Optimization of very high gravity fermentation process for ethanol production from industrial sugar beet syrup

In order to reduce production costs and environmental impact of bioethanol from sugar beet low purity syrup 2, an intensification of the industrial alcoholic fermentation carried out by Saccharomyces cerevisiae is necessary. Two fermentation processes were tested: multi-stage batch and fed-batch fermentations with different operating conditions. It was established that the fed-batch process was the most efficient to reach the highest ethanol concentration. This process allowed to minimize both growth and ethanol production inhibitions by high sugar concentrations or ethanol. Thus, a good management of the operating conditions (initial volume and feeding rate) could produce 15.2% (v/v) ethanol in 53 h without residual sucrose and with an ethanol productivity of 2.3 g L h⁻¹.     

Reduction of irreversibility generation in sugar and ethanol production from sugarcane

Sugarcane is one of the most important industries of the Brazilian economy, and its main products are sugar and ethanol. Most of the industrial plants produce both products in an integrated process, in which the sugarcane bagasse is a by-product that can be used as a fuel in the cogeneration system. The bagasse is used as the only fuel of the plant, supplying all energy required for the process, and also producing electricity surplus that may be sold to the grid. In this paper, exergy analysis is used to assess an integrated sugar and ethanol plant with its cogeneration system. The plant was divided into eight sub-systems to evaluate the irreversibility generation in each separately. Data from typical sugarcane factories in Brazil, which produce sugar and ethanol, were used in the process simulation. The analysis has shown that the sub-systems with the highest contribution for the total irreversibility generation of the plant were co-generation, juice extraction and fermentation. Some improvements are proposed, including process thermal integration and the introduction of more efficient equipments for prime mover and steam and electricity generation. The analysis indicated that the total irreversibility could be reduced by 10% should those changes be implemented.     

Research on ethanol production and use from sugar beet in Turkey

Emissions of greenhouse gases such as CO₂, CO, CH₄ and NO_X from fossil fuel use are implicated in climate change. The use of bioethanol is one means to reduce fossil fuel use and emissions of greenhouse gases. This study investigated research to produce ethanol from sugar beet and use as fuel in Turkey. The calculated demand for bioethanol amounted to some 220,000 m³ where a 5% ethanol mix in petrol was used. Turkey has the potential to produce 30 million ton of sugar beet, which is sufficient to meet the bioethanol demand.     

Optimizing acid-hydrolysis: a critical step for production of ethanol from mixed wood chips

Ethanol can be produced from renewable lignocellulosic materials such as various types of natural woods. The cellulose contents of wood can be converted to ethanol in a two-step process where acid-hydrolysis converts cellulose to glucose sugars by hydrolysis (saccharification) and the resulting sugars can be converted to ethanol by fermentation. The main challenge of producing fuel ethanol from renewable lignocellulosic biomass through acid-hydrolysis and fermentation is overcoming the cost-limiting factors associated with various stages of this technology. In this study, sugar recovery rates from a mixture of wood chips were investigated through three sets of acid-hydrolysis experiments. Wood chips were sorted to include equal ratios (by weight) of softwood and hardwood. Acid concentration and the heating period were the two main factors affecting dextrose yields. It was found that with the use of 26% by weight sulfuric acid, highest dextrose yields could be reached within $\text{2}\text{h}$ of heating time. This corresponds to overall conversion efficiency of mixed wood chip cellulose to dextrose in the range of 78–82% based on theoretical values.     

A model for industrial production of fuel grade ethanol from sugar beets

In this work we describe a model for industrial production of low cost ethanol from sugar beets. Care is taken to cover the energy needs of the factory in part by using dry pulp as fuel and in part by solar energy, using suitable solar collectors. Also, care is taken for recovery of rejected energy of vinasse, and we propose the use of one distillation column, instead of three column distillation plants which are used for the production of pure ethanol. A method of high fermentation rate, for reduction of cost, is proposed, and the rejected yeast per day from Laval separators. is processed as an animal protein food (8 kg pressed yeast per 1001 spirit). The mass and energy balance is given and a cost analysis of spirit production in current prices. This cost is 25.0 Dr or $0.50 per 1 (1$ - 50 Dr).     

