• Journal of Energy Engineering
• /
• v.24 no.3
• /
• pp.1-5
• /
• 2015

This study is to investigate the effect of torrefaction on enzymatic hydrolysis of lignocellulosic biomass for bio-ethanol production. As a pretreatment, the torrefaction of lignocellulosic biomass was conducted in temperature of $250{\sim}350^{\circ}C$ in the absence of oxygen. Tween-80, nonionic surfactant, was tested to enhance saccharification efficiency by coping with hydrophobicity resulted from torrefaction. As a result, the glucose production from enzymatic hydrolysis of biomass pretreated by torrefaction was greater than that obtained from the non-pretreated biomass. Sugar conversion was higher when the biomass was saccharified with addition of tween-80. It was found that torrefaction can be applied as a preptreatment for lignocellulosic biomass and tween-80 is needed to enhance its enzyme saccharification.

• Journal of Nutrition and Health
• /
• v.17 no.1
• /
• pp.31-40
• /
• 1984

A new microassay was proposed for the determination of serum thiobarbituric acid(TBA) value greatly enhanced by ferric ion under anaerobic condition. One ${\mu}mole$ of $FeCl_{3}$ per $10{\mu}l$ of serum was added to the TBA reaction mixture containing serum protein precipitate. The reaction mixture was heated on boiling water-bath for 50min under $N_{2}$ flushing. The sensitivity of this assay was greatly enhanced by 40 times comparing with that of Yagi's method (1976). In favour of the enhancement, this test could be measured by colorimetry or spectrophotometry with the sample size of $10-20{\mu}l$ serum. The sensitivity and reproducibility were also improved by means of partial dehydration of the butanol extract with $(NH_{4})_{2}SO_{4}$ salting-out. Serum TBA values of healthy human at different age groups were determined by this proposed method.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.05a
• /
• pp.275-278
• /
• 2003

본 연구에서는 축산폐수공공처리장내에 설치된 Pilot-scale SBR(유효부피,20㎥)를 이용하여 sub-cycle의 폭기/무산소구간을 최적화하기 위하여 DO를 입력으로 하여 넓은 운전조건에서 적용될 수 있는 퍼지제어기를 개발하고, 또한 부하이상을 신속히 진단하여 유입부하량을 제어할 수 있는 퍼지 시스템 제어기를 개발하였다. DO값을 입력으로 한 퍼지제어기로서 안정성과 연속성에서 우수하였으나 시스템에 따라서 소속함수의 범위를 재조정해야 할 필요가 있다. DO미분값은 변화폭이 큰 지점을 검출함으로써 지연시간(lag time)의 DO값에 관계없이 적용할 수 있는 장점이 있다. 제어기의 적용성과 안정성을 높이기 위해서는 두 가지 제어인자를 동시에 고려할 필요가 있으며 퍼지 소속함수에 대한 입력으로서 DO값과 DO미분값을 적용하였다. 그 결과 폭기구간에서 매우 안정적이고 신속하게 폭기제어지점의 검출을 보여주고 있어 최적화된 제어가 가능함을 보여준다. 현장실험결과 지연시간에서의 DO가 높고 외란이 심한 경우에도 적용될 수 있음을 보여주었다.

• Food Science of Animal Resources
• /
• v.32 no.3
• /
• pp.346-353
• /
• 2012

This study was carried out in order to investigate the relationship of antioxidant enzyme activity, lipid oxidation, and aroma pattern of Hanwoo (Korean cattle) beef for 8 d at $15^{\circ}C/RH$ 100% under 0% $O_2$/20% $CO_2/80%\;N_2$, 25% $O_2$/20% $CO_2/55%\;N_2$, 50% $O_2$/20% $CO_2/30%\;N_2$, and 75% $O_2$/20% $CO_2/5%\;N_2$-conditions. The reduction of $O_2$ and the induction of $CO_2$ were shown in the 25-75% $O_2$-groups during storage and total change rates of $O_2$ and $CO_2$ were followed in order: 25%>50%>75%. Catalase activity was not significantly different among all groups. During storage, glutathione peroxidase activity decreased by increasing the $O_2$ concentration and was followed at 8 d in order: 0%>25%>50%>75% (p<0.05). From 2 d of storage, TBARS content had significant (p<0.05) differences in order: 0%>25%>50%>75%. The CIE $L^*$ value was higher (p<0.05) in the 25-75% $O_2$-groups, compared with the 0% $O_2$-group. During the first time, the CIE $a^*$ value was higher (p<0.05) in order: 0%<25%<50%<75% but was lower (p<0.05) in the 25-75% $O_2$-groups from 2 d of storage than in the 0% $O_2$-group. The CIE $b^*$ value was higher (p<0.05) in the 25-75% $O_2$-groups than in the 0% $O_2$-group and had significant (p<0.05) differences at 0 and 8 d in order: 0%<25%<50%<75%. Aroma patterns with the electronic nose were clearly discriminated between the 0% $O_2$-groups and the 25-75% $O_2$-groups at 8 d of storage. Therefore, high oxygen reduced stabilities of antioxidant enzymes, lipid oxidation, and color in Hanwoo beef. Furthermore, antioxidant enzyme activities and lipid oxidation could affect aroma patterns.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.10
• /
• pp.1024-1030
• /
• 2006

