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Techno-economical two-step fermentation plant design for biobutanol production from cooked rice: food waste
Abstract
Issues related to food wastage have become a significant threat to sustainable development, particularly in developing countries. Cooked rice, reported as one of the abundant regional food wastes, is a...
... Pervaporation -100 1460 . [151] 10 Pervaporation Oil palm frond 77,220 2300 [104] 11 Adsorption Oil palm frond 77,220 7765 [104] 12 Vacuum Corn stover 92,000 1850 [163] 13 Distillation with heat integration Cooked rice waste 96,360 1240 [152] 14 Distillation with divided wall column Butanol-water mixture 40,000 3.3 million $/year [24] 15 Distillation Glucose 100,000 5330 [164] 16 Distillation sago 100,000 3900 [164] A fixed quantity of 150 g carbohydrate/kg feed was considered. ...
... [132] Table 6 shows the approximate energy consumption for the described PI schemes for plant capacities up to 100,000 tons per year. [145][146][147][148][149][150][151][152][153][154][155][156][157][158][159][160][161][162][163][164] A combined process requires a maximum energy consumption of only 9.61 MJ/kg butanol (2.66 kWh/ kg butanol). Except for the heat duties from DWC the remaining energy requirement for 1 year is 0.1 million kWh (0.38 million MJ). ...
... [151] Decanter-assisted distillation employing heat integration was analyzed for butanol production from Japanese cooked rice waste. [152] Based on the lab results, the techno-economic analysis was performed using SuperPro designer. A plant capacity of 10 MT/h rice was considered. ...
Biobutanol is a potential biofuel produced from various biomass and can serve as a suitable alternative to the nonrenewable fossil-based gasoline fuel. The fermentative microbes used for biobutanol production are solvent-producing Clostridium organisms by Acetone-Butanol-Ethanol (ABE) fermentation. The major challenges of ABE fermentation are butanol toxicity to the host strain, lack of effective fermentation strategies, inefficient butanol separation, and low 0.5–2% w/w yield. Butanol forms an azeotropic mixture with water and requires 79.5 MJ/kg energy for separation using conventional distillation when the energy content of butanol is only 36 MJ/kg; hence the separation by traditional distillation processes is inefficient. Recent developments in membrane technology, coupled with novel extractants and adsorbents, are promising for efficient, energy-effective, and economical bio-butanol separation. Among the techniques, liquid-liquid extraction has shown a high separation efficiency of 75–85% butanol with an energy demand of 25 MJ/kg, whereas adsorption and pervaporation have shown an energy demand of 35–40 MJ/kg. In the present review, a critical analysis of the recent trends, strategies, technical prospects, challenges, and economical evaluation of different methods of biobutanol recovery is presented.
... The overall production cost, operating cost, fixed capital, and revenue was calculated. The cost analysis provides an overview of the investment, annual operating cost, annual revenue, return on investment, payback period, IRR (Internal Rate of Return), and NPV (Net Present Value) [23,24]. ...
Lipases are widely used in many biochemical industries. Media optimization is considered one of the best ways to produce a large quantity of lipase economically. This study used Response Surface Methodology (D - Optimal design in MODDE 13 to comprehend the effect of different media on the enzyme activity. The enzyme activity was highest under the following conditions: 10.1 g/L of peptone, 7.5 g/L of Yeast Extract, and 13.9 mL/L of Olive oil. A feasibility analysis of lipase production from the microbes using the optimized data was performed, and at optimized conditions, lipase activity increased from 0.757 μmol/min to 0.959 μmol/min. A simulation study for large-scale batch production for lipase was conducted using SuperPro Designer (v10), and techno-economic data was analyzed. The expected cost per unit volume of lipase was estimated to be 4393.96 $. Thus, process optimization with technoeconomic analysis could be helpful for industrial-scale lipase production.
Electromicrobial production (EMP), where electrochemically generated substrates (e.g., H2) are used as energy sources for microbial processes, has garnered significant interest as a method of producing fuels and other value-added chemicals from CO2. Combining these processes with direct air capture (DAC) has the potential to enable a truly circular carbon economy. Here, we analyze the economics of a hypothetical system that combines adsorbent-based DAC with EMP to produce n-butanol, a potential replacement for fossil fuels. First-principles-based modeling is used to predict the performance of the DAC and bioprocess components. A process model is then developed to map material and energy flows, and a techno-economic assessment is performed to determine the minimum fuel selling price. Beyond assessing a specific set of conditions, this analytical framework provides a tool to reveal potential pathways toward the economic viability of this process. We show that an EMP system utilizing an engineered knallgas bacterium can achieve butanol production costs of <1.58/L) if a set of optimistic assumptions can be realized.
Nowadays, renewable and cleaner biofuel requirements increase with the increase in economic, environmental, and social concerns. Biobutanol is a preferable alternative fuel due to its outstanding properties compared to other alcohol-based biofuels. Two alternative downstream process configurations are designed in this study to obtain high-purity alcohol products from isopropanol–butanol–ethanol (IBE) fermentation broth with the same feed flowrate and compositions. In process configuration 1, the excess amount of water in the fermentation broth is mainly taken away using a preconcentration column. In process configuration 2, an extractor-extractive distillation hybrid system is used to remove the excess amount of water from the system. The results show that the first configuration is superior with a 62% reduction in total annual cost (TAC). Besides economic superiority, process configuration 1 is also quantitatively better than process configuration 2 in terms of gas emissions and energy demand to purify butanol. As a result, process configuration 1 is found as an eco-efficient downstream separation sequence for IBE purification process.
Food Processing Industries are bound to increasingly adopt digital technologies in order to ensure product safety and quality, minimize costs in the face of low profit margins, shorten lead times and guarantee timely delivery of an increasing number of products despite production dead times and uncertainties. The concept of a digital twin put forward in the context of Industry 4.0 encompasses a digital model of the production model that mimics the physical system, interacts with it and can be used to design, monitor and optimize its performance. In this paper, the application of integrated process and digital twin models in food processing is discussed in the context of process simulation and production scheduling. The modeling challenges, opportunities and special characteristics that distinguish food from other process industries are also discussed. The potential benefits from implementing a digital modeling approach on a food process are presented with the help of a large-scale brewery case study.
Given their historic emissions and economic capability, we analyze a leadership role for representative industrialized regions (EU, US, Japan, and Australia) in the global climate mitigation effort. Using the global integrated assessment model REMIND, we systematically compare region-specific mitigation strategies and challenges of reaching domestic net-zero carbon emissions in 2050. Embarking from different emission profiles and trends, we find that all of the regions have technological options and mitigation strategies to reach carbon neutrality by 2050. Regional characteristics are mostly related to different land availability, population density and population trends: While Japan is resource limited with respect to onshore wind and solar power and has constrained options for carbon dioxide removal (CDR), their declining population significantly decreases future energy demand. In contrast, Australia and the US benefit from abundant renewable resources, but face challenges to curb industry and transport emissions given increasing populations and high per-capita energy use. In the EU, lack of social acceptance or EU-wide cooperation might endanger the ongoing transition to a renewable-based power system. CDR technologies are necessary for all regions, as residual emissions cannot be fully avoided by 2050. For Australia and the US, in particular, CDR could reduce the required transition pace, depth and costs. At the same time, this creates the risk of a carbon lock-in, if decarbonization ambition is scaled down in anticipation of CDR technologies that fail to deliver. Our results suggest that industrialized economies can benefit from cooperation based on common themes and complementary strengths. This may include trade of electricity-based fuels and materials as well as the exchange of regional experience on technology scale-up and policy implementation.
