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To improve sugar yields from wheat straw (WS), response surface methodology (RSM) was adopted to optimize potassium hydroxide combined urea pretreatment and enzymatic hydrolysis of WS. Glucose and xylose yields from the pretreated WS were used as responses during the whole optimization. Potassium hydroxide concentration, time and temperature during pretreatment were found to have significant effects on sugar yields. Sugar yields could be enhanced while WS was pretreated using 45 g/L potassium hydroxide solution containing 15 g/L urea with solid to liquid ratio of 1:5 (g/mL) at 74.0 °C for 50 min. Cellulose recovery, hemicellulose recovery, and lignin removal after optimization were 98.1%, 72.6%, and 75.8%, respectively. In addition, enzyme loading, biomass loading, and reaction time during enzymatic hydrolysis also had significant effects on sugar yields. Maximal yields of glucose (610.25 mg/gds, miligram per gram dry substrate) and xylose (221.26 mg/gds) could be achieved while hydrolysis was carried out at 50 °C for 32.8 h with 141 g/L of biomass loading, 8.1 FPU/gds (filter paper activity unit per gram dry substrate) of enzyme loading and 0.4% (w/v) of polysorbate 80. The corresponding cellulose conversion and hemicellulose conversion were 97.2% and 90.4%, respectively. [ABSTRACT FROM AUTHOR]

Solvent-producing Clostridium acetobutylicum was purified and used in an acetone-butanol-ethanol (ABE) fermentation process. The objective of this study is to design a fermentation medium for the synthesis of butanol and determine the ideal glucose concentration for appropriate microbe ingestion. The fermentation medium was incubated at 37 °C for up to 90 h before inoculation while being sparged with nitrogen gas under anaerobic conditions. Based on the optical density of fermentation media, the growth rate was also monitored. At 60 g/L of glucose, which was the optimum condition for fermentation, the process followed a log phase pattern until the death phase, with the largest growth taking place between 10 h and 50 h after incubation. The C. acetobutylicum steadily consumed the glucose content, reaching its maximal consumption with only around 12 g/L remaining. In contrast to acetone and ethanol, which produced the highest concentrations at 6.4 g/L and 5.2 g/L, respectively, butanol productions were seen appropriately, with the greatest concentration yielding 11.2 g/L of butanol. This shows that C. acetobutylicum expressed its active metabolism for up to 60 g/L and further increase of glucose content will deteriorate the performance of butanol production. [ABSTRACT FROM AUTHOR]

The preparation of bio-butanol from corn starch requires saccharification and fermentation processes. In view of the fact that the pH value at the later stage of fermentation is applicable to the enzymatic hydrolysis of glucoamylase, the effects of simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) were compared in this paper. 11.2 g/L butanol and 21.5 g/L total solvent could be obtained by the SSF process, while the yield was 9.74 g/L butanol and 17.2 g/L total solvent in the SHF process. The SSF process required a shorter overall process time (120 h) than the SHF process (144 h) and resulted in a large increase of 38.9% in butanol productivity (2.25 g/Ld for SSF compared to 1.62 g/Ld for SHF). These results show that the application of SSF can reduce the fermentation overall time, simplify the fermentation process, and reduce equipment investment and operating costs. [ABSTRACT FROM AUTHOR]

This study investigated the optimal yeast strains for producing single cell protein based on waste sugar beet pulp (SBP) under various biomass loads. All tested strains were capable of growing on the waste biomass. Candida utilis and Saccharomyces cerevisiae Ethanol Red produced the greatest increase in protein on fresh SBP (ΔN 1.84%). Scheffersomyces stipitis (ΔN 2.27%) provided the highest increase on dried SBP. All tested strains showed significant assimilation of nitrogenous compounds. Based on the crude fiber content after fermentation, the largest reduction in fiber occurred with Candida utilis R6 (10.5%) on fresh SBP, and Yarrowia lipolytica (13.1%) on dried SBP. These results demonstrate the potential of SBP as a substrate for the production of single cell protein and highlight the importance of selecting the appropriate strains to optimize the process. [ABSTRACT FROM AUTHOR]

