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        검색결과 172

        141.
        2016.11 서비스 종료(열람 제한)
        도시생활폐기물소각재(MSWI ash)을 매립하게 되면 장기적으로 중금속이 침출된다. 급속탄산화를 통하여 MSWI ash 내의 중금속을 탄산염 형태로 고정하여, 중장기적으로 침출을 방지할 수 있다. 본 연구에서는 급속 탄산화 방법을 통하여 소각재인 fly ash의 중금속 저감 및 이산화탄소 저감에 대해 수행하였다. NH4OH, NH4SCN, 및Ca(OH)2를 이용하여 test 하였으며, 소각재의 중금속을 탄산화 전, 후를 비교하여 중금속이 침출량을 비교 하였다. 추가적으로 이산화탄소가 fly ash에 포집된 이산화탄소 저감량을 나타내면서 이산화탄소 흡수제의 재사용 가능성을 확인하였다. 흡수제를 재생하는 과정에서 나온 CO32-이온에 의해 탄산화 된 금속염들의 성분 분석을 위해, XRD (X-ray diffraction analyzer(Ultima Ⅳ))를 사용하였다. 그리고 FE-SEM(Field emission scanning electron microscope, JEOL-7800)으로 filtering후 건조시킨 샘플과 fly ash의 표면구조를 촬영하고 비교하였다.
        142.
        2016.11 서비스 종료(열람 제한)
        온실가스인 이산화탄소는 다른 온실가스에 비해 Global Warming Potential(GWP)가 가장 낮지만 배출량이 전체 온실가스 중 88 %의 비중을 차지하고 있다. 많은 국가에서 기후변화에 관심을 가지고 이산화탄소 저감에 대한 연구개발이 활발히 일어나고 있다. 본 연구에서는 암모늄 화합물을 이용하여 이산화탄소를 포집하고 산업폐기물의 금속이온을 이용하여 무기재료인 탄산칼슘을 생성하는 다양한 방법을 소개한다. 탄산칼슘 생성을 위해 칼슘이온이 포함된 탈황석고, 폐시멘트를 이용하였다. 결과에서 이산화탄소 포집 성능 및 최종생성물의 결정구조를 확인하였으며, 이산화탄소 loading 값  는 약 2.0의 값을 가진다. X-Ray Diffraction, Scanning Electron Microscope의 분석을 통하여 탄산칼슘이 생성되었음을 확인하였으며, 결정구조는 Vaterite가 생성됨을 확인할 수 있다. 효과적인 공정을 위하여, 생성물을 생성한 후 용액을 회수하여 재이용할 수 있어 연속적인 공정이 가능하다. 회수된 용액의 재이용의 가능성을 보기위하여 이산화탄소를 재흡수 시키면서 같은 공정을 2cycle씩 진행하여, 연속적인 공정의 잠재성을 확인하였다.
        143.
        2016.10 KCI 등재 서비스 종료(열람 제한)
        Generally, metal working fluids (MWFs) are used to reduce friction in metalworking processes. In addition to mineral oils, MWFs contain many chemical substances, such as anticorrosive agents, extreme-pressure additives, and stabilizers, as well as high concentrations of organics and ammonia nitrogen. Accordingly, MWFs must be managed to advanced treatment for hydro-ecological conservation. This study investigated the removal efficiency of ammonia nitrogen from MWFs according to operating time, applied voltage, distance between electrodes, and NaCl concentration using aluminum in a batch-type reactor. The experimental results were as follows: First, without NaCl, removal efficiencies of ammonia nitrogen were 69.6%, 37.9%, and 22.7%, when the distance between electrodes was adjusted to 1, 4, and 7 cm, respectively, at 15 V for 60 min. Secondly, without NaCl, removal efficiencies of ammonia nitrogen were 49.5 and 90.9% when the voltage was adjusted to 5 V and 10 V, respectively, for 60 min and 94.6% at 15 V for 40 min. Lastly, with the addition of NaCl 10 mM, the removal efficiency of ammonia nitrogen was 40.3% and 11.5% greater than that of no addition of NaCl at 5 V for 60 min and at 10 V for 30 min.
