• Microbiology and Biotechnology Letters
• /
• v.49 no.1
• /
• pp.88-94
• /
• 2021

The seaweed, Gracilaria verrucosa (red seaweed) was fermented to produce bioethanol. Optimal thermal acid hydrolysis conditions were determined as 200 mM H₂SO₄ and 10% (w/v) seaweed slurry at 130℃ for 60 min yielding 47.5% of pretreatment efficiency (E_p). After the thermal acid hydrolysis, enzymatic saccharification was carried out with 16 U/ml Viscozyme L, Cellic CTec2 or mixture of Viscozyme L and Cellic CTec2 to G. verrucosa hydrolysates. Enzymatic saccharifications with Viscozyme, Cellic CTec2 or mixture of those yielded 7.3 g/l glucose with efficiency of saccharification, E_s = 34.9%, 11.6 g/l glucose with E_s = 64.4% and the mixture of those 9.6 g/l glucose with E_s = 56.6%, respectively. Therefore, based on the E_s value, Cellic CTec2 was selected for the optimal enzyme for enzymatic saccharification of G. verrucosa hydrolysate. The ethanol productions with non-adapted S. cerevisiae CEN-PK2 (wild type) and S. cerevisiae CEN-PK2 with adaptive evolution to galactose produced 8.5 g/l ethanol with Y_EtOH = 0.19 and 21.5 g/l ethanol with Y_EtOH = 0.50 at 144 h, respectively. From these results, the ethanol production by S. cerevisiae with adaptive evolution showed high concentration of ethanol production using G. verrucosa as a substrate.

• Korean Chemical Engineering Research
• /
• v.56 no.4
• /
• pp.441-446
• /
• 2018

Herbaceous biomass is easier at chemical conversion than woody biomass. However, pretreatment must be needed because it has substantially lignin. Organsolv is good at fractionation of enzymatic hydrolysis inhibitors such as lignin and it is reusable by distillation when it has low molecular weight. Flow-through process can prevent recondensation of fractionated components and easily separate liquid from the biomass. In this study, the pretreatment was performed for decreasing additional process by using ethanol without catalyst because this process has a lot of operation expense at bio-alcohol production process. Flow-through pretreatment was performed at $150{\sim}190^{\circ}C$ with 30~99.5 wt% ethanol during 20~60 minutes. Also the phsyco-chemical pretreatment was performed for decreasing reaction time and temperature.

• Applied Chemistry for Engineering
• /
• v.27 no.2
• /
• pp.171-178
• /
• 2016

Extensive efforts from all over the world have been made to solve energy problems, such as high oil prices, global warning due to the depletion of oil. Among them, biofuel has been drawing attention as a clean energy, which can replace fossil fuels. However, conventional biofuels were often converted from eatable biomass such as sugar cane, corn and soy which should be replaced with uneatable biomass. In this study, a techno-economical evaluation of the gasification of biomass waste with mixed alcohol synthesis process was performed. Considering available domestic biomass wastes, a 2000 ton/day conversion plant were assumed to produce 533000 L/day ethanol. Also, financial data from previous studies were evaluated and used and economical sensitivities with various operation conditions were established. Economic analysis were conducted by the payback period and internal rate of return (IRR) and net present value (NPV). Sensitivity analyses of raw material costs, initial investment, the major process cost, ethanol price changes and operating costs were all performed.

• Journal of the Korean Wood Science and Technology
• /
• v.43 no.6
• /
• pp.826-837
• /
• 2015

In this study, we produced bioethanol from the original hydrolysate obtained during oxalic acid pretreatment of lignocellulosic biomass. The bioethanol was separated and concentrated by pervaporation and the residue after pervaporation was evaluated for its antioxidant activity. Xylose ($37.28g/{\ell}$) was the major product in the original hydrolysate. The original hydrolysate contained acetic acid, furfural and total phenolic compounds (TPC) as fermentation inhibitors. Acetic acid was removed by electrodialysis (ED), and $12.21g/{\ell}$ of bioethanol was produced from ED-treated hydrolysate. The TPC of ethyl acetate extracts from the residue obtained (OA-E) during pervaporation was 86.81 mg/100 g (extract). The $IC_{50}$ values of DPPH and ABTS radical scavenging activities, and reducing power of OA-E were $0.87mg/m{\ell}$, $0.85mg/m{\ell}$, and $0.59mg/m{\ell}$, respectively. Sugar degradation products and the phenolic compounds in OA-E were determined by GC-MS.

