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Biomass Conversion and Biorefinery
Journal Prestige (SJR): 0.493  Citation Impact (citeScore): 1 Number of Followers: 11  Partially Free JournalISSN (Print) 2190-6815 - ISSN (Online) 2190-6823 Published by Springer-Verlag  [2626 journals]
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- Synergistic effect of ultrasonic and microwave pretreatment on improved
biohydrogen generation from palm oil mill effluent- Abstract: Abstract This study aims to investigate the effect of the ultrasonic, microwave, and combined ultrasonic-microwave pretreatment of palm oil mill effluent (POME) sludge before fermentation to analyze hydrogen (H2) production and chemical oxygen demand (COD) removal efficiency in batch fermentation. Experimental results showed that the pretreatment of sludge (ultrasonication, microwave, and ultrasonication-microwave pretreatment) had positively influence the H2 production and COD removal efficiency during fermentation as compared to control one (without any pretreatment). Combined ultrasonication-microwave pretreatment of POME sludge was shown to be more effective for increasing both H2 production and COD removal from POME with the highest cumulative H2 and COD removal efficiency of 4080 mL H2/L-POME and 75.56%, respectively. The improvement observed for cumulative H2 production and COD removal was 12.14% and 21.42%, respectively, compared to the control one. These observations concluded that the POME sludge pretreatment with ultrasonication-microwave irradiation could be an effective strategy for improved treatment of POME with simultaneous production of H2.
PubDate: 2021-01-12
- Abstract: Abstract This study aims to investigate the effect of the ultrasonic, microwave, and combined ultrasonic-microwave pretreatment of palm oil mill effluent (POME) sludge before fermentation to analyze hydrogen (H2) production and chemical oxygen demand (COD) removal efficiency in batch fermentation. Experimental results showed that the pretreatment of sludge (ultrasonication, microwave, and ultrasonication-microwave pretreatment) had positively influence the H2 production and COD removal efficiency during fermentation as compared to control one (without any pretreatment). Combined ultrasonication-microwave pretreatment of POME sludge was shown to be more effective for increasing both H2 production and COD removal from POME with the highest cumulative H2 and COD removal efficiency of 4080 mL H2/L-POME and 75.56%, respectively. The improvement observed for cumulative H2 production and COD removal was 12.14% and 21.42%, respectively, compared to the control one. These observations concluded that the POME sludge pretreatment with ultrasonication-microwave irradiation could be an effective strategy for improved treatment of POME with simultaneous production of H2.
- Machine learning prediction of higher heating value of biomass
- Abstract: Abstract Recently, biomass sources are important for energy applications. There is need for analyzing of the biomass model based on different components such as carbon, ash, and moisture content since the biomass sources are important for energy applications. In this paper, an extreme learning machine (ELM) is used to estimate efficiency. ELM was implemented for single-layer feed-forward neural network (SLFN) architectures. Because biomass modeling could be a very challenging task for conventional mathematical, it is suitable to apply machine learning models which could overcome nonlinearities of the process. The main attempt in this study was to develop a machine learning model for prediction of the higher heating values of biomass based on proximate analysis. According the prediction accuracy (coefficient of determination and root mean square error) of the higher heating value of the biomass, the inputs’ influence was determined on the higher heating value. According to the obtained results, fixed carbon has less moderate coefficient, ash has less correlation coefficient, and volatile matter has the most correlation coefficient. Therefore, the volatile matter percentage weight has the highest relevance on the higher heating value of the biomass. On the contrary, the ash has the smallest relevance on the higher heating value of the biomass based on machine learning approach.
PubDate: 2021-01-12
- Abstract: Abstract Recently, biomass sources are important for energy applications. There is need for analyzing of the biomass model based on different components such as carbon, ash, and moisture content since the biomass sources are important for energy applications. In this paper, an extreme learning machine (ELM) is used to estimate efficiency. ELM was implemented for single-layer feed-forward neural network (SLFN) architectures. Because biomass modeling could be a very challenging task for conventional mathematical, it is suitable to apply machine learning models which could overcome nonlinearities of the process. The main attempt in this study was to develop a machine learning model for prediction of the higher heating values of biomass based on proximate analysis. According the prediction accuracy (coefficient of determination and root mean square error) of the higher heating value of the biomass, the inputs’ influence was determined on the higher heating value. According to the obtained results, fixed carbon has less moderate coefficient, ash has less correlation coefficient, and volatile matter has the most correlation coefficient. Therefore, the volatile matter percentage weight has the highest relevance on the higher heating value of the biomass. On the contrary, the ash has the smallest relevance on the higher heating value of the biomass based on machine learning approach.
- Simultaneous production of astaxanthin and lipids from Chlorella
sorokiniana in the presence of reactive oxygen species: a biorefinery
approach- Abstract: The current study aimed to investigate the concurrent production of astaxanthin and lipids using Chlorella sorokiniana under mixotrophic conditions in an external loop airlift photobioreactor (ELAPB). Supplementation of Fe2+ into the media in the red phase (stress phase) induced the astaxanthin production. The maximum yield of 154.36 mg L−1 was obtained by the end of the red phase, which is equivalent to 3.4% of the dry biomass weight. The role of reactive oxygen species in the formation of astaxanthin, which protects the microalgal cells from different oxidative stress, has been elucidated. Apart from astaxanthin, unsaturated fatty acids (81.34%) were also produced with excellent biodiesel properties. Unsaturated fatty acids viz., palmitoleic acid (16:1), have resulted in high yields (22.85%), followed by linoleic acid (18:2), 28.27%; oleic acid (C18:1), 14.38%; and eicosapentaenoic acid (20:5), 4.49%. Hence, the simultaneous production of high value-added products, viz., astaxanthin, and lipids makes the whole process economically viable and environmentally sustainable and elevates the commercial potential during scale-up. The astaxanthin radical scavenging activity was also assessed by H2O2 assay, and the maximum scavenging activity was determined as 91%. The study confers the potential advantages of algal cultivation for high-value commercial product synthesis towards additional revenue generation and development of an efficient microalgae-based biorefinery process. Graphical abstract
PubDate: 2021-01-12
- Abstract: The current study aimed to investigate the concurrent production of astaxanthin and lipids using Chlorella sorokiniana under mixotrophic conditions in an external loop airlift photobioreactor (ELAPB). Supplementation of Fe2+ into the media in the red phase (stress phase) induced the astaxanthin production. The maximum yield of 154.36 mg L−1 was obtained by the end of the red phase, which is equivalent to 3.4% of the dry biomass weight. The role of reactive oxygen species in the formation of astaxanthin, which protects the microalgal cells from different oxidative stress, has been elucidated. Apart from astaxanthin, unsaturated fatty acids (81.34%) were also produced with excellent biodiesel properties. Unsaturated fatty acids viz., palmitoleic acid (16:1), have resulted in high yields (22.85%), followed by linoleic acid (18:2), 28.27%; oleic acid (C18:1), 14.38%; and eicosapentaenoic acid (20:5), 4.49%. Hence, the simultaneous production of high value-added products, viz., astaxanthin, and lipids makes the whole process economically viable and environmentally sustainable and elevates the commercial potential during scale-up. The astaxanthin radical scavenging activity was also assessed by H2O2 assay, and the maximum scavenging activity was determined as 91%. The study confers the potential advantages of algal cultivation for high-value commercial product synthesis towards additional revenue generation and development of an efficient microalgae-based biorefinery process. Graphical abstract