Efficient saccharification of lignocellulosic biomass requires concerted development of a pretreatment method, an enzyme cocktail and an enzymatic process, all of which are adapted to the feedstock. Recent years have shown great progress in most aspects of the overall process. In particular, increased insights into the contributions of a wide variety of cellulolytic and hemicellulolytic enzymes have improved the enzymatic processing step and brought down costs. Here, we review major pretreatment technologies and different enzyme process setups and present an in-depth discussion of the various enzyme types that are currently in use. We pay ample attention to the role of the recently discovered lytic polysaccharide monooxygenases (LPMOs), which have led to renewed interest in the role of redox enzyme systems in lignocellulose processing. Better understanding of the interplay between the various enzyme types, as they may occur in a commercial enzyme cocktail, is likely key to further process improvements.
In this article, the geographical location and availability of the most important crop residues generated in Mexico over the last 10 years (2008—2017) were determined. This study estimates the gross number of residues for the four most important cultivars in Mexico named conventional residues (CRs) such as corn, wheat, sorghum, and barley, and estimates were also made for regionally important crops identified as nonconventional residues (NCRs) such as coffee, sugarcane, and beans. The total and sustainable energy potentials (TEP and SEP) for agricultural residues were calculated, in similar way the butanol and electricity production potentials were also calculated if these residues were processed under a nonconventional biorefinery scheme; the calculated availability of crop residues was 59,059,666 ton/year, thus demonstrating that Mexico could have great potential for bioenergy production. The estimated TEP was 1,787,241,249 PJ/year, and the SEP was 78,724,689 PJ/year. The production of butanol and its production cost were calculated for the main crop residues; the butanol volume ranged from 7,348 ton/day to 161,610 ton/day, and the volume of crops of regional importance ranged from 6,461.9 ton/day to 151,389 ton/day. The minimum butanol production cost was 2000 ton/day of feedstock. The surplus electricity was determined for all crop residues.
Among the driving factors for the high production cost of cellulosic butanol lies the pretreatment and product separation sections, which often demand high amounts of energy, chemicals, and water. In this study, techno-economic analysis of several pretreatments and product separation technologies were conducted and compared. Among the pretreatment technologies evaluated, low-moisture anhydrous ammonia (LMAA) pretreatment has shown notable potential with a pretreatment cost of 1.98/L, 0.61/L, respectively. Evaluation of different product separation technologies for acetone-butanol-ethanol (ABE) fermentation process have shown that in situ stripping has the lowest separation cost, which was 0.38/L, 0.45/L, respectively. The evaluations have shown that production of cellulosic butanol using combined LMAA pretreatment and in situ stripping or with dual extraction recorded among the lowest butanol production cost. However, dual extraction model has a total solvent productivity of approximately 6% higher than those of in situ stripping model.
Renewable liquid biofuels for transportation have recently attracted enormous global attention due to their potential to provide a sustainable alternative to fossil fuels. In recent years, the attention has shifted from first-generation bioethanol to the production of higher molecular weight alcohols, such as biobutanol, from cellulosic feedstocks. The economic feasibility of such processes depends on several parameters such as the cost of raw materials, the fermentation performance and the energy demand for the pretreatment of biomass and downstream processing. In this work, two conceptual process scenarios for isobutanol production, one with and one without integrated product removal from the fermentor by vacuum stripping, were developed and evaluated using SuperPro Designer®. In agreement with previous publications, it was concluded that the fermentation titer is a crucial parameter for the economic competitiveness of the process as it is closely related to the energy requirements for product purification. In the first scenario where the product titer was 22 g/L, the energy demand for downstream processing was 15.8 MJ/L isobutanol and the unit production cost of isobutanol was 1.42/L. The uncertainty associated with the choice of modeling and economic parameters was investigated by Monte Carlo simulation sensitivity analysis.
Lignocellulosic biomass is generally considered as a promising feedstock for the production of value added compounds, due to its availability, low cost and potential sustainable use. Coffee cut-stems (CCS) are a cut of 15–20 cm of length above the land where the coffee plant is cultivated and it is obtained at high quantities after crop renewal. Its high cellulose content makes it a potential sugar platform for different products. The objective of this work is to determine the potential of CCS as a raw material for acetone–butanol–ethanol (ABE) fermentation in technical, economic and environmental terms. The overall ABE fermentation was simulated using the commercial software Aspen Plus to obtain the mass and energy balances. Simulation included the composition of lignocellulosic residue, which was determined experimentally. The whole slurry obtained in the acid pretreatment was sent to enzymatic saccharification. Then the liquid fraction (rich in pentoses and hexoses) was used for fermentation step as carbon source. The process was proposed in this way to determine the influence of inhibitors in ABE fermentation yield through the comparison with other works that include detoxification step. The yield for the process was 140 kg ABE per ton of CCS. The operating costs were calculated using the software Aspen Economic Analyzer. The influence of the cost of the raw materials on the Net Present Value (NPV), the production cost of ABE solvents and the distribution cost by process stages were determined. Additionally, a scale analysis was performed to determine its influence on the NPV. The simulation demonstrated a Minimum Processing Scale for Economic Feasibility (MPSEF) of 64.6 ton/h of CCS. Finally, an environmental assessment using the Waste Reduction Algorithm (WAR) software was proposed to determine environmental impact.
Continuous fermentation of dilute acid-pretreated de-oiled rice bran (DRB) to butanol by the Clostridium acetobutylicum YM1 strain was investigated. Pretreatment of DRB with dilute sulfuric acid (1%) resulted in the production of 42.12 g/L total sugars, including 25.57 g/L glucose, 15.1 g/L xylose and 1.46 g/L cellobiose. Pretreated-DRB (SADRB) was used as a fermentation medium at various dilution rates, and a dilution rate of 0.02 h−1 was optimal for solvent production, in which 11.18 g/L of total solvent was produced (acetone 4.37 g/L, butanol 5.89 g/L and ethanol 0.92 g/L). Detoxification of SADRB with activated charcoal resulted in the high removal of fermentation inhibitory compounds. Fermentation of detoxified-SADRB in continuous fermentation with a dilution rate of 0.02 h−1 achieved higher concentrations of solvent (12.42 g/L) and butanol (6.87 g/L), respectively, with a solvent productivity of 0.248 g/L.h. This study showed that the solvent concentration and productivity in continuous fermentation from SADRB was higher than that obtained from batch culture fermentation. This study also provides an economic assessment for butanol production in continuous fermentation process from DRB to validate the commercial viability of this process.
Background
Beer is the most popular alcoholic beverage worldwide. In the manufacture of beer, various by-products and residues are generated, and the most abundant (85% of total by-products) are spent grains. Thanks to its high (hemi)cellulose content (about 50% w/w dry weight), this secondary raw material is attractive for the production of second-generation biofuels as butanol through fermentation processes.
