• Journal of Plant Biology
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• v.34 no.4
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• pp.253-260
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• 1991

Spirodela polyrhiza and Lemna aequinoctialis often occurred at the sites of high ammonium concentration and at the sites of high nitrate concentration, respectively. We investigated the different distribution between two species in relation to the type of nitrogen sources and their concentrations. Our experiments showed that L. aequinoctialis grew faster than S. polyrhiza in nitrate media with lower than 15 mM concentration. The nitrate uptake was also faster in L. aequinoctialis than in S. polyrhiza. However, neither differences in growth nor in uptake patterns between these two species were observed in ammonium media. Glutamine synthetase (GS), glutamate dehydrogenase (GDH) and glutamate synthetase (GOGAT) activities were higher in L. aequinoctialis. In particular, nitrate reductase activity (NRA) in L. aequinoctialis was 12.1 times as high as that in S. polyrhiza. These results showed that the two species responded varyingly to the types of nitrogen sources and their concentrations. Therefore, the difference in geographic distribution between the two species appeared to reflect the interspecific differences in enzyme activities and, subsequently, nitrogen absorption abilities.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.1
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• pp.77-82
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• 2013

The growth and removal capacity of nitrogen and phosphorus of Chlorella vulgaris were evaluated in artificial wastewater with different nitrogen and phosphorus concentrations as element growing components for microalgae growth. The nitrogen concentration was varied in 9, 15, 30 and 60 mg-N/L with fixed phosphorus concentration of 3 mg-P/L. The growth and phosphorus removal capacity of C. vulgaris were high at initial nitrogen concentration of 15 and 30 mg-N/L, and the corresponding N/P ratios calculated were 5 and 10. In the case of varying in 1.5, 3, 6 and 10 mg-P/L of phosphorus concentration with fixed nitrogen concentration of 30 mg-N/L, the growth and removal capacity of nitrogen and phosphorus were excellent with phosphorus concentration of 3 and 6 mg-P/L. The corresponding N/P ratios were shown as 10 and 5. Therefore, the appropriate N/P ratio was concluded between 5 and 10 for wastewater treatment using C. vulgaris.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.586-589
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• 2002

The Ultra Violet(UV) emission characteristics of Neon + Nitrogen gas-mixture discharge was investigated in AC plasma display panel. The firing voltage of Ne+$N_2$ gas-mixture discharge increased with increasing nitrogen concentration. The UV intensity emitted from the gas discharge also increased with increasing nitrogen concentration. The UV efficiency increase with increasing $N_2$ partial pressure at low $N_2$ concentration, and then UV efficiency is saturated at high $N_2$ concentration.

• Journal of Plant Biology
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• v.7 no.1
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• pp.5-10
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• 1964

The effects of briquette ashes on the growth of vegetable (cabbage, lettuce, spinach and radish) and their fresh weight under the culture of the soil mixed with the briquette ashes, and on the chemical properties of the soil were investigated. The growth rate of these palnts and chemical properteis of the soil has shown some influence due to different concentration of briquette ashes added to the soil. The increase of growth in cabbage and lettuce was remarkably found by the plot treated with 1/50 concentration of briquette ashes. The fresh weight of vegetable plants was increased with high concentration of briquette ashes, but if the concentration of briquette ashes was too high, it was rather depressed. Chemical properties in the soil after cultivation of the plants were more depressed than before cultivation. In contrast the available nitrogen content in the soil after cultivation was more increased than before cultivation of the plants. The reduction of available nitrogen and nitrate nitrogen was associated with the increasing intensity of briquette ashes, but available phosphorus content was increased with high concentration of briquette ashes, though its content was not so high as the results obtained by Han(8). The values of total exchangeable base and pH in the soils treated with briquette ashes were increased with a high degree of the concentration of ashes. The value of pH was not significant, and pH value of lime plots was higher than that of briquette ashes. The average value of the water content did not show any difference, and the difference of the content of organic matter in the soil in which different vegetable grew into the plots reached to the significance of a 5% level.

• Journal of Microbiology and Biotechnology
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• v.21 no.10
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• pp.1073-1080
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• 2011

In order to investigate and generalize the effects of carbon and nitrogen sources on the growth of and lipid production in Chlorella sp. 227, several nutritional combinations consisting of different carbon and nitrogen sources and concentrations were given to the media for cultivation of Chlorella sp. 227, respectively. The growth rate and lipid content were affected largely by concentration rather than by sources. The maximum specific growth was negatively affected by low concentrations of carbon and nitrogen. There is a maximum allowable inorganic carbon concentration (less than 500~1,000 mM bicarbonate) in autotrophic culture, but the maximum lipid content per gram dry cell weight (g DCW) was little affected by the concentration of inorganic carbon within the concentration. The lipid content per g DCW was increased when the microalga was cultured with the addition of glucose and bicarbonate (mixotrophic) at a fixed nitrogen concentration and with the lowest nitrogen concentration (0.2 mM), relatively. Considering that lipid contents per g DCW increased in those conditions, it suggests that a high ratio of carbon to nitrogen in culture media promotes lipid accumulation in the cells. Interestingly, a significant increase of the oleic acid amount to total fatty acids was observed in those conditions. These results showed the possibility to induce lipid production of high quality and content per g DCW by modifying the cultivation conditions.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.861-863
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• 1998

