• Environmental Engineering Research
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• 제11권3호
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• pp.156-163
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• 2006

In this study, substrate removal characteristics were analyzed to reduce the cost of external carbon dosage at Sudokwon Landfill Site Management Corporation in Korea by utilizing oxygen uptake rate (OUR) and nitrate uptake rate (NUR) tests. To estimate and evaluate the substrate removal characteristics obtained by the batch tests, the lab-scale MLE process was operated. By-products of J Co. (sugar manufactory) and S Co. (fine chemical industry) were selected as the concerned carbon sources through a comparison of carbon and nitrogen contents. MeOH was tested as a control experiment. Until the steady state, the fraction of $RBDCOD_{OUR}$ concentration to COD concentration of J Co., S Co. by-products and MeOH increased and reached levels of 98%, 82%, and 100%, respectively. During the 20th operating day, the fraction of $RBDCOD_{NUR}$ concentration to COD concentration was 95%, 81%, and 83%, respectively. These fractions of $RBDCOD_{NUR}$ concentration to $RBDCOD_{OUR}$ concentration increased according to acclimation periods and reached levels of 99%, 97%, and 81%, respectively, on the 20th day. The results obtained from the lab-scale MLE process operation using the concerned carbon sources as external carbon were similar to that observed by OUR and NUR tests.

• Advances in nano research
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• 제9권1호
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• pp.25-32
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• 2020

In this work, we report the use of caffeine as an alternative source of nitrogen to successfully dope graphene (quaternary 400.6 eV and pyridinic at 398 eV according XPS), as well as the growth of silver nanowires (in-situ) in the surface of nitrogen doped graphene (NG) sheets. We used the improved graphene oxide method (IGO), chemical reduction of graphene oxide (GOx), and impregnation with caffeine as source of nitrogen for doping and subsequently, silver nanowires (NW) grow in the surface by the reduction of silver salts in the presence of NG, achieving a numerous of growth of NW in the graphene sheets. As supporting experimental evidence, the samples were analyzed using conventional characterization techniques: SEM-EDX, XRD, FT-IR, micro RAMAN, TEM, and XPS.

• 한국미생물·생명공학회지
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• 제51권4호
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• pp.449-456
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• 2023

Sugar or dextrose increases the cost of production of xanthan gum by Xanthomonas campestris. Brewers' Spent Grain (BSG) was chosen as a source of fermentable sugars. BSG is a significant industrial by-product generated in large quantities from the breweries. Primarily used as animal feed due to its high fiber and protein content, BSG holds great potential as an economically and ecologically sustainable substrate for fermenting biomolecules. This study explores BSG's potential as a cost-effective carbon source for producing xanthan, utilizing Xanthomonas campestris NCIM 2961. An aqueous extract was prepared from BSG and inoculated with the bacterium under standard fermentation conditions. After fermentation, xanthan gum was purified using a standard protocol. The xanthan yield from BSG media was compared to that from MGYP media (control). The fermentation parameters, including pH, temperature, agitation and duration were optimized for maximum xanthan gum yield by varying them at different levels. Following fermentation, the xanthan gum was purified from the broth by alcoholic precipitation and then dried. The weight of the dried gum was measured. The obtained xanthan from BSG under standard conditions and commercial food-grade xanthan were characterized using FTIR. The highest xanthan yields were achieved at 32 ℃, pH 6.0, and 72 h of fermentation at 200 rpm using BSG media. The FTIR spectra of xanthan from BSG media closely resembled that of commercial food-grade xanthan. The results confirm the potential of BSG as a cost-effective alternative carbon source for xanthan production, thereby reducing production costs and solid waste.

