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Optimization of Fermentation Conditions for the Production of Ethanol from Stalk Juice of Sweet Sorghum by Immobilized Yeast Using Response Surface Methodology
Abstract
Optimization of three parameters, including initial total sugar concentration, supplement rate of (NH4)2SO4, and particles stuffing rate, was attempted using response surface methodology based on a Box−Behnken design for the optimal production of ethanol by immobilized yeast fermentation of stalk juice of Liaotian number 1 sweet sorghum cultivar in shaking flasks. The correlation analysis of the mathematical regression model indicated that the quadratic polynomial model could be employed to optimize ethanol production. The optimum conditions were found to be an initial total sugar concentration of 22.88%, supplement rate of (NH4)2SO4 of 0.244%, and particles stuffing rate of 25.15%. At the optimum conditions, the maximum predicted ethanol yield of 93.83% was obtained. The ethanol yield and fermentation time of verification experiments in the shaking flask were 92.37% and 14 h at the corresponding parameters, respectively, while they were 93.23% and 13 h, respectively, in a 5 L bioreactor, in which the predicted value of ethanol yield was very close to experimental values. In addition, the fermentation time of the stalk juice of sweet sorghum was about 3−4 times shorter with immobilized yeast than that of conventional fermentation technology. Thus, by immobilized yeast fermentation of the stalk juice of sweet sorghum, the Box−Behnken design was found to be the favorable strategy investigated with respect to the optimization of fermentation conditions for ethanol production.
... Large-scale production of diatoms is still a challenge whether it is open system or closed one. Traditionally, the closed system is used largely for the production of microalgae (Shen et al. 2009). However, it is not cost effective, and productivity is less. ...
... This technique can also be utilized to design new models, formulation, experiment, and to optimize different cultural parameters by lowering the number of experiments(Coninck et al. 2000;Majeed et al. 2016). RSM is also being used for the optimization of microbial development(Popa et al. 2007;Mei et al. 2009;Majeed et al. 2016). ...
Fossil fuel is demanding but there are several concerns with its utilization. Besides its restricted availability it is also the reason for global warming and emission of greenhouse gases. Among most of the developed countries, the government is trying to encourage renewable energy resources in order to control CO2 emission and to secure domestic resources. Biofuel is obtained by biomass conversion related to solid biomass, liquid fuel, and different biogases. The use of biofuel offers environmental benefits since they are renewable, available at low cost, and biodegradable; they also have diversity in transportation, like butanol, biodiesel, bioethanol, and bio-oil. During sugar fermentation microbes are inoculated which leads to biofuel production. Many variables like temperature, pH, time, agitation, additives, metal ions, and surfactants/solvents affect biofuel yield.
... Large-scale production of diatoms is still a challenge whether it is open system or closed one. Traditionally, the closed system is used largely for the production of microalgae (Shen et al. 2009). However, it is not cost effective, and productivity is less. ...
... This technique can also be utilized to design new models, formulation, experiment, and to optimize different cultural parameters by lowering the number of experiments(Coninck et al. 2000;Majeed et al. 2016). RSM is also being used for the optimization of microbial development(Popa et al. 2007;Mei et al. 2009;Majeed et al. 2016). ...
The requirement and demand of incessant supply of energy is inexorable and it is increasing globally every day. Traditional organic energy reservoirs, fossil fuels, are depleting while increasing environmental pollution. Considering the substantial necessity and risks, scientists are probing for substitute of renewable energy resources with lower environmental hazards. Green biotechnology finds the ways for green energy using biomass as a substrate for the generation of biofuels. Biofuel technology has gathered the attention worldwide as it is a feasible and attractive source of energy fulfilling all the current standards of energy production. Biofuel production can make more feasible and economical choosing the suitable substrate for required fuel and proper application of pretreatment and process conditions. Biofuels use photosynthetic products or cellulosic or lignocellulosic substrates as feedstock for microorganisms, and the mutual reaction after fermentation and saccharification yields biofuels. Biofuels are categorized according to the type of substrate used, and yield is dependent on the pretreatment of substrate. Pretreatments depend upon the type of substrate, and the whole synchronized process produces good commercial scale biofuels. This chapter reveals different types of substrates and their role for the production and improvement of biofuels technology. To tackle the emerging twin crisis of energy and resources, development of biofuels technology as an alternative approach of traditional nonrenewable energy system is mandatory.
... Softwood hemicellulose is dominated by glucomannans while the hemicelluloses of hardwood and agricultural residues are dominated by xylan. However, degree of acetylation in hardwood hemicelluloses is higher than in softwood hemicelluloses [46,47]. ...
... Still, it receives a lot of attention in for instance China, where pilot plants are in operation [45]. A potential weak point of this crop is a high rate of sugar degradation at ambient temperatures [46]. However, in contrast to sugarcane, it is harvested at least twice per year, which reduces the need for storage. ...
Biofuels production and utilisation can reduce the emission of greenhouse gases, dependence on fossil fuels and also improve energy security. Ethanol is the most important biofuel in the transportation sector; however, its production from lignocelluloses faces some challenges. Conventionally, lignocellulosic hydrolysis and fermentation has mostly been performed by separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF). SHF results in product inhibition during enzymatic hydrolysis and increased contamination risk. During SSF, suboptimal conditions are used and the fermenting organism cannot be reused. Bacterial contamination is another major concern in ethanol production, which usually results in low ethanol yield.
In these studies, the above-mentioned challenges have been addressed. A novel method for lignocellulosic ethanol production ‘Simultaneous saccharification filtration and fermentation (SSFF)’ was developed. It circumvents the disadvantages of SSF and SHF; specifically, it uses a membrane for filtration and allows both the hydrolysis and fermentation to be carried out at different optimum conditions. SSFF also offers the possibility of cell reuse for several cultivations. The method was initially applied to pretreated spruce, with a flocculating strain of yeast Saccharomyces cerevisiae. SSFF was further developed and applied to pretreated wheat straw, a xylose rich lignocellulosic material, using encapsulated xylose fermenting strain of S. cerevisiae. High solids loading of 12% suspended solids (SS) was used to combat bacterial contamination and improve ethanol yield. Oil palm empty fruit bunch (OPEFB) was pretreated with fungal and phosphoric acid in order to improve its ethanol yield. An evaluation of biofuel production in Nigeria was also carried out.
SSFF resulted in ethanol yield of 85% of the theoretical yield from pretreated spruce with the flocculating strain. Combination of SSFF with encapsulated xylose fermenting strain facilitated simultaneous glucose and xylose utilisation when applied to pretreated wheat straw; this resulted in complete glucose consumption and 80% xylose utilisation and consequently, 90% ethanol yield of the theoretical level. High solids loading of 12% SS of pretreated birch resulted in 47.2 g/L ethanol concentration and kept bacterial infection under control; only 2.9 g/L of lactic acid was produced at the end of fermentation, which lasted for 160 h while high lactic acid concentrations of 42.6 g/L and 35.5 g/L were produced from 10% SS and 8% SS, respectively. Phosphoric acid pretreatment as well as combination of fungal and phosphoric pretreatment improved the ethanol yield of raw OPEFB from 15% to 89% and 63% of the theoretical value, respectively.
In conclusion, these studies show that SSFF can potentially replace the conventional methods of lignocellulosic ethanol production and that high solids loading can be used to suppress bacterial infections during ethanol productions, as well as that phosphoric acid pretreatment can improve ethanol yield from lignocellulosic biomass.
... When batch-feeding or in situ ethanol removal processes are used with SSF, much higher ethanol concentrations and cellulose conversion can be achieved with minimal enzyme dosage. Simultaneously, ethanol production can be enhanced more effectively [45][46][47][48]. ...
The simultaneous saccharification and fermentation (SSF) technique holds promise for the conversion of lignocellulose to ethanol. However, the optimal fermentation temperature of yeast is lower than the enzymatic hydrolysis temperature of the saccharification process, which leads to the temperature of the actual production process of SSF usually being lower than 38 °C. In this work, two ultraviolet (UV)-induced mutations were performed step by step using Saccharomyces cerevisiae BY4742 as the original strain to enable the yeast to perform well at higher temperatures. Thermotolerant strains obtained through mutagenesis and screening, YUV1-1 and YUV2-2, were utilized for fermentation and SSF at a targeted temperature of 40 °C. They obtained ethanol yields comparable to those at 38 °C in SSF, whereas the ethanol yields of the original strain at 40 °C decreased by about 10% compared to those at 38 °C. This study proves that thermotolerant strains adapted to elevated fermentation and SSF temperatures can be obtained through UV mutagenesis and screening, thereby increasing the stability of the fermentation and SSF processes and lowering the subsequent distillation costs.
... Its seed, stalk juice, and bagasse are the source of starch, sucrose, and cellulose, respectively. The ethanol productivity of sorghum grain (Dyartanti et al., 2015;Barcelos et al., 2011), stalk juice (Bridgers et al., 2011;Mei et al., 2009;Liu and Shen, 2008), and cellulosic components (Cardoso et al., 2018;Tang et al., 2018;Solihat et al., 2017;Cardoso et al., 2013;McIntosh and Vancov, 2010) have been evaluated. Approximately 3000À4000 L/ha/year of ethanol can be produced from sorghum stalk (Carioca and Leal, 2011). ...