- Optimization of steam explosion parameters for improved biotechnological
use of wheat straw- Abstract: Abstract Using lignocellulosic raw materials as substrate for biotechnological applications has been a focus of research during the last two decades. They contain sugars, which can be used in industrial fermentation processes, in from of polysaccharides (cellulose, hemicellulose). Wheat straw, one representative of lignocellulosic materials, is sustainably and abundantly available, especially in Europe and North America. However, wheat straw, just like any other lignocellulosic material, needs to be pretreated in one way or the other in order to generate sufficient quantities of monosaccharides. One widely used pretreatment for lignocellulosic material is steam explosion combined with enzymatic hydrolysis. In this study, the effects of steam exploding wheat straw in combination with water are presented. By impregnation with water, saccharide yields from subsequent enzymatic hydrolysis increased from 18.8 to 22.6 g L−1 for glucose and 13.8 to 16.4 g L−1 for xylose, respectively. Moreover, the basic steam explosion parameters residence time and temperature were optimized in ranges from 5 to 20 min and 180–200 °C. This further optimization increased the maximum saccharide yield to 41.2 g L−1 for glucose (200 °C, 15 min) and 18.9 g L−1 for xylose (190 °C, 10 min). Finally, the growth of the intensively investigated biotechnological production host Yarrowia lipolytica on hydrolysates derived from different steam explosion parameters was evaluated. Y. lipolytica grew well in media containing up to 90% wheat straw hydrolysate as sole carbon source, demonstrating the potential as substrate for biotechnological processes.
PubDate: 2021-01-12
- Abstract: Abstract Using lignocellulosic raw materials as substrate for biotechnological applications has been a focus of research during the last two decades. They contain sugars, which can be used in industrial fermentation processes, in from of polysaccharides (cellulose, hemicellulose). Wheat straw, one representative of lignocellulosic materials, is sustainably and abundantly available, especially in Europe and North America. However, wheat straw, just like any other lignocellulosic material, needs to be pretreated in one way or the other in order to generate sufficient quantities of monosaccharides. One widely used pretreatment for lignocellulosic material is steam explosion combined with enzymatic hydrolysis. In this study, the effects of steam exploding wheat straw in combination with water are presented. By impregnation with water, saccharide yields from subsequent enzymatic hydrolysis increased from 18.8 to 22.6 g L−1 for glucose and 13.8 to 16.4 g L−1 for xylose, respectively. Moreover, the basic steam explosion parameters residence time and temperature were optimized in ranges from 5 to 20 min and 180–200 °C. This further optimization increased the maximum saccharide yield to 41.2 g L−1 for glucose (200 °C, 15 min) and 18.9 g L−1 for xylose (190 °C, 10 min). Finally, the growth of the intensively investigated biotechnological production host Yarrowia lipolytica on hydrolysates derived from different steam explosion parameters was evaluated. Y. lipolytica grew well in media containing up to 90% wheat straw hydrolysate as sole carbon source, demonstrating the potential as substrate for biotechnological processes.
- Fiber characterization of old corrugated container bleached pulp with
laccase and glycine pretreatment- Abstract: Abstract In response to deal with the increasingly serious environmental problems and shortage of fiber raw materials, biological enzyme pretreatment is an effective way to replace a large number of chemical additives to improve the properties of waste paper fibers. Fiber characterization of old corrugated container bleached pulp with laccase and glycine (Lac/Gly) pretreatment was investigated by means of Fourier transform infrared spectroscopy (FTIR), headspace gas chromatography (HSGC), fiber quality measurements (FQA), X-ray diffraction method (XRD), and atomic force microscope (AFM). Results showed that, compared with the control pulp, the whiteness and brightness of the Lac/Gly-treated pulp increased by 16.17% and 7.41%, respectively. And the FTIR showed that Lac/Gly pretreatment promotes the effective removal of lignin by hydrogen peroxide (H2O2) bleaching. The content of carboxyl groups in pulp increased remarkably by 21.92%. The paper physical analysis showed that the paper strength properties have improved remarkably. The fiber quality analyses indicated that the fiber length, coarseness, and curl index changed a little. The XRD analysis showed that the crystallinity decreased by 5.83% due to Lac/Gly treatment. The AFM analysis showed that through Lac/Gly treatment, the lignin and extracts over the fiber surface are decreased significantly.
PubDate: 2021-01-11
- Abstract: Abstract In response to deal with the increasingly serious environmental problems and shortage of fiber raw materials, biological enzyme pretreatment is an effective way to replace a large number of chemical additives to improve the properties of waste paper fibers. Fiber characterization of old corrugated container bleached pulp with laccase and glycine (Lac/Gly) pretreatment was investigated by means of Fourier transform infrared spectroscopy (FTIR), headspace gas chromatography (HSGC), fiber quality measurements (FQA), X-ray diffraction method (XRD), and atomic force microscope (AFM). Results showed that, compared with the control pulp, the whiteness and brightness of the Lac/Gly-treated pulp increased by 16.17% and 7.41%, respectively. And the FTIR showed that Lac/Gly pretreatment promotes the effective removal of lignin by hydrogen peroxide (H2O2) bleaching. The content of carboxyl groups in pulp increased remarkably by 21.92%. The paper physical analysis showed that the paper strength properties have improved remarkably. The fiber quality analyses indicated that the fiber length, coarseness, and curl index changed a little. The XRD analysis showed that the crystallinity decreased by 5.83% due to Lac/Gly treatment. The AFM analysis showed that through Lac/Gly treatment, the lignin and extracts over the fiber surface are decreased significantly.
- Convective drying of Moringa oleifera seeds: kinetics modelling and
effects on oil yield from different extraction techniques- Abstract: Abstract This work shows the convective drying kinetics of moringa seeds (Moringa oleifera L) at different drying temperatures 40, 50, 60, 70, and 80 °C and the effect drying on the extracted oil yield. Four simplified models were fitted to the kinetics data, and a phenomenological mathematical model (PMM) was developed to describe the process. The simplified model that better represented the experimental data was Verma, with a global relative mean error of 1.31%. The PMM with the use of an equilibrium boundary condition at the surface produced better results than those obtained when considering the convective condition, indicating that the effects of external mass transfer resistance are neglected. The moringa oil was extracted from all dried seeds conditions using different extraction techniques, such as Soxhlet technique, ultrasound-assisted, and mechanical extraction; and the maximum oil yield obtained for dry seeds was 43.06%, 31.53%, and 24.93% respectively. All drying temperatures of the moringa seed do not show influence the oil yield obtained in each extraction method used.