• Journal of Plant Biotechnology
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• 제34권2호
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• pp.111-118
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• 2007

가속도가 붙은 지구온난화 문제와 수 십년 이내로 예상되는 화석연료의 고갈은 지속가능하면서도 환경친화적인 새로운 형태의 에너지 출현을 필요로 하고 있다. 이러한 추세에 맞추어 태양광, 조력, 지열, 풍력, 수소 에너지와 더불어 바이오에너지가 대체에너지로서 주목받고 있다. 바이오에너지는 태양에너지를 유기물로 변환하는 식물을 재료로 하여 바이오 에탄올이나 바이오디젤 등을 생산하여 사용하는 것으로 대체 에너지가 갖춰야 할 조건을 두루 갖춘 최적의 신재생에너지로 고려되고 있다. 하지만 바이오에너지가 진정한 의미에서의 환경친화적이면서 지속가능성을 갖추기 위해서는 아직 기술적으로 해결해야할 문제점들이 많다. 최근 미국에서 바이오에탄올 생산을 위한 옥수수 소비량이 늘어 곡물 및 사료 가격의 급등 현상으로 이어지고 있다. 또한 이러한 현상은 개발도상국 식량자원의 선진국 유입 등으로 빈곤의 심화 등이 새로운 문제점으로 지적되고 있다. 따라서 곡물이 아닌 비식용 부위를 이용한 에탄올 생산이 대안으로 여겨지고 있는 바 셀룰로스 에탄올은 이러한 문제점을 극복할 수 있는 대체에너지로서 자리매김하고 있다. 셀룰로스 바이오에탄올은 사람 등의 동물이 소화하지 못하는 바이오매스의 대부분을 차지하는 식물 세포벽을 곰팡이 등에서 분리한 효소로 분해한 후 여기서 생성되는 당을 발효과정을 통해 생산되는 에탄올로서 전술한 바와 같은 문제점을 해결할 수 있는 유망한 대안 에너지로 고려되고 있다.

• Journal of Plant Biotechnology
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• 제34권2호
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• pp.103-109
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• 2007

The increasing industrialization of the world has led to precipitous rise for the demand of petroleum-based fuels. The world is presently confronted with the twin crises of fossil fuel depletion and environmental pollution. The search for alternative fuels, which promise a harmonious correlation with sustainable development, energy conservation, efficiency and environmental preservation, has become highly pronounced in the present. Bioenergy is playing an increasingly important role as an alternative and renewable source of energy. Use of Bioenergy has several potential environmental advantages. The most important perhaps is reduction in life cycle greenhouse gases emissions relatives petroleum fuels, since bioenergy is derived from plants which convert Carbon dioxide ($CO_{2}$) into Carbohydrates in their growth. Bioenergy includes solid biomass, biomas and liquid bio-fuels which are fuels derived from crop plants, and include biomass that's directly burned. The two most important bio liquid fuels today are bioethanol from fermenting grain, grass, straw or wood, and biodiesel from plant seed oil.

• Advances in Automotive Engineering
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• 제1권1호
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• pp.79-104
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• 2018

A detailed literature review is presented for the applications of the heat pump technologies on the electric vehicles Heating, Ventilation and Air Conditioning (HVAC) system. Due to legal regulations, automotive manufacturers have to produce more efficient and low carbon emission vehicles. Electric vehicles can be provided these requirements but the battery technologies and energy managements systems are still developing considering battery life and vehicle range. On the other hand, energy consumption for HVAC units has an important role on the energy management of these vehicles. Moreover, the energy requirement of HVAC processes for different environmental conditions are significantly affect the total energy consumption of these vehicles. For the heating process, the coolant of internal combustion (IC) engine can be utilized but in electric vehicles, we have not got any adequate waste heat source for this process. The heat pump technology is one of the alternative choices for the industry due to having high coefficient of performance (COP), but these systems have some disadvantages which can be improved with the other technologies. In this study, a literature review is performed considering alternative refrigerants, performance characteristics of different heat pump systems for electric vehicles and thermal management systems of electric vehicles.

• 한국분무공학회지
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• 제12권4호
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• pp.204-210
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• 2007

The worldwide energy problem and global warming cause the need of alternative fuels which feature low carbon-dioxide emission and another energy source. Liquefied Petroleum Gas (LPG) is one of the alternative fuels widely used as domestic and transportational fuel. The third generation LPLi fuel supply system has merits in the increase of engine power and low emissions. The injectors used in LPLi system should overcome a leakage problem and satisfy the durability conditions. Therefore, 1000 hour durability test of the injectors was carried out throughout this research. First, the spray pattern and the penetration length of the selected injectors is graphically shown. Next, the leakage amount with respect to the injection cycle is introduced. Finally, the shapes of nozzle holder and nozzle tip after durability test was investigated by analyzing the microscopic image of the injector tip. The variation in the shape of nozzle tip mainly due to the residue of rubber materials is found to be the reason for leakage.

