Development and economic analysis of bioethanol production facilities using lignocellulosic biomass.

An integrated process for bioethanol production from Miscanthus sacchariflorus was used to construct a bench-scale plant constructed and an economic analysis was carried out to investigate the feasibility of its application to a commercial plant. The bench-scale plant was operated for 1 month and an economic analysis and sensitivity analysis was performed on the data acquired. In this study, 100,000 kL of bioethanol could be produced annually from 606,061 tons of M. sacchariflorus and the production cost was calculated to be US$1.76/L. However, the by-products of this process such as xylose molasses and lignin can be sold or used as a heat source, which can decrease the ethanol production costs. Therefore, the final ethanol production cost was calculated to be US$1.31/L, and is considerably influenced by the enzyme cost. The results and data obtained should contribute to the development of a commercial-scale lignocellulosic bioethanol plant.

Utilization of by-products derived from bioethanol production process for cost-effective production of lactic acid.

The by-products of bioethanol production such as thin stillage (TS) and condensed distillers solubles (CDS) were used as a potential nitrogen source for economical production of lactic acid. The effect of those by-products and their concentrations on lactic acid fermentation were investigated using Lactobacillus paracasei CHB2121. Approximately, 6.7 g/L of yeast extract at a carbon source to nitrogen source ratio of 15 was required to produce 90 g/L of lactic acid in the medium containing 100 g/L of glucose. Batch fermentation of TS medium resulted in 90 g/L of lactic acid after 48 h, and the medium containing 10 % CDS resulted in 95 g/L of lactic acid after 44 h. Therefore, TS and CDS could be considered as potential alternative fermentation medium for the economical production of lactic acid. Furthermore, lactic acid fermentation was performed using only cassava and CDS for commercial production of lactic acid. The volumetric productivity of lactic acid [2.94 g/(L·h)] was 37 % higher than the productivity obtained from the medium with glucose and CDS.

Pretreatment solution recycling and high-concentration output for economical production of bioethanol.

The purpose of this study was to enhance the economic efficiency of producing bioethanol. Pretreatment solution recycling is expected to increase economic efficiency by reducing the cost of pretreatment and the amount of wastewater. In addition, the production of high-concentration bioethanol could increase economic efficiency by reducing the energy cost of distillation. The pretreatment conditions were 95 °C, 0.72 M NaOH, 80 rpm twin-screw speed, and flow rate of 90 mL/min at 18 g/min of raw biomass feeding for pretreatment solution recycling. The pretreatment with NaOH solution recycling was conducted five times. All of the components and the pretreatment efficiency were similar, despite reuse. In addition, we developed a continuous biomass feeding system for production of high-concentration bioethanol. Using this reactor, the bioethanol productivity was investigated using various pretreated biomass feeding rates in a simultaneous saccharification and fermentation (SSF) process. The maximum ethanol concentration, yield, and productivity were 74.5 g/L, 89.5%, and 1.4 g/L h, respectively, at a pretreated biomass loading of approximately 25% (w/v) with an enzyme dosage of 30 FPU g/cellulose. The results presented here constitute an important contribution toward the production of bioethanol from Miscanthus.

Repeated-batch fermentation using flocculent hybrid, Saccharomyces cerevisiae CHFY0321 for efficient production of bioethanol.

In this study, the repeated-batch fermentation of liquefied cassava medium using the flocculent hybrid Saccharomyces cerevisiae CHFY0321 was investigated for semicontinuous, high-throughput production of bioethanol. Cassava medium was selected due to the industrial requirement for a cheap starchy substrate. Fermentations were performed by simultaneous saccharification and fermentation (SSF) with a set of ten batches successfully completing a series within the repeated fermentation process. In addition, pH of the culture medium was not controlled to simplify ethanol production for future use in industry. Optimal recycling volume was found to be 5%. Volumetric productivity, final ethanol concentration, and ethanol yield were measured at 3.34 g l(-1) h(-1), 84.5 g l(-1), and 90.7%, respectively. Cell recycling (24.5 g DCW l(-1)) resulted in 1.8-fold decrease in fermentation time (24 h) and 1.8-fold increase in volumetric productivity compared with the ordinary batch fermentation. Therefore, repeated-batch SSF using flocculent CHFY0321 demonstrates the possibility of cost-effective bioethanol production by eliminating additional saccharification and inoculation steps.