Results
This study reports the ability of two laccase preparations from Pleurotus ostreatus to delignify and detoxify milled brewer’s spent grains (BSG). Up to 94% of phenols reduction was achieved. Moreover, thanks to the mild conditions of enzymatic pretreatment, the formation of other inhibitory compounds was avoided allowing to apply the sequential enzymatic pretreatment and hydrolysis process (no filtration and washing steps between the two phases). As expected, the high detoxification and delignification yields achieved by laccase pretreatment resulted in great saccharification. As a fact, no loss of carbohydrates was observed thanks to the novel sequential strategy, and thus the totality of polysaccharides was hydrolysed into fermentable sugars. The enzymatic hydrolysate was fermented to acetone-butanol-ethanol (ABE) by Clostridium acetobutilycum obtaining about 12.6 g/L ABE and 7.83 g/L butanol within 190 h.
Conclusions
The applied sequential pretreatment and hydrolysis process resulted to be very effective for the milled BSG, allowing reduction of inhibitory compounds and lignin content with a consequent efficient saccharification. C. acetobutilycum was able to ferment the BSG hydrolysate with ABE yields similar to those obtained by using synthetic media. The proposed strategy reduces the amount of wastewater and the cost of the overall process. Based on the reported results, the potential production of butanol from the fermentation of BSG hydrolysate can be envisaged.
In this study, switchgrass was investigated as a renewable feedstock for fermentative production of acetone, butanol and ethanol (ABE). For this purpose, switchgrass was first subjected to alkaline pretreatment, which reduces its recalcitrance and increases enzyme accessibility. Both simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) were applied. The pretreated switchgrass solids inhibit ABE fermentation, presumably due to the residual lignin portion, as evidenced by the toxicity test of various model phenolic compounds. Addition of a non-ionic surfactant, Tween 80, alleviated the phenol-induced inhibition. As constrained by the “solid effects” the upper limit of solid loading that SSF could process was in the range of 5–6%. SSF with 5% solid loading produced a total of 12.3 g/L ABE solvents with 7.8 g/L of butanol. SHF was further applied to process higher solid loadings. A total of 14.3 g/L ABE solvent with 8.5 g/L of butanol was produced from SHF with 7% solid loading. SSF gave an overall bioconversion yield close to that of pure sugar control, whereas SHF was able to avoid the “solid effects” with a slightly lower overall bioconversion yield.
The effect of pH and butyric acid supplementation on the production of butanol by a new local isolate ofClostridium acetobutylicumYM1 during batch culture fermentation was investigated. The results showed that pH had a significant effect on bacterial growth and butanol yield and productivity. The optimal initial pH that maximized butanol production was pH 6.0 ± 0.2. Controlled pH was found to be unsuitable for butanol production in strain YM1, while the uncontrolled pH condition with an initial pH of 6.0 ± 0.2 was suitable for bacterial growth, butanol yield and productivity. The maximum butanol concentration of 13.5 ± 1.42 g/L was obtained from cultures grown under the uncontrolled pH condition, resulting in a butanol yield (YP/
S
) and productivity of 0.27 g/g and 0.188 g/L h, respectively. Supplementation of the pH-controlled cultures with 4.0 g/L butyric acid did not improve butanol production; however, supplementation of the uncontrolled pH cultures resulted in high butanol concentrations, yield and productivity (16.50 ± 0.8 g/L, 0.345 g/g and 0.163 g/L h, respectively). pH influenced the activity of NADH-dependent butanol dehydrogenase, with the highest activity obtained under the uncontrolled pH condition. This study revealed that pH is a very important factor in butanol fermentation byC. acetobutylicumYM1.
Butanol is considered a superior biofuel, as it is more energy dense and less hygroscopic than the more popular ethanol, resulting in higher possible blending ratios with gasoline. However, the production cost of the acetone-butanol-ethanol (ABE) fermentation process is still high, mainly due to the low butanol titer, yield and productivity in bioprocesses. The conventional recovery by distillation is an energy-intensive process that has largely restricted the economic production of biobutanol. Other methods based on gas stripping, liquid-liquid extraction, adsorption, and membranes are also energy intensive due to the bulk removal of water.
This techno-economic study compares several process technologies for the production of ethanol from lignocellulosic material, based on a 5- to 8-year time frame for implementation. While several previous techno-economic studies have focused on future technology benchmarks, this study examines the short-term commercial viability of biochemical ethanol production. With that goal, yields (where possible) were based on publicly available experimental data rather than projected data. Four pretreatment technologies (dilute-acid, 2-stage dilute-acid, hot water, and ammonia fiber explosion or AFEX); and three downstream process variations (pervaporation, separate 5-carbon and 6-carbon sugars fermentation, and on-site enzyme production) were included in the analysis. Each of these scenarios was modeled and economic analysis was performed for an “nth plant” (a plant with the same technologies that have been employed in previous commercial plants) to estimate the total capital investment (TCI) and product value (PV). PV is the ethanol production cost, including a 10% return on investment. Sensitivity analysis has been performed to assess the impact of process variations and economic parameters on the PV.
Simultaneous saccharification and fermentation (SSF) is a widely used approach for lignocellulosic butanol production. However, the major drawbacks for SSF lie in poor cellulase activity, sugar yield and butanol productivity at temperature below 37 °C. For the first time, a genetically engineered Clostridium acetobutylicum with enhanced thermotolerance at 39–45 °C was applied to high temperature SSF of corn stover pretreated by dilute sulfuric acid and aqueous ammonia. The optimized SSF at 42 °C with 12 h pre-hydrolysis gave 10.8 g/L butanol and 18.2 g/L ABE using pretreated solids and overlimed acid-treated liquid, obtaining butanol yield and productivity of 0.18 g/g-substrate and 0.18 g/L/h. Significant improvements on butanol production and productivity were achieved compared to conventional SSF process. The demonstrated SSF made full use of the sugars from acid pretreatment and acid-treated liquid for hydrolysis, reduced total cellulase usage, and contributed to hydrolysis and fermentation efficiency, indicating its potential for improving lignocellulosic butanol production.
The red seaweed, Gelidium amansii, contains proteins such as R-phycoerythrin and R-phycocyanin, as well as polysaccharides. Initial protein extraction from G. amansii yielded 53 μg/g R-phycoerythrin and 56 μg/g R-phycocyanin. After protein extraction, monosaccharides were produced using hyper thermal acid hydrolysis and enzymatic saccharification. Acetone–butanol–ethanol (ABE) was produced by Clostridium acetobutylicum KCTC 1790. To overcome the different pH requirements for monosaccharide consumption and solvent production, a two-stage pH control culture strategy was developed. Fermentation at pH 6.0 supported a high cell growth rate and both glucose and galactose were consumed completely. The pH was then shifted from 6.0 to 4.5 to produce ABE after 84 h. The maximum ABE concentration reached 15.5 g/L in comparison to 3.1 g/L under fermentation without pH control. The two-stage pH control strategy is a suitable method for ABE production from G. amansii.