In traditional pulping, black liquor is burned in an alkali recovery system to produce energy. According to the integrated forest biorefinery (IFBR) concept, hemicellulose is partially pre-extracted prior to pulp production to generate value-added products. Corn stalks have a remarkable carbohydrate content (75% w/w), and thus were examined in this study in terms of the IFBR concept. The hemicelluloses were pre-extracted with hot water (90, 120, 135, and 150 °C), NaOH, and NaOH + NaBH4 (50, 70, and 90 °C) for 4 h. NaOH charges of 16.7, 26.7, and 33.3% were explored. The extracts were utilized to produce bioethanol and biodegradable films, and papermaking pulps were produced from the solid fractions. Differences among groups were identified via analysis of variance, and the Duncan's test was applied to determine those differences that were significant. The results showed that the alkaline pre-extraction (26.7% NaOH at 50 °C) removed 35.6% of the xylose from the stalk structure. The liquid fraction collected from the hot water pre-extraction at 150 °C gave a 14.7% (g/100 g soluble material) yield of bioethanol. Moreover, the theoretical ethanol yield was calculated as 89.4%. The addition of gluten and nanocellulose to the xylan enabled the production of high-quality biodegradable films. Furthermore, the pulps produced from the hot water pre-extracted solid fractions were comparable in yield and pulp properties to the control soda pulp. [ABSTRACT FROM AUTHOR]

Furfural produced during lignocellulose pretreatment to reduce the recalcitrance inhibits the growth of Saccharomyces cerevisiae and reduces ethanol yield. To reduce the adverse effect of furfural on S. cerevisiae, exogenous ergosterol was supplemented and the impact on S. cerevisiae under furfural stress was studied. The lag phage was shortened by 50%, and the maximum ethanol yield was increased by 158% with 50 mg/L ergosterol supplementation under 4 g/L furfural stress. Flow cytometry analysis results showed that permeable cells and intracellular reactive oxygen species were decreased by 45 and 53%, respectively with the addition of ergosterol under furfural stress. The fatty acid composition of S. cerevisiae was changed; the intracellular glycerol and ergosterol content was increased after ergosterol supplementation. The saturation of fatty acid was increased. Addition of ergosterol promoted cell growth by decreasing oxidative stress. Under 4 g/L furfural stress, the lag phage of S. cerevisiae BY4741 (erg3Δ) and S. cerevisiae BY4741 (erg5Δ) was longer than that of S. cerevisiae BY4741, and the maximum ethanol concentration was decreased. [ABSTRACT FROM AUTHOR]

Industrial production of biogas offers a way to manage distillery leachate. The waste is usually subjected to anaerobic digestion for producing biogas. However, the effluent from anaerobic processes has high chemical oxygen demand (COD) and is harmful to the environment. An effective method of lowering COD is ozonation. Effluent from biogas plants after ozonation has the potential for use in breeding grounds for plants of the Lemnaceae family. Thus, they can provide a valuable additional source of biomass for the production of bioethanol. Lemna minor L. and Spirodela polyrhiza cultures were grown in media with the addition of 2.5% PFE, which had been treated by ozonation for between 6 and 50 min. Using ozonated effluent was an effective cultivation technique in all variants. The analyzed parameters were plant growth, chlorophyll index, fresh plant weight and photosynthetic traits (net photosynthesis, stomatal conductance, transpiration and concentration of intercellular CO2). The best growth of Lemna minor L. was observed in the media with PFE treated for 12 min. Similar effects were obtained for S. polyrhiza, with ozone treatment for 12 and 25 min. The results show the potential of using ozone-treated post-fermentation leachate as a supplement in culture media. [ABSTRACT FROM AUTHOR]