PubDate: 2021-01-11
- Abstract: Abstract This work shows the convective drying kinetics of moringa seeds (Moringa oleifera L) at different drying temperatures 40, 50, 60, 70, and 80 °C and the effect drying on the extracted oil yield. Four simplified models were fitted to the kinetics data, and a phenomenological mathematical model (PMM) was developed to describe the process. The simplified model that better represented the experimental data was Verma, with a global relative mean error of 1.31%. The PMM with the use of an equilibrium boundary condition at the surface produced better results than those obtained when considering the convective condition, indicating that the effects of external mass transfer resistance are neglected. The moringa oil was extracted from all dried seeds conditions using different extraction techniques, such as Soxhlet technique, ultrasound-assisted, and mechanical extraction; and the maximum oil yield obtained for dry seeds was 43.06%, 31.53%, and 24.93% respectively. All drying temperatures of the moringa seed do not show influence the oil yield obtained in each extraction method used.
- Valorizing municipal organic waste to produce biodiesel, biogas, organic
- Abstract: Economically viable alternatives for utilizing municipal solid waste are still a major challenge for society, especially in less developed countries. A potential pathway is using the organic fraction of municipal solid waste (OFMSW) to produce energy, biofuels, organic fertilizers, and value-added chemical compounds. We evaluated an integrated biorefinery structure for the treatment of used cooking oil, pruning biomass, and organic and food residues to produce biodiesel, biogas, organic compost, 1,3-propanediol, and electrical energy at the campus of the Federal University of Pernambuco, which was considered a case study to represent a small city of Northeastern Brazil. A pilot transesterification plant, a biodigestion unit, and a compost unit were installed to process 3.3 tons daily of OFMSW produced. Additionally, research was carried out to produce 1,3-propanediol on a laboratory scale from residual glycerol. The quality of the biodiesel generated from the used cooking oil met national technical standards and the conversion of residual oil into biodiesel reached 93%. The average biogas production was 0.584 ± 0.176 Nm3 kgVS−1, with an average methane production of 50% generating up to 44 MWh of electricity per year. The organic compost produced met the quality requirements of organic fertilizers, such as maturation and nutrient contents. Glycerol treatment increased the yield of 1,3-propanediol production. Our findings demonstrate that the integrated biorefinery will lead to a reduction of US$ 80,000 in the costs of OFMSW management. More importantly, this approach generates incentives for circular economy initiatives in small municipalities in Brazil and other less developed countries. Graphical abstract
PubDate: 2021-01-11
- Abstract: Economically viable alternatives for utilizing municipal solid waste are still a major challenge for society, especially in less developed countries. A potential pathway is using the organic fraction of municipal solid waste (OFMSW) to produce energy, biofuels, organic fertilizers, and value-added chemical compounds. We evaluated an integrated biorefinery structure for the treatment of used cooking oil, pruning biomass, and organic and food residues to produce biodiesel, biogas, organic compost, 1,3-propanediol, and electrical energy at the campus of the Federal University of Pernambuco, which was considered a case study to represent a small city of Northeastern Brazil. A pilot transesterification plant, a biodigestion unit, and a compost unit were installed to process 3.3 tons daily of OFMSW produced. Additionally, research was carried out to produce 1,3-propanediol on a laboratory scale from residual glycerol. The quality of the biodiesel generated from the used cooking oil met national technical standards and the conversion of residual oil into biodiesel reached 93%. The average biogas production was 0.584 ± 0.176 Nm3 kgVS−1, with an average methane production of 50% generating up to 44 MWh of electricity per year. The organic compost produced met the quality requirements of organic fertilizers, such as maturation and nutrient contents. Glycerol treatment increased the yield of 1,3-propanediol production. Our findings demonstrate that the integrated biorefinery will lead to a reduction of US$ 80,000 in the costs of OFMSW management. More importantly, this approach generates incentives for circular economy initiatives in small municipalities in Brazil and other less developed countries. Graphical abstract
- Metal nanoparticle mixtures to improve the biogas yield of cattle manure
- Abstract: Abstract Metal nanoparticle elements such as Fe, Ni, and Co are promising in improving the performance and stability of anaerobic digestion. However, the impact of nanoparticle mixtures of Fe, Ni, and Co on biogas production from anaerobic digestion of cattle manure still needs further studies. Therefore, this study investigated the effect of the most effective concentrations of nanoparticle additives on biogas and CH4 production and H2S mitigation during anaerobic digestion of cattle manure. The nanoparticle additive concentrations were selected from the findings of previous studies and were 30 mg/L Fe, 2 mg/L Ni, and 1 mg/L Co at four combinations. Biogas production increased by 14.61% upon the use of nanoparticle mixtures of 30 mg/L Fe and 2 mg/L Ni compared with control (cattle manure-only). Furthermore, the addition of nanoparticle mixtures of 30 mg/L Fe, 2 mg/L, and 1 mg/L Co increased CH4 production by 19.30% compared with control. Moreover, H2S production decreased by 35.10% in the presence of nanoparticles mixture of 30 mg/L Fe, 2 mg/L, and 1 mg/L Co in comparison with control. Modified Gompertz and logistic function models were used to determine the kinetic constant of the reaction. The modified Gompertz model has the better predicting ability for cattle manure anaerobic digestion.
PubDate: 2021-01-11
- Abstract: Abstract Metal nanoparticle elements such as Fe, Ni, and Co are promising in improving the performance and stability of anaerobic digestion. However, the impact of nanoparticle mixtures of Fe, Ni, and Co on biogas production from anaerobic digestion of cattle manure still needs further studies. Therefore, this study investigated the effect of the most effective concentrations of nanoparticle additives on biogas and CH4 production and H2S mitigation during anaerobic digestion of cattle manure. The nanoparticle additive concentrations were selected from the findings of previous studies and were 30 mg/L Fe, 2 mg/L Ni, and 1 mg/L Co at four combinations. Biogas production increased by 14.61% upon the use of nanoparticle mixtures of 30 mg/L Fe and 2 mg/L Ni compared with control (cattle manure-only). Furthermore, the addition of nanoparticle mixtures of 30 mg/L Fe, 2 mg/L, and 1 mg/L Co increased CH4 production by 19.30% compared with control. Moreover, H2S production decreased by 35.10% in the presence of nanoparticles mixture of 30 mg/L Fe, 2 mg/L, and 1 mg/L Co in comparison with control. Modified Gompertz and logistic function models were used to determine the kinetic constant of the reaction. The modified Gompertz model has the better predicting ability for cattle manure anaerobic digestion.