... Where A, B, and C are coded values of temperature of incubation (°C), the water activity of the fermentative media (substrate), and time of incubation (h), respectively. According to Mei et al. [39], the coefficient of determination (R 2 ) analyzed the accuracy of the polynomial equation in the fermentation process. The R 2 value determines the accuracy of the RSM model. ...
This study includes the utilization of sweet lemon peel (SLP) and sugarcane bagasse (SB) in solid-state fermentation using Kluyveromyces marxianus for bioflavor compounds production adopting response surface methodology. The major flavor compounds, 2-phenylethanol (2-PE) and 2-phenylethyl acetate (2-PEA) were quantified using gas chromatography-mass spectrometry with and without adding any supplements. Quantification of flavor compounds indicated that without adding any accessory in the substrate, the concentration of 2-PE using SLP and SB was 0.15 ± 0.003 mg/g and 0.14 ± 0.002 mg/g, respectively. Whereas 2-PEA concentration using SLP and SB was observed as 0.01 ± 0.008 mg/g and 0.02 ± 0.001 mg/g, respectively. The addition of l-phenylalanine (l-phe) in the substrates showed 30%-75% enhancement in the production of 2-PE and 2-PEA. The present study indicates that the K. marxianus is a potential microbial cell factory for the production of 2-PE and 2-PEA with the addition of synthetic l-phe having a plethora of applications in food and pharmaceutical industries.
... RSM is a group of statistical techniques for designing experiments, building models, evaluating the effects of factors and selecting optimum conditions in a limited number of experiments (Baş and Boyaci, 2007). In recent years, this efficient mathematical approach has been extensively used for optimisation of alcoholic fermentation with free (Le Man et al., 2010;Grahovac et al., 2011Grahovac et al., , 2012 and immobilised (Mei et al., 2009;Yu et al., 2009;Ercan et al., 2013) yeast cells. ...
... (NH 4 ) 2 SO 4 served as a source of nutrients, including N and SO 4 − , as well as to modify the C/N ratio. 25 Nitrogen promotes yeast growth and thus favors ethanol production as well as ethanol tolerance. Ammonium ions are rapidly taken up by yeasts and converted directly into amino acids. ...
BACKGROUND
The identification of new resources for producing biofuels and chemical‐based products is crucial for processes sustainability. This study presents a valorization route to produce ethanol and ethylene using cocoa's mucilage juice (MJ) residue from cocoa farms of variety ‘Arriba’ (AC). The processing parameters to maximize the ethanol production and subsequent selective conversion into ethylene were determined. Ethanol production has been carried out by investigating the effect of three parameters: the temperature of fermentation, the initial fermentation pH and the addition of (NH4)2SO4 as an N source in the presence of free Saccharomyces cerevisiae NCYC 366. Consecutively, the selectivity of ethanol–ethylene conversion using a zeolite‐based ZSM‐5 catalyst was evaluated at different temperatures and ethanol concentrations.
RESULTS
During ethanol production, the best sugar conversion was reached at 30 °C, adjusting the initial pH to 5 and without nitrogen source, resulting in 86.83% sugar conversion, the maximum ethanol concentration of 68.65 g L⁻¹ and maximum ethanol production rate of 2.03 g L⁻¹ h⁻¹ after 168 h of fermentation. On the other hand, ethylene was produced using ZSM‐5‐based zeolite catalyst with >99.9% of efficiency in the temperature range 240–300 °C. In addition, selective ethylene formation was found at 240 °C and 30 g L⁻¹ ethanol.
CONCLUSION
The approach hereby presented shows the valorization of MJ waste of AC variety to produce ethanol and ethylene with minimum processing input costs, demonstrating a successful route to convert a farm residue into a bio‐based product with enhanced marketability. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).
... The Box-Behnken design (BBD) is a class of second-order designs based on three-level, interlocking, incomplete factorial designs [22]. BBD provides relatively fewer design points than other full factorial designs for determining a complex response function, which is experimentally more efficient and less expensive [23]. In addition, all design points in the BBD stay within the safe operating zone, as the design does not include combination of variables at their highest or lowest level simultaneously, thus avoiding experiments under extreme conditions [24]. ...
The ruthenium polypyridyl complex [Ru(dppz)2PIP]²⁺ (dppz: dipyridophenazine, PIP: (2-(phenyl)-imidazo[4,5-f ][1,10]phenanthroline), or Ru-PIP, is a potential anticancer drug that acts by inhibiting DNA replication. Due to the poor dissolution of Ru-PIP in aqueous media, a drug delivery agent would be a useful approach to overcome its limited bioavailability. Mesoporous silica nanoparticles (MSNs) were synthesized via a co-condensation method by using a phenanthrolinium salt with a 16 carbon length chain (Phen-C16) as the template. Optimization of the synthesis conditions by Box–Behnken design (BBD) generated MSNs with high surface area response at 833.9 m²g⁻¹. Ru-PIP was effectively entrapped in MSNs at 18.84%. Drug release profile analysis showed that Ru-PIP is gradually released, with a cumulative release percentage of approximately 50% at 72 h. The release kinetic profile implied that Ru-PIP was released from MSN by diffusion. The in vitro cytotoxicity of Ru-PIP, both free and MSN-encapsulated, was studied in Hela, A549, and T24 cancer cell lines. While treatment of Ru-PIP alone is moderately cytotoxic, encapsulated Ru-PIP exerted significant cytotoxicity upon all the cell lines, with half maximal inhibitory concentration (IC50) values determined by MTT (([3-(4,5-dimethylthiazol-2-yl)-2,5-dephenyltetrazolium bromide]) assay at 48 h exposure substantially decreasing from >30 µM to <10 µM as a result of MSN encapsulation. The mechanistic potential of cytotoxicity on cell cycle distribution showed an increase in G1/S phase populations in all three cell lines. The findings indicate that MSN is an ideal drug delivery agent, as it is able to sustainably release Ru-PIP by diffusion in a prolonged treatment period.
... To overcome this problem, response surface methodology is being widely used as it allows more experimental trials within a short time, with accuracy, and each medium component is considered in its interaction with the others. 5,6 For improving the performance and function of the enzyme's catalytic activity, characterization is a vital step. The application of the cellulase enzyme in the biofuel industries demands the identification of a stable enzyme that can be active at high pH and increased temperature. ...
The aim of this study was to boost the production rate of a novel thermo-alkalotolerant cellulase (FPase) enzyme from the fungal isolate Aspergillus terreus PPCF. Initially, the extracellular FPase activity was 0.166 ± 0.03 UmL-1 in the culture filtrate, which further increased up to 0.91 ± 0.13 UmL-1 under optimized conditions (3% w/v wheat bran and 0.5% w/v ammonium sulfate). Through response surface methodology, the FPase activity was enhanced to 10.78 UmL1 under the cumulative effect of different factors. The zymogram analysis revealed only one activity band, with the molecular weight of ~110 KDa. The optimum pH was 7.0, but the enzyme was stable in a pH range of 4-10. The optimum temperature was 50 °C, but the stability range of the enzyme was 30-90 °C. The maximum effect of Mg2+ was observed on the FPase enzyme. The findings of the present study demonstrate the thermo- and alkalotolerance of the obtained cellulase enzyme, which will be beneficial to the biofuel and other industries.
... The development of nanobiocatalyst is an example of emerging and innovative breakthroughs of nanotechnology and biotechnology (Rai et al. 2018). Many metal oxides are currently used for the immobilization of cellulose (Mei et al. 2009). The following are the techniques adopted for immobilization (Kim et al. 2018). ...
... The development of nanobiocatalyst is an example of emerging and innovative breakthroughs of nanotechnology and biotechnology (Rai et al. 2018). Many metal oxides are currently used for the immobilization of cellulose (Mei et al. 2009). The following are the techniques adopted for immobilization (Kim et al. 2018). ...
Biofuels, generally defined as any energy-enriched chemical derived from biomass, combine various unique characteristics such as renewable energy sources, biodegradability, low toxicity, diversity and easy and local availability. The biofuels not only represent an alternative to the depletion of fossil fuel resources, but their combustion is considered to be carbon neutral unlike the combustion processes of fossil fuels which produce a majority of CO2 emissions in the Earth’s atmosphere (Zuliani et al. 2018). In recent years, almost all bioethanol produced in the world has a starch or sugar-based plant origin which comes under the category of first-generation biofuels for which edible plants are used as feedstock, such as starch from corn, wheat, rice, etc., and sucrose from sugarcane and sugar beet (Naik et al. 2010). Even though these primary sources of biomass are the most exploited, inherent competition between foods versus fuels is highly debatable (Leo et al. 2016). The second-generation biofuel, on the other side, does not compete against food supplies as they are based on the non-food raw material. The second-generation biofuel production is typically from lignocellulosic biomasses like wood wastes, perennial grasses, forest litters, agricultural residues and others (Robak and Balcerek 2018) that are majorly dominated by cellulosic components followed by hemicelluloses and less amount of lignin. As these polymeric carbohydrates are relatively difficult to hydrolyze to simpler sugar forms and subsequently, their conversion into ethanol is not only challenging but also slightly time-consuming and costly (Wongwatanapaiboon et al. 2012). 178Thus, given these facts, there is an expansive demand to develop proficient technologies capable of resolving the issues that have raised in the field of bioethanol production. Nanotechnology is one of the most growing areas of research in biofuels and bioenergy fields, especially the subarea of nano-cellulosic materials which have attracted considerable attention from researchers in the past decade. Nanotechnology has different applications, such as modification in feedstocks, development of more efficient catalysts, development of nanomaterials and others that hold great potential to resolve the major bottlenecks of biofuels and bioenergy field (Rai et al. 2016). The nanomaterials possess exceptional characteristics such as high surface areas, a high degree of crystallinity, catalytic activity, stability, adsorption capacity, durability and efficient storage which could collectively help to optimize the overall system and can widely be exploited in biofuel systems. They also have a high potential for recovery, reusability and recycling. Another promising application of nanotechnology in the biofuel industry is enzyme (biocatalysts) immobilization during lignocellulosic ethanol production processes. The advantages nanostructures offer in this area include a large surface area for high enzyme loading, higher enzymatic stability and possibility of enzyme reusability which could reduce the operational cost of large-scale biofuel production plants (Kim et al. 2018, Nizami and Rehan 2018). In this context, the chapter aims to focus on the application of nanotechnology to biofuels production, especially highlight the immobilization of ligninolytic and cellulolytic enzymes followed by a discussion about safety issues concerning this technology.