There is an increased research interest in methods for transparent wood production and its use. Wood transparency could be achieved by its delignification followed by an impregnation process with polymers having proper optical properties. However, delignification processes are mainly time consuming and not environmentally friendly. The possibility of treating mahogany wood (Swietenia macrophylla King) with 20% hydrogen peroxide for 70, 100, 135, and 170 min at 103 °C is presented in this research. According to the treatment duration, lignin content decreased 40 to 94% relative to its initial content in the control samples, whilst the cell structure remained intact. Due to the light scatter effect, caused mainly by wood tissue structure, the direct optical transmittance of treated samples in the visible light spectrum (400 to 800 nm) was less than 40%. Simultaneously, the total optical transmittance of samples treated for 100 and 135 min reached values between 70 to 80% with high values of the haze at approximately 30 and 60%. Optical transmittance in the visible spectrum area of the samples treated for 170 min was from 45 to 80% and the haze from 25 to 45%. [ABSTRACT FROM AUTHOR]

The combustion of oil palm empty fruit bunch (OPEFB) can cause severe fouling, slagging, and ash melt-down problems, which originate from its non-organic components such as potassium, calcium, and silicon. To improve the usability of OPEFB as raw materials for combustion energy generation, the effects of pretreatments with various solution on the chemical composition and the thermal degradation were investigated. Soaking pretreatments with alkali, acidic, and neutral conditions were applied. The acid soaking pretreatments resulted in the reduction of the alkaline ash materials, although the silicon and the chlorine were effectively reduced by the alkali or the water soaking pretreatment. The changes in the ash composition by the different pretreatment conditions resulted in the changes of thermal properties. The pretreated OPEFB showed increased thermal degradation temperatures, indicating the improvement of the thermal stability by the pretreatment. The results of the various pretreatments showed that the water soaking pretreatment of OPEFB could be a promising pretreatment method to improve the applicability for combustion as a bio-fuel, in terms of economic viability and environmental sustainability. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is a renewable resource that is widely abundant and can be used to produce biofuels such as methanol and ethanol. Because biofuels have the potential to alleviate shortages of energy in today's world, they have attracted much research attention. The pretreatment of lignocellulose is an important step in the conversion of biomass products. The pretreatment can destroy the crosslinking effect of lignin and hemicellulose on cellulose, remove lignin, degrade hemicellulose, and change the crystal structure of cellulose. The reaction area between the enzyme and the substrate is enlarged, and the yield of subsequent enzymatic hydrolysis and microbial fermentation products is significantly increased. Conventional pretreatment methods help convert lignocellulosic material to sugars, but the treatments also produce some inhibitors, which are mainly organic acids, aldehydes, phenols, and other substances. They may affect the subsequent saccharification and growth of fermentation microorganisms, thereby reducing the bioconversion of the lignocellulose. It is therefore necessary to take effective means of detoxification. This paper reviews lignocellulose pretreatment methods, with an emphasis on inhibitors and their management. A summary is provided of detoxification methods, and the future use of lignocellulosic biomass for fuels prospects. [ABSTRACT FROM AUTHOR]

The butanol acetone ratio (B/A ratio) is a critical index to evaluate the process of ABE fermentation. In this article, fern root starch with yeast extract added (FY) was used as substrate for ABE fermentation. The final B/A ratio in a 5 L anaerobic fermentor reached the highest levels of 3.42, which signified an increment of 41% compared with corn. The mechanisms for the high B/A ratio of FY substrate were as follows: 1) the weakened organic acid circuit resulted in decreased acetone synthesis; 2) the NADH level of butanol synthesis was high; 3) coA transferase activity was low and butanol dehydrogenase activity was high. The final butanol concentration and substrate utilization were examined in a 5 L anaerobic fermentor, and the results validated the feasibility of ABE fermentation with FY as substrate. [ABSTRACT FROM AUTHOR]