Exergy analysis of the sugar production process from sugar beets

The exergy analysis of chemical processes is a powerful tool for process optimization, taking into account both ecological and economical restrictions. This study deals with the application of exergy analysis to the industrial process of production of white refined sugar beets. Energy and exergy band diagrams are presented. The exergetic performance of the process is calculated. The locations and magnitudes of exergy losses are determined and possible improvements are discussed. © 1998 John Wiley & Sons, Ltd.     

Optimization of ethanol production from high dry matter liquefied dry sweet sorghum stalks

The ability of sweet sorghum to be utilized as feedstock for ethanol production at high initial dry material concentration was investigated. Sweet sorghum, after being dried, was liquefacted employing commercial cellulase solution Celluclast^® 1.5L, in order submerged fermentation to be permitted under high-solids concentrations. The presence of a separate enzymatic liquefaction step at 350 kg m⁻³ initial DM enhanced both ethanol production and productivity by 29.76% and 250%, respectively. Response surface methodology, based on the central composite design was applied to explore the combined effect of liquefaction duration and enzyme loading in order liquefaction conditions to be optimized. When the optimum conditions were tested using an enzyme load of 8.32 FPU g⁻¹ of dry material for 8.6 h at 50 °C, high productivity (3.0 kg m⁻³ h⁻¹) and final ethanol production (62.5 kg m⁻³) were achieved.     

Optimization of microwave pretreatment on wheat straw for ethanol production

An orthogonal design (L₉(3⁴)) was used to optimize the microwave pretreatment on wheat straw for ethanol production. The orthogonal analysis was done based on the results obtained from the nine pretreatments. The effect of four factors including the ratio of biomass to NaOH solution, pretreatment time, microwave power, and the concentration of NaOH solution with three different levels on the chemical composition, cellulose/hemicellulose recoveries and ethanol concentration was investigated. According to the orthogonal analysis, pretreatment with the ratio of biomass to liquid at 80 g kg⁻¹, the NaOH concentration of 10 kg m⁻³, the microwave power of 1000 W for 15 min was confirmed to be the optimal condition. The ethanol yield was 148.93 g kg⁻¹ wheat straw at this condition, much higher than that from the untreated material which was only 26.78 g kg⁻¹.     

木质纤维素制取燃料乙醇菌种的研究

目前,随着石油资源的日益枯竭,寻求一种廉价的、清洁的、可再生的新型能源成为各国能源领域科研人员的一项重要任务.乙醇作为一种工业燃料,具有许多优点,利用生物质制取燃料乙醇技术,越来越受到人们的广泛关注.文章报道了国内外近年来利用木质纤维素稀酸水解液制取燃料乙醇的菌种的研究现状,主要包括木质纤维素稀酸水解液乙醇发酵的酵母菌、细菌及基因重组菌的菌种构建等.     

The sustainability of ethanol production from sugarcane

The rapid expansion of ethanol production from sugarcane in Brazil has raised a number of questions regarding its negative consequences and sustainability. Positive impacts are the elimination of lead compounds from gasoline and the reduction of noxious emissions. There is also the reduction of CO₂ emissions, since sugarcane ethanol requires only a small amount of fossil fuels for its production, being thus a renewable fuel. These positive impacts are particularly noticeable in the air quality improvement of metropolitan areas but also in rural areas where mechanized harvesting of green cane is being introduced, eliminating the burning of sugarcane. Negative impacts such as future large-scale ethanol production from sugarcane might lead to the destruction or damage of high-biodiversity areas, deforestation, degradation or damaging of soils through the use of chemicals and soil decarbonization, water resources contamination or depletion, competition between food and fuel production decreasing food security and a worsening of labor conditions on the fields. These questions are discussed here, with the purpose of clarifying the sustainability aspects of ethanol production from sugarcane mainly in São Paulo State, where more than 60% of Brazil's sugarcane plantations are located and are responsible for 62% of ethanol production.     