        144.
        2016.09 KCI 등재 서비스 종료(열람 제한)
        산화대 금 광석에 존재하는 적철석을 암모니아 용액을 이용하여 제거하여 금과 은의 회수율을 향상시키고자 하였다. 산화대에는 석영, 적철석, 백운모가 존재하고 있으며, 적철석은 수성기원으로 형성되었다. 다양한 변수에 대하여 암모니아 용출실험을 수행한 결과, Fe 최대 용출 인자는 -45 μm 입도 크기, 1.0 M의 황산 농도, 5.0 g/l의 황산암모늄 농도 그리고 2.0 M의 과산화수소 농도일 때였다. 이 암모니아 용출용액으로부터 침철석이 침전-형성되는 것을 확인하였으며, 고체-잔류물에서 Fe-제거 량이 증가할수록 Au와 Ag 회수율이 증가하였다.
        145.
        2015.10 KCI 등재 서비스 종료(열람 제한)
        The effects of Houttuynia cordata powder on the growth performance of ducks were investigated. Ninety ducks were assigned into one of three dietary treatments as a completely randomized design for 6 weeks: feeds supplemented with 1% or 2% H. cordata and a control group. No significant difference was observed in feed conversion among the three groups (p > 0.05), but addition of H. cordata had a significantly positive effect (p < 0.05) on initial and final body weight, weight gain, and feed intake of the ducks. Furthermore, the effects of chemical treatment (comprising 50 g and 100 g aluminum chloride [AlCl3] per kilogram litter) on the ammonia (NH3) flux in duck litters were also investigated. Duck litter was treated with AlCl3 at a depth of 8 cm by top-dressing; this resulted in a significant difference on NH3 flux (p < 0.05) during the experimental period (but not at 2 weeks). NH3 flux at 6 weeks were reduced by 25.4% and 37.5% by treatment with 1% and 2% H. cordata, respectively, compared with the control groups. In conclusion, enriching the diets of the ducks with 2% H. cordata and adding 100 g AlCl3 to their litter has beneficial effects on increasing their growth performance and reducing NH3 flux in their environment.
        146.
        2015.05 서비스 종료(열람 제한)
        Livestock wastewater has high potential as one of energy resources because this wastewater is including high organic matter. Therefore the studies attempting to bio-gasification and bio-electricity generation using livestock wastewater is being tried. The pre-treatment system used in this study was the purpose to control the ammonia nitrogen in conjunction with the system and the microbial fuel cell. Because ammonia nitrogen is to inhibit the electricity generation efficiency of microbial fuel cell. These studies were to ascertain the effect of oxidants on the nitrogen removal in the pre-treatment system using catalyst and microbubbles to treat the ammonia nitrogen. The three kinds of oxidant such as air, oxygen (O2), and hydrogen peroxide (H2O2) were used to know the ammonia and nitrate nitrogen removal. This system was operated with four kinds of conditions. First method is O2 gas with 100 mL/min with 1ml of 30% H2O2 was supplied to the wastewater. A second method, the O2, with 400 and 1,000 mL/min was supplied through the flow meter before livestock wastewater was flow in the reactor. The last method, air was supplied 800 mL/min. The nitrate removal had no significant difference all conditions except the air supply. On the other hand, the ammonia and nitrate nitrogen removal when oxygen was supplied with 1000 mL O2/min was higher than that of the other conditions. The removal rate when air was supplied 800 mL/min was similar to the value in the supplied with 400 ml O2/min. This result showed that oxidant was important factor to improve the ammonia nitrogen removal rate.
        147.