... Fermentation of sweet sorghum using yeast has an advantage of rapid fermentation [10]. Sufficient nutrients like carbon and nitrogen are required for the yeast to grow and reproduce but inorganic salts present in sweet sorghum juice is not enough to meet the need of fermentation [11]. Saccharomyces cerevisiae shows high ethanol productivity, high tolerance to ethanol and tolerance to inhibitory compounds present in hydrolysate of LB. ...
Ethanol is a clear, colourless, flammable, oxygenated hydrocarbon with the chemical formula C 2 H 5 OH. Ethanol has been made since ancient times by fermenting sugars. All the ethanol used for fuel and alcoholic drinks including most of the industrial ethanol, is made by this process. In the present study, the bioethanol production was optimized by Saccharomyces cerevisiae using sorghum stovar as a substrate. Ethanol fermentation from crude enzymes hydrolysed sorghum stovar was analyzed in the present research and the reducing sugar content was recorded maximum after 60 hours. The effect of pH (3.5, 4.5, 5.5 and 6.5), temperatures (25°C, 30°C, 35°C and 40°C) and inoculum level (4%, 6%, 8% and 10%) on ethanol yield from sorghum stovar using the yeast Saccharomyces cerevisiae was estimated. It was concluded that the ethanol yield was maximum at pH 6.5, 35°C and 10% inoculum level.
... The fermentation time could be 3-4 times shorter than that of conventional fermentation technology when immobilized yeast Saccharomyces cerevisiae CICC 1308 is involved in the production of ethanol from sweet sorghum stalk juice. Using this strain in a 5 L bioreactor, the fermentation time is reported to be between 11 and 13 hours (Mei et al., 2009;Liu and Shen, 2008). Sweet sorghum can be treated in a similar way as sugar cane, including the use of industrial yeast like Saccharomyces cerevisiae Y940 for fermentation. ...
Sweet sorghum (Sorghum bicolor (L.) Moench) represent an emerging alternative feedstock with great potential for bioethanol production. Sweet sorghum stalks can be crushed to extract the sugar-rich juice (containing mainly sucrose, glucose and fructose) which can be directly fermented into ethanol with high efficiency by Saccharomyces cerevisiae yeast. This fast-acting microorganism with high ethanol-tolerance displays high ethanol yields and maintains high cell viability during the fermentation under very high gravity conditions (with high total sugar concentrations). The objective of this study is to review the current state of knowledge on the bioethanol production from stalk juice of different sweet sorghum varieties by Saccharomyces cerevisiae (industrial and isolated yeast strains), assessing also the effects of process variables, nutrient supplementation and feeding systems (batch and fed-batch fermentations) on the final ethanol concentration.
... To overcome this problem, response surface methodology is being widely used because in this we can do more experimental trials within short time with accuracy and each medium component has interaction with each other. Now this time, response surface methodology is more widely used approach for optimization studies in various processes [22][23][24][25]. Considering these facts, we made attempt to isolate and identify cellulolytic bacterial strain originally isolated from the gut of Labeo rohita, optimize medium through response surface methodology and application of the cellulase enzyme for saccharification process. ...
Background
Cellulases are enzyme which have potential applications in various industries. Researchers are looking for potential cellulolytic bacterial strains for industrial exploitation. In this investigation, cellulase production of Bacillus cereus was explored while attacking poplar twigs. The bacterium was isolated from the gut of freshwater fish, Labeo rohita and identified by 16S rRNA gene sequencing technology. Various nutritional conditions were screened and optimized through response surface methodology. Initially, Plackett-Burman design was used for screening purpose and optimization was conducted through Box-Bhenken design.
Results
The maximum cellulase production occurred at 0.5% yeast extract, 0.09% MgSO4, 0.04% peptone, 2% poplar waste biomass, initial medium pH of 9.0, and inoculum size of 2% v/v at 37 °C with agitation speed of 120 rpm for 24 h of submerged fermentation. The proposed model for optimization of cellulase production was found highly significant. The indigenously produced cellulase enzyme was employed for saccharification purpose at 50 °C for various time periods. Maximum total sugars of 31.42 mg/ml were released after 6 h of incubation at 50 °C.The efficiency of this enzyme was compared with commercial cellulase enzyme revealing significant findings.
Conclusion
These results suggested potential utilization of this strain in biofuel industry.
... RSM is a group of statistical techniques for designing experiments, building models, evaluating the effects of factors and selecting optimum conditions in a limited number of experiments (Baş and Boyaci, 2007). In recent years, this efficient mathematical approach has been extensively used for optimisation of alcoholic fermentation with free (Le Man et al., 2010;Grahovac et al., 2011Grahovac et al., , 2012 and immobilised (Mei et al., 2009;Yu et al., 2009;Ercan et al., 2013) yeast cells. ...
The production of bioethanol as an alternative to fossil fuel has been increasing owing to growing biofuel demand. Combination of yeast immobilisation and media optimisation has become a popular technique for the improvement of bioethanol technology. The aim of this study was the optimisation, by response surface methodology, of sodium alginate concentration and nitrogen and phosphorus content in media for bioethanol production using immobilised Saccharomyces cerevisiae. Ratio of carbon, nitrogen and phosphorus (C : N : P) in media was calculated based on optimum factors values and initial glucose content. The developed model predicts that maximum product concentration, minimum 'eluted' yeast cells number and minimum nutrients content are achieved when the sodium alginate concentration is 71.99 g/L and C : N : P ratio is 50 : 3.5 : 1.3. The obtained results can be used for techno-economic analysis of the process to select optimum fermentation conditions for industrial application.
... These immobilized enzymes could be magnetically recovered and recycled for a new cellulosic hydrolysis process (Abraham et al. 2014) (Fig. 7.1). For immobilization of enzyme nowadays, many metal oxides are being used (Mei et al. 2009). Two techniques are generally used for immobilization of enzymes on nanoparticles, and these are covalent binding and physical adsorption. ...
The depletion in the limited sources of fossil fuels has generated the problem of energy crisis all over the world. This hunt forces scientific community towards the search for cost-effective, environment-friendly, renewable alternative sources which can replace fossil fuels and fulfill the increasing demands of energy. In this context, the use of lignocellulosic material (plant residues) composed of cellulose, hemicellulose, and lignin becomes the first choice. In the process of ethanol production, first lignocellulosic material is broken down and hydrolyzed into simple sugars like cellulose, and then these sugars are fermented into biofuels such as ethanol in the presence of enzymes like cellulases. The use of cellulases makes the process expensive, and therefore, immobilization of these enzymes on solid supports like nanoparticles can help to recover the enzyme, which ultimately decreases the cost of process. Therefore, the use of nanotechnology and nanomaterials could be one possible avenue to improve biofuel production efficiency and reduction in the processing cost.
This chapter discusses important existing pretreatment approaches involved in the pretreatment of plant biomass use for biofuel production. The emphasis is given on the role of nanotechnological solutions for the development of novel, efficient, and inexpensive strategies for the production of biofuels.
... RSM is also used for designing models, experiments, formulation, estimating the effects of several parameters and determining the optimal culture conditions for better responses and lowering the number of needed experiments (Coninck et al., 2000). To optimize the development of microbes, RSM is a better adopted approach (Balusu et al., 2005;Popa et al., 2007;Wang et al., 2008;Mei et al., 2009). The present study was designed for isolation and identification of cellulase producing bacteria from fish gut contents following optimization of medium using response surface methodology. ...
In this study different species of Aeromonas were isolated from gut of Labeo rhoita and identified by 16SrDNA gene sequencing technology. All isolated species were evaluated for exoglucanase production in submerged fermentation. Of all tested species, Aeromonas bestiarum was found best for maximum production of exoglucanase after 24 h of fermentation at 35 °C using sugarcane bagasse as substrate. To enhance exoglucanase production, various factors were screened by Plackettt-Burman designe and optimizations of significant parameters were carried out by BoxBehnken design of response surface methodology. Among nine parameters screened, substrate concentration, yeast extract and (NH4)2SO4 concentration were found significant. The optimized levels of these parameters were. 2.5% sugarcane bagasse, 0.2% yeast extract and 0.6% (NH4)2SO4 which yielded maximum (3.766 IU) exoglucanase production after 24h of fermentation period. These results suggested the potential utilization of this strain for nutritional purpose to promote the growth of fishes for commercialization of aquaculture.
