• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.465-469
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• 2006

Two mesophilic trickling bed bioreactors filled with two different types of media, hydrophilic- and hydrophobic-cubes, were designed and tested for hydrogen production via anaerobic fermentation of sucrose. Each reactor consisted of a column packed with polymeric cubes and inoculated with heat-treated sludge obtained from anaerobic digestion tank. A defined medium containing sucrose was fed with changing flow rate into the capped reactor, hydraulic retention time and recycle rate. Hydrogen concentrations in gas-phase were constant, averaging 40% for all conditions tested. Hydrogen production rates increased up to $10.5 L{\cdot};h^{-1}{\cdot}L^{-1}$ of reactor when influent sucrose concentrations and recycle rates were varied. Hydrophobic media provided higher value of hydrogen production rate than hydrophilic media at the same operation conditions. No methane was detected when the reactor was under a normal operation. The major fermentation by-products in the liquid effluent of the both trickling biofilters were acetate and butyrate. The reactor filled with hydrophilic media became clogged with biomass and bio gas, requiring manual cleaning of the system, while no clogging occurred in the reactor with hydrophobic media. In order to make long-term operation of the reactor filled with hydrophilic media feasible, biofilm accumulation inside the media in the reactor with hydrophilic media and biogas produced from the reactor will need to be controlled through some process such as periodical backwashing or gas-purging. These tests using trickling bed biofilter with hydrophobic media demonstrate the feasibility of the process to produce hydrogen gas in a trickle-bed type of reactor. A likely application of this reactor technology could be hydrogen gas recovery from pre-treatment of high carbohydrate-containing wastewaters.

• 자원리싸이클링
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• 제30권6호
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• pp.12-18
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• 2021

수성가스 전환 반응은 가스화로 생성된 합성 가스에 수소 생산 증가와 H₂/CO 비율 제어를 위해 수증기를 첨가하는 가스화 후속 공정이다. 본 연구에서는 RPF(Refuse plastic fuel) 가스화 시스템의 합성가스를 대상으로 수성가스 전환 반응을 연구하였다. 수성가스 전환 반응은 촉매를 이용하여 high temperature shift(HTS) 와 low temperature shift(LTS) 반응에 대하여 lab scale 관형 반응기를 이용하여 반응 온도, steam/carbon ratio, 유량의 변화가 H₂ 생성과 CO 전환율에 미치는 영향을 조사하였다. 운전 온도는 HTS 시스템이 250-400℃, LTS 시스템이 190-220℃이며 steam/carbon ratio는 1.5-3.5로 변화시켰다. 반응 모의 가스의 농도는 RPF 합성가스의 농도를 기준으로 CO, 40vol%, H₂, 25vol%, CO₂, 25vol%이다. 반응 온도와 steam/carbon ratio가 증가함에 따라 CO 전환율 및 H₂ 생성량이 증가하고, 유량이 증가하면 촉매층의 체류시간 단축으로 CO 전환율과 H₂ 생성량이 감소하였다.

• 상하수도학회지
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• 제11권2호
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• pp.112-127
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• 1997

The purpose of this study is to get optimum operating factors of Upflow Anaerobic Sludge Blanket (UASB) reactor by introducing methods that make it to reduce inhibition possible in each process wastewater treatment. The used substrates, concentrated corn starch liquid (CSL) wastewater, modified starch, filtering and decoloring wastewater, ion refining wastewater, and mixed wastewater including modified starch and not including modified starch, are generated from molasses process. The seeding sludge is the digested sludge that had been applied to molasses wastewater. Batch test to reduce the inhibition factors that might be existed in each wastewater was examined. Based on the this test, the optimum operating factors according to alkalinity and pH variation was studied through the continuous test using three 5.5 L UASB reactor. The first reactor added $NaHCO_3$ to control alkalinity. The hydraulic retention time (HRT) reduced to 8 hours and the organic loading rate increased gradually. The second reactor changed the pH of influent from 7.0 to 6.0 using NaOH. The third reactor was operated without changes to compare the above two reactors. As the result, the inhibition in concentrated CSL wastewater was removed by adding iron (II). When trace metals were added to mixed wastewater not including modified starch, the digestability by gas production rate increased to more fifty percentage than mixed wastewater that was not adding the trace metals. The reason that the inhibition did not decreased in spite of adding trace metals and nutrients was influenced by high concentration generated during the acid fermentation. The UASB reactors using the mixed wastewater with the most effective performance were operated as 500 mg/L as $CaCO_3$ alkalinity and 6.0 pH at steady state, and at this time, the gas production rates were 283 and 311mL gas/g $COD_{added}$. The COD removal rates were 84.7 and 86.3%, respectively.