        2015.05 서비스 종료(열람 제한)
        The amount of nutrients entering the soil annually about 100 million tonnes. Among the 100 million tons of nutrients is chemical fertilizers 600,000 tons with manure compost/liquid fertilizer 400,000tons. Fifty percent of nutrients is sprayed to soil but the crop is not used. So building up nutrients in the soil is released into the water together. There is no system that can maintain nutrient balance of the country. Chemical fertilizers and manure compost manure is used on an ongoing basis. Rivers, oceans, lakes, and reservoirs become serious problems of eutrophication. Nitrogen and phosphorus is the cause of eutrophication. As the excessive accumulation of water discharged to the environment, resulting in algae and red tides. The government responded by introducing the amount of total nutrient system in 2008. So the amount of nutrient that can be sprayed on the soil was picked reduced. For the reason, the farmers is became the handling of manure seriously. Since 2012, the manure is that speculation was banned in the ocean. Processing method and system response measures on land was needed. In this study were investigated for reuse and to remove the ammonium nitrogen contained less than 80 % of the total nitrogen with the Air stripping technique.
        150.
        2014.07 KCI 등재 서비스 종료(열람 제한)
        This research investigated the feasibility of rice husk as a biosorbent for removal of ammonium ion from aqueous solutions. To improve the sorption functionality of rice husk, the carboxyl groups were chemically bound to the surface of the rice husk by graft polymerization of acrylic acid using potassium peroxydisulphate as a redox initiator. The removal of ammonium ion by rice husk grafted with acrylic acid (RH-g-AA) was studied in a batch mode and fixed bed columns. The kinetic and equilibrium data obtained from batch experiments follow the second-order kinetics and fit well with the Langmuir isotherm model. The sorption energy determined from D-R model was 8.61 kJ/mol indicating an ion-exchange process as the primary sorption mechanism. To determine the characteristic parameters of the column useful for process design, four mathematical models; Bed Depth Service Time (BDST), Bohart-Adams, Clark and Wolborska models were applied to experimental data obtained from the fixed bed columns with varying bed heights. All models were found to be suitable for simulating the whole or a definite part of breakthrough curves, but the Wolborska model was the best. The fixed bed sorption capacity determined from the Wolborska model was in the range 33.3 ~ 40.5 mg/g close to the value determined in the batch process. The thickness of mass-transfer zone was calculated to be approximately 40 mm from DBST model. The RH-g-AA sorbent could be regenerated by a simple acid washing process without a serious lowering the sorption capacity or physical durability.
        151.
        2014.03 KCI 등재 서비스 종료(열람 제한)
        저 품위 엽납석 광석에 포함된 불순물 Fe를 제거하기 위하여 입도크기, 황산농도, 황산암모늄농도, 과산화수소농도 그리고 온도변화에 따른 제거 효율에 대하여 연구하였다. 저 품위 엽납석 광석에서 자형의 입방체 황철석이 포함된 것을 반사현미경으로 관찰할 수 있었으며, X-선 회절분석결과 주 구성광물은 석영과 딕카이트였다. 실험 결과 Fe 용출율이 최대로 나타나는 입도 -325 mesh에서, 황산농도는 2.0 M에서, 황산암모늄 농도는 10.0 g/l, 과산화수소 농도 3.0 M 그리고 최적의 용출 온도는 70℃에서였다. 용해 동역학 분석에서, Fe 용해는 황철석 표면에서 일어나며 화학적 반응에 통제되는 것으로 그리고 0.066/R, [H2SO4]1.156, [(NH4)2SO4]0.745, [H2O2]0.428 에 비례하는 것으로 나타났다.
        152.
        2013.09 KCI 등재 서비스 종료(열람 제한)
        황철석 시료로부터 Fe를 효과적으로 용출시키기 위하여 마이크로웨이브 에너지와 암모니아 용액을 적용하였다. 황철석을 마이크로웨이브에 60분 동안 노출시키자 적철석과 자류철석으로 상변환되었다. 그리고 암모니아 용액에 의하여 Fe가 최대로 용출되는 마이크웨이브 노출시간은 60분이였다. Fe 용출율이 99% 이상으로 나타나는 시료와 마이크로웨이브 노출 조건은 325-400 mesh의 황철석 시료와 60분에서였다. 그리고 암모니아 용출 조건은 0.3 M의 황산, 2.0 M의 황산암모늄 그리고 0.1 M의 과산화수소 농도에서였다. 고체-잔류물에 대하여 XRD 분석을 수행한 결과 황철석, 적철석 그리고 자류철석은 암모니아 용액에 의하여 완전히 제거되었지만 석영은 제거되지 않았다.