In Asia, uneaten cooked rice is the highest portion amongst many forms of food wastes that are thrown away. In order to make use of the thrown-away rice and potentially use it for liquid fuels, steamed Japanese rice was evaluated on biobutanol production through a two-step fermentation by amylase-producing Aspergillus oryzae, and solvent-producing Clostridium acetobutylicum YM1. The effects of sterilization and providing anaerobic conditions on solvent production in acetone-butanol-ethanol (ABE) fermentation cannot be underestimated. Several conditions, including aerobic, anaerobic, sterile, and non-sterile were investigated concerning the solvent production capability of Clostridium acetobutylicum YM1. The maximum solvent production was 11.02 ± 0.22 g/l butanol and 18.03 ± 0.34 g/l total ABE from 75 g/l dried rice. The results confirmed that the solvent production performance of the YM1 strain was not affected by the sterilization conditions. In particular, 10.91 ± 0.16 g/l butanol and 16.68 ± 0.22 g/l ABE were produced under non-sterile and aerobic conditions, which can reduce industrial-scale production costs.
The microbial pathway of butanol biosynthesis is a unique route for the production of a biomass-derived advanced biofuel with high potential to be utilized in place of the fossil fuels. In the present study, Nesterenkonia sp. strain F was applied as a beneficial partner for Clostridium acetobutylicum in “starch-to-butanol process”. The capability of Nesterenkonia sp. strain F in secreting organic solvent-tolerant amylase was utilized for upgrading the yield of solvent, i.e., acetone, butanol, and ethanol (ABE), production under aerobic conditions. Monitoring the amylolytic activity and glucose concentration throughout the co-culture revealed higher amylase activity and glucose concentration in comparison with the single culture. After optimizing the culture conditions with response surface methodology (RSM), 10.6 g/L butanol was produced from untreated potato starch (UPS) with a high yield of 0.23 g/g ABE. To assess the performance of the co-culture at larger scale, the fermentation was conducted in a 5 L fermenter continually aerated with a rate of 0.05 vvm and 150 rpm. This led to production of 9.7 g/L butanol, 5.0 g/L acetone, and 0.3 g/L ethanol with a yield and productivity of 0.20 g/g and 0.21 g/L.h, respectively. Furthermore, ABE production from tannin-containing sorghum grain was improved by about 7-fold.
Rice straw (RS) is one of the lignocellulosic wastes with the highest global production. The main objective of this study was to maximise the butanol production by Clostridium beijerinckii DSM 6422 from RS pretreated by microwave-assisted hydrothermolysis. Two different fermentation strategies were compared: separate hydrolysis and fermentation (SHF, two-step process) and simultaneous saccharification and fermentation (SSF, one-step process). In parallel, the variables that significantly affected the butanol production were screened by using fractional factorial designs. Butanol concentration and productivity at 48 h were, respectively, 8% and 173% higher in SSF than in SHF. A one-step process was more efficient than a two-step process, especially considering the time savings derived from much higher productivity. From these results, SSF was further optimised by response surface methodology with central composite design over the key factors on the butanol production at 48 h: initial pH, enzyme loading and yeast extract concentration. The optimum point yielded a butanol productivity of 0.114 g L⁻¹h⁻¹, with a butanol-biomass ratio of 51 g kg⁻¹ of raw RS (ABE-biomass ratio of 77.0 g kg⁻¹ of raw RS). The parameter with the greatest effect was enzyme loading, with an optimal value of 13.5 FPU g-dw⁻¹. This study showed that microwave-processed RS has great potential as a substrate for the butanol production from ABE fermentation when combining process stages by SSF.
Biobutanol produced by acetone-biobutanol-ethanol (ABE) fermentation process has been revisited in the light of its use as “drop in” liquid biofuel to be blended with gasoline. In this study, renewable feedstock like rice straw, sugarcane bagasse and microalgal hydrolysate were used in ABE fermentation via separate hydrolysis and fermentation. Clostridium acetobutylicum ATCC 824 was used as the fermenting organism. Alkali pretreatment followed by enzymatic hydrolysis was used for rice straw and sugarcane bagasse. In batch fermentation, a biobutanol titer and yield of 9.10 g/L and 0.42 mol/mol glucose (0.17 g biobutanol/g glucose), respectively was obtained from rice straw, while sugarcane bagasse achieved a biobutanol titer and yield of 8.40 g/L and 0.40 mol/mol glucose (0.16 g biobutanol/g glucose), respectively. Higher microalgal biomass loading with 3% acid pretreatment severely inhibited fermentation performance. Unhydrolyzed microalgal biomass at a loading of 180 g/L in ABE fermentation resulted in 4.32 g/L biobutanol and 0.09 g biobutanol/g microalgae as yield. C. acetobutylicum was immobilized in polyvinyl alcohol (PVA) for improving the cell loading in fermentation and protect the cells from biobutanol toxicity. With rice straw hydrolysate as a feedstock and in the absence of yeast extract, a biobutanol titer, yield and productivity of 13.80 g/L, 0.90 g/L/h, and 0.58 mol biobutanol/mol glucose (0.23 g biobutanol/g glucose), respectively were obtained. Hence, rice straw is a potential feedstock for biobutanol production for fuel use.
Acetone, butanol and ethanol (ABE) mixture separation from dilute aqueous fermentation products is an important process for the biofuel industry. Here, we present a novel approach for ABE recovery using microwave induced membrane distillation (MD). Carbon nanotubes (CNTs) and octadecyl amide (ODA) functionalized CNTs were immobilized on membrane surfaces and were used in sweep gas MD separation of ABE. The ABE flux, separation factor and mass transfer coefficient obtained with CNT and CNT-ODA immobilized membranes were remarkably higher than those of the commercial pristine membrane under various experimental conditions. The ABE flux enhancement reached as high as 105, 100 and 375% for the CNIM and 63, 62 and 175% for CNIM-ODA respectively. The ABE flux obtained was nearly ten times higher than that reported previously for pervaporation. The mass transfer coefficient also increased significantly along with a lower activation energy for the modified membranes. Mechanistically speaking, the immobilization of carbon nanotubes on the active membrane layer led to preferential sorption of ABE leading to enhanced separation. This phenomenon has been validated by the reduction of contact angles for the aqueous ABE mixtures on the CNT and CNT-ODA immobilized membranes indicating enhanced interaction of ABE on the membrane surface.
This study aims to evaluate the two-phase anaerobic digestion process of a cassava starch-based polymer, determining the ideal organic load to obtain the best results in terms of removal of solids and production of methane and hydrogen. Two reactors were used: one with an agitation and mixing system for the acidogenic phase, and the other was a tubular reactor for the methanogenic phase, both with ascending flow and semi-continuous feeding, with the effluent from the acidogenic reactor conducted from the methanogenic reactor. The loads were defined as concentrations of 8, 10, 12, and 14 g L⁻¹ (on a wet basis), having HRT of 5 days for the acidogenic reactor and 20 days for the methanogenic. The analysis of the results showed that the concentration of 10 g L⁻¹ had the best results for hydrogen and methane production in acidogenic and methanogenic phases, presenting 19.9 mL gVS⁻¹ and 249.1 mL gVS⁻¹, respectively. This treatment also showed the highest levels of gases in the biogas (43.2 % hydrogen in the acidogenic phase, and 76.6 % methane in the methanogenic phase). In addition, it showed the highest volatile solid removal means, reaching 84.0 % in the methanogenic phase. Thus, the anaerobic biodigestion process in two phases for the degradation of the polymer based on cassava starch presents technical feasibility, with high methane and hydrogen production; and concentrations above 10 g L⁻¹, under the test conditions, cause destabilization in the reactors by the great formation of volatile acids and consequent reduction in the stability of microbiological cultures.