... Portanto, as curvas da produção de etanol já exibem o rendimento da fermentação em comparação com o teórico. (Whitfield et al., 2012;Mei et al., 2009). Assim como o presente trabalho, Laopaiboon et al. (2007), constataram a inexistência de uma fase de latência no crescimento de leveduras em sorgo sacarino, demonstrando não existirem compostos inibitórios no caldo estudado. ...
... (Gangadharan et al. 2008; Prajapati et al. 2015), ethanol production (Mei et al. 2009), hydrogen production (Guo et al. 2009), phytase production (Singh and Satyanarayana 2008), avermectin production (Gao et al. 2009 ), phenazine- 1-carboxylic acid production (Su et al. 2010), cellulose production (Mohite et al. 2012), and cellulase production (Hegde et al. 2013; Thakkar and Saraf 2014). However, there are very few reports on statistical optimization of siderophore production. ...
... (Gangadharan et al. 2008; Prajapati et al. 2015), ethanol production (Mei et al. 2009), hydrogen production (Guo et al. 2009), phytase production (Singh and Satyanarayana 2008), avermectin production (Gao et al. 2009 ), phenazine- 1-carboxylic acid production (Su et al. 2010), cellulose production (Mohite et al. 2012), and cellulase production (Hegde et al. 2013; Thakkar and Saraf 2014). However, there are very few reports on statistical optimization of siderophore production. ...
We report the enhanced production of siderophore in succinate medium by applying two-stage statistical approach, i.e., Plackett–Burman design and response surface methodology (RSM) using central composite design (CCD). In the first stage of optimization, out of 11 variable components of succinate medium, succinic acid, pH and temperature were found as significant components that influenced the siderophore production in Pseudomonas aeruginosa RZS9. The second stage of RSM using CCD consisted of optimizing the concentrations of the variables. Here, 0.49 g/100 ml concentration of succinic acid, pH 7.08 and temperature of 27.80 °C yielded the maximum (68.41 %) siderophore units. All the significant components exhibited quadratic effect on siderophore production. The F value of 28.63, multiple correlation coefficient (R²) of 0.9626, percent coefficient of variation of 8.81 values indicated that the model was significant and that the experimental data was satisfactorily adjusted to the quadratic model. During validation of these experiments, 6.10 % increase in siderophore yield was obtained. Scale-up of this protocol optimized at shake flask level up to 5 L-capacity reactor further enhanced the siderophore yield. We claim it to be the first report on statistical optimization of siderophore production by P. aeruginosa RZS9.
Electronic supplementary material
The online version of this article (doi:10.1007/s13205-016-0365-2) contains supplementary material, which is available to authorized users.
... Many investigators have studied ethanol production from sweet sorghum juice. Both suspended cultures and immobilized yeast cells have been investigated for ethanol production from sweet sorghum juice [39,[42][43][44][45]51]. In commercial practice, because the sugars in sweet sorghum juice are readily fermentable, the juice cannot be stored in its native state without losses of sugar, and subsequently ethanol. ...
Considerable efforts have been made in the USA and other countries to develop renewable feedstocks for production of fuels and chemicals. Among these, sorghum has attracted strong interest because of its many good characteristics such as rapid growth and high sugar accumulation, high biomass production potential, excellent nitrogen usage efficiency, wide adaptability, drought resistance, and water lodging tolerance and salinity resistance. The ability to withstand severe drought conditions and its high water usage efficiency make sorghum a good renewable feedstock suitable for cultivation in arid regions, such as the southern US and many areas in Africa and Asia. Sorghum varieties include grain sorghum, sweet sorghum, and biomass sorghum. Grain sorghum, having starch content equivalent to corn, has been considered as a feedstock for ethanol production. Its tannin content, however, may cause problems during enzyme hydrolysis. Sweet sorghum juice contains sucrose, glucose and fructose, which are readily fermentable by Saccharomyces cerevisiae and hence is a good substrate for ethanol fermentation. The enzyme invertase, however, needs to be added to convert sucrose to glucose and fructose if the juice is used for production of industrial chemicals in fermentation processes that employ microorganisms incapable of metabolizing sucrose. Biomass sorghum requires pretreatment prior to enzymatic hydrolysis to generate fermentable sugars to be used in the subsequent fermentation process. This report reviews the current knowledge on bioconversion of sorghum to fuels and chemicals and identifies areas that deserve further studies.
... Ethanol production from sweet sorghum has been studied experimentally by many investigators. Both suspended cultures and immobilized yeast cells have been investigated for ethanol production from sweet sorghum juice (Laopaiboon et al., 2007;Laopaiboon et al., 2009;Liu and Shen, 2008;Mei et al., 2009;Wu et al., 2010). The residual bagasse obtained after juice extraction has also been used as feedstock for ethanol production in several studies. ...
An integrated process has been proposed for a sweet sorghum biorefinery in which all carbohydrate components of the feedstock were used for production of fuel ethanol and industrial chemicals. In the first step, the juice was extracted from the stalks. The resultant bagasse was then pretreated using the soaking in aqueous ammonia (SAA) process, which did not result in significant loss of cellulose and hemicellulose, to enhance subsequent enzyme hydrolysis for production of fermentable sugars. Following pretreatment, the bagasse was hydrolyzed with a commercial enzyme product containing high hemicellulase activity (Accellerase XY). The xylose-rich solution obtained after solid/ liquid separation was used for production of value-added co-products using suitable microorganisms. The value-added co-products produced to demonstrate the feasibility were astaxanthin and D-ribose. The residual solids were then hydrolyzed with a commercial enzyme product containing high cellulase activity (Accellerase 1500), with the juice extracted in the first step used as make-up water. By combining the sugar in the juice with the glucose released from the residual solids by enzyme hydrolysis, high ethanol concentrations could be achieved, which resulted in lower distillation cost than if pure water were used for enzyme hydrolysis and subsequent fermentation, as normally performed in cellulosic ethanol production.
... According to the predictions of the model, the ethanol yield is at a maximum (6.5% v/v) at the maximum values of the initial glucose content (175-200 g/L), regardless of the sodium alginate concentration. These results are in agreement with the fact that a combination of a high sugar in the medium and immobilized yeast cells lead to high ethanol production (12,13). ...
Ethanol is an important industrial chemical with emerging potential as a biofuel to replace fossil fuels. In order to enhance the efficiency and yield of alcoholic fermentation, combined techniques such as cells immobilization and media optimization have been used. The aim of this study was the optimization of sodium alginate concentration and glucoseand yeast extract content in the media for ethanol production with immobilized cells of Saccharomyces cerevisiae. Optimization of these parameters was attempted by using aBox-Behnken design using the response surface methodology. The obtained model predicts that the maximum ethanol content of 7.21% (v/v) is produced when the optimal values ofsodium alginate concentration and initial content of glucose and yeast extract in the medium are 22.84 g/L, 196.42 g/L and 3.77 g/L, respectively. To minimize the number of yeastcells "eluted" from the alginate beads and residual glucose content in fermented media, additional two sets of optimization were made. The obtained results can be used for furthertechno-economic analyses of the process to select the optimum conditions of the fermentation process for industrial application.
... Fermentation of sweet sorghum using yeast has an advantage of rapid fermentation (Liu and Shen, 2008b). Sufficient nutrients like carbon and nitrogen are required for the yeast to grow and reproduce but inorganic salts present in sweet sorghum juice is not enough to meet the need of fermentation (Mei et al., 2009). Sipos et al. (2010) have shown that yeast extract, ammonium, urea, calcium and magnesium have effects on both growth and fermentation, thus stimulating fermentation rate and ethanol production. ...
Ethanol is one of the main bio-based molecule produced worldwide, mainly from corn and other starchy crops. Starchy substrates employed as raw materials for ethanol production which cannot be directly fermented to ethanol by certain microorganisms. This is because yeasts, which are employed for fermentation, cannot utilize the starch molecules made up of long chains of glucose molecules hence prior to fermentation need to hydrolyze to simpler fermentable sugars into simple glucose molecules. Although corn starch to ethanol is a mature process, corn production is not feasible in different region. Except corn starch, there are some low impact tuber crops including cassava, sweet potato, yam, aroids, sugar beet, etc. which offer a viable alternative starchy raw material that can be converted to useful sugar feed stocks needed for the production of ethanol and other value added products. It requires simultaneous saccharification and fermentation for a better ethanol yield. Production of this renewable fuel, especially from starchy materials such as tuber crops, holds a remarkable potential to meet the future energy demand because of its high production and comparatively less demand for use as food and fodder. Thus, the present review focuses on various starchy crops for bioethanol production, fermentation techniques and microorganisms used in fermentation process along with its future prospective.
... The fermentation was carried out by Sacharomyces cereviceae in the presence of minimal salt medium as described above and under optimized growth conditions where carbon (2%), nitrogen (0.24%), phosphate (0.24%), temperature (35°C), stirring (150 rpm), pH (5.5), and cellulolytic hydrolysate of sugarcane bagasse having 23.75 g/L of sugar of pulp and paper mill effluent was inoculated with S. cereviceae (10%, v/v; OD 0.6) for production of ethanol (Mei et al., 2009). Samples were removed after 6, 12, 24, 48, and 72 h, and production of ethanol was determined by spectroscopic and gas chromatography methods after samples were centrifuged at 13000 rpm for 2 min, and the supernatant was filtered through a 0.45-µm filter to remove solids. ...