- A mathematical model for optimizing a biofuel supply chain with
outsourcing decisions under the carbon trading mechanism- Abstract: Abstract Carbon trading is a market-based mechanism for controlling carbon emissions by providing economic incentives to reduce emissions. In recent years, there has been an increasing interest in modeling supply chain networks under this scheme; however, to date, only a limited number of researchers have investigated the implication of this mechanism for biofuel supply chains. The optimization model presented in this paper examines a trade-off between the cost of trading carbon credits and costs associated with outsourcing of the biomass pretreatment process when carbon emissions exceed the predetermined carbon cap in a biofuel supply chain. To demonstrate the applicability of the model, we analyzed challenges in supplying different sources of biomass to two biorefinery plants and shipping the produced biofuels to multiple demand zones. The results showed that carbon emission reductions have a relatively nonlinear pattern when the carbon credit price increases linearly. Furthermore, we presented significant managerial and policy insights on the impact of different carbon emission caps on total costs and total emissions. Moreover, we analyzed the cost adjustment between trading carbon credits and outsourcing decisions for different carbon cap settings. This paper ends with suggestions for further development of the presented model for future researches.
PubDate: 2021-01-10
- Abstract: Abstract Carbon trading is a market-based mechanism for controlling carbon emissions by providing economic incentives to reduce emissions. In recent years, there has been an increasing interest in modeling supply chain networks under this scheme; however, to date, only a limited number of researchers have investigated the implication of this mechanism for biofuel supply chains. The optimization model presented in this paper examines a trade-off between the cost of trading carbon credits and costs associated with outsourcing of the biomass pretreatment process when carbon emissions exceed the predetermined carbon cap in a biofuel supply chain. To demonstrate the applicability of the model, we analyzed challenges in supplying different sources of biomass to two biorefinery plants and shipping the produced biofuels to multiple demand zones. The results showed that carbon emission reductions have a relatively nonlinear pattern when the carbon credit price increases linearly. Furthermore, we presented significant managerial and policy insights on the impact of different carbon emission caps on total costs and total emissions. Moreover, we analyzed the cost adjustment between trading carbon credits and outsourcing decisions for different carbon cap settings. This paper ends with suggestions for further development of the presented model for future researches.
- Biochemical characteristics of a novel ethanol-tolerant xylanase from
Bacillus subtilis subsp. subtilis JJBS250 and its applicability in
saccharification of rice straw- Abstract: Abstract The present study reports the partial purification and characterisation of a novel xylanase from Bacillus subtilis subsp. subtilis JJBS250 followed by its applicability in the saccharification of rice straw. Bacterial xylanase was partially purified by gel filtration chromatography using Sephadax G-50 matrix that displayed optimal activity at 60 °C and pH 7.0 with half-life values of 1420 and 718 min at 60 °C and 80 °C, respectively. Bacterial xylanase showed high tolerance to ethanol with Km and Vmax values of 1.62 mg/ml and 23.92 U/ml, respectively, for beechwood xylan. Maximum amount of reducing sugars was obtained from sodium carbonate pretreated rice straw (151.65 mg/g substrate) as compared to untreated biomass (90.49 mg/g substrate) using 20 U/g enzyme dose at 60 °C and pH 7.0 after 48 h. Furthermore, the saccharification of pretreated rice straw was improved by synergistic action of bacterial and fungal xylanases. Analysis of rice straw using scanning electron microscopy (SEM), x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy clearly showed the morphological changes and delignification in rice straw after pretreatment. Bacterial xylanase exhibiting novel properties including ethanol tolerance and high thermostability is highly suitable for the production of second generation biofuels in simultaneous saccharification and fermentation process using lignocellulosic substrates.
PubDate: 2021-01-09
- Abstract: Abstract The present study reports the partial purification and characterisation of a novel xylanase from Bacillus subtilis subsp. subtilis JJBS250 followed by its applicability in the saccharification of rice straw. Bacterial xylanase was partially purified by gel filtration chromatography using Sephadax G-50 matrix that displayed optimal activity at 60 °C and pH 7.0 with half-life values of 1420 and 718 min at 60 °C and 80 °C, respectively. Bacterial xylanase showed high tolerance to ethanol with Km and Vmax values of 1.62 mg/ml and 23.92 U/ml, respectively, for beechwood xylan. Maximum amount of reducing sugars was obtained from sodium carbonate pretreated rice straw (151.65 mg/g substrate) as compared to untreated biomass (90.49 mg/g substrate) using 20 U/g enzyme dose at 60 °C and pH 7.0 after 48 h. Furthermore, the saccharification of pretreated rice straw was improved by synergistic action of bacterial and fungal xylanases. Analysis of rice straw using scanning electron microscopy (SEM), x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy clearly showed the morphological changes and delignification in rice straw after pretreatment. Bacterial xylanase exhibiting novel properties including ethanol tolerance and high thermostability is highly suitable for the production of second generation biofuels in simultaneous saccharification and fermentation process using lignocellulosic substrates.
- Enzymatic deinking of office waste printed paper: optimization via
response surface methodology- Abstract: Abstract In traditional deinking process, large amounts of chemicals are required which makes these methods expensive and polluting. Also, application of sustainable material implies the use of green processes to reduce waste and pollution. Green enzymatic deinking processes are alternatives to those technologies that have negative effects on the environment. In this work, we applied response surface methodology for deinking the electrophotography-printed paper based on a systematic experimental pattern. The individual and interactive effects of enzymatic deinking parameters including time, temperature, and enzyme dosage on the handsheet properties were investigated. Different analyses were carried out to determine the best process conditions of enzymatic deinking to optimize the handsheet properties (i.e., tensile, burst, whiteness, and brightness). The obtained responses of an oven-dried fiber at 45 min, 43 °C and the enzyme concentration of 1 mg/15 g were 12.44, 0.65, 72.20, and 87 for tensile strength, burst strength, whiteness, and brightness, respectively. Measuring the optical density of the deinked handset after printing showed that the printability of the deinked paper is in the desired range.
PubDate: 2021-01-09
- Abstract: Abstract In traditional deinking process, large amounts of chemicals are required which makes these methods expensive and polluting. Also, application of sustainable material implies the use of green processes to reduce waste and pollution. Green enzymatic deinking processes are alternatives to those technologies that have negative effects on the environment. In this work, we applied response surface methodology for deinking the electrophotography-printed paper based on a systematic experimental pattern. The individual and interactive effects of enzymatic deinking parameters including time, temperature, and enzyme dosage on the handsheet properties were investigated. Different analyses were carried out to determine the best process conditions of enzymatic deinking to optimize the handsheet properties (i.e., tensile, burst, whiteness, and brightness). The obtained responses of an oven-dried fiber at 45 min, 43 °C and the enzyme concentration of 1 mg/15 g were 12.44, 0.65, 72.20, and 87 for tensile strength, burst strength, whiteness, and brightness, respectively. Measuring the optical density of the deinked handset after printing showed that the printability of the deinked paper is in the desired range.