• 한국환경농학회지
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• 제23권3호
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• pp.148-157
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• 2004

사과 및 배 시표에서 농약 다성분의 gas chromatography를 이용한 잔류분석법 확립을 위하여 199가지의 농약을 선정하여 retention time 및 검출기에 따라 ECD 5 그룹 및 NPD 5 그룹의 10개 그룹으로 분류하였다. 시료의 종류에 따른 분석조건을 확립하기 위한 회수율 시험은 농약들의 log $P_{ow}$ 값과 화학적 분류에 따라 총 18개 (ECD 11개, NPD 7개)의 농약을 선정하였다. 예비 실험 후 확립된 분석방법에 따라 10개 그룹의 혼합 표준용액으로 사과 및 배에 대한 회수율시험을 행하였다. 그 결과, 총 196가지의 농약의 70%에 해당하는 사과에서 136개, 배에서 133개의 농약들에서 회수율 70에서 120%의 양호한 결과를 나타내었다. 그러나 사과에서 43개, 배에서 45개의 농약들이 70% 미만의 회수율을 보였고, fenvalerate는 120% 이상의 회수율을 나타내었으며, 사과에서 17개 및 배에서 18개의 농약들은 검출이 되지 않았다. 그러나 확립된 분석법은 SOP에 의한 신속하고 수월한 수행으로 농산물 중의 잔류농약을 검출 및 모니터링하는 목적에 적합하다고 사료된다.

• Environmental Engineering Research
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• 제19권2호
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• pp.123-130
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• 2014

Percolation is the important process of extracting the soluble constituents of a fine mesh, porous substance by passage of a liquid through it. In this study, bio-wastes were percolated under various conditions through continuous percolation processes, and the energy potential of percolate was evaluated. The representative bio-wastes from the K composting plant in Darmstadt, Germany were used as the sample for percolation. The central objective of this study was to determine the optimal amount of process water and the optimum duration of percolation through the bio-wastes. For economic reasons, the retention time of the percolation medium should be as long as necessary and as short as possible. For the percolation of the bio-wastes, the optimal percolation time was 2 hr and maximum percolation time was 4 hr. After 2 hr, more than two-thirds of the organic substances from the input material were percolated. In the first percolation process, the highest yields of organic substance were achieved. The best percolation of the bio-wastes was achieved when the process water of 2 L for the first percolation procedure and then the process water of 1.5 L for each further percolation procedure for a total 8 L for all five procedures were used on 1,000 g fresh bio-waste. The gas formation potentials of 0.83 and $0.96Nm^3/ton$ fresh matter (FM) were obtained based on the percolate from 1 hr percolation of 1,000 g bio-waste with the process water of 2 L according to the measurement of the gas formation in 21 days (GB21). This method can potentially contribute to reducing fossil fuel consumption and thus combating climate change.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.537-540
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• 2001

A parallel TBF system that is consisted of two TBFs was developed f ‘ or the long-term treatment of gas-phase trichloroethylene (TCE). Each TBF was operated for TCE degradation or reactivation in a parallel mode, and the effect of switching time and operation variables between the two reactors was investigated. Within 12 hr after switching from TCE degradation to reactivation mode, the MO activity increased up to the initial level. More than 50 % of TCE was degraded for feed concentrations ranging from 5 to 17 ppmv, and completely 100 % removed at concentration of less than 5 ppmv, while TCE removal decreased severely over 28 ppmv. In various empty bed retention times (EBRTs), ranging 상 om 5.2 to 10.7 min, the optimal EBRT was 10.7 min that TCE conversion achieved more than 50 %. For the inlet loading below 23.4 mg TCE/L/day, TCE was entirely removed. The maximal TCE elimination capacity in this system was about 66.63 mg TCE/L/day. During the continuous treatment of TCE over 3 months, TCE removal efficiency was maintained at the range of about 50 %. In these results, the parallel TBF system can be available for the continuously TCE biodegrading operation.