Cryptococcus albidus and Saccharomyces cerevisiae was used for separate hydrolysis and fermentation of sugar cane bagasse for production of ethanol. Lignocellulolytic enzymes, CMCase (34 U/ml), FPase (3 U/ml), β-glucosidase (2.3 U/ml), laccase (32 U/ml), and xylanase (12 U/ml), were assayed by fungus, however, after optimization of process parameters, an increase of 1.5-fold sugar (375 mg/g) from bagasse and production of lignocellulolyic enzymes were determined. The sugar produced by sugar cane bagasse was subsequently treated by Saccharomyces cerevisiae, indicating enhanced production of ethanol at 40 h was 38.4 g/L, reached to a maximum at 50 h, and then it was decreased.
... Response surface methodology (RSM) is followed for identifying the effect of individual variables and for seeking the optimal fermentation conditions for a multivariable system with minimum numbers of experiments efficiently. It has been successfully adopted to optimize the production of ethanol by different microorganisms [18][19][20][21]. Central composite design (CCD) is the most widely used response surface design that provides statistical models which help in understanding the interactions among the parameters that have been optimized [22,23]. ...
We report the first time statistical study of the optimization for ethanol production from hot-water sugar maple hemicellulosic wood hydrolyzate by Escherichia coli FBWHR. Response surface methodology was employed to investigate the effect of fermentation media on the ethanol production from concentrated hot-water sugar maple hemicellulosic wood extract hydrolyzate by Escherichia coli FBWHR. The critical media components were firstly selected according to Plackett–Burman design and further optimized by central composite design. Based on the response surface analysis, the optimum concentrations of the significant components were obtained: yeast extract, 10.19 g/L; tryptone, 14.55 g/L; Na2HPO4•7H2O, 23.21 g/L; KH2PO4, 5 g/L and NH4Cl, 2 g/L. An ethanol concentration of 15.23 ± 0.21 g/L was achieved under the optimized media, which agreed with the predicted value. Ethanol production was enhanced to 22.18 ± 0.13 g/L by scaling up the fermentation from shaker flask to 1.3 L bioreactor.
... Still, it receives a lot of attention in for instance China, where pilot plants are in operation [45]. A potential weak point of this crop is a high rate of sugar degradation at ambient temperatures [46]. However, in contrast to sugarcane, it is harvested at least twice per year, which reduces the need for storage. ...
Nigeria is among the World’s 10 most important exporters of petroleum, but has several difficulties in its domestic energy situation. Power outages are frequent in the cities and 49% of the population has no access to electricity at all. The use of fossil fuels and firewood causes many environmental problems and the population increase in combination with a growing economy results in unmanageable amounts of waste in the cities. The use of biofuels has the potential to alleviate some of these problems and this review aims at evaluating the situation regarding biofuel production in Nigeria through literature studies and contacts. It was found that in spite of good geographic conditions and high investment in biofuel production, progress has been slow. The Nigerian sugarcane sector does not yet satisfy the domestic demand for sugar, while large-scale sugarcane-based ethanol production seems distant. Ethanol production from cassava would require input of energy and enzymes and would probably be too expensive. Sweet sorghum, which is relatively easy to process into bioethanol, has some advantages in a Nigerian context, being widely cultivated. Biodiesel production runs the risk of becoming controversial if edible crops currently being imported would be used. Jatropha curcas (non-edible) is an interesting crop for biodiesel production but the complete life cycle of this process should be further analyzed. The biofuel concept, which would bring the most immediate benefits, is probably biogas production from waste. It requires no irrigation or input of land and also provides a cleaner environment. Besides it would reduce the widespread use of firewood and produce fertilizer.
... The effects of interactions amongst inhibitors on yeast growth rate, final cell density, and ethanol yield are of large importance for bioethanol research. While these responses have previously been the focus of a large degree of study using factorial designs, these studies have been limited by the inability of shake flasks or UV/Vis spectrometers to accommodate a large number of parallel trials [11][12][13][14]. ...
A high-throughput screening experiment to establish the individual and mixture effects of various common inhibitors found in lignocellulosic hydrolysates on the growth kinetics and ethanol production of Saccharomyces cerevisiae was carried out. Fermentations were performed utilizing 96-well microtiter plates to allow for carrying out fermentations in parallel, around which a central composite design of experiments was used to select inhibitor concentrations in each well. The individual and interaction effects of six common inhibitors were quantified using response surface fits of the growth rate, as determined by optical absorbance measurements and final cell density. For growth rate, 4-hydroxy-methylbenzaldehyde (phenol aldehyde) was found to be the strongest inhibitor of growth rate over the concentration range studied, while m-cresol (phenolic) had the least effect on growth rate and the largest inhibitory effect on final cell density. Both positive and negative interactions between inhibitors were found to affect both growth rate and maximum cell density. For example, both furfural and guaiacol when combined with m-cresol were found to have a positive effect on cell growth (less inhibitory), while guaiacol and m-cresol had a negative interaction with 4-hydroxy-methylbenzaldehyde. At all conditions studied, S. cerevisiae produced identical or higher ethanol yields compared to the inhibitor-free control fermentation which was attributed to the effects of physiological stress cause by the some inhibitors. These results quantify both the interactions of various inhibitors as well as their individual effects in a rapid and easy-to-perform experiment which can be easily expanded to include further inhibitors. Such a design can also be used for rapid and efficient screening of different pretreatments and feedstocks in the emerging field of lignocellulosic biofuels.
... Central composite experimental design (CCD) was employed to evaluate the combined effects of the three independent variables by 20 sets of experiments. 41 The fundamental assumption and experimental implication of RSM have been discussed elsewhere. 42 An empirical secondorder polynomial regression model for the three parameters can be expressed as (1) ...
Photocatalytic degradation of norfloxacin (NOR) (10 mg/L) was studied using tungsten bismuth loaded carbon iron complexes (C/Fe–Bi2WO6) under simulated solar light (SSL) irradiation in a cylindrical reactor. Three experimental parameters were chosen as independent variables: pH, C/Fe–Bi2WO6 concentration, and H2O2 concentration. A central composite experimental design (CCD) was used to establish a quadratic model as a functional relationship between the removal efficiency of NOR and the three independent variables. The optimal values of operating parameters under the related constraint conditions were found at a pH of 7.10, a C/Fe–Bi2WO6 concentration of 0.78 g/L, and a H2O2 concentration of 227 mg/L. Under the optimal conditions, the removal efficiency of NOR reached 91.66%. Regression analysis with an R2 value of 0.9728 indicated a good correlation between the experimental results and the predicted values.
... Still, it receives a lot of attention in for instance China, where pilot plants are in operation [45]. A potential weak point of this crop is a high rate of sugar degradation at ambient temperatures [46]. However, in contrast to sugarcane, it is harvested at least twice per year, which reduces the need for storage. ...
Nigeria is among the World’s 10 most important exporters of petroleum, but has several difficulties in its domestic energy situation. Power outages are frequent in the cities and 49% of the population has no access to electricity at all. The use of fossil fuels and firewood causes many environmental problems and the population increase in combination with a growing economy results in unmanageable amounts of waste in the cities. The use of biofuels has the potential to alleviate some of these problems and this review aims at evaluating the situation regarding biofuel production in Nigeria through literature studies and contacts. It was found that in spite of good geographic conditions and high investment in biofuel production, progress has been slow. The Nigerian sugarcane sector does not yet satisfy the domestic demand for sugar, while large-scale sugarcane-based ethanol production seems distant. Ethanol production from cassava would require input of energy and enzymes and would probably be too expensive. Sweet sorghum, which is relatively easy to process into bioethanol, has some advantages in a Nigerian context, being widely cultivated. Biodiesel production runs the risk of becoming controversial if edible crops currently being imported would be used. Jatropha curcas (non-edible) is an interesting crop for biodiesel production but the complete life cycle of this process should be further analyzed. The biofuel concept, which would bring the most immediate benefits, is probably biogas production from waste. It requires no irrigation or input of land and also provides a cleaner environment. Besides it would reduce the widespread use of firewood and produce fertilizer.
Keywords: Nigeria, Biofuels, Bioethanol, Biogas, Biodiesel
Ultrasound has gained recognition within the field of pain intervention owing to its definite advantage of visually localizing the specified target and additionally owing to perceived advantages of safety, accuracy, and potency. Ultrasound permits satisfactory imaging of the posterior parts of the spine and paraspinal soft tissues. Despite the introduction of newer and less consuming time’s methods with the possibility of intravascular injection, there is still insufficient clinical evidence to prove the safety of the ultrasound as a sole image guide intervention, especially for transforaminal injection. It is essential to considering safety tips and be aware of complications that are typically terribly unpleasant and cause unwanted social and legal consequence. The most important injection warnings are damage to the spinal cord and nerve roots, intravascular injection and vascular damage, loss of consciousness, paraplegia and incontinence. The object of this review article is to discuss the untoward dangerous complication which can happen after ultrasound-guided spine injections and explain how to diagnosis and manage them. Further technical and equipment advancements are needed to improve and reduce the existing limitations associated with the ultrasound-guided spine injection technique until that time the multimodality imaging guidance is safer.