Optimization of acidic hydrolysis conditions of rice husk for fermentable sugar production

Lignocellulosic biomass (LSB) is the most abundantly available renewable source in the world. Rice husk (RH) is also one of the LSB. In this study, the optimization of dilute acid hydrolysis conditions of RH by using one-factor-at-a-time method was performed. The optimum hydrolysis conditions of RH were determined as 131.04°C, 1:10.28 (w/v) of solid:liquid ratio, 1.47% (w/v) of acid ratio and 24.05 min, which yielded as 25.52 g/L of fermentable sugar concentration. Furthermore, the chemical composition of hydrolysate was also examined and the levels of phenolics, 5-hydroxymethylfurfural (HMF), acetate, glucose, and fructose+xylose were found as 0.89, 0, 3.27, 2.10, and 13.80 g/L, respectively. Accordingly, RH can be utilized as a favorable feedstock for the production of value-added products.     

Combined production of sugar, ethanol and electricity: Thermoeconomic and environmental analysis and optimization

Many works have shown the potential of the Brazilian sugarcane industry as an electricity supplier. However, few studies have studied how this potential could be achieved without jeopardizing the production of sugar and ethanol. Also, the impact of modifications in the cogeneration plant on the costs of production of sugar and ethanol has not been evaluated. This paper presents an approach to the problem of exergy optimization of cogeneration systems in sugarcane mills. A general model to the sugar and ethanol production processes is developed based on data supplied by a real plant, and an exergy analysis is performed. A discussion is made about the variables that most affect the performance of the processes. Then, a procedure is presented to evaluate modifications in the cogeneration system and in the process, and their impact on the production costs of sugar, ethanol and electricity. Furthermore, a discussion on the renewability of processes is made based on an exergy index of renewability. As a general conclusion, besides adding a new revenue to the mill, the generation of excess electricity improves the exergo-environmental performance of the mill as a whole.     

Optimization of ethanol production from sweet sorghum (Sorghum bicolor) juice using response surface methodology

Sweet sorghum juice was fermented into ethanol using Saccharomyces cerevisiae (ATCC 24858). Factorial experimental design, regression analysis and response surface method were used to analyze the effects of the process parameters including juice solid concentration from 6.5 to 26% (by mass), yeast load from 0.5 g L⁻¹ to 2 g L⁻¹ and fermentation temperature from 30 °C to 40 °C on the ethanol yield, final ethanol concentration and fermentation kinetics. The fermentation temperature, which had no significant effect on the ethanol yield and final ethanol concentration, could be set at 35 °C to achieve the maximum fermentation rate. The yeast load, which had no significant effect on the final ethanol concentration and fermentation rate, could be set at 1 g L⁻¹ to achieve the maximum ethanol yield. The juice solid concentration had significant inverse effects on the ethanol yield and final ethanol concentration but a slight effect on the fermentation rate. The raw juice at a solid concentration of 13% (by mass) could be directly used during fermentation. At the fermentation temperature of 35 °C, yeast solid concentration of 1 g L⁻¹ and juice solid concentration of 13%, the predicted ethanol yield was 101.1% and the predicted final ethanol concentration was 49.48 g L⁻¹ after 72 h fermentation. Under this fermentation condition, the modified Gompertz's equation could be used to predict the fermentation kinetics. The predicted maximum ethanol generation rate was 2.37 g L⁻¹ h⁻¹.     

Biohydrogen production by extracted fermentation from sugar beet

In the study, the production of biohydrogen by extracted fermentation from sugar beet was evaluated. Effects of initial amount of sugar beet, biomass and particle size of sugar beet on biohydrogen formation were investigated. The hydrogen (H₂) gas was predicted to be 78.6 mL at initial dry weight of sugar beet 24.6 g L^?1 and H₂ yield was calculated as 81.9 mLH₂ g^?1TOC while biomass concentration (1 g L^?1) and particle size (0.3 cm) were constant. The peak H₂ gas volume was predicted to be 139.9 mL at the low particle size of 0.1 cm. Hydrogen gas production potential was predicted as 143.6 mL h^?1. The peak value of 197.9 mLH₂ g^?1TOC was obtained with particle size of 0.1 cm when dry weight of sugar beet and initial amount of biomass was kept constant at 24.6 g L^?1 and 1 g L^?1, respectively.     