- Role of organosolv pretreatment on enzymatic hydrolysis of mustard biomass
for increased saccharification- Abstract: Abstract This study focusses mainly on assessing the effectiveness of acetone organosolv process as a pretreatment strategy on mustard (Brassica juncea) biomass. We used aqueous acetone as the solvent and sulfuric acid as a catalyst for ease of cellulosic saccharification. The acetone organosolv pretreatment of mustard straw and stalk (MSS) biomass was investigated for the effect of acetone concentration (SC), acid catalyst concentration (AC), and treatment duration (t) using a full factorial design of the experiment and subsequent Pareto analysis of their effects. The 23 full factorials design contained 12 runs, each of which was deployed to pretreat weighed amount of MSS biomass. Each of the different products of these 12 runs was further saccharified using cellulase enzyme produced by Trichoderma reesei. Among the variables, the time has a pronounced effect during pretreatment on glucose yield. Since the increase in time from 30 to 90 min caused an increase of 3.39 g/L in glucose concentration, the increase in acid catalyst concentration from 0.2 to 0.4% caused an increment of 0.7 g/L in glucose content, while the rise in acetone concentration from 50 to 80% caused an increment of 0.44 g/L in glucose concentration. The reducing sugars generated after hydrolysis of MSS biomass can be utilised for the production of bioethanol by Saccharomyces cerevisiae. The FTIR data and SEM studies of untreated and treated MSS biomass were performed to indicate the pretreatment of the MSS biomass. Therefore, after pretreatment MSS biomass can be an alternative substrate for bioethanol production. This study is an attempt to promote the valorization of widely available MSS biomass for bioethanol production by using a statistically optimized process.
PubDate: 2021-01-08
- Abstract: Abstract This study focusses mainly on assessing the effectiveness of acetone organosolv process as a pretreatment strategy on mustard (Brassica juncea) biomass. We used aqueous acetone as the solvent and sulfuric acid as a catalyst for ease of cellulosic saccharification. The acetone organosolv pretreatment of mustard straw and stalk (MSS) biomass was investigated for the effect of acetone concentration (SC), acid catalyst concentration (AC), and treatment duration (t) using a full factorial design of the experiment and subsequent Pareto analysis of their effects. The 23 full factorials design contained 12 runs, each of which was deployed to pretreat weighed amount of MSS biomass. Each of the different products of these 12 runs was further saccharified using cellulase enzyme produced by Trichoderma reesei. Among the variables, the time has a pronounced effect during pretreatment on glucose yield. Since the increase in time from 30 to 90 min caused an increase of 3.39 g/L in glucose concentration, the increase in acid catalyst concentration from 0.2 to 0.4% caused an increment of 0.7 g/L in glucose content, while the rise in acetone concentration from 50 to 80% caused an increment of 0.44 g/L in glucose concentration. The reducing sugars generated after hydrolysis of MSS biomass can be utilised for the production of bioethanol by Saccharomyces cerevisiae. The FTIR data and SEM studies of untreated and treated MSS biomass were performed to indicate the pretreatment of the MSS biomass. Therefore, after pretreatment MSS biomass can be an alternative substrate for bioethanol production. This study is an attempt to promote the valorization of widely available MSS biomass for bioethanol production by using a statistically optimized process.
- Bioremediation of hexavalent chromium-contaminated wastewater by Bacillus
thuringiensis and Staphylococcus capitis isolated from tannery sediment- Abstract: The widespread use of hexavalent chromium Cr(VI) in the leather industry causes substantial environmental problems when effluents are left untreated. Therefore, the present work attempts to assess the ability of Bacillus thuringiensis (V45) and Staphylococcus capitis (S21), isolated from tannery industry sediment, to detoxify Cr(VI) by reducing the oxidation state. Initially, the minimum tolerance of chromium by both bacteria was found up to 1000 μg/mL. V45 could tolerate Cr(VI) (520 μg/mL), and S21 could also tolerate hexavalent Cr(VI) (340 μg/mL). Similarly, both bacteria were able to tolerate other metals such as Hg2+ (40 μg/mL), Cu2+ (30 μg/mL), Ni2+ (60 μg/mL), Zn2+ (40 μg/mL), and Pb2+ (30 μg/mL). V45 and S21 could decrease Cr(VI) at a primary concentration of 50 μg/mL up to 86.42% and 97.34%, respectively. In optimization experiments, the best temperature to decrease Cr(VI) was shown to be 35 °C with pH 7 for 96 h. The occurrence of Cu2+ and Na+ slightly increased during the decrease of hexavalent Cr(VI) by V45, while the isolate S21 exhibited the same effects with Cu2+, Mn2+, and Na+. The carboxylate and amino conjugates in the biomass are intricate in the bioreduction of Cr(VI), as confirmed by FTIR spectroscopy. In addition, SEM imagery revealed the accumulation of Cr(VI) around both types of bacterial cells. The occurrence of other elements was evident from SEM-EDS spectroscopy. This study demonstrated the ability of native bacterial populations (V45 and S21) in tannery sediment to reduce Cr(VI) compounds. Graphical abstract
PubDate: 2021-01-08
- Abstract: The widespread use of hexavalent chromium Cr(VI) in the leather industry causes substantial environmental problems when effluents are left untreated. Therefore, the present work attempts to assess the ability of Bacillus thuringiensis (V45) and Staphylococcus capitis (S21), isolated from tannery industry sediment, to detoxify Cr(VI) by reducing the oxidation state. Initially, the minimum tolerance of chromium by both bacteria was found up to 1000 μg/mL. V45 could tolerate Cr(VI) (520 μg/mL), and S21 could also tolerate hexavalent Cr(VI) (340 μg/mL). Similarly, both bacteria were able to tolerate other metals such as Hg2+ (40 μg/mL), Cu2+ (30 μg/mL), Ni2+ (60 μg/mL), Zn2+ (40 μg/mL), and Pb2+ (30 μg/mL). V45 and S21 could decrease Cr(VI) at a primary concentration of 50 μg/mL up to 86.42% and 97.34%, respectively. In optimization experiments, the best temperature to decrease Cr(VI) was shown to be 35 °C with pH 7 for 96 h. The occurrence of Cu2+ and Na+ slightly increased during the decrease of hexavalent Cr(VI) by V45, while the isolate S21 exhibited the same effects with Cu2+, Mn2+, and Na+. The carboxylate and amino conjugates in the biomass are intricate in the bioreduction of Cr(VI), as confirmed by FTIR spectroscopy. In addition, SEM imagery revealed the accumulation of Cr(VI) around both types of bacterial cells. The occurrence of other elements was evident from SEM-EDS spectroscopy. This study demonstrated the ability of native bacterial populations (V45 and S21) in tannery sediment to reduce Cr(VI) compounds. Graphical abstract
- Acid-catalyzed fractionation of almond shells in