Novel processes for the production of acetone-butanol-ethanol (ABE) from municipal solid waste (MSW) were developed and simulated using Aspen Plus®. In scenario 1, a conventional distillation system was used, while a gas stripping system was coupled with a fermenter in scenario 2. In scenario 3, pervaporation (PV) and gas stripping systems right after the fermentation reactor were applied. Gas stripping increased the total ABE produced while the addition of the PV module decreased the number of distillation columns from 6 to 2 as well as created 6.4% increments in the amount of butanol in comparison with scenario 1. Economical evaluation resulted in having payout periods of 15.9, 4.4, and 2.9 years for scenarios 1 to 3, respectively. These results show that using MSW as an inexpensive sugar-rich feedstock together with gas stripping PV system is a promising solution to overcome the major obstacles in the way of the ABE production.
In this study, an innovative approach is proposed for the integral valorization of all sugars (cellulosic and hemicellulosic) contained in a lignocellulosic residue, as is brewer's spent grain (BSG), through the production of an advanced biofuel such as biobutanol. For this purpose, the whole slurry obtained in the microwave assisted dilute sulfuric acid pretreatment under optimized conditions (147 °C, 2 min and 1.26% H2SO4) at a biomass loading as high as 15% (w/v) was enzymatically hydrolyzed without previous solid-liquid separation and the highly concentrated solution of sugars recovered was fermented to butanol by Clostridium beijerinckii after detoxification with activated charcoal. In this way, all sugars (pentoses and hexoses) contained in BSG could be fermented using a single bioreactor, leading to 11 g/L of butanol and 16 g/L of ABE, which correspond with butanol and ABE yields of 0.21 and 0.32 g/g, respectively. The mass balance revealed then an overall yield of 91 kg butanol/t BSG and 138 kg ABE/t BSG.
This study evaluates the techno-economic feasibility of sophorolipid (SL) production process that co-utilizes food waste, glucose and oleic acid as substrates. Two variables are considered in terms of (a) Plant construction: Purchasing equipment either from the US or Mainland China and (b) Production: to produce SL crystals (about 97% active) or a concentrated SL liquid/syrup (about 78% active). Hence, four scenarios are generated: Scenario I: equipment made in the USA + SL crystals; Scenario II: equipment made in the USA + SL syrup; Scenario III: equipment made in China + SL crystals; Scenario IV: equipment made in China + SL syrup. It is found that all scenarios are economically feasible and Scenario I has the highest net profit. Scenario III has the highest internal rate of return, net present value and the shortest payback period at a 7% discount rate. Finally, comparison of food waste-related techno-economic studies was conducted.
The ingestion of l-ergothioneine (EGT) is thought to provide health benefits. It is also expected that the fermented rice bran or rice with Aspergillus oryzae (A. oryzae) would be EGT-rich and easily available foodstuffs. Based on this concept, a liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method was developed to identify and quantify EGT in the A. oryzae-fermented rice bran and rice. We optimized the derivatization protocol using 2-iodo-N-(8′-quinolinyl)acetamide, which improved the LC retention and ESI-MS/MS sensitivity of EGT. The pretreatment procedure and LC/ESI-MS/MS conditions were also optimized to achieve the sensitive (limit of quantification, 0.080 μg/g), precise (intra- and inter-assay relative standard deviations, ≤ 7.8% and 5.8%, respectively) and accurate (94.9–100.0%) quantification of EGT in the samples. The EGT contents in the fermented rice bran were 176 ± 39 μg/g (mean ± standard deviation, n = 3), which were greater than those in the fermented white rice (59.8 ± 20.4 μg/g) and brown rice (85.5 ± 32.3 μg/g). The EGT in rice bran was enriched 140 times by the fermentation for 45 h. These results revealed that rice bran is a suitable material for making the EGT-rich foodstuffs by the A. oryzae-fermentation.
Microalgal biorefineries have recently emerged as a potentially economically viable option for the co-production of value-added products and fuels, such as biodiesel (via the transesterification of lipids) and biobutanol (via the fermentation of carbohydrates). Whilst microalgal biodiesel has been studied extensively, microalgal biobutanol has received less attention due to the low product yields of the biochemical process from which biobutanol is obtained: the Acetone-Butanol-Ethanol (ABE) fermentation. In this work, we evaluate the potential of a microalgae-based biorefinery by: i) quantifying biobutanol production via ABE fermentation of microalgae (raw and hydrolysate form) using a medium optimised via surface response analysis (SRA) methodology; ii) quantifying biodiesel (fatty acid methyl esthers, FAMEs) production via transesterification of microalgae (raw, hydrolysed, and fermented form). Using SRA-optimised medium, butanol fermentation yields of 10.31% (g g⁻¹ cdw) and 10.07% (g g⁻¹ glucose) were attained by microalgae in raw and hydrolysate form, respectively. Meanwhile, the raw, hydrolysed, and fermented microalgae yielded up to 0.92%, 3.82% and 3.29% (g g⁻¹ cdw) biodiesel, respectively. Results highlight the importance of pre-treatment methods and further support the development of microalgal biorefineries for dual biofuel production.
The production of biofuels such as butanol is usually limited by the availability of inexpensive raw materials and high substrate cost. Using food crops as feedstock in the biorefinery industry has been criticized for its competition with food supply, causing food shortage and increased food prices. In this study, cassava bagasse as an abundant, renewable, and inexpensive byproduct from the cassava starch industry was used for n-butanol production. Cassava bagasse hydrolysate containing mainly glucose was obtained after treatments with dilute acid and enzymes (glucoamylases and cellulases) and then supplemented with corn steep liquor for use as substrate in repeated-batch fermentation with engineered Clostridium tyrobutyricum CtΔack-adhE2 in a fibrous-bed bioreactor. Stable butanol production with high titer (>15.0 g/L), yield (>0.30 g/g), and productivity (~0.3 g/L∙h) was achieved, demonstrating the feasibility of an economically competitive process for n-butanol production from cassava bagasse for industrial application.
Cooked high-amylose rices have slower digestibility, giving nutritional benefits, but inferior eating qualities. Molecular structural mechanisms for this inferior eating quality are found here using structural analysis by size-exclusion chromatography of both the parent starch and starch leached during cooking. All commonly-accepted sensory attributes of cooked rice were characterized by a trained human panel. Hardness, with the strongest negative correlation with panelist preference, was the dominant but not sole factor determining palatability. Hardness was controlled by the amounts of medium and long amylopectin chains and amylose in the starch, and by amylose content and amount of longer amylopectin chains in the leachate. This gives knowledge and understanding of the molecular structural characteristics of starch controlling cooked-rice preference: not just high amylose but also other aspects of molecular structure. This can help rice breeders to target starch-synthesis genes to select slowly digested (healthier) rices with acceptable palatability.