Sequestration of fermentation CO2 from ethanol production

Renewable energy from biomass is conventionally thought to avoid emissions of the greenhouse gas CO₂ by replacing the roles of fossil fuels. We show that if the off-gases produced during the fermentation of sugars to fuel–ethanol were captured and, for example, injected deep underground to keep them from the atmosphere, then the production of ethanol could lead to the net removal of CO₂ from the atmosphere in addition to avoiding gasoline-related CO₂ emissions by using the ethanol as a transportation fuel. We give estimates of net CO₂ emissions for current systems for the production of fuel–ethanol, these systems modified to sequester fermentation CO₂, and gasoline-related CO₂ emission offsets. We consider future developments that might affect the scope and economic feasibility of the sequestration of fermentation CO₂.     

Optimization of media conditions for the production of ethanol from sweet sorghum juice by immobilized Saccharomyces cerevisiae

In order to obtain high ethanol yield and fermentation rate, response surface methodology (RSM) was employed to study the effect of culture medium on the ethanol productivity from stalk juice of sweet sorghum by immobilized yeast. A 2³ central composite design (CCD) was chosen to explain the combined effects of the medium constituents, viz. nitrogen (adjusted by adding (NH₄)₂SO₄), phosphorus (adjusted by adding KH₂PO₄), and pH. A mathematical correlation about the influence of the nitrogen, phosphorus, and pH on the ethanol productivity was established. It predicted that the maximum ethanol production rate (119.12 g/l h) was observed for a medium consisting of 0.77 g/l phosphorus, 2.15 g/l nitrogen, and pH = 6.39. Under this condition, the ethanol fermentation rate was 122.85 g/l h.     

基于灰色关联和层次分析的家用热水器方案优化

综合考虑经济、环保、节能、可靠性等指标进行家用热水器方案的选择.根据灰色系统关联分析法和层次分析法原理,建立了评价分析的数学模型;对郑州地区三口之家的热水器利用方案进行了分析.找到了综合最优方案.通过客观地选择评价指标和权重系数,提高了家用热水器方案选择的全面性和科学性.     

Screening for sugar and ethanol processing characteristics from anatomical fractions of wheat stover

Due to concerns with stover collection systems, soil sustainability, and processing costs to produce ethanol, there are opportunities to investigate the optimal plant fractions to collect. Wheat stover fractions were separated by hand and analyzed for glucan, xylan, acid-soluble lignin, acid-insoluble lignin, and ash composition. Internodes had the highest glucan content (38.2% zero percent moisture basis) and the other fractions varied between 29.9% and 33.4%. The stover fractions were pretreated with either 0%, 0.4%, or 0.8% NaOH for 2 h at room temperature, washed, autoclaved, and saccharified. In addition, acid pretreated samples underwent simultaneous saccharification and fermentation (SSF) to ethanol. In general, the acid and alkaline pretreatments produced similar trends with leaves requiring very little pretreatment to achieve high conversion rates (greater than 80%). Chaff responded very well to pretreatment and high conversion efficiencies resulted when pretreated under alkaline or acidic conditions. Nodes and internodes were more recalcitrant than the other anatomical fractions. Pretreatment with 0.8% sulfuric acid (0.24 g sulfuric acid/g biomass) did not result in a significantly higher conversion of glucan to ethanol as the native material. Pretreatment with 0.8% NaOH (0.06 g NaOH/g biomass) at room temperature for 2 h resulted in high conversion efficiencies for all plant fractions, greater than 73% of the available glucan. These differences in pretreatment susceptibilities suggest that a biomass collection system that removes specific portions of wheat stover could result in significant differences in ethanol production costs.