellulosic-hydrogen fermentation. The first st... more The 55 ± 1 and 80 ± 1°C presented long-term stable cellulosic-hydrogen fermentation. The first study on the effect of temperature shock on bioH 2 production of cellulose. The reactor under 55 or 80°C appeared to be more resilient to the shock than 37°C. The recovery period after the 2nd shock was shorter than after the 1st shock.
Water Research, 2022
[Bmim]FeCl4, or 1‑butyl‑3-methylimidazolium tetrachloroferrate, is a typical ionic liquid (IL). I... more [Bmim]FeCl4, or 1‑butyl‑3-methylimidazolium tetrachloroferrate, is a typical ionic liquid (IL). Its recyclable, magnetic, multicomponent, and solvent-free nature makes it a particularly attractive ionic liquid for use in industrial processes. Despite its widespread use, the potential hazards that [Bmim]FeCl4 might pose to the environment, including productive microorganisms, have not been explored. In this study, the dose-response of [Bmim]FeCl4 in anaerobic digestion (AD) was investigated to assess the potential toxification and biochar-dependent detoxification in microbial communities, including enzymatic activity and molecule docking dynamics. Our results showed that methane production (31.52 mLmax/gVS) was sharply inhibited following [Bmim]FeCl4 treatment. Moreover, increasing the dosage of [Bmim]FeCl4 caused more dissolved organic matter (DOM) to be generated. Interestingly, 0.4 g/L of [Bmim]FeCl4 could stimulate the high activity of microbial hydrolase and ATPase. However, a higher concentration of 2.65 g/L prevented these enzymatic processes from continuing. At the cellular level, higher concentration of [Bmim]FeCl4 (>0.4 g/L) increased malondialdehyde (MDA) levels, leading to a higher cell lethal rate and weakening of the secondary structures of protein (especially, the amide I region). At the molecular level, the competitive H-bonding in the active sites caused low activity and consummated more energy. At the community level, structural equation modeling (SEM) revealed that [Bmim]FeCl4 and biochar were the main drivers for microbial community succession. For instance, high [Bmim]FeCl4 (8 g/L) benefited the growth of Clostridium sensu_stricto (from ≤1% to 27%). It is worth mentioning that biochar reversed the inhibition with high α-diversity, which caused a resurgence in the activity of previously inhibited ATPase and hydrolase. H2-trophic methanogens (Methanolinea and Methaofastidisoum) were sensitive to [Bmim]FeCl4 and decreased linearly while acetoclastic methanogens (Methanosaeta) were unchanged. These findings were consistent with the short-term activity tests and further verified by functional analysis.