• 한국연초학회지
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• 제25권1호
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• pp.27-33
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• 2003

This study was conducted to determine the changes of nitrogen compounds in lamina and midrib during the curing process with the different curing methods, such as priming and stalk-cut curing. After KB 108 burley tobacco was cultivated by the different fetilization levels such as standard and 20% higher, only the tips and leaf were harvested. Though the contents of total alkaloid and total nitrogen were similar in lamina, midrib showed a very low contents of those components by the different curing method and fertilization levels. The content of nitrate-nitrogen in lamina increased during a middle of curing process, and then these compound was decreased during an end of curing process by stalk-cut curing method. Nitrate-nitrogen contents in the lamina by the priming curing showed a high level caused by rapid drying process during an end of curing process. That component in midrib was 5-6 times higher than that of lamina. The contents of ammonia-nitrogen in the lamina and midrib were increased during a curing process. Though those amount in tips showed a similar by a different fetilization and curing method, midrib of stalk-cut curing showed a slow increasing during a curing process.

• 한국물환경학회지
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• 제38권4호
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• pp.171-176
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• 2022

Recently, an autotrophic single-stage nitrogen removal (ASSNR) process based on the anaerobic ammonium oxidation (ANAMMOX) reaction has been proven as an economical ammonia treatment. It is highly evident that double-layered gel beads are a promising alternative to the natural biofilm for ASSNR because of the high mechanical strength of poly(vinyl alcohol) (PVA)/alginate structure and efficient protection of ANAMMOX bacteria from dissolved oxygen (DO) due to the thick outer layer. However, the thick outer layer results in severe mass transport limitation and consequent lowered bacterial activity. Therefore, the effects of the thickness of the outer layer on the overall reaction rate were tested in the biofilm model using AQUASIM for ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and ANAMMOX bacteria. A thickness of 0.5~1.0 mm is preferred for the maximum total nitrogen (TN) removal. In addition, a DO of 0.5 mg/L resulted in the best total nitrogen removal. A higher DO induces NOB activity and consequent lower TN removal efficiency. The optimal density of AO B and NO B density was 1~10% for a 10% ANAMMOX bacterial in the double-layered PVA/alginate gel beads. The real effects of operating parameters of the thickness of the outer layer, DO and concentrations of biomass balance should be intensively investigated in the controlled experiments in batch and continuous modes.

• 한국수산과학회지
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• 제12권4호
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• pp.293-296
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• 1979

굴(Crassostrea gigas)의 질소배설과 산소소비에 미치는 수온 및 염분의 상호영향을 조사한 결과는 다음과 같다. 1. 굴은 수온과 염분변화에 따라 질소배설율과 배설암모니아 및 아미노산간의 배설비에 현저한 변동을 보였으며 산소소비량에도 역시 많은 변동을 보였다. 2. 질소배설율과 산소소비율은 염분이 증가함에 따라 특히 고염분일 때 고수온$(29^{\circ}C)$의 경우에 현저히 감소하였으나 저온분에서는 상당히 증가하였다. 이것은 생리적 내성의 고온단계와 저염분에 대한 포상작용에 기인한 결과라고 생가된다. 3. 암모니아를 주로 배설하였으나 상당한 량의 아미노-질소도 배설하였으며, 특히 상염분-온난온도대$(32.5\%_{\circ}-22^{\circ}C$에서는 아미노산의 배설량이 우세하였다. 그리고 어느 실험온도에서나 고염분에서 아미노-질소의 배설량은 감소하였고 저염분에서는 증가하였다. 4. 배설암모니아-질소에 대한 소비산소의 원자비 (O: N비)는 저온$(15^{\circ}C)$에서는 현저히 낮고 상온 및 고온($22^{\circ}$ 및 $29^{\circ}C$)에서는 높았다. 그러나 저온분의 경우 고온에서는 현저히 감소되었다.