This study proposes a dynamic model that describes key characteristics of fermentative butanol production from glucose and xylose mixtures. The model has 12 parameters and incorporates noncompetitive inhibitory interaction between sugars as well as inhibitions due to high substrate and butanol concentrations. Different pre-growth strategies to achieve co-utilization of sugars were explored together with their effects on fermentation kinetics. Mixed sugar fermentation by the cultures pre-grown on a mixture of glucose and xylose showed a higher endurance to inhibition, a 2-fold increase in butanol production and a 1.5-fold increase in total sugar consumption compared to cultures pre-grown on xylose only. The average squared correlation coefficients (r2) between experimental observations and model predictions were 0.917 and 0.926 for fermentations done by the cultures pre-grown on xylose only, and pre-grown on a mixture of glucose and xylose, respectively. Sensitivity analysis on the model parameters revealed that the growth parameters were the most critical. The proposed model can serve as a basis for modeling of microbial butanol production from lignocellulosic biomass and be applied to other substrates and microorganisms.
A review of the potential feedstock (Agricultural residues ‐ AR and Agro‐food waste ‐ AFW) for the production of second‐generation ethanol and butanol is presented. The maximum biofuel production rate from AR and AFW was estimated based on the feedstock availability rate, the average composition and the biofuel yield reported in the literature. According to our estimations, the contribution of ethanol and butanol to the current European biofuel accounts could be 32% and 23% if traditional pre‐treatments are applied and 40% and 19% if they are produced by innovative pre‐treatments, respectively. Finally, the analysis has been applied to a local scenario (Campania ‐ Italy), in view of a potential decentralized exploitation of AR and AFW.
Pretreatment is an important upstream process that affects the economics of biofuels production from lig-nocellulose. Hydrotropic reagent sodium xylene sulfonate (SXS) was used in this study to treat wheat straw for efficient butanol production. Effects of temperature, time, SXS concentration on pretreatment were evaluated. In addition, a modified SXS pretreatment method with pH adjusted to 3.5 by formic acid was also conducted for efficient wheat straw conversion by removing hemicellulose fraction. Composition analysis, structure characterization , enzymatic hydrolysis and fermentation tests were conducted. The results showed that modified SXS pretreatment can be considered as an efficient method for improving wheat straw conversion efficiency for ABE production. The hexoses and pentoses in the enzymatic hydrolysates can be used by C. acetobutylicum for butanol production with 12.41 g L −1 ABE produced, and the overall ABE yield of 100 g ABE/kg wheat straw was obtained. This study revealed that hydrotropic pretreatment provides an alternative potential to the conventional pretreatment processes for butanol production.
Corn starch is the traditional substrate for butanol production by Clostridium acetobutylicum. However, the production suffers the problems of high substrate price and low sugar utilization yield. Waste P.pastoris semi-solid enriches with carbohydrate/protein and could be potentially used as an alternative substrate. In this study, NaOH was used to treat the waste semi-solid into suspensions. The fermentations were implemented by largely reducing initial starch content, and then adding the suspensions into broth after fermentations entered solventogenesis phase. Using the mixed substrate, final butanol concentrations in a 7 L anaerobic fermentor could reach and stabilize around 9.5–10.5 g/L, which was equivalent to that using 15% pure corn-starch; total sugar utilization yield largely increased from 50% to more than 90%, as disaccharides/trisaccharides were effectively utilized; 53% carbohydrate in the semi-solid was effectively digested which was beneficial for waste amount reduction; 57% expensive corn-starch could be saved.
Techno-economic analysis was conducted to evaluate a food and beverage (F&B) waste valorisation process for sugar syrup production via integrated biorefinery. A comprehensive process model was developed with a capacity of 10 metric tons (MT) hour⁻¹ of food waste and 14 MT hour⁻¹ of beverage waste. Three scenarios were proposed with different types of sugar syrups as the main products: Scenario I) fructose syrup, Scenario II) high fructose syrup-42, and Scenario III) glucose-rich syrup. Mass balance showed conversion yields of 0.24 MT sugar syrups per MT of F&B waste, while lipids (0.07 MT per MT of F&B waste) and insect feed (0.44 MT per MT of F&B waste) were the co-products proposed to be used for other industrial biorefinery processes. All scenarios were observed to be economically self-sustainable with net profit generation (US92-294 million). Along with the net production costs (US443-665 MT⁻¹), the sugar syrups derived from the F&B waste have relatively low minimum selling prices of US157-747 MT⁻¹ at a 5% discount rate. Lastly, sensitivity analysis was performed which found that the prices of sugar syrups were the largest determinants of their profitability. This study proposes a significant techno-economic basis for F&B waste biorefinery, which offers a successful demonstration for food and drink industries adopting these biotechnological processes for the same plant size.
Cellulose, in addition to hemicellulose and lignin, makes the major fraction of lignocellulosic biomass- the only sustainable feedstock to meet the long-term sustainable energy need of the world. Cellulose is soluble in a number of solvents, e.g., concentrated phosphoric acid (CPA), N-methylmorpholine-N-oxide (NMMO), and ionic liquids (ILs), and can be regenerated by an anti-solvent without major derivatization for various applications. For one, the regenerated and much less crystalline cellulose is highly reactive for its biological conversion to sugars, fuels, and chemicals mediated with enzymes and/or microbes. This ability can be used as a core pretreatment step for improved bioprocessing of lignocelluloses. In this comprehensive review, cellulose solvent-based lignocellulosic fractionation technologies for enhanced enzymatic hydrolysis to improve biofuels and renewable chemicals production are reviewed. The first part is focused on the background information of lignocellulosic biomass, lignocellulosic derived biogas, biohydrogen, and ethanol as well as acetone, butanol, and ethanol (ABE) production, and enzymatic hydrolysis. In the second part, the conditions for pretreatments applying CPA, NMMO, and ILs solvents, improvements in enzymatic hydrolysis rates and yields for solids resulting from application of these pretreatments, and the features of lignocellulosic structure affecting the improved bioprocessing have been thoroughly reviewed.
Six conceptual process scenarios for the production of biobutanol from lignocellulosic biomass through acetone‐butanol‐ethanol (ABE) fermentation, using reported data on process performances, were developed with ASPEN Plus® V8.2 software. The six scenarios covered three fermentation strategies, i.e. batch separate hydrolysis and fermentation (SHF), continuous SHF, and batch simultaneous saccharification and fermentation (SSF) integrated with gas stripping (GS). The two downstream processing options considered were double‐effect distillation (DD) and liquid‐liquid extraction and distillation (LLE&D). It was found that the SSF‐GS/DD scenario was the most energy efficient with a liquid fuel efficiency of 24% and an overall efficiency of 31%. This was also the scenario with the best economic outcome, with an internal rate of return (IRR) of 15% and net present value (NPV) of US$387 million. The SSF‐GS/DD scenario was compared to a similar molasses process, based on the product flow rates, and it was found that the molasses process was more energy efficient with a gross energy value (GEV) of 23 MJ kg1 butanol compared to −117 MJ kg1 butanol for the lignocellulosic process. In addition, the molasses‐based process was more profitable with an IRR of 36% compared to 21%. However, the energy requirements for the molasses process were supplied from fossil fuels, whereas for the lignocellulose processes a portion of the feedstock was diverted to provide process energy. Improved environmental performance is therefore associated with the lignocellulosic process. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd
A techno-economic analysis was conducted to validate the commercial viability of commercial-scale lignocellulosic bio-butanol production by pretreatment and hydrolysis using concentrated sulfuric acid, and a continuous fermentation. The process was simulated using Aspen Plus®, and the data was based on the results of laboratory and pilot plant operation, and demonstration plant design. The production cost and minimum butanol selling price (MBSP) for a base case of 40,000 t/y plant capacity and 60 /t in increments of 10 /t in increments of 20,000 t/y), and equity rate (from 20 to 100% in increments of 20%). The MBSP was determined to be 2668 /t when capacity is doubled (from 40,000 t/y to 80,000 t/y). Production cost should be reduced approximately 55% in oder to secure commercial viability. This study suggests R&D and business strategies to enhance the commercial viability of lignocellulosic bio-butanol technology.