• 청정기술
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• 제27권3호
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• pp.269-274
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• 2021

바이오에너지는 탄소중립을 추구하는 방안 중 하나로 간주되고 있다. 그러나 수확된 식물 바이오매스를 연소하면 필연적으로 대기 중 이산화탄소는 일정기간 동안 화석을 연소할 때보다 더 많아진다. 본 논문에서는 이 탄소부채의 총량과 상환기간을 예측하고 최소화하는 방법을 제안한다. 사례연구로는 현재 사용되고 있는 화석연료를 바이오매스로 일시에 전환할 경우에 대한 탄소순환 영향평가를 수행한다. 이를 통해 탄소중립 개념의 근본적인 취약성을 지적한다. 바이오에너지의 지속가능성을 위한 실행방안으로는 숲 면적 감소분에 비례하는 추가식림 및 숲 질량 증가분에 비례하는 추가수확 공식을 제안하였다. 최적화 결과, 탄소부채 상환기간은 약 70년, 대기 중 이산화탄소는 최대 50% 이상, 정상상태에서 3% 증가가 예상된다. 이는 이론적으로 예측한 최상의 결과이며 실제로는 이보다 나쁠 것으로 추정된다. 따라서 바이오매스는 진정으로 탄소 중립적이지 않으며, 화석연료의 대체에너지원으로서 부적합하다. 본 연구에서 제안된 방법은 이미 사용 중인 바이오에너지의 현재 및 미래 탄소부채 최소화를 통해 탄소중립으로의 접근에 기여할 수 있을 것으로 예상된다.

• Environmental Engineering Research
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• 제19권3호
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• pp.293-298
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• 2014

An anaerobic photosynthetic treatment process utilizing purple non-sulfur photosynthetic bacteria (PNSB) was applied to the recovery of organic carbon from food processing wastewater. PNSB cells, by-product from the treatment, have high nutrition such as proteins and vitamins which are a good alternative for fish feed. Effects of light source on performance of anaerobic photosynthetic process were investigated in this study. Two bench-scale photo-bioreactors were lighted with infrared light emitting diodes (LEDs) and tungsten lamps covered with infrared transmitting filter, respectively, aiming to supply infrared light for photosynthetic bacteria growth. The photo-bioreactors were operated to treat noodle-processing wastewater for 323 days. Hydraulic retention time (HRT) was set as 6 days. Organic removals in the photo-bioreactor lighted with infrared LEDs (91%-95%) was found higher than those in photo-bioreactor with tungsten lamps with filter (79%-83%). Biomass production in a 150 L bench-scale photo-bioreactor was comparable to a 8 L small-scale photo-bioreactor in previous study, due to improvement of light supply efficiency. Application of infrared LEDs could achieve higher treatment performance with advantages in energy efficiency and wavelength specifity.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.538-543
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• 2006

A packed bed reactor (PBR) was fed with nitrate containing synthetic wastewater or effluent from a sequencing batch reactor used for nitrification. The C source introduced into the PBR consisted of volatile fatty acids (VFAs) produced from anaerobic acidogenesis of food wastes. When nitrate loading rates ranged from $0.50\;to\;1.01\;kg\;N/m^{3}{\cdot}d$, the PBR exhibited $100{\sim}98.8%\;NO_{3}^{-}-N$ removal efficiencies and nitrite concentrations in the effluent ranged from $0\;to\;0.6\;NO_{2}^{-}-N\;mg/L$. When the PBR was further investigated to determine nitrate removal activity along the bed height using a nitrate loading rate less than $1.01\;kg\;N/m^{3}{\cdot}d$, 100% nitrate removal efficiency was observed. Approximately 83.2% nitrate removal efficiency was observed in the lower 50% of the packed-bed height. When reactor performance at a C/N ratio of 4 and a C/N ratio of 5 was compared, the PBR showed better removal efficiency (96.5%) of nitrate and less nitrite concentration in the effluent at the C/N ratio of 5. VFAs were found to be a good alternative to methanol as a carbon source for denitrification of a municipal wastewater containing 40 mg-N/L.