• Journal of Microbiology and Biotechnology
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• 제19권2호
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• pp.161-166
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• 2009

Certain microalgae have been known to use light and various carbon sources to produce carbohydrates, mainly in the form of starch. This is one of the pertinent feedstocks replacing agricultural products for the production of bioethanol by yeast. This study focuses upon dilute acid hydrothermal pretreatments at low cost and high efficiency to compete with current methods, and employs Chlamydomonas reinhardtii UTEX 90 as the feedstock. With dry cells of 5%(w/v), the algal biomass was pretreated with sulfuric acid(1-5%) under temperatures from 100 to $120^{\circ}C$, from 15 to 120 min. As a result, the glucose release from the biomass was maximum at 58%(w/w) after pretreatment with 3% sulfuric acid at $110^{\circ}C$ for 30 min. This method enabled not only starch, but also the hydrolysis of other oligosaccharides in the algal cell in high efficiency. Arrhenius-type of model equation enabled extrapolation of some yields of glucose beyond this range. The pretreated slurry was fermented by yeast, Saccharomyces cerevisiae S288C, resulting in an ethanol yield of 29.2% from algal biomass. This study suggests that the pretreated algal biomass is a suitable feedstock for ethanol production and can have a positive impact on large-scale applied systems.

• Journal of Animal Science and Technology
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• 제62권1호
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• pp.74-83
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• 2020

Organic waste used as a feedstock in the anaerobic digestion (AD), it includes carbon and nitrogen. Carbon and nitrogen have an effect on the various digestive characteristics during AD, however, the study is rare about those of the interaction. This study investigates the influence of carbon type and carbon to nitrogens (C/N ratios) on the AD characteristics of organic waste. Experimental treatments involved a combination of three carbon types with three C/N ratios. The AD tests were carried out using a 125-mL serum bottle at a constant temperature of 37℃ and moisture 95% for 18 days. Degradation pattern shows the difference among three-carbon treatments, the starch group was faster than other groups. Maximum methane production date was similar between starch (9.96 ± 0.05 day) and xylan group (10.0 ± 0.52 day), those of the cellulose group (14.6 ± 1.80 day) was slower than other groups (p < 0.05). The lag phase was only affected by the carbon type (p < 0.05). Ammonia nitrogen was mainly affected by nitrogen concentration regardless of carbon type (p < 0.05). This study showed that xylan is useful as feedstock in order to decrease the lag phase, and it showed that ammonia was independently affected by the nitrogen concentration.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.267-274
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• 2018

Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of Tetraselmis sp., we used three types of chemical inhibitors that can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions. The starch synthesis pathway in chloroplasts and the cytosol can be inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,2-cyclohexane diamine tetraacetic acid (CDTA), respectively. Degradation of glycine into ammonia during photorespiration was blocked by aminooxyacetate (AOA) to maintain biomass concentration. Inhibition of starch synthesis pathways in the cytosol by CDTA increased fatty acid productivity by 27% under nitrogen deficiency, whereas the blocking of photorespiration in mitochondria by AOA was increased by 35% under nitrogen-sufficient conditions. The results of this study indicate that blocking starch or photorespiration pathways may redirect the carbon flux to fatty acid synthesis.

• 한국수소및신에너지학회논문집
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• 제29권6호
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• pp.648-653
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• 2018

Bran of barley causes high viscosity in bioethanol production due to the large amount of ${\beta}$-glucans and fiber. High viscosity is the main cause of decreased productivity and decreased facility efficiency in ethanol production. In order to prevent high viscosity, this study investigated the possibility of bioethanol from barley by debranning. As a result, it was able to reduced the viscosity (22.8 cP to 17.5 cP). And the fermentation speed and yield were improved as the activity of the enzyme and activity of yeast was also increased was improved due to the removal of non-fermentable components. In conclusion, debranning was advantageous in two ways. Firstly, bran removal increased the starch content of the feedstock and decreased viscosity of mash, improving ethanol fermentation. Secondly, by-products produced by debranning can use valuable products. It was remarkable results to the feasibility of bioethanol production from debranned barley.

• Korean Chemical Engineering Research
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• 제46권5호
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• pp.977-982
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• 2008

유가의 급등과 화석 연료의 고갈, 환경 오염문제 등에 대비하기 위하여 대체 수송 연료로서의 바이오에탄올에 대한 관심이 고조되고 있으며, 이에 따라 바이오에탄올 생산비용 절감을 위한 연구가 매우 활발하다. 본 연구에서는 에탄올 생산성 향상을 위하여 Zymomonas mobilis의 에탄올 발효특성을 Saccharomyces cerevisiae와 비교하였다. 음료용 에탄올 생산균주로 오랫동안 사용되어 온 효모와 연료용 에탄올 생산균주로서의 Z. mobilis의 가능성을 검토한 바 최종 에탄올 생성 농도는 큰 차이가 없었으나, 에탄올 생성속도는 Z. mobilis가 S. cerevisiae에 비해 2배 이상 빨랐다. 에탄올 생산성을 비교해 보면 현미, 쌀보리, 카사바의 경우 Z. mobilis는 $2.19g/l{\cdot}h$, $2.60g/l{\cdot}h$, $3.12g/l{\cdot}h$인 반면 S. cerevisiae는 $0.68g/l{\cdot}h$, $1.03g/l{\cdot}h$, $1.28g/l{\cdot}h$ 이었다. 증류액 내의 불순물은 S. cerevisiae는 iso-amylalcohol이 Z. mobilis는 ethyl heptanoate 농도가 상대적으로 높았다.

• 펄프종이기술
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• 제47권1호
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• pp.24-34
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• 2015

Domestic companies supplying electricity must increase obligatory duty to use renewable energy annually. If not met with obligatory allotment, the electricity-supply companies must pay RPS (Renewable Portfolio Standards) penalty. Although the power plants using a pulverizing coal firing boiler could co-fire up to around 3 per cent with wood pellets mixed in with coal feedstock without any major equipment revamps, they recorded only about 60 per cent fulfillment of RPS. Consequently, USD 46 million of RPS penalty was imposed on the six power supplying subsidiaries of GENCOs in 2014. One of the solutions to reduce the RPS penalty is that the power supply companies adopt the co-firing of torrefied lignocellulosic biomass in coal plants, which may contribute to the use of over 30 per cent of torrefied biomass mixed with bituminous coals. Extra binder was required to form pellets using torrefied biomass such as wood chips, PKS (Palm Kernel Shell) and EFB (Empty Fruit Bunch). Instead of corn starch, 30, 50 and 70 per cent of Larix saw dusts were respectively added to the torrefied feedstocks such as Pinus densiflora chips, PKS and EFB. The addition of saw dusts led to the decrease of the calorific values of the pellets but the forming ability of the pelletizer was exceedingly improved. Another advantage from the addition of saw dusts stemmed from the reduction of ash contents of the pellets. Finally, it was confirmed that torrefied oil palm biomass such as PKS and EFB could be valuable feedstocks in making pellets through improved binding ability.