• Korean Chemical Engineering Research
• /
• v.60 no.1
• /
• pp.100-115
• /
• 2022

In this study, integrated hybrid system (IHS) composed of two alternatively-operating UV/photocatalytic reactor (AOPR) process and biofilter processes of a biofilter system having two units (i.e., R_up and R_dn) with an improved design (R reactor) and a conventional biofilter (L reactor) was constructed, and its transient behavior was observed to perform the successful treatment of waste air containing ethanol and hydrogen sulfide (H₂S). At the IHS-operating stages of HA1, HA2 and HA3T of reversed feed direction, the AOPR process showed not only ethanol-removal efficiencies of 55, 50 and 45%, respectively, but also H₂S-removal efficiencies of 70, 60 and 37%, respectively. In particular, a drastic decrease of H₂S-removal efficiency at the stage of HA3T was observed due to a doubling of H₂S-inlet concentration fed to AOPR from 10 ppmv to 20 ppmv at the stage of HA3T. The order of ethanol-breakthroughs and the order of the magnitude of ethanol-removal efficiencies at the sampling ports of each unit of R reactor at the stages of HA1, HB1, HA2, HB2, and the first half of HA3T, were reversed, respectively, at the stages of the second half of HA3T and HB3T. In case of H₂S, R reactor did not show H₂S-breakthrough as prominent as the ethanol-breakthrough, but showed the trend similar to the ethanol-breakthrough.

• Journal of the Korean Applied Science and Technology
• /
• v.29 no.4
• /
• pp.638-652
• /
• 2012

This study is written by the methods of investigation of references be attached, and includes the background introduced, manufacturing processes, original properties, standards, amounts produced, market situation, ways of applied currently, and policies as a fuel manufactured by biomass on individual countries through the scope of worldwide, especially focused on bioethanol, biodiesel and biogas. It is prepared over multiple angles for the references, who want to getting information and searching desired ways in the future regarding to bioenergy. It is concluded that bioenergy is one of the useful renewable energy, and must to take a step forward by the approaching of multiple points, and finally showed some directions by the way of comparing of the situations and references nowaday.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.6
• /
• pp.704-711
• /
• 2017

Korea, which has a high dependency on energy imports, is greatly affected by fluctuations in international oil prices. In order to offset these effects, various policies such as 'diversification of energy sources' and 'energy mix' are being pursued. Renewable Fuel Standard (RFS) is a policy promoted for this purpose, and a compulsory mixing system is applied only to the diesel. In order to reduce dependence on fossil fuels in various countries, they are concentrating on the dissemination of bio-alcohol as well as bio-diesel, and commercialization through various verification. In this study, evaluation of domestic materials and vehicles was carried out to promote domestic bio alcohol fuel. We analyzed the fuel characteristics of domestic quality standard items by mixing them with gasoline of automobile at a certain mixing ratio (0%, 3%, 6%, and 10%).

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.53 no.3
• /
• pp.339-346
• /
• 2008

The contents of starch, moisture, crude protein, crude fat, crude fiber, and ash of different varieties of various crops such as brown rice, barley, corn, sweet potato were analyzed. The average starch contents of brown rice, barley, corn, and sweet potato were $70.1{\pm}0.4\;{\sim}\;72.2{\pm}2.1$, $68.7{\pm}0.2\;{\sim}\;71.4{\pm}1.2$, $67.6{\pm}0.8\;{\sim}\;69.4{\pm}1.8$, and $21.7{\pm}0.9\;{\sim}\;28.3{\pm}0.5%$, respectively. The ground powder of each starchy substrate was suspended in distilled water, and then liquefied, saccharified, and fermented by dried active yeast at 32 for 4 days. By statistical analysis, the effectiveness of the contents of the different components such as starch, moisture, crude protein, crude fat, crude fiber, and ash of the crops on the ethanol production were examined. The results showed that the starch content positively affected the ethanol production in all the tested cereals and sweet potato. In brown rice, ash content affected negatively the ethanol production. In barley, protein content affected negatively the ethanol production, while fiber content affected positively the ethanol production. The sweet potato containing higher content of moisture produced less amount of ethanol.

• Journal of Applied Biological Chemistry
• /
• v.60 no.4
• /
• pp.333-338
• /
• 2017

Cellulosic alcohol fermentation has recently gained more attention in the production of ethanol, butanol, and 2,3-butanediol. However, it was revealed that the process had several hurdles, such as, an expensive cost for biomass decomposition to yield fermentable sugars and a production of byproduct lignin. As an alternative for the process through biomass saccharification, the alcohol production through syngas from biomass has been studied. In this study, we reviewed acetogen and its central metabolic pathway, Wood-Ljungdahl route, capable of utilizing syngas. Furthermore, the metabolic engineering strategies of acetogen for bio-alcohol production from syngas was also reviewed with a brief perspective.

• Fire Science and Engineering
• /
• v.33 no.5
• /
• pp.1-6
• /
• 2019

The recent development of biofuel production technology facilitates the widespread use of bioethanol and biodiesel by mixing them with fossil fuels. However, the use of these new blended fuels in combustion could result in severe safety problems, such as fire and explosion. In this study, numerical simulation was performed on the well-stirred reactor (WSR) to simulate the autoignition temperature (AIT) in homogeneous combustion and clarify the effect of ethanol addition on the AIT, the most important property for assessing the potential for fire and explosion. Response surface methodology (RSM) was introduced as a design of experiment (DOE), enabling the AIT to be predicted and optimized systematically with respect to three independent variables: ethanol mole fraction, equivalence ratio, and pressure. The results show that the autoignition temperature primarily depends on the ethanol mole fraction and pressure, while the effects of the equivalence ratio are independent of the AIT. RSM accurately predicted the experimental AIT, indicating that this method can be used to effectively predict the key properties involved in fires and explosions.