The development of sustainable bioethanol fuel production from food waste has increasingly become an attractive topic. Food waste is recognized as the most available and costless feedstock. Therefore, ethanol production has been adopted as cost-efficient and an ecological way for FW disposal. This paper reviewed the microorganisms utilized for ethanol fermentation, the effect of enzymatic hydrolysis on ethanol concentration, optimization of accurate process parameters, and recycling of huge volumes of stillage for ethanol production towards reducing any incurred environmental burdens and minimizing the cost. The statistical tools which may enhance the process efficiency had been presented. Also, the perspective and the future development were introduced. All these aimed to fully utilize the food waste and also reduce the cost for side-product in this process; proper operation conditions and the control methods for stillage recycling were considered as the methods to improve ethanol fermentation from food waste.
The application of high-potential thermotolerant yeasts is a key factor for successful ethanol production at high temperatures. Two hundred and thirty-four yeast isolates from Greater Mekong Subregion (GMS) countries, i.e., Thailand, The Lao People's Democratic Republic (Lao PDR) and Vietnam were obtained. Five thermotolerant yeasts, designated Saccharomyces cerevisiae KKU-VN8, KKU-VN20, and KKU-VN27, Pichia kudriavzevii KKU-TH33 and P. kudriavzevii KKU-TH43, demonstrated high temperature and ethanol tolerance levels up to 45°C and 13% (v/v), respectively. All five strains produced higher ethanol concentrations and exhibited greater productivities and yields than the industrial strain S. cerevisiae TISTR5606 during high-temperature fermentation at 40°C and 43°C. S. cerevisiae KKU-VN8 demonstrated the best performance for ethanol production from glucose at 37°C with an ethanol concentration of 72.69g/L, a productivity of 1.59g/L/h and a theoretical ethanol yield of 86.27%. The optimal conditions for ethanol production of S. cerevisiae KKU-VN8 from sweet sorghum juice (SSJ) at 40°C were achieved using the Box–Behnken experimental design (BBD). The maximal ethanol concentration obtained during fermentation was 89.32g/L, with a productivity of 2.48g/L/h and a theoretical ethanol yield of 96.32%. Thus, the newly isolated thermotolerant S. cerevisiae KKU-VN8 exhibits a great potential for commercial-scale ethanol production in the future.
Sweet sorghum juice is gaining importance as a raw material for the first-generation ethanol production in the period between harvests of sugar cane. Breeding programs are seeking to improve sorghum quality to increase productivity, what has generated an excessive number of samples to be analyzed. Thus, the aim of this paper was to develop rapid and low-cost methods based on partial least-squares (PLS) and near-infrared spectroscopy (NIRS) for the determination of four quality chemical parameters of sweet sorghum. Spectra were recorded with a transflectance accessory, and robust models were built with 500 samples obtained from more than 200 hybrids and inbred strains. Optimization by variable selection was carried out with ordered predictors selection (OPS), providing simpler, more interpretable and predictive multivariate calibration models. The methods were developed in the working ranges of 5.5−18.1 °Brix, 1.2−5.2%, 0.3−13.0%, and 9.8−83.0% for degrees Brix, reducing sugars, polarizable sugars, and apparent purity, respectively. Root-mean-square errors of prediction (RMSEP) of 0.3 °Brix, 0.3%, 0.6%, and 5.3% were obtained for these four parameters, respectively. Finally, a complete multivariate analytical validation was carried out, and the methods were considered linear, accurate, sensitive, and without bias.
The technological process of a pilot-scale plant for fuel ethanol production from sweet sorghum stalk by solid state fermentation was described and energy consumptions of ethanol and byproduct production processes were analyzed. By applying the technology of solid-state fermentation, the conversion rate of ethanol reached 95.8% of the theoretical value. In addition, by utilizing the stalk bagasse comprehensively, the recycling and reusing of the waste heat was realized. As a result, the conversion process had an environment friendly characteristics. The annual yields of the anhydrous ethanol, protein feed and fiber pulp from the stalk were 1000 t/a, 1500 t/a and 5000 t/a, respectively. Result showed that the total energy consumption of the pilot-scale plant was 4.31 × 10 6 kW · h/a when waste heat recovering was considered. The energy consumptions per unit production of anhydrous ethanol, protein feed and fiber pulp were 2759.67 kW · h/t, 36.86 kW · h/t, and 298.41 kW · h/t, respectively. The recovered waste heat in anhydrous ethanol production process was 8.9 × 10 5 kW · h/a. The energy recovering rate during ethanol production from sweet sorghum stalk was 62.9%, which was higher than that of ethanol production from food materials such as corn.
The technological process of pilot-scale plant for fuel ethanol production from sweet sorghum stem by solid state fermentation, which was set up in Weihai city, Shandong province of China, was described and techno-economic assessment of the plant was conducted with cost and profit analysis. Results showed that the ethanol conversion efficiency relative to theoretical yield was up to 95.8%. The residual vinasse was re-fermented and protein feed with 8% crude protein was obtained. The cost and benefit analysis showed that costs of absolute ethyl alcohol production and protein feed production were 5033.8 yuan/t and 101 yuan/t, respectively. Cash flow analysis showed that Net Present Value, Internal Return Rate and Profit/Cost of financial analysis in project level were 2817.5 thousands yuan, 16.05% and 0.953, respectively when the social discount rate was 10%. And the dynamic pay-back period was 9-10 years. As a result, the project has a certain ability of making a profit. The sensitivity analysis showed that the sensitivity of IRR to changes of product price and operating cost was the highest and the sensitivity of IRR to initial investment was the lowest. The market risk of this project depends mainly on the product price at the current scale and technological conditions.
In order to reduce the sugar loss of sweet sorghum stalk during natural storage and to understand relation between sugar loss and change of enzyme activity, the effects of pretreatment of sweet sorghum stalk with plant growth regulator including gibberellin (GA3), potassium salt of maleic hydrazide (KMH), and Na salt of naphthalene acetic acid (NAA-Na) on its sugar content and change of related enzyme activity during natural storage were investigated. Results showed that the storage period of sweet sorghum stalk can be prolonged to 3-4 months with pretreatment of suitable types and doses of plant growth regulators. The sugar contents of sweet sorghum stalks with pretreatment of GA3 (40 mg/L), KMH (400 mg/L) and NAA-Na (70 mg/L) after 112 d storage were 95%, 92% and 94% of their initial sugar contents, respectively, which were significantly higher than that of the control. In addition, the pretreatments of sweet sorghum stalk with suitable types and doses of plant growth regulators can significantly regulate its biological enzyme activities related to aging and sugar metabolism. Three types of plant growth regulators can slow down the sugar loss of sweet sorghum stalk after harvesting through regulating related enzyme activities. The research can provide a scientific reference for the storage of sweet sorghum stalk for large scale bioethanol production.
Cellulase catalyzes the conversion of cellulose into monomeric units which has many biologically important applications. Cost of production of cellulase which is great hindrance in the current era can be greatly reduced by using lignocellulosic wastes as substrate for the enzyme production. The current study mainly focuses on the production and optimization of cellulose using jackfruit waste as substrate and Aspergillus fumigatus JCF as microorganism. Substrate was pretreated with different chemicals and 0.5N NaOH was selected as the best pretreatment method. The enzyme with activity of 3.3 IU/ml was further used for the production of bioethanol through simultaneous saccharification and fermentation using agricultural wastes as substrate. The presence of yeast along with cellulase enzyme greatly reduces the accumulation of sugar in the fermentation media. Bioethanol production was tried using both treated and untreated substrates. Out of all the substrates tried pretreated sugarcane leaves liberated maximum bioethanol of about 18g/l.
Fly ash-based polymeric aluminum ferric chloride (PAFC) was prepared from fly ash leached with acid; the PAFC was used as a coagulant to treat coal-washing wastewater. The effects of pH, reaction temperature, and reaction time on coagulant performance were investigated, with optimal conditions determined using response surface methodology. The coagulation mechanism of PAFC was explored by comparing its performance with commercially available polyaluminum chloride (PAC), using scanning electron microscopy and infrared spectroscopy analyses. Results showed that the optimum PAFC preparation conditions were at a pH of 3.60, a reaction temperature of 92°C, and a reaction time of 2.30 h. Under these conditions, the removal of suspended solids and chemical oxygen demand in treated coal-washing wastewater reached efficiencies of over 81 and 70%, respectively. This means that the prepared PAFC is an effective coal-washing wastewater treatment technique, combining the advantages of polyaluminum and polyferric coagulants.
Cellulase is an efficient enzymatic catalyst that hydrolyses cellulosic substances. The high costs associated with using enzymes for industrial applications can be reduced by immobilizing the cellulase. In the current study, cellulase produced by Aspergillus fumigatus JCF was immobilized onto MnO2 nanoparticles, which improve the activity of cellulase and offer a superior support. The surface characteristics of synthesized MnO2 nanoparticles and cellulase-bound MnO2 nanoparticles were investigated by scanning electron microscopy, and Fourier transform infrared spectroscopy was used to analyze the functional characteristics of the immobilized cellulase. The maximum cellulase binding efficiency was 75%. The properties of the immobilized cellulase, including activity, operational pH, temperature, thermal stability, and reusability were investigated and were found to be more stable than for the free enzyme. It was found that cellulase immobilized on MnO2 nanoparticles could be used to hydrolyze cellulosic substances over a broad range of temperature and pH. The results confirmed that cellulase immobilized on MnO2 nanoparticles was very efficient in terms of cellulolytic activity. © 2015, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.