        153.
        2012.12 KCI 등재 서비스 종료(열람 제한)
        The vertical distributions of nitrifying bacteria in aerobic fixed biofilm were investigated to evaluate the relationship between nitrification performance and microbial community at different HRT. Fluorescent in situ hybridization (FISH) and portable ion selective microelectrode system were adopted to analyze microbial communities and ions profiles according to the biofilm depth. Cilia media packed MLE (Modified Ludzack-Ettinger) like reactor composed of anoxic, aerobic Ⅰ/Ⅱ was operated with synthetic wastewater having COD 200 mg/L and NH4 +-N 40 mg/L at HRT of 6 hrs and 4 hrs. Total biofilm thickness of aerobic Ⅰ, Ⅱ reactor at 4 hrs condition was over two times than that of 6 hrs condition due to the sufficient substrate supply at 4 hrs condition (6 hrs; aerobic Ⅰ 380 ㎛ and Ⅱ 400 ㎛, 4 hrs; aerobic Ⅰ 830 ㎛ and Ⅱ 1040 ㎛). As deepen the biofilm detection point, the ratio of ammonia oxidizing bacteria (AOB) was decreased while the ratio of nitrite oxidizing bacteria (NOB) was maintained similar distribution at both HRT condition. The ratio of AOB was higher at 4 hrs than 6 hrs condition and NH4 +-N removal efficiency was also higher at 4 hrs with 89.2% than 65.4% of 6 hrs. However, the ratio of NOB was decreased when HRT was reduced from 6 hrs to 4 hrs and NO2 --N accumulation was observed at 4 hrs condition. Therefore, it is considered that insufficient HRT condition could supply sufficient substrate and enrichment of AOB in all depth of fixed biofilm but cause decrease of NOB and nitrite accumulation.
        154.
        2012.12 KCI 등재 서비스 종료(열람 제한)
        The ion selective microelectrodes (ISME) have been applied to observe the continuous profiles of NO3-N and NH4-N in bulk solutions or biofilms. In order to evaluate the performance and applicability of ion concentration measuring system, the characteristics, such as slope of calibration curve, detection limit and potentiometric selectivity coefficient were investigated. The slopes of calibration curve showed high degree of correspondence for each target ion concentrations. And the detection limits of nitrate and ammonia ion selective microelectrode were 10-4.7 M and 10-4.4 M, respectively. These ion selective microelectrodes were proved that their own performance could be maintained for 16 days after making. NO3-N and NH4-N selective microelectrodes were also adapted to detect the continuous ion profiles of cilia media packed MLE (Modified Ludzack-Ettinger) process. And the monitored nitrate and ammonia ion profiles with the ion selective microelectrode were stable and well corresponded to the results with conventional ion chromatograph. However, the electric potential was unstable until 8 hr because of the unknown noise. The tip shape and performance of the ion selective microelectrode was stably kept over 2 days continuous monitoring.
        155.