Genus Nitrospira and Nitrobacter species are the key nitrite-oxidizing bacteria(NOB) in nitrifying wastewater treatment plants. It has been hypothesized that genus Nitrospira are K-strategists(low $K_6$ value) that can exploit low amounts of nitrite more efficiently than Nitrobacter. In contrast, Nitrobacter species are r-strategists(high $V_{max}$) that can grow faster than Nitrospira. It has also been known that the availability of organic compounds and dissolved oxygen as well as nitrite affects the distribution of NOB. In this study, we determined the distribution and competition of NOB in wastewater nitrification systems where nitrite, organic compounds, and dissolved oxygen concentrations were compositively varied. For the purpose, several compounds of the laboratory-scale nitrificaiion bioreactor and full-scale $A_2O$ wastewater treatment plant and their distribution of NOB were analyzed and compared. The analysis showed that Nitrobacter was the dominant NOB in nitrification bioreactor where average nitrite was maintained at 5 mg-N/L with very low organic concentration in aerobic condition, whereas Nitrospira was the dominant NOB in full-scale $A_2O$ plant where nitrite was maintained very low and organic compounds were maintained relatively high in alternating aerobic-anoxic condition. The result indicates that nitrite concentration is more critical factor than organics and dissolved oxygen which determines the dominant NOB in nitrification system and it is confirmed that Nitrospira and Nitrobacter showed the characteristics of r-strategist and K-strategist, respectively.

• Korean Journal of Mineralogy and Petrology
• /
• v.35 no.2
• /
• pp.101-109
• /
• 2022

The mobility and transport of radioactive cesium are crucial factors to consider for the safety assessment of high-level radioactive waste disposal sites in granite. The retardation of radionuclides in the fractured crystalline rock is mainly controlled by the hydrochemical condition of groundwater and surface reactions with minerals present in the fractures. This paper reports the experimental results of cesium sorption to the Wonju Granite, a typical Mesozoic granite in Korea, performed in an anaerobic chamber that mimics the anoxic environment of a deep disposal site. We measured the rates and amounts of cesium (¹³³Cs) removed by crushed granite samples in different electrolyte (NaCl, KCl, and CaCl₂) solutions and a synthetic groundwater solution, with variations in the initial cesium concentration (10^-5, 5×10^-6, 10^-6, 5×10^-7 M). The cesium sorption kinetic and isotherm data were successfully simulated by the pseudo-second-order kinetic model (r²= 0.99) and the Freundlich isotherm model (r²= 0.99), respectively. The sorption distribution coefficient of granite increased almost linearly with increasing biotite content in granite samples, indicating that biotite is an effective cesium scavenger. The cesium removal was minimal in KCl solution compared to that in NaCl or CaCl₂ solution, regardless of the ionic strength and initial cesium concentration that we examined, showing that K⁺ is the most competitive ion against cesium in sorption to granite. Because it is the main source mineral of K⁺ in fracture fluids, biotite may also hinder the sorption of cesium, which warrants further research.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.12 no.1
• /
• pp.84-93
• /
• 2004

This study was performed : 1) to find the suitable HRT(hydralic retention time), 2) to evaluate the effects of the ratio of mixing/aeration time and injection time of external carbon source, for the removal of organics, nitrogen and phosphorus in swine wastewater by SBR(sequencing batch reactor process), which is one of the biological treatment process. The result of this study were summarized as follows : (1) As the ratio of mixing/aeration time was higher, $NH_4{^+}-N$ removal efficiency was increased and it was increased with increasing injection time of external carbon source because nitrification was affected by denitrification microbes propagation when injection time of external carbon soruce was shorted. T-N removal efficiency was increased with increasing the ratio of mixing/aeration time and injection time of external carbon source. (2) The T-P removal efficiency showed a great difference in each operating condition, and it was increased with increasing the ratio of mixing/aeration time increased and when the injection time of external carbon source was shorted because denitrification was done with effect by denitrification microbes propagation. (3) The highest removal efficiency of organic and nitrogen were obtained by the operating condition of Run 4-1(the ratio of mixing/aeration time : 16.5/5.5, injection time of external carbon source : 15hours) and T-P were obtained by the operation condition of Run 4-2(the ratio of mixing/aeration time : 16.5/5.5, injection time of external carbon source : 3hours), and efficiency(effluent concentration)of $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, T-N and T-P in the treated water was 96.1%, 87.7%, 90.6%, 86.6% and 84.5%, respectively.