Batch tests were employed to estimate the optimal conditions for photocatalytic degradation of tetracycline using In2S3 under natural solar radiation by response surface methodology. Three key operating parameters, such as dosages of In2S3, initial concentration of tetracycline and an initial pH value, were selected, and their interrelationships were studied by the Box–Behnken design. The experimental data and ANOVA analysis showed that the coefficient of determination (R2) was 0.9998, which demonstrated that the model was significant. The optimum conditions were predicted to give a maximal removal efficiency of 100% at the In2S3 dosage of 2.5 g/L, an initial tetracycline concentration of 20 mg/L and pH of 7.0. The prediction was tested by triplicate experiments, where a removal efficiency of 100% was achieved under the chosen optimal conditions. This excellent correlation between the predicted and measured values provided confidence in the model.
The use of sweet sorghum [(Sorghum biocolor (L) Moench] to provide bioethanol as a biofuel for the transportation sector still represents a challenge. Sweet sorghum has a high yield of sucrose content in comparison to well know selected agricultural carbon sources, such as grains, most of them in competition in the food industry. Also, sweet sorghum lignocellulosic biomass can be used for bioethanol production. The aim of this work was to evaluate a biotechnological process that involves ethanol production using different sweet sorghum extracts. In consequence, we investigated the growth performance of three Zymomonas mobilis bacterial strains with different degrees of resistance against antimetabolites (Z. mobilis NCIMB 11163, 7. mobilis NCIMB 11163/76 and Z. mobilis CPPR4) on five sweet sorghum extracts (LC99, Prut, F135ST, 11100 and Sudan grass) with different polyphenol contents (2.245, 2.328, 2.713, 2.876 and 2.934mg% respectively) with inhibitory bacterial growth effect. Our results showed that ethanol production by Zymomonas mobilis CPPR4 was with 1.62% percent higher on extract from improved (F135ST) sorghum variety when compared to Sudan grass extract used throughout this study, after 65 h of fermentation.
The waste from beer fermentation broth (WBFB) has been found an excellent and inexpensive resource for bioethanol production. We tried to evaluate the saccharification and fermentation capabilities of WBFB to confirm its effectiveness for bioethanol production. The saccharification potentials of the WBFB were evaluated at various temperatures (30, 40, 50, 60 and ). It was found that the saccharification capabilities increased with temperature and highest reached maximum at and after 4h. Ethanol production from a mixture of WBFB and chemically defined media (CDM) without addition of any microbial species confirmed the fermentation capabilities of WBFB. Simultaneous saccharification and fermentation were performed using WBFB, starch solution and CDM as culturing media. The maximum yield of bioethanol production was obtained at . The saccharifying enzymes and the yeast cells present in WBFB were essential factors for the production of bioethanol from WBFB without any additional enzymes or microbial cells.
This study deals with a new and better protocol to prepare chromium methionine using aqueous ethanol solution as the reaction medium. Response surface methodology (RSM) coupled with Box-Behnken design was employed to model and optimize the operational parameters of this protocol. The ethanol content of aqueous ethanol, the molar ratio of methionine and Cr(III), reaction temperature, and reaction time were chosen as independent variables, and their combined effects on the conversion of Cr(III) (response 1) and the yield of chromium methionine (response 2) were investigated. The optimal values of the parameters were found to be the following: ethanol content of aqueous ethanol is 48.5%; n(Met)/n(NaOH)/n(CrCl3·6H2O) = 4.31:4.31:1; reaction time is 127 min; reaction temperature is 81.1 °C; initial Cr(III) concentration is 0.25 mol/L. The conversion of Cr(III) and the yield of chromium methionine are up to 99.79% and 99.23%, respectively, under the optimal conditions. The analysis of variance (ANOVA) and regression with R2 values of 0.9984 for the conversion of Cr(III) and 0.9974 for the yield of chromium methionine illustrate that the experimental results are in good agreement with the predicted values, and the models can be used to predict the synthesis of chromium methionine successfully.
The culture conditions for gibberellic acid (GA3) production by the fungus Penicillium variable (P. variable) was optimized using a statistical tool, response surface methodology (RSM). Interactions of culture conditions and optimization of the system were studied using Box-Behnken design (BBD) with three levels of three variables in a batch flask reactor. Experimentation showed that the model developed based on RSM and BBD had predicted GA3 production with R (2) = 0.987. The predicted GA3 production was optimum (31.57 mg GA3/kg substrate) when the culture conditions were at 7 days of incubation period, 21% v/w of inoculum size, and 2% v/w of olive oil concentration as a natural precursor. The results indicated that RSM and BBD methods were effective for optimizing the culture conditions of GA3 production by P. variable mycelia.
Ethanol demand is increasing drastically in the present time due to its blending in automotive fuels, which
is desirable for getting clean exhaust and fuel sufficiency. The higher cost of cultivation of sugarcane/-beets,
highly sensitive molasses rates, and ultimately instabilities in the price of ethanol have created grounds to
search for an alternative source for ethanol production. Sweet sorghum has shown potential as a raw material
for fuel-grade ethanol production due to its rapid growth rate and early maturity, greater water use efficiency,
limited fertilizer requirement, high total value, and wide adoptability. Ethanol-producing companies, research
institutions, and governments can coordinate with farmers to strategically develop value-added utilization of
sweet sorghum. Fuel-grade ethanol production from sweet sorghum syrup can significantly reduce India’s
dependence on foreign oil and also minimize the environmental threat caused by fossil fuels.
With world reserves of petroleum fast depleting, in recent years ethanol has emerged as most
important alternative resource for liquid fuel and has generated a great deal of research interest
in ethanol fermentation. Research on improving ethanol production has been accelerating for both
ecological and economical reasons, primarily for its use as an alternative to petroleum based fuels. Field
crops offer potential source of fuel, offering promise as large-scale energy and based on its genetic
diversity, climatic adaptation, biomass and sugar production. Lignocellulosic biomass is the most
abundant organic raw material in the world. Production of ethanol from renewable lignocellulosic
resources may improve energy availability, decrease air pollution and diminish atmospheric CO2
accumulation. The aim of the present review is to highlight on major agricultural, industrial and
urban waste, which could be used for ethanol production in an ecofriendly and profitable manner.
Primarily, the utilization of these wastes for ethanol production will reduce dependency on foreign oil
and secondly, this will remove disposal problem of wastes and make environment safe from pollution.
Fermentation of sugar by Saccharomyces cerevisiae, for production of ethanol in an immobilized cell reactor (ICR) was successfully carried out to improve the performance of the fermentation process. The fermentation set-up was comprised of a column packed with beads of immobilized cells. The immobilization of S. cerevisiae was simply performed by the enriched cells cultured media harvested at exponential growth phase. The fixed cell loaded ICR was carried out at initial stage of operation and the cell was entrapped by calcium alginate. The production of ethanol was steady after 24 h of operation. The concentration of ethanol was affected by the media flow rates and residence time distribution from 2 to 7 h. In addition, batch fermentation was carried out with 50 g/l glucose concentration. Subsequently, the ethanol productions and the reactor productivities of batch fermentation and immobilized cells were compared. In batch fermentation, sugar consumption and ethanol production obtained were 99.6% and 12.5% v/v after 27 h while in the ICR, 88.2% and 16.7% v/v were obtained with 6 h retention time. Nearly 5% ethanol production was achieved with high glucose concentration (150 g/l) at 6 h retention time. A yield of 38% was obtained with 150 g/l glucose. The yield was improved approximately 27% on ICR and a 24 h fermentation time was reduced to 7 h. The cell growth rate was based on the Monod rate equation. The kinetic constants (K(s) and mu(m)) of batch fermentation were 2.3 g/l and 0.35 g/lh, respectively. The maximum yield of biomass on substrate (Y(X-S)) and the maximum yield of product on substrate (Y(P-S)) in batch fermentations were 50.8% and 31.2% respectively. Productivity of the ICR were 1.3, 2.3, and 2.8 g/lh for 25, 35, 50 g/l of glucose concentration, respectively. The productivity of ethanol in batch fermentation with 50 g/l glucose was calculated as 0.29 g/lh. Maximum production of ethanol in ICR when compared to batch reactor has shown to increase approximately 10-fold. The performance of the two reactors was compared and a respective rate model was proposed. The present research has shown that high sugar concentration (150 g/l) in the ICR column was successfully converted to ethanol. The achieved results in ICR with high substrate concentration are promising for scale up operation. The proposed model can be used to design a lager scale ICR column for production of high ethanol concentration.
In order to attain a higher ethanol yield and faster ethanol fermentation rate, orthogonal experiments of ethanol fermentation with immobilized yeast from stalk juice of sweet sorghum were carried out in the shaking flasks to investigate the effect of main factors, namely, fermentation temperature, agitation rate, particles stuffing rate and pH on ethanol yield and CO(2) weight loss rate. The range analysis and analysis of variance (ANOVA) were applied for the results of orthogonal experiments. Results showed that the optimal condition for bioethanol fermentation should be A(4)B(3)C(3)D(4), namely, fermentation temperature, agitation rate, particles stuffing rate and pH were 37 degrees C, 200rpm, 25% and 5.0, respectively. The verification experiments were carried out in shaking flasks and 5L bioreactor at the corresponding parameters. The results of verification experiments in the shaking flasks showed that ethanol yield and CO(2) weight loss rate were 98.07% and 1.020gh(-1), respectively. The results of ethanol fermentation in the 5L bioreactor showed that ethanol yield and fermentation time were 93.24% and 11h, respectively. As a result, it could be concluded that the determined optimal condition A(4)B(3)C(3)D(4) was suitable and reasonable for the ethanol fermentation by immobilized Saccharomyces cerevisiae. The conclusion in the research would be beneficial for application of ethanol fermentation by immobilized S. cerevisiae from stalk juice of sweet sorghum.