        2011.12 KCI 등재 서비스 종료(열람 제한)
        본 연구는 난과 식물의 암모니아 피해 증상을 정확하게 알기 위해 팔레놉시스, 심비디움, 덴파레, 온시디움을 이용하여 밀폐된 챔버에서 수행하였다. 암모니아 가스처리 농도는 0, 30, 60, 100, 300, 400mg・L-1으로 하였다. 암모니아 가스 처리 조건은 온도 26±1.9℃, 습도 82.4±11.2%로 15시간 처리하여 피해 증상과 정도를 조사하였다. 하루 중 가스 피해 증상이 심한 시간대를 알기 위해 암모니아에 민감한 온시디움를 이용하여 200mg・L-1 농도로 하여 가스 노출시간을 2, 4시간씩 6등분하여 처리하였다. 팔레놉스시는 암모니아 300mg・L-1 이상이 되어야 피해가 발생하며 심비디움, 온시디움, 덴파레는 100mg・L-1 이상에서 피해가 발생하였다. 특히 온시디움이 가장 민감하였다. 가스 농도가 증가할수록 피해엽율은 증가하였는데 400mg・L-1에서는 83.4%였다. 엽록소 형광측정값(Fv/Fm) 또한 감소하였다. 하루 중 시간대별 피해증상은 주간 06~18시에 주로 나타나며 10~16시가 심하게 나타났다. 잎의 주요 피해 증상은 잎이 회갈색으로 급격히 마르며 가장 자리가 말리고 피해 받은 잎은 점점 옅은 황갈색으로 변하거나 건조되었다.
        156.
        2010.12 KCI 등재 서비스 종료(열람 제한)
        Phenylalanine ammonia-lyase (PAL), a key enzyme of the phenylpropanoid biosynthesis pathway, is activated by a number of developmental and environmental cues. The coding region of the NtPAL4 gene was 2,154 bp in length, and its deduced protein was composed of 717 amino acids. Sequence analysis of NtPAL4 cDNA from tobacco (Nicotiana tabacum L.) revealed high structural similarity to PAL genes of other plant species. The NtPAL4 gene exists as a single copy in the tobacco plant, and its transcripts were strongly expressed in flowers and leaves. NtPAL4 expression was significantly induced in response to NaCl, mannitol, and cold treatments, but it was not induced by abscisic acid (ABA). NtPAL4 expression decreased gradually after treatment with ABA and H2O2; however, NtPAL4 transcripts accumulated after treatment with methyl viologen (MV). Our results suggest that the NtPAL4 gene may function in response to abiotic stresses.
        157.
        2010.04 KCI 등재 서비스 종료(열람 제한)
        Allium sativum, belongs to a member of the onion family (Alliaceae) are economically important vegetables because of the culinary value and medicinal purpose. Using PCR strategy with degenerated primers targeted to conserved regions of orthologous phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H) sequences available, full-length PAL and C4H from A. sativum. The amino acid sequence of these genes is highly conserved, particularly AsPAL and AsC4H has greater than 70% amino acid identity to other plants. AsPAL and AgC4H were most highly expressed in roots of A. sativum, whereas lowest level of transcript was detected in flower. Phenolic compounds most highly produced in flowers of A. sativum. The presented sequences and expression an alysis of PAL and C4H will provide possible material to enhance the understading of phenolic compounds synthesis in A. sativum.
        159.
        2008.11 KCI 등재 서비스 종료(열람 제한)
        Aerated submerged bio-film (ASBF) pilot plant has been developed. The presented studies optimized an inexpensive method of enhanced wastewater treatment. The objectives of this research were to describe pilot scale experiments for efficient removal of dissolved organic and nitrogen compounds by using ASBF reactor in plug-flow reactor (PFR) and improve understanding of dissolved organic matter and nitrogen compounds removal rates with dynamic relationships between heterotrophs and autotrophs in the fixed-film reactor. This research explores the possibility of enhancing the performance of shallow wastewater treatment lagoons through the addition of specially designed structures. This direct gas-phase contact should increase the oxygen transfer rate into the bio-film, as well as increase the micro-climate mixing of water, nutrients, and waste products into and out of the bio-film. This research also investigated the efficiency of dissolved organic matter and ammonia nitrogen removals in the ASBF. As it was anticipated, nitrification activity was highest during periods when the flow rate was lower, but it seemed to decline during times when the flow rate was highest. And ammonia nitrogen removal rates were more sensitive than dissolved organic matter removal rates when flow rates exceeded 2.2 L/min.
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