γ-valerolactone/water- Abstract: Abstract The fractionation of almond shells, an agro-industry residue available in some Mediterranean climate regions, was investigated using acid-catalyzed hydrolysis in γ-valerolactone (GVL)/water. A set of non-isothermal experiments at nominal temperatures of 120, 140, and 160 °C and sulfuric acid concentrations from 25 to 75 mM were developed using a constant 80% w/w GVL in water concentration and a reaction time of up to 120 min. GVL was an efficient medium and promoted solubilization of both lignin and hemicellulose, even at low temperature during the initial period of reactor heating, while cellulose conversion was limited. A temperature of 160 °C gave the highest extraction of lignin and hemicellulose, but recovery of hemicellulose carbohydrates was better below 140 °C. Sulfuric acid concentrations above 45 mM promoted excessive dehydration of xylose and glucose to furans and humins, which were recovered with lignin. A model was developed to describe the kinetics of lignin and hemicellulose solubilization. It distinguished three fractions of different reactivity in each polymer (lignin or hemicellulose): fast-reacting, slow-reacting, and unreactive. The amount of each fraction was correlated with acid concentration and reaction temperature. Activation energies and the other parameters in the model were obtained numerically by least-squares optimization using the data from the non-isothermal experiments. Activation energies for the fast-reacting and slow-reacting fractions of hemicellulose were 142 and 39.7 kJ mol−1, and for those of lignin 134 and 71.7 kJ mol−1, respectively. Acid concentration had a larger influence than temperature on establishing the amounts of slow-reacting hemicellulose and lignin, whereas temperature was the dominant variable concerning the fractions of non-reacting polymers.
PubDate: 2021-01-08
- Abstract: Abstract The fractionation of almond shells, an agro-industry residue available in some Mediterranean climate regions, was investigated using acid-catalyzed hydrolysis in γ-valerolactone (GVL)/water. A set of non-isothermal experiments at nominal temperatures of 120, 140, and 160 °C and sulfuric acid concentrations from 25 to 75 mM were developed using a constant 80% w/w GVL in water concentration and a reaction time of up to 120 min. GVL was an efficient medium and promoted solubilization of both lignin and hemicellulose, even at low temperature during the initial period of reactor heating, while cellulose conversion was limited. A temperature of 160 °C gave the highest extraction of lignin and hemicellulose, but recovery of hemicellulose carbohydrates was better below 140 °C. Sulfuric acid concentrations above 45 mM promoted excessive dehydration of xylose and glucose to furans and humins, which were recovered with lignin. A model was developed to describe the kinetics of lignin and hemicellulose solubilization. It distinguished three fractions of different reactivity in each polymer (lignin or hemicellulose): fast-reacting, slow-reacting, and unreactive. The amount of each fraction was correlated with acid concentration and reaction temperature. Activation energies and the other parameters in the model were obtained numerically by least-squares optimization using the data from the non-isothermal experiments. Activation energies for the fast-reacting and slow-reacting fractions of hemicellulose were 142 and 39.7 kJ mol−1, and for those of lignin 134 and 71.7 kJ mol−1, respectively. Acid concentration had a larger influence than temperature on establishing the amounts of slow-reacting hemicellulose and lignin, whereas temperature was the dominant variable concerning the fractions of non-reacting polymers.
- Graphene oxide–coated pyrolysed biochar from waste sawdust and its
application for treatment of cadmium-containing solution: batch, fixed-bed
column, regeneration, and mathematical modelling- Abstract: Abstract Cadmium being a heavy metal, which is also a known pollutant, had a wide variety of usage in many industries like electro-plating industries, phosphate fertilizers, batteries, mining, stabilizers, pigments, and alloys. In this study, sawdust was used to produce the nanocoated adsorbent. Sawdust is non-hazardous low-cost waste materials and easily available. Thermally activated biochar was produced from sawdust and coated with graphene oxide nanomaterials in two different methods, and the synthesized nanocomposite was used to remove cadmium present in solution. Batch study was performed to optimize different parameters for better removal. Experiments were performed and the best condition optimized for removal of cadmium was found to be pH 7.5 and temperature 35 °C or 308.15 K, with 1 g/L adsorbent dose, and within 2 h, i.e. 120 min, above 55.68 mg/g removal capacity was attained with initial metal concentration of 50 mg/L. The modified saw dust composite was more effective in removal of cadmium than the normal sawdust-based composites. The characterization of the nanocomposite was done to know the internal structure of the composite. The continuous fixed-bed column study was performed, and the study followed Admas–Bohart model. The batch and column study results showed that this nanocoated composite can be an alternative for the treatment of pollutant present in the solution. The regeneration of the composite showed a sustainable use of the composite for the treatment of pollutant.
PubDate: 2021-01-08
- Abstract: Abstract Cadmium being a heavy metal, which is also a known pollutant, had a wide variety of usage in many industries like electro-plating industries, phosphate fertilizers, batteries, mining, stabilizers, pigments, and alloys. In this study, sawdust was used to produce the nanocoated adsorbent. Sawdust is non-hazardous low-cost waste materials and easily available. Thermally activated biochar was produced from sawdust and coated with graphene oxide nanomaterials in two different methods, and the synthesized nanocomposite was used to remove cadmium present in solution. Batch study was performed to optimize different parameters for better removal. Experiments were performed and the best condition optimized for removal of cadmium was found to be pH 7.5 and temperature 35 °C or 308.15 K, with 1 g/L adsorbent dose, and within 2 h, i.e. 120 min, above 55.68 mg/g removal capacity was attained with initial metal concentration of 50 mg/L. The modified saw dust composite was more effective in removal of cadmium than the normal sawdust-based composites. The characterization of the nanocomposite was done to know the internal structure of the composite. The continuous fixed-bed column study was performed, and the study followed Admas–Bohart model. The batch and column study results showed that this nanocoated composite can be an alternative for the treatment of pollutant present in the solution. The regeneration of the composite showed a sustainable use of the composite for the treatment of pollutant.
