This study investigated the production of d-lactic acid from unutilized sugarcane bagasse using steam explosion pretreatment. The optimal steam pressure for a steaming time of 5?min was determined. The steam-exploded sugarcane bagasse was hydrolyzed using cellulase (Meicelase) and then the hydrolyzate was subjected to fermentation substrate. By enzymatic saccharification using Meicelase, the highest recovery of glucose from raw bagasse, 73.7?%, was obtained at a steam pressure of 20?atm. For extracted residue with water after steam explosion, the glucose recovery increased up to 94.9?% at a steam pressure of 20?atm. These results showed that washing with water is effective in removing enzymatic reaction inhibitors. After steam pretreatment (steam pressure of 20?atm), d-lactic acid was produced by Lactobacillus delbrueckii NBRC 3534 from the enzymatic hydrolyzate of steam-exploded bagasse and washed residue. The conversion rate of d-lactic acid obtained from the glucose concentration was 66.6?% for the hydrolyzate of steam-exploded bagasse without washing with water and 90.0?% for that derived from the extracted residue with water after steam explosion. These results also demonstrated that the hydrolyzate of steam-exploded bagasse (without washing with water) contains fermentation inhibitors and washing with water can remove them. 相似文献
Three acid-producing strains, AFB-1, AFB-2 and AFB-3, were isolated during this study, and their roles in anaerobic digestion of waste activated sludge (WAS) were evaluated. Data of 16S rRNA method showed that AFB-1 and AFB-2 were Bacillus coagulans, and AFB-3 was Escherichia coli. The removal in terms of volatile solids (VS) and total chemical oxygen demand (TCOD) was maximized at 42.7% and 44.7% by inoculating Bacillus coagulans AFB-1. Besides, the optimal inoculum concentration of Bacillus coagulans AFB-1 was 30% (v/v). Solubilization degree experiments indicated that solubilization ratios (SR) of WAS reached 20.8%±2.2%, 17.7%±1.48%, and 11.1%±1.53%. Volatile fatty acids (VFAs) concentrations and compositions were also explored with a gas chromatograph. The results showed that VFAs improved by 98.5%, 53.0% and 11.6% than those of the control, respectively. Biochemical methane potential (BMP) experiments revealed that biogas production increased by 90.7% and 75.3% when inoculating with Bacillus coagulans AFB-1 and AFB-2. These results confirmed that the isolated acid-producing bacteria, especially Bacillus coagulans, was a good candidate for anaerobic digestion of WAS.
Environmental Science and Pollution Research - Cadmium (Cd) pollution has led to a serious deterioration in soil quality, plant growth, and human health. Therefore, restoration of soil quality is... 相似文献
Environmental Science and Pollution Research - Biological treatment in wastewater treatment plants releases high amounts of pathogenic bioaerosols. Quantitative microbial risk assessment is a... 相似文献