As-casted high nitrogen alloys (Fe-25%Mn-12%Cr-1%Ni) have been investigated to study core material. Nitrogen concentration in molten alloys was increased with increasing the square root of nitrogen gas pressure in melting chamber. This result can be explained by Sievert's law. Nitrogen that dissolved as a interstital solid solution element in austenite stainless steel increased lattice parameter and hardness. Electric resistivity($\rho$) was increased with increasing nitrogen concentration and was about $80{\mu}{\Omega}cm$ at room temperature. Coefficient of linear thermal expansion of the nitrogen steel was about $22{\times}10^{-6}/^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.326-334
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• 2022

This study was carried out to investigate the optimal nitrogen concentration level suitable for forage rice growth by hydroponic cultivation in the salinity concentration of 0.1~0.3% which is similar to that of Muan reclaimed paddy field, and based on this results, to estimate optimal nitrogen fertilization level by field experiment in Muan reclaimed paddy for maximum forage production by cultivation of Yeongwoo rice. As a result of the growth response to the salt and nitrogen concentrations in the hydroponic cultivation experiment, the growth amount increased as the nitrogen concentration increased in the range of 0~24 me/L in the absence of salt stress. However, at a salt concentration of 0.1~0.3%, the growth amount was the highest at a nitrogen concentration of 12 me/L, and at higher nitrogen concentrations of that, the rice growth decreased as the nitrogen concentration increased. Therefore, nitrogen concentration of 12 me/L was judged to be an appropriate concentration for forage rice growth at salt concentration of 0.1~0.3%, and a nitrogen fertilization amount level corresponding to a nitrogen concentration of 12 me/L was actually applied to the Muan reclaimed paddy field for forage rice cultivation during two years. The amount of nitrogen fertilizer was tested with three treatments, which are 18 kg/10a considered appropriate, and 1.5 times and 2 times of the appropriate amount, and the planting density was tested with 2 treatments of 15 hills/m² and 26 hills/m². As a result of the reclaimed paddy field experiment, the yield was the highest when nitrogen fertilizer was applied at 18 kg/10a in the planting density of both treatments. Looking at the yield according to planting density, the high planting density plot yielded higher than the low planting density plot. In other words, when the planting density was 26 hills/m² and the nitrogen fertilization amount was 18 kg/10, the highest dry matter yield of 1,763 kg/10a was obtained. From the results of hydroponics and reclaimed field experiments, we could conclude that the productivity of forage rice decreased more as the nitrogen concentration increased when the nitrogen concentration was higher than the optimal level under salt stress.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.1
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• pp.105-111
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• 2016

This paper presents the applicability of natural zeolite (Clinoptilolite) for recovery of ammonium nitrogen from high-strength wastewater stream. Isotherm experiments showed the ammonium exchange Clinoptilolite followed Freundlich isotherm and its maximum exchange capacity was $18.13mg\;NH_4{^+}-N/g$ zeolite. The X-ray photoelectron spectroscopy (XPS) analysis indicated that a significant amount of nitrogen was adsorbed to the Clinoptilolite. Optimal flowrate for recovery of high concentration ammonium nitrogen was determined at 16 BV/d (=19.2 L/min) throughout the lab-scale column studies operated under various flowrate conditions. This study also provided a method to determine the recovery rate of final product of nitrogen fertilizer based on the model application to the lab-scale continuous data.

• Journal of Environmental Health Sciences
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• v.23 no.1
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• pp.95-104
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• 1997

The objectives of this study are to investigate the effect of media on the removal efficiency of nitrate-nitrogen and the biofilm thickness in the fluidized bed biofilm reactor(FBBR) used for the high rate denitrification of nitric acid wastewater. Granular activated carbon(GAC) of 1.274 mm diameter and sand of 0.455 mm diameter were used as the media in the FBBR of 0.05 m diameter and 1.5 m height. As the nitrate-nitrogen concentration of the influent was increased stepwise from 600 to 4800 mg/l, the nitrate- and nitrite-nitrogen concentration of the effluent, biofilm thickness and biofilm dry density were measured to study the effects of media on the denitrification efficiency. The biofilm thickness increased with the substrate loading rate, and the biofilm dry density decreased with the increase of the biofilm thickness. At the influent nitrate-nitrogen concentration of 2400 mg/l, the removal efficiency in the FBBR with GAC was 88%, while that in the FBBR with sand was 99.6%. The biofilm in the FBBR with GAC was so thick, 754.9 $\mu$m, as to increase the mass transfer resistance, compared to that, 143.7 $\mu$m, in the FBBR with sand. The maximum specific denitrification rate in the FBBR with GAC was 15.0 kg-N/m$^3\cdot$ day, while that in the FBBR with sand was 18.0 kg-N/m$^3\cdot$ day. The biomass concentration in the FBBR with sand exhibited the high value 37 kg/m$^3$.

• Korean Journal of Microbiology
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• v.27 no.4
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• pp.373-377
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• 1989

The effects of environmental factors on the extracellular release of organic carbon by Scenedesmus qudricauda were studied. The PER (percentage extracellular release) was greater at high temperature and at high concentration of nitrogen and phosphate. The PER variation according to the change of M/P ratio showed high values at each extreme N/P ratio. This result suggested that the limitation of nitrogen or phosphorous resulted in the accumulation of carbohydrates as photosynthetic products, and the products in high concentration were excreted through algal cell membrane.