- Synergistic effect of acidity balance and hydrothermal pretreatment
severity on alkali extraction of hemicelluloses from corn stalk- Abstract: Abstract The current hemicelluloses extraction methods have problems such as low extraction ratio and quality. In the previous study, a new pH pre-corrected hydrothermal pretreatment has been proved effective in improving enzymatic hydrolysis of cellulose while retaining higher hemicelluloses without degradation. In this investigation, the synergistic effect of alkali loading and hydrothermal pretreatment severity on hemicelluloses preservation was studied. After pretreatment, the hemicelluloses were extracted with alkali. The results show that hemicelluloses extracted with 10% (w/v) NaOH after pH pre-corrected hydrothermal pretreatment at the severity of 2.0 contained no cellulose. At this condition, the ratios of hemicelluloses dissolution and recovery were the highest. The extracted hemicelluloses had the lowest color value, branch degree, and polydispersity.
PubDate: 2021-01-08
- Abstract: Abstract The current hemicelluloses extraction methods have problems such as low extraction ratio and quality. In the previous study, a new pH pre-corrected hydrothermal pretreatment has been proved effective in improving enzymatic hydrolysis of cellulose while retaining higher hemicelluloses without degradation. In this investigation, the synergistic effect of alkali loading and hydrothermal pretreatment severity on hemicelluloses preservation was studied. After pretreatment, the hemicelluloses were extracted with alkali. The results show that hemicelluloses extracted with 10% (w/v) NaOH after pH pre-corrected hydrothermal pretreatment at the severity of 2.0 contained no cellulose. At this condition, the ratios of hemicelluloses dissolution and recovery were the highest. The extracted hemicelluloses had the lowest color value, branch degree, and polydispersity.
- Euphorbia tirucalli stem bark and phylloclades’ oil quality variability
and implication for energy use- Abstract: Abstract Liquid biofuels have emerged as a worldwide alternative fuel with potential to replace fossil fuels. Due to their wide availability as derivatives of organic materials from plants, they have attracted much attention and investment in developing countries including Tanzania, as alternative sources of energy. This study examined effects of oil quality from stem barks and phylloclades of Euphorbia tirucalli trees of different girth sizes (viz., 20 cm, 30 cm, 40 cm, 50 cm, 60 cm, 70 cm, and 80 cm) from semi-arid, coastal, and southern highlands in Dodoma, Dar es Salaam, and Mbeya Southern highland, agro-ecological zones in Tanzania. Using Soxhlet extraction method, oils were extracted from E. tirucalli stem barks with different girth sizes while oils from phylloclades were extracted from matured apical phylloclades collected from shoots of E. tirucalli trees from which the stem bark samples had been collected. Oil yields were determined by measuring the weight of oil (g) by the total weight of sample extracts used (20 g), and the average oil yield on each sample was determined. Oil quality was evaluated as oxidative stability index (OSI), acid values (AVs), and percent free fatty acids (%FFAs). Their results were then compared with the European Union (EU) oil quality standard specifications prescribed in EN 14214 of 6 h, 0.5 mg KOH/g, max and 0.020 maximum wt% limits, respectively. Differences in the quality of E. tirucalli (stem bark and phylloclades) oil were analyzed statistically with paired-sample t test (two-tailed) using the SPSS 15.0 software package. Results showed that the difference in OSIs from stem barks were not significantly higher (3–5 h) than phylloclades (3–4 h) at the p > 0.5 level. Also, the difference in AVs and %FFAs from the stem barks (7.6–7.4 mg KOH and 3.8–3.6%) was not significantly lower than those from the phylloclades (8.4–8.1 mg KOH and 4.3–4.0%) respectively. The quality of oil from stem bark and phylloclades samples at different stem girth sizes semi-arid agro-ecological zone was not significantly higher than from southern highland and coastal agro-ecological zones, respectively. Thus, there were no significant differences in the quality of E. tirucalli oil (stem bark and phylloclades) among stem girth sizes in different agro-ecological zones. The AVs and %FFAs of oils from stem bark and phylloclades were higher than the recommended standards, while the OSIs were below the biofuel standard limit. High AVs and %FFAs reduced oil quality by producing considerably low OSIs values than recommended standards. Finally, the study concluded that E. tirucalli oil requires purification to reduce levels of AV and %FFA contents so that the oil becomes suitable for application as liquid biofuel for energy generations.
PubDate: 2021-01-08
- Abstract: Abstract Liquid biofuels have emerged as a worldwide alternative fuel with potential to replace fossil fuels. Due to their wide availability as derivatives of organic materials from plants, they have attracted much attention and investment in developing countries including Tanzania, as alternative sources of energy. This study examined effects of oil quality from stem barks and phylloclades of Euphorbia tirucalli trees of different girth sizes (viz., 20 cm, 30 cm, 40 cm, 50 cm, 60 cm, 70 cm, and 80 cm) from semi-arid, coastal, and southern highlands in Dodoma, Dar es Salaam, and Mbeya Southern highland, agro-ecological zones in Tanzania. Using Soxhlet extraction method, oils were extracted from E. tirucalli stem barks with different girth sizes while oils from phylloclades were extracted from matured apical phylloclades collected from shoots of E. tirucalli trees from which the stem bark samples had been collected. Oil yields were determined by measuring the weight of oil (g) by the total weight of sample extracts used (20 g), and the average oil yield on each sample was determined. Oil quality was evaluated as oxidative stability index (OSI), acid values (AVs), and percent free fatty acids (%FFAs). Their results were then compared with the European Union (EU) oil quality standard specifications prescribed in EN 14214 of 6 h, 0.5 mg KOH/g, max and 0.020 maximum wt% limits, respectively. Differences in the quality of E. tirucalli (stem bark and phylloclades) oil were analyzed statistically with paired-sample t test (two-tailed) using the SPSS 15.0 software package. Results showed that the difference in OSIs from stem barks were not significantly higher (3–5 h) than phylloclades (3–4 h) at the p > 0.5 level. Also, the difference in AVs and %FFAs from the stem barks (7.6–7.4 mg KOH and 3.8–3.6%) was not significantly lower than those from the phylloclades (8.4–8.1 mg KOH and 4.3–4.0%) respectively. The quality of oil from stem bark and phylloclades samples at different stem girth sizes semi-arid agro-ecological zone was not significantly higher than from southern highland and coastal agro-ecological zones, respectively. Thus, there were no significant differences in the quality of E. tirucalli oil (stem bark and phylloclades) among stem girth sizes in different agro-ecological zones. The AVs and %FFAs of oils from stem bark and phylloclades were higher than the recommended standards, while the OSIs were below the biofuel standard limit. High AVs and %FFAs reduced oil quality by producing considerably low OSIs values than recommended standards. Finally, the study concluded that E. tirucalli oil requires purification to reduce levels of AV and %FFA contents so that the oil becomes suitable for application as liquid biofuel for energy generations.