• 대한환경공학회지
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• 제37권10호
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• pp.578-582
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• 2015

가축분뇨에 포함된 질소이온의 저감 효과가 마이크로버블과 촉매와 접촉하는 시간을 증가시켜 향상되는지를 알아보았다. 마이크로버블과 촉매를 이용하는 반응기 2개를 연속 배치시키고, 첫번째 반응기(1단)를 거쳐 다음 반응기(2단)로 이송되도록 하였으며 각 반응기에서는 2시간씩 반응하도록 하였다. 가축분뇨의 마이크로버블과 촉매와의 반응시간 2시간과 4시간 경과했을 때, 산화제로 공기를 사용하였을 때는 암모니아성 질소 제거율은 15.6%에서 39.3%로, 산소를 넣었을 때는 18.3%에서 52.8%로 증가하여 반응시간이 길수록, 그리고 산소를 사용할 때 제거율이 더 높은 것으로 나타났다. 아질산성질소와 질산성질소의 경우도 산소를 이용할 때 반응시간에 따라 아질산성질소는 80.2%에서 90.4%로, 질산성질소는 60.0%에서 75%로 반응시간이 길수록, 그리고 산소를 사용할 때 더 높은 것으로 나타났다. 유기오염물질의 경우 TCOD의 제거능이 SCOD의 제거능 보다 높게 나타났는데 이것은 생물학적으로 분해가 불가능한 물질의 분해가 더 많이 된 것을 의미하며, 이 시스템 이후 생물학적 처리를 수행하는 경우 유출수의 유기오염물질 농도를 줄일 수 있을 것으로 판단된다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.501-504
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• 2004

High quality GaN layer was obtained on 0001 sapphire substrate using ammonia($NH_3$) as a nitrogen source by gas source molecular beam epitaxy. As a result, RHEED is used to investigate the relaxation processes which take place during the growth of GaN. In-situ RHEED(reflection high electron energy diffraction) appeared streaky-like pattern. The full Width at half maximum of the x-ray diffraction(FWHM) rocking curve measured from plane of GaN has exhibited as narrow as 8arcmin and surface roughness was 7.83nm. Photoluminescence measurement of GaN was investigated at room temperature, where the intensity of the band edge emission is much stronger than that of deep level emission. The GaN epitaxy layer according to various growth condition was investigated.

• Journal of Microbiology and Biotechnology
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• 제29권12호
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• pp.1993-2005
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• 2019

Thermophilic anaerobic digestion (TAD) is characterized by higher biogas production rates as a result of assumedly faster microbial metabolic conversion rates compared to mesophilic AD. It was hypothesized that the thermophilic microbiome with its lower diversity than the mesophilic one is more susceptible to disturbances introduced by alterations in the operating factors, as an example, the supply of nitrogen-rich feedstock such as poultry manure (PM). Laboratory scaled TAD experiments using cattle slurry and increasing amounts of PM were carried out to investigate the (in-) stability of the process performance caused by the accumulation of ammonium and ammonia with special emphasis on the microbial community structure and its dynamic variation. The results revealed that the moderate PM addition, i.e., 25% (vol/vol based on volatile substances) PM, resulted in a reorganization of the microbial community structure which was still working sufficiently. With 50% PM application, the microbial community was further stepwise re-organized and was able to compensate for the high cytotoxic ammonia contents only for a short time resulting in consequent process disturbance and final process failure. This study demonstrated the ability of the acclimated thermophilic microbial community to tolerate a certain amount of nitrogen-rich substrate.