With the circulating fluidized bed reactor as main structure, an integrated facility was developed for the fast pyrolysis of biomass. The bed is divided into two zones according to the pyrolysis and secondary reaction and the main chemical process can be modelled. Based on the variation of the pyrolysis gas composition and the bio-oil ingredients, the experimental data highlights the important effects of temperature, heating rate and residence time. The main trend is that the higher temperature and longer residence time contribute to the secondary reaction and the lower heating rate favors the carbonization so that the liquid production is reduced. The best bio-oil yield is 63% in weight. The component analysis of bio-oil shows that most compounds in bio-oil are nonhydrocarbons, while alkanes, aromatics and bitumen are relatively low. The physical properties of bio-oil include high water and oxygen content as well as low pH and LHV.
Stem bark and pith of sweet sorghum were analyzed with reference to their sucrose, simple reducing sugars, cellulose, hemicelluloses, lignin and associated phenolic acids contents. Moreover, lignin monomeric units (guaiacyl and syringyl) engaged in non-condensed structures were characterized by thioacidolysis, whereas cell wall associated phenolic acids (p-coumaric and ferulic acids) were estimated by alkaline hydrolysis at 170°C. The results obtained showed that bark and pith are heterogeneous as far as their chemical composition and the structure of their chemical components are concerned. In particular, the pith content in water soluble sugars is twice as high compared with the one in the bark, whereas bark is enriched in lignocellulosic fibres. Bark lignin is twice as important in content and less condensed in structure compared to pith lignin. p-Coumaric acid is the predominant p-hydroxycinnamic acid associated to the cell walls, whereas ferulic acid is present in significant quantities.
Ethanol tolerance, osmotolerance and sugar conversion efficiency were used to screen yeasts for potential ethanol production from sweet-stem sorghum juice. Of the ten strains of Saccharomyces sp. that produced ethanol from the sorghum juice or from yeast extract/phosphate/sucrose (YEPS) media, the best sugar conversion efficiencies were greater than 85% for the strains Vin7, SB9, N96 and GSL. Vin7 and SB9 had higher sugar conversion efficiencies for sweet-stem sorghum juice, while strains N96 and GSL gave higher conversions in YEPS.
The relationship between total soluble sugar content and Brix in stalk juice of sweet sorghum was determined through one-dimensional linear regression. Meanwhile, bioethanol fermentation experiments were conducted in shaking flasks and 10 l fluidized bed bioreactor with stalk juice of Yuantian No. 1 sweet sorghum cultivar when immobilized yeast was applied. The experimental results in the shaking flasks showed that the order of influence on improving ethanol yield was (NH4)2SO4>MgSO4>K2HPO4, and the optimum inorganic salts supplement dose was determined as follows: K2HPO4 0%, (NH4)2SO4 0.2%, MgSO4 0.05%. When the optimum inorganic salts supplement dose was used in fermentation in 10 l fluidized bed reactor, the fermentation time and ethanol content were 5 h and 6.2% (v/v), respectively, and ethanol yield was 91.61%, which was increased by 9.73% than blank. In addition, the results showed that the fermentation time was about 6–8 times shorter in fluidized bed bioreactor with immobilized yeast than that of conventional fermentation technology. As a result, it can be concluded that the determined optimum inorganic salts supplement dose could be used as a guide for commercial ethanol production. The fluidized bed bioreactor with immobilized yeast technology has a great potential for ethanol fermentation of stalk juice of sweet sorghum.
Ethanol production from mixtures of sweet stem sorghum juice and sorghum grain was investigated under normal and very high gravity (VHG) fermentation conditions. Fermentation was carried out using Saccharomyces cere6isiae yeast strain N96 at 30°C. For VHG fermentation, sucrose was added to the sweet sorghum juice to obtain a concentration of 34 g per 100 ml of dissolved solids. Fermentation was carried out for 96 h using malted and unmalted milled sorghum grain from sorghum cultivars DC-75 and SV-2. Under VHG conditions, maximum ethanol levels were about 16.8% (v/v) and 11% (v/v) for media containing malted and unmalted milled sorghum grain, respectively. Although fermentation did not occur to completion, levels of ethanol obtained under VHG conditions were three times higher than the levels obtained under normal fermentation conditions. Under VHG conditions, about 8 g/100 ml of dissolved solids remained in the fermentation media after ethanol production had ceased while under normal fermentation conditions, about 4 g/100 ml of dissolved solids remained unused in the fermentation media. There was an initial decline in free amino nitrogen (FAN) levels up to 34 h followed by an increase up to 96 h under VHG fermentation conditions. Levels of assayable proanthocyanidins (PAs) from sorghum cultivar DC-75 were reduced during fermentation. © 2000 Elsevier Science B.V. All rights reserved.
A mathematical model was developed to describe the effects of temperature on the kinetic parameters of ethanol fermentation by the flocculating yeast, Saccharomyces cerevisiae M30, using cane molasses as the substrate. Three state variables, biomass, ethanol and the substrate and 12 kinetics parameters were used to describe the phenomenon. The kinetic parameters of the model were determined by using the least-square method. The influence of temperature and initial sugar concentration on cell activities was investigated and quantified. Arrhenius relationships between operating temperature and the maximum specific growth rate, specific production rate, specific death rate were then established. The activation energy for growth, ethanol production and death rate were 3.461 × 104, 3.496 × 104 and 1.777 × 105 kJ/kmol, respectively. Polynomial equations were established for the effects of temperature on the other kinetic parameters. A high temperature led to a decrease in the ethanol and cell yields but an increase in the inhibition effect of ethanol and sugar on cell growth and ethanol production. In addition, an inhibition effect of the initial sugar concentration on cell growth was clearly observed. The adopted mathematical model could describe very well the dynamics of ethanol fermentation from the beginning up to the stationary phase.
Sweet sorghum carbohydrates were simultaneously saccharified and fermented to ethanol by a mixed culture of Fusarium oxysporum and Saccharomyces cerevisiae in a bioreactor. Fusarium oxysporum was grown aerobically for the production of the enzymes necessary for the saccharification of sorghum cellulose and hemicellulose. Saccharomyces cerevisiae, together with F. oxysporum, converted the soluble sugars to ethanol. Three batches of sorghum were used, harvested at different periods of the year. The optimum yield of bioconversion and ethanol concentration was 5·2–8·4 g ethanol/100 g of fresh sorghum and 3·5–4·9% (w/v), respectively, depending on the composition of sorghum stalks. In all experiments, the ethanol yield exceeded the theoretical, based on soluble sugars, by 20·0–32·1% due to bioconversion of polysaccharides to ethanol.
Statistical experimental design was used to optimize the conditions of simultaneous saccharification and fermentation (SSF), viz. temperature, pH and time of fermentation of ethanol from sago starch with co-immobilized amyloglucosidase (AMG) and Zymomonas mobilis MTCC 92 by submerged fermentation. Maximum ethanol concentration of 55.3 g/l was obtained using a starch concentration of 150 g/l. The optimum conditions were found to be a temperature of 32.4 °C, pH of 4.93 and time of fermentation of 17.24 h. Thus, by using SSF process with co-immobilized AMG and Z. mobilis cells MTCC 92, the central composite design (CCD) was found to be the most favourable strategy investigated with respect to ethanol production and enzyme recovery.
A class of incomplete three level factorial designs useful for estimating the coefficients in a second degree graduating polynomial are described. The designs either meet, or approximately meet, the criterion of rotatability and for the most part can be orthogonally blocked. A fully worked example is included.
Compared to grain sorghums, sweet sorghums typically have lower grain yield and thick, tall stalks which accumulate high levels of sugar (sucrose, fructose and glucose). Unlike commercial grain sorghum (S. bicolor ssp. bicolor) cultivars, which are usually F1 hybrids, commercial sweet sorghums were selected as wild accessions or have undergone limited plant breeding. Although all sweet sorghums are classified within S. bicolor ssp. bicolor, their genetic relationship with grain sorghums is yet to be investigated. Ninety-five genotypes, including 31 sweet sorghums and 64 grain sorghums, representing all five races within the subspecies bicolor, were screened with 277 polymorphic amplified fragment length polymorphism (AFLP) markers. Cluster analysis separated older sweet sorghum accessions (collected in mid 1800s) from those developed and released during the early to mid 1900s. These groups were emphasised in a principle component analysis of the results such that sweet sorghum lines were largely distinguished from the others, particularly by a group of markers located on sorghum chromosomes SBI-08 and SBI-10. Other studies have shown that QTL and ESTs for sugar-related traits, as well as for height and anthesis, map to SBI-10. Although the clusters obtained did not group clearly on the basis of racial classification, the sweet sorghum lines often cluster with grain sorghums of similar racial origin thus suggesting that sweet sorghum is of polyphyletic origin within S. bicolor ssp. bicolor
Food Analysis;Southwest China Normal University Press:Chong Qing, People’s Republic of China
- M F Hu
Production and Utilization-Applied Energy Technology Series
- C E Wyman
Ethanol Technology-New Version
- S B Jia
- S Q Li
- G F Wu