- Synthesis and kinetics study of trimethylolpropane fatty acid triester
from oleic acid methyl ester as potential biolubricant- Abstract: Abstract The use of trimethylolpropane triesters as biodegradable lubricant base oil substitute mineral oils could significantly reduce the environmental pollution. In the present work, a commercial oleic acid (72% C18) was utilized as a precursor for the manufacture of trimethylolpropane triesters (TMPTE) through a two-step transesterification process. Oleic acid methyl ester (OME) produced from the first step was subsequently interacted with trimethylolpropane (TMP) using sodium methylate to produce TMPTE. The effect of the operating parameters, temperatures (90 °C, 100 °C, 110 °C, 120 °C, and 130 °C), molar ratio of OME to TMP (3:1, 4:1, 5:1, and 7:1), vacuum pressure (20, 50, 100, and 200 mbar), and catalyst amount (0.5, 0.7, 0.9, and 1.1(w/w)) was investigated. Under the selected reaction conditions (temperature 120 °C, oleic acid methyl ester to trimethylolpropane molar ratio 4:1, catalyst amount 0.9%w/w, vacuum pressure 20 mbar and reaction time 2 h), the final product composition was approximately 85.47% TMPTE, 10.80% TMPDE, 1.40%TMP ME, and 2.33% OME. The kinetics/mathematical model explains the chemical kinetics of transesterification of oleic acid methyl esters (OME) with trimethylolpropane (TMP) to produce biolubricant which has been investigated at temperature 120 °C. To support forward reaction, the excess amount of OME was increased by 10:1 (OME/TMP). The kinetic model suggested for the transesterification process of OME with TMP in this work based on three reversible series-parallel reaction mechanisms. The kinetics equations were solved using LINGO PROGRAM. A harmony between the experimental data and theoretically estimated values was achieved.
PubDate: 2021-01-08
- Abstract: Abstract The use of trimethylolpropane triesters as biodegradable lubricant base oil substitute mineral oils could significantly reduce the environmental pollution. In the present work, a commercial oleic acid (72% C18) was utilized as a precursor for the manufacture of trimethylolpropane triesters (TMPTE) through a two-step transesterification process. Oleic acid methyl ester (OME) produced from the first step was subsequently interacted with trimethylolpropane (TMP) using sodium methylate to produce TMPTE. The effect of the operating parameters, temperatures (90 °C, 100 °C, 110 °C, 120 °C, and 130 °C), molar ratio of OME to TMP (3:1, 4:1, 5:1, and 7:1), vacuum pressure (20, 50, 100, and 200 mbar), and catalyst amount (0.5, 0.7, 0.9, and 1.1(w/w)) was investigated. Under the selected reaction conditions (temperature 120 °C, oleic acid methyl ester to trimethylolpropane molar ratio 4:1, catalyst amount 0.9%w/w, vacuum pressure 20 mbar and reaction time 2 h), the final product composition was approximately 85.47% TMPTE, 10.80% TMPDE, 1.40%TMP ME, and 2.33% OME. The kinetics/mathematical model explains the chemical kinetics of transesterification of oleic acid methyl esters (OME) with trimethylolpropane (TMP) to produce biolubricant which has been investigated at temperature 120 °C. To support forward reaction, the excess amount of OME was increased by 10:1 (OME/TMP). The kinetic model suggested for the transesterification process of OME with TMP in this work based on three reversible series-parallel reaction mechanisms. The kinetics equations were solved using LINGO PROGRAM. A harmony between the experimental data and theoretically estimated values was achieved.
- Editorial to the special thematic issue “Advances in Thermo-chemical
Gasification of Biomass and Syngas Applications” with selected
contributions from the “International Conference on Polygeneration
Strategies 2019” (ICPS19)- PubDate: 2021-01-07
- PubDate: 2021-01-07
- Material flow of cellulose in rice straw to ethanol and lignin recovery by
NaOH pretreatment coupled with acid washing- Abstract: Abstract Agricultural residues could become feedstocks for biobased products as they are renewable, carbon neutral, and do not compete with food. In India, > 130 MT rice straw is available annually for alternate uses. Exploiting this abundant biomass for biochemical production will pave way for bio-based economy. Rice straw is highly recalcitrant due to lignin-carbohydrate complex and high ash. For production of value added products, the cellulose fraction is very important and also lignin can be used. However, for overall economic efficiency, it is imperative to separate and recover these fractions maximally from biomass and convert them into high value products at high titers and efficiency. Biomass has to be deconstructed to access these fractions. An improvised pretreatment with sodium hydroxide (NaOH) coupled with acidified water wash enabled high retrieval of cellulose and lignin. More than 80% of cellulose present in raw rice straw was recovered in pretreated solids and lignin (> 65%) recovered from acidification of alkali prehydrolysates/wash waters. Enzymatic hydrolysis of solids with commercial cellulases resulted in 80–100% glucan conversion at 6% and 3% loading respectively yielding ~ 5.5% and 3.3% sugar syrups which can be fermented to value added chemicals. Saccharomyces cerevisiae LN fermented hydrolysates with 77–97% efficiency producing 0.508 gg−1 and 0.403 gg−1ethanol within 24 h consuming all glucose while xylose was unutilized. Material calculations showed that this process converted 63% of cellulose present in rice straw to ethanol potentially yielding 135 L ethanol and ~ 100 Kg lignin per ton of rice straw with limited water use.
PubDate: 2021-01-07
- Abstract: Abstract Agricultural residues could become feedstocks for biobased products as they are renewable, carbon neutral, and do not compete with food. In India, > 130 MT rice straw is available annually for alternate uses. Exploiting this abundant biomass for biochemical production will pave way for bio-based economy. Rice straw is highly recalcitrant due to lignin-carbohydrate complex and high ash. For production of value added products, the cellulose fraction is very important and also lignin can be used. However, for overall economic efficiency, it is imperative to separate and recover these fractions maximally from biomass and convert them into high value products at high titers and efficiency. Biomass has to be deconstructed to access these fractions. An improvised pretreatment with sodium hydroxide (NaOH) coupled with acidified water wash enabled high retrieval of cellulose and lignin. More than 80% of cellulose present in raw rice straw was recovered in pretreated solids and lignin (> 65%) recovered from acidification of alkali prehydrolysates/wash waters. Enzymatic hydrolysis of solids with commercial cellulases resulted in 80–100% glucan conversion at 6% and 3% loading respectively yielding ~ 5.5% and 3.3% sugar syrups which can be fermented to value added chemicals. Saccharomyces cerevisiae LN fermented hydrolysates with 77–97% efficiency producing 0.508 gg−1 and 0.403 gg−1ethanol within 24 h consuming all glucose while xylose was unutilized. Material calculations showed that this process converted 63% of cellulose present in rice straw to ethanol potentially yielding 135 L ethanol and ~ 100 Kg lignin per ton of rice straw with limited water use.