A sustainable food waste valorisation process was proposed by designing a plant with a capacity of 10 metric tons (MT) hour⁻¹ of food waste powder with a 20-year lifetime. Three scenarios were proposed with different products: Scenario I) lactic acid, Scenario II) lactide, Scenario, and III) poly(lactic acid) (PLA). Mass balance showed conversion yields of 3.1 MT of 80% lactic acid, 1.7 MT of lactide, and 1.3 MT of poly(lactic acid) from 10 MT of food waste powder. All scenarios were economically feasible, but Scenario I had the highest annual net profits (US234,803,060) and the shortest payback period (5.1 years) at a discount rate of 5%. The minimum selling prices of lactic acid, lactide and poly(lactic acid) were US2073 MT⁻¹ and US$3330 MT⁻¹, respectively. Sensitivity analysis showed that the prices of lactic acid, lactide and poly(lactic acid) were the largest determinants of the profitability in the plant while the sale of by-products (animal feed) was also critical to the plant's economics. This work has cast insights on the techno-economic performance of a sustainable food waste treatment under a decentralised approach in urban areas.
The biodegradable fraction of municipal solid waste (BMSW), dominantly composed of starchy and lignocellulosic materials, has high potential to be used for liquid biofuel production. Hot water or dilute acid treatment at high temperature was utilized for the solubilization or hydrolysis of the starch fraction and pretreatment of the lignocellulosic fraction. The treatment liquor, which was rich in sugars and starch, was evaluated for acetone, butanol, and ethanol (ABE) production by Clostridium acetobutylicum, and it was found that phenolic compounds, especially tannins, critically inhibited the butanol production. To improve ABE production, the extraction of phenolic compounds prior to hot water or dilute acid treatment was evaluated. Among the evaluated extractants, i.e., acetone, ethanol, butanol, and water, ethanol showed the highest amount of tannin extraction, resulting in an 87% reduction in tannin content. Dilute acid treatment of the ethanol extracted BMSW at 140 °C for 60 min resulted in a liquor containing 23 g/L glucose and 41 g/L soluble starch, which was fermented to the highest ABE concentration of 17 g/L with productivity of 0.24 g/L/h. The fermentation of liquor obtained by dilute acid treatment of butanol, acetone, and water-extracted BMSW was accompanied by 9, 6, and 4 g/L ABE production. Even by hot water treatment, the liquor obtained from ethanol extracted BMSW was fermented to the highest ABE concentration of 8 g/L. In addition to the liquor, the pretreated lignocellulosic material was subjected to enzymatic hydrolysis and ABE fermentation, leading to production of 5–6 g/L ABE. This process resulted in the production of 83.9 g butanol, 36.6 g acetone, and 20.8 g ethanol from each kg of BMSW. Moreover, the co-production of ethanol by ABE fermentation reduced concerns about organic extractor loss in the extraction process, which was inescapable in the tannin extraction process.
Increasing worldwide energy consumption and limited availability of fossil fuels propelled the researchers to develop advanced fuels (biobutanol) for its commercial development. In the present work, pea pod waste from vegetable sector was investigated for biobutanol production using C. acetobutylicum B 527 through series of steps viz. compositional analysis, drying study, saccharification, detoxification, and fermentation. Proximate analysis suggested that pea pod waste is rich in holocellulose content with 32.08% of cellulose and 21.12% of hemicellulose on dry basis and hence has a huge potential to be used as carbon source during biobutanol production. In order to enhance storability and subsequent saccharification, drying kinetics of pea pod waste was carried out in varied temperature range (60–120 °C) and the experimental data was simulated by using moisture diffusion control model. Saccharification of pea pod waste samples resulted into total sugar release of 30–48 g/L. Subsequently, 95% phenolics and 30% acetic acid were removed using activated charcoal detoxification. The acetone-butanol-ethanol (ABE) fermentation of detoxified pea pod waste slurries resulted in 4.25–5.94 g/L total solvents with about 50% sugar utilization. Overall, the utilization of pea pod waste will serve as basis for valorization of vegetable waste biomass for ABE production.
Butyl butyrate (BB) is a valuable chemical that can be used as flavor, fragrance, extractant, etc. in various industries. Meanwhile, BB can also be used as a fuel source with excellent compatibility as gasoline, aviation kerosene and diesel components. The conventional industrial production of BB is highly energy-consuming and generates various environmental pollutants. Recently, there have been tremendous interests in producing BB from renewable resources through biological routes. In this study, based on the fermentation using the hyper-butyrate producing strain Clostridium tyrobutyricum ATCC 25755, efficient BB production through in situ esterification was achieved by supplementation of lipase and butanol into the fermentation. Three commercially available lipases were assessed and the one from Candida sp. (recombinant, expressed in Aspergillus niger) was identified with highest catalytic activity for BB production. Various conditions that might affect BB production in the fermentation have been further evaluated, including the extractant type, enzyme loading, agitation, pH, and butanol supplementation strategy. Under the optimized conditions (5.0 g L(-1) of enzyme loading, pH at 5.5, butanol kept at 10.0 g/L), 34.7 g L(-1) BB was obtained with complete consumption of 50 g L(-1) glucose as the starting substrate. To our best knowledge, the BB production achieved in this study is the highest among the ever reported from the batch fermentation process. Our results demonstrated an excellent biological platform for renewable BB production from low-value carbon sources. This article is protected by copyright. All rights reserved.
This study aims to propose a biorefinery pretreatment technology for the bioconversion of sugarcane bagasse (SB) into biofuels and N-fertilizers. Performance of diluted acid (DA), aqueous ammonia (AA), oxidate ammonolysis (OA) and the combined DA with AA or OA were compared in SB pretreatment by enzymatic hydrolysis, structural characterization and acetone-butanol-ethanol (ABE) fermentation. Results indicated that DA-OA pretreatment improves the digestibility of SB by sufficiently hydrolyzing hemicellulose into fermentable monosaccharides and oxidating lignin into soluble N-fertilizer with high nitrogen content (11.25%) and low C/N ratio (3.39). The enzymatic hydrolysates from DA-OA pretreated SB mainly composed of glucose was more suitable for the production of ABE solvents than the enzymatic hydrolysates from OA pretreated SB containing high ratio of xylose. The fermentation of enzymatic hydrolysates from DA-OA pretreated SB produced 12.12 g/L ABE in 120 h. These results suggested that SB could be utilized efficient, economic, and environmental by DA-OA pretreatment.