• Asian-Australasian Journal of Animal Sciences
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• 제5권1호
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• pp.33-37
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• 1992

Napier grass (Pennisetum purpureum Schum.) harvested at an early growth stage was ensiled with 4% of molasses in a polyethylene bag silo which contained 15 kg of chopped forage each. Dry matter (DM) content of the silage was so low as 14.75%, although chemical quality of the silage was very high. Ratio of ammonia nitrogen to total nitrogen was 6.59%, and the pH value of the silage was 3.79. Nutritive value of the silage was estimated using goats and compared to that of a timothy hay as a reference ration. Feeding level of each rations was adjusted to a level of nitrogen (N) recommendation. DM and N digestibilities of the silage were 65.0 and 54.5%, respectively, but those of the timothy hay were 37.6 and 37.2%. Feeding of the napier grass silage maintained body weight and kept positive N retention. Ammonia N concentration in the rumen fluid in goats fed the napier grass silage increased after feeding, but blood urea concentration was constant. Feeding of the timothy hay did not increase ammonia N concentration in the rumen fluid, but increased blood urea concentration. These facts indicated that the napier grass silage had enough digestible DM and N for maintenance ration to goats.

• 한국물환경학회지
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• 제22권1호
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• pp.83-90
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• 2006

Performance and operation of BAC in ozone-BAC advanced water treatment process were investigated using the pilot scale test plant built in D water purification plant. The performance was evaluated by the removal efficiencies of DOC, BDOC, ammonia nitrogen and THMs. The effect of EBCT on DOC removal was experimented for an effective operating condition, and the amount of attached biofilm was analyzed in various water temperatures and position of BAC. Two removal mechanisms, adsorption and biological decomposition by attached biofilm, were predominant to decrease the concentration of various contaminants. DOC was removed 40%, and the removal rate was decreased in winter time due to the lowered activity of attached biofilm. BDOC was effectively removed. THMs and ammonia nitrogen were mainly removed not in ozonation process but in BAC. Water temperature deeply influenced in removal efficiency of ammonia nitrogen. The amount of attached biofilm depended on water temperature and height of packed activated carbon column. Considering DOC removal efficiency and design EBCT of commercial BAC plant, the proper EBCT was 12.5 minutes.

• 한국환경보건학회지
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• 제31권4호
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• pp.280-286
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• 2005

The purpose of this investigation was to evaluate removal efficiency of $NH_4-N$ using the soil column. Soil, oyster shell and natural zeolite were used as a supporting media of soil column. Removal efficiencies of $NH_4-N$ were $35.9\%,\;41\%\;and\;93.4\%$ for the soil column packed with soil, natural $zeolite(20\%)$ and oyster $shell(20\%)$ at HRT of 72 hours, respectively. The addition of $20\%$ oyster shell to the soil accelerated nitrification in soil column. The influent ammonia nitrogen was mostly converted to nitrate nitrogen in the soil column and little ammonia nitrogen was found in the effluent. When the influent $NH_4-N$ concentration was 200 mg/l, the NIL-N removal was decreased at HRT of 48 hours, while nitrification was significantly increased after mechanical aeration. It was suggested that nitrification from higher $NH_4-N$ concentration was more affected by aeration in soil column process. The number of nitrifiers was approximately in a level of about $10^6\;MPN/g{\cdot}soil$ in the soil column mixed with oyster shell ($20\%$).

• Membrane and Water Treatment
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• 제9권2호
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• pp.123-128
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• 2018

Common aquaculture practices include the use of certain pharmaceuticals such as antibiotics in avoiding diseases and promoting a healthier growth of the culture. The aim of this study is to monitor and assess the influence of different low oxytetracycline concentrations on the transformation of nitrogen compounds under aeration condition in a lab-scale recirculating aquaculture system (RAS). Over $1mg\;L^{-1}$ dose of oxytetracycline to aquaculture had induced ammonia($NH_4-N$), nitrate($NO_3-N$), soluble COD accumulation in RAS. In addition, nitrous oxide ($N_2O$) emission from RAS was significantly reduced during the oxytetracycline dose periods. After ceasing the dose of oxytetracycline, ammonia oxidation and nitrous oxide re-emission were observed. This observation indicated that low concentrations of oxytetracycline could affect the nitrogen species in RAS. Also, the emission mechanisms of $N_2O$ may not be only dependent on nitrification process but also dependent on denitrification process in our RAS system.