• Environmental Analysis Health and Toxicology
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• 제15권1_2호
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• pp.53-59
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• 2000

The purpose of this study is the development of the simple and precise determination method of ethyl isocyanate (EIC) and propyl isocyanate (PIC) through derivatization using secondary aliphatic amines by gas chromatography with flame ionization detector. The urea derivatives are quantitatively and simultaneously derived from EIC and PIC with secondary aliphatic amines such as dipropylamine, dibutylamine. and dipentylamine in methylene chloride, and confirmed by thin layer chromatography and gas chromatography with mass selective detector. For GC/FID, according to the increasing carbon atom of the amines, the retention time and peak area of the urea derivatives are increased. The instrumental detection limits for EIC and PIC were about 23.3∼34.8 $\mu\textrm{g}$ and 21.6∼28.9 $\mu\textrm{g}$, respectively.

• 한국토양비료학회지
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• 제30권3호
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• pp.295-300
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• 1997

12개 지역의 한국자생차 향기성분을 기체크로마토그래프 및 질량분광계를 이용하여 분석한 결과는 다음과 같다. 다엽중의 향기성분으로 70~80개 성분을 GC를 이용해 분리할수 있었고, 그중 52개 성분은 GC/MSD로 동정하였는데, 이들을 분류하면 alcohol류 19종, aldehyde류 5종, hydrocarbon류 2종, ketone류 6종, ester류 4종, lactone류 3종, acid류 2종, phenol류 3종, pyrazine류 4종, 그리고 질소화합물 4종이였다. 이중 geraniol, linalool oxide, 1-hexanol, ehtanol등이 주요 향기 성분이었다.

• Journal of Microbiology and Biotechnology
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• 제6권1호
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• pp.30-35
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• 1996

Distillery wastewater was used in a thermophilic laboratory-scale two stage anaerobic digester to test the effects of the redox potential of the first acidogenic reactor on the performance of the system. The digester consisted of first a acidogenic reactor and the an upflow anaerobic sludge blanket (UASB) reactor. The digestor was operated at a hydraulic retention time (HRT) of 48 h. Under these conditions, about 90% of the chemical oxygen demand as measured by the chromate method ($COD_{cr}$) was removed with a gas production yield of 0.4 l/g-COD removed. The redox potential of the acidogenic reactor was increased when the reactor was purged with nitrogen gas or agitation speed was increased. The increase in reduction potential was accompanied by an increase in acetate production and a decrease in butyrate formation. A similar trend was observed when a small amount of air was introduced into the acidogenic reactor. It is believed that the hydrogen partial pressure in the acidogenic reactor was decreased by the above mentioned treatments. The possible failure of anaerobic digestion processes due to over-loading could be avoided by the above mentioned treatments.

• Journal of Microbiology and Biotechnology
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• 제23권2호
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• pp.195-204
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• 2013

While structured packing modules are known to be efficient for surface wetting and gas-liquid exchange in abiotic surface catalysis, this model study explores structured packing as a growth surface for catalytic biofilms. Microbial biofilms have been proposed as selfimmobilized and self-regenerating catalysts for the production of chemicals. A concern is that the complex and dynamic nature of biofilms may cause fluctuations in their catalytic performance over time or may affect process reproducibility. An aerated continuous trickle-bed biofilm reactor system was designed with a 3 L structured packing, liquid recycling and pH control. Pseudomonas diminuta established a biofilm on the stainless steel structured packing with a specific surface area of 500 $m^2m^{-3}$ and catalyzed the oxidation of ethylene glycol to glycolic acid for over two months of continuous operation. A steady-state productivity of up to 1.6 $gl^{-1}h^{-1}$ was achieved at a dilution rate of 0.33 $h^{-1}$. Process reproducibility between three independent runs was excellent, despite process interruptions and activity variations in cultures grown from biofilm effluent cells. The results demonstrate the robustness of a catalytic biofilm on structured packing, despite its dynamic nature. Implementation is recommended for whole-cell processes that require efficient gas-liquid exchange, catalyst retention for continuous operation, or improved catalyst stability.