The present study makes a consistent and comparative assessment of the overall exergy, financial and environmental efficiencies of two biomass-to-fuels (utilised in internal combustion engines with spark ignition) conversion options and based on this result, gives a recommendation as to which of the options assessed is most desirable. These options are methanol to gasoline (MTG) and biochemical butanol, while as feedstock the solid residue of sugar cane, bagasse, was considered. For the work presented in this study, a base case scenario has first been developed for each pathway by employing either Aspen Plus or SuperPro Designer (as simulators) to perform mass and energy balance calculations while Matlab software has been used for modelling the reaction kinetics of each process. Based on the simulations, thermodynamic (exergy analysis), economic (financial and risk analysis) and environmental (CO2 emissions) evaluations were carried out. Afterwards, sensitivity analyses have been performed in order to define the key parameters of each conversion route. Exergy and economic analysis favour the gasoline production while butanol produces less CO2 emissions. The study concludes with multicriteria decision analysis (MCDA) where each process is issued a score according to the investigated criteria. This makes it possible for the investigated procedures to be compared on the same basis. According to this analysis, the production of gasoline achieves a higher overall score than butanol production, i.e. 97% and 90% respectively.
Biobutanol has comparable fuel properties to gasoline; however, its commercial production through acetone-butanol-ethanol (ABE) fermentation from lignocellulosic biomass is still encumbering due to low product yield, energy extensive recovery method and butanol toxicity to microbes. Recent development of simultaneous saccharification, vacuum fermentation and recovery technique has potentials to reduce these problems and improve butanol yield, which has gained significant attention as an emerging alternative way for ABE fermentation. Thus, the main objective of this study was to assess the techno-economic feasibility of commercial-scale ABE fermentation for a 113.4 million liter/year (30 million gallon/year) butanol production and identify operational targets for process improvement. Commercial dilute sulfuric acid pretreatment and corn stover feedstock were used in this study. Experimental data on the pretreatment of corn stover, and the ABE fermentation and recovery were gathered from recent publications. Process modeling and economic analyses were performed using a modeling software-SuperPro Designer. Estimated butanol production costs were 0.6/liter, which is competitive with current gasoline price; however, achieving these targets will require further research and development efforts on the ABE fermentation.
The feedstock of the Acetone-Butanol-Ethanol (ABE) fermentation is a key issue for the economic success of the biotechnological route to produce biobutanol. Residues from agro-alimentary industries are particularly interesting as renewable substrates for the ABE fermentation because they are abundant and un-competitive with food sources. The residues are also a pressing issue for industries because more than 50% of the processed feedstocks are discharged and their disposal is particularly expensive. However, the high fraction of sugars of the residues makes them a promising interesting feedstock for the production of butanol.
This contribution is about the characterization of the ABE fermentation by Clostridium acetobutylicum DSM 792 using sugars from fruit peels. Apple and pear peel extracts were tested as substrate for the fermentation. Batch tests were carried out under a wide interval of peels to water mass ratio. The conversion process was characterized in terms of metabolites and cell production, sugars conversion, specific rate of butanol production and of sugar consumption, butanol and cell yields.
The fermentation tests with feedstock peels to water mass ratios lower than 1/6 were characterized by total sugar conversion and low butanol concentration (
The development of renewable fuels has achieved enormous progress motivated by the rapid decline in petroleum resources and their oscillating price. After a wave of interest in bioethanol and biodiesel, biobutanol has been intensely investigated over the last decade and is considered a suitable renewable fuel. Biobutanol is most often produced through the Acetone-Butanol-Ethanol (ABE) bacterial fermentation process. This process is plagued, however, with high recovery costs because of the low final butanol concentration (∼0.01 g/g, 1 wt%) due to product inhibition on the microorganisms. To partly alleviate this problem and increase productivity, in situ butanol recovery techniques from the fermentation broth were proposed. These integrated methods increase the final concentration of butanol, and as a result improve the separation efficiency of the process. This paper compares the economic feasibility of a large-scale continuous ABE fermentation process with and without integrating a vacuum separation unit. It is illustrated that based on the current market price of butanol, only the integrated fermentation process is economically feasible for discount rates up to ∼45%. Adding an in situ butanol recovery technique made this process profitable compared to the conventional fermentation process analyzed under two different scenarios: constant fermenter volume and constant butanol production rate. The net present values (NPV) of the conventional process were found to be negative for both scenarios, whereas the integrated vacuum process had a NPV of US$ 87 000 000 at the end of 10 years of operation based on a discount rate of 10%. This article is protected by copyright. All rights reserved
In this study, the techno-economic evaluation of a combined bioprocess based on solid state fermentation for fermentative hydrogen production from food waste was carried out. The hydrogen production plant was assumed to be built in Hangzhou and designed for converting 3 ton food waste per day into hydrogen. The total capital cost (TCC) and the annual production cost (APC) were US88298.1/year, respectively. The overall revenue after the tax was US$146473.6/year. The return on investment (ROI), payback period (PBP) and internal rate of return (IRR) of the plant were 26.75%, 5years and 24.07%, respectively. The results exhibited that the combined bioprocess for hydrogen production from food waste was feasible. This is an important study for attracting investment and industrialization interest for hydrogen production from food waste in the industrial scale.
A new solvent-producing Clostridium has been isolated from soil used in intensive rice cultivation. The 16S rRNA analysis of the isolate indicates that it is closely related to Clostridium acetobutylicum, with a sequence identity of 96%. The new isolate, named C. acetobutylicum YM1, produces biobutanol from multiple carbon sources, including glucose, fructose, xylose, arabinose, glycerol, lactose, cellobiose, mannitol, maltose, galactose, sucrose and mannose. This isolate can also utilize polysaccharides such as starch and carboxylmethyl cellulose (CMC) for the production of biobutanol. The ability of isolate YM1 to produce biobutanol from agro-industrial wastes was also evaluated for rice bran, de-oiled rice bran, palm oil mill effluent and palm kernel cake. The highest concentration of biobutanol (7.27 g/L) was obtained from the fermentation medium containing 2% (w/v) fructose, with a total acetone–butanol–ethanol (ABE) concentration of 10.23 g/L. The ability of isolate YM1 to produce biobutanol from various carbon sources and agro-wastes indicates the promise of the use of this isolate for the production of biobutanol, a renewable energy resource, from readily available renewable feedstocks.
The Acetone-Butanol-Ethanol (ABE) fermentation is receiving renewed interest as a way to upgrade renewable resources for the production of products with high added value as chemicals and fuels. Main pre-requisites of fermentation feedstocks are abundance and un-competitiveness with food sources and they are fulfilled by lignocellulosic biomass. This contribution reports about the characterization of the ABE fermentation by Clostridium acetobutylicum DSM 792 adopting sugars representative for hydrolysis products of lignocellulosic biomass: glucose, mannose, arabinose, and xylose. Batch fermentation tests with binary mixtures of sugars were performed to assess the possible crossed/coupled effects of the investigated sugars on the fermentation performances. The mass ratio of sugars in binary mixture tests was set at 1:1 and the total initial concentration was set at 60 g/L. The conversion process was characterized as a function of the time in terms of biomass, acids, and solvents concentrations as well as of pH and total organic compounds. The simultaneously fermentation of binary mixture of sugars enhances the conversion of the investigated sugars into butanol/solvents. The xylose fermentation appears to be improved when it is mixed with the investigated sugars.