• Journal of Life Science
• /
• v.15 no.4 s.71
• /
• pp.584-589
• /
• 2005

To investigate factors affecting the removal of phosphorus from the practical wastewater in the F-STEP PROCESS using a loess ball and Chromobacterium WS 2-14, first, the loess ball size and calcining temperature, initial pH, initial phosphorus concentration, working temperature, and aeration were studied. A $2\~4mm$ of loess ball made at $960^{\circ}C$ of calcining temperature was the most suitable one for the removal of phosphorus. When the initial pH was increased from 3.0 to 6.0, the removal efficiency of phosphorus was increased. Especially, at 6.0 of initial pH, the maximum removal efficiency of phosphorus was $88.7\%$. The maximum removal efficiency of phosphorous was gained, 1.8mg/h when the initial concentration of phosphorous was 5.0mg/1. When the operating temperature was $30^{\circ}C$, the maximum removal efficiency of phosphorus was obtained. In the case of aeration, when it was increased from 0.5 to 5.0L/min, the removal efficiency of phosphorus was increased. On the other hand, above 7.0 L/min, the removal efficiency of phosphorus did not increased. Using the optimum operation conditions, pilot tests for the effective removal efficiency of phosphorus were carried out for 65 days. The average removal efficiency of phosphorus was $92.0\%$. The average removal efficiency of COD, BOD, and SS were 77.1, 74.2, and $86.4\%$, respectively. from the results, it can be concluded that F-STEP PROCESS using loess ball might be useful process for phosphorus removal.

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.10
• /
• pp.724-729
• /
• 2013

Simultaneous nitrification and denitrification (SND) occurs concurrently in the same reactor under micro dissolved oxygen (DO) conditions. Anaerobic zone was applied for phosphorus release prior to an aerated membrane bio-reactor (MBR), and anoxic zone was installed by placing a baffle in the MBR for enhancing denitrification even in high DO concentration in the MBR. Phosphorus removal was tested by alum coagulation in the anaerobic reactor preceding to MBR. DO concentration were 2.0, 1.5, 1.0, 0.75 mg/L in the MBR at different operating stages for finding optimum DO concentration in MBR for nitrogen removal by SND. pH was maintained at 7.0~8.0 without addition of alkaline solution even with alum addition due to high alkalinity in the raw sewage. Both TCODcr and $NH_4^+$-N removal efficiency were over 90% at all DO concentration. TN removal efficiencies were 50, 51, 54, 66% at DO concentration of 2.0, 1.5, 1.0, 0.75 mg/L, respectively. At DO concentration of 0.75 mg/L with addition of alum, TN removal efficiency decreased to 54%. TP removal efficiency increased from 29% to 95% by adding alum to anaerobic reactor. The period of chemical backwashing of the membrane module increased from 15~20 days to 40~50 days after addition of alum.

• Economic and Environmental Geology
• /
• v.42 no.5
• /
• pp.395-401
• /
• 2009

The smectite-illite (SI) reaction is a ubiquitous process in siliciclastic sedimentary environments. For the last 4 decades the importance of smectite to illite (S-I) reaction was described in research papers and reports, as the degree of the (S-I) reaction, termed "smectite illitization", is linked to the exploration of hydrocarbons, and geochemical/petrophysical indicators. The S-I transformation has been thought that the reaction, explained either by layer-by-layer mechanism in the solid state or dissolution/reprecipitation process, was entirely abiotic and to require burial, heat, and time to proceed, however few studies have taken into account the bacterial activity. Recent laboratory studies showed evidence suggesting that the structural ferric iron (Fe(III)) in clay minerals can be reduced by microbial activity and the role of microorganisms is to link organic matter oxidation to metal reduction, resulting in the S-I transformation. In abiotic systems, elevated temperatures are typically used in laboratory experiments to accelerate the smectite to illite reaction in order to compensate for a long geological time in nature. However, in biotic systems, bacteria may catalyze the reaction and elevated temperature or prolonged time may not be necessary. Despite the important role of microbe in S-I reaction, factors that control the reaction mechanism are not clearly addressed yet. This paper, therefore, overviews the current status of microbially mediated smectite-to-illite reaction studies and characterization techniques.