• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.120-130
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• 1996

Crisphead lettuce(Lactuca sativa L.) was grown in NFT to investigate the effects of NO$_3$-N and NH$_4$-N ratio in nutrient solution and elevated $CO_2$ treatment in the crisphead lettuce growth. This experiment has been conducted under three different ratios of NO$_3$-N:NH$_4$-N(100:0, 75:25, 50:50) with two $CO_2$ concentration (control, 1500ppm ). The results are as follows; 1. In the case of not controlling pH and EC in nutrient solution, pH was gradually increased in NO$_3$-N:NH$_4$-N=100:0 treatment but rapidly decreased in the nutrient solution 2. Daily changes of NO$_3$-N and NH$_4$-N were observed without controlling the nutrient solution. In the treatments of NO$_3$-N:NH$_4$-N ratios were 75:25 and 50:50, NO$_3$-N absorption rates were 27.7% and 26.1%, while NH$_4$-N absorption rates were 87.9% and 71.2%, respectively. 3. There was little differences in total nitrogen of leaves. However phosphorus, potassium, calcium and magnesium contents were highly shown in the treatment of $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. 4. Higher $CO_2$ assimilation rate was shown in plants grown under $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. It dropped significantly with the increase of NH$_4$- N rates in nutrient solution. 5. Fresh weight, leaf number, root length and root weight of crisphead lettuce were far better in the treatment of $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. Growth differences by $CO_2$ elevation were not shown in other NO$_3$-N:NH$_4$-N treatments. 6. The highest nitrate contents of leaves were shown in NO$_3$-N single treatment but shown the lowest vitamin C contents. Nitrate contents of leaves were decreased by $CO_2$ but the effect was slight treatment.

• Journal of Bio-Environment Control
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• v.18 no.1
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• pp.40-45
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• 2009

The experiment has investigated the effects of growth, yield, fruit quality and cation absorption of strawberry 'Akihime' in different $NO_3-N:NH_4-N$ ratio in nutrient solution. $NO_3-N:NH_4-N$ ratios were 5.5:0, 4.0:1.5 and $3.0:2.5me{\cdot}L^{-1}$. As the ratio of $NH_4-N$ increased, pH was decreased by $5.0{\sim}6.0$ and EC sustained $0.8{\sim}1.0dS{\cdot}m^{-1}$ during experiment. Though in high $NH_4-N$ ratio of $3.0:2.5me{\cdot}L^{-1}$, the absorption of cations(K, Ca and Mg) was not inhibited. Treatment in contained $NH_4-N$ showed a tendency of increasing of petiole length and leaf width. The fruit length, fruit width, fruit weight and soluble solids were not significantly different. Yield per plant was lowest in $4.0:1.5\;me{\cdot}L^{-1}$, of $NO_3-N:NH_4-N$ ratio. Malformation fruit has not shown during the whole growth period.

• Korean Journal of Environmental Agriculture
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• v.10 no.1
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• pp.27-31
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• 1991

This study was conducted to examine the adsorption capacity of $NH_4\;^+-N$ by natural zeolite for the purpose of investigating the possibility for $NH_4\;^+-N$ eliminator of Korean natural zeolite. The dominant clay minerals of zeolite were clinoptilolite and mordenite. The reaction of $NH_4\;^+-N$ adsorption by zeolite reached equilibrium after 4hrs. The amount of $NH_4\;^+-N$ adsoption by zeolite was not significantly affected by the particle size of zeolite. The order of $NH_4\;^+-N$ adsorption by zeolite according to exchangeable cations was Na-> Ca> K-saturated zeolite. The amount of $NH_4\;^+-N$ adsorption by zeolite was increased with increasing pH of solution and the ratio of zeolite to the volume of solution. The isothermal curvel of $NH_4\;^+-N$ adsorption by zeolite was conformed to Langmuir equation.

• Journal of Bio-Environment Control
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• v.2 no.2
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• pp.119-125
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• 1993

The effect of NO$_3$-N and NH$_4$-N ratio on the growth of Perilla frutescens in deep flow culture was studied in winter season. NO$_3$-N and NH$_4$-N were treated in the ratios of 12 : 0, 9 : 3, 6 : 6(me/ $\ell$ ). The pH of the nutrient solution was increased an NO$_3$-N:NH$_4$-N=12 : 0 treatment, and decreased in the treatments containing NH$_4$-N, greatly in NO$_3$-N : NH$_4$-N = 6 : 6 treatment. The EC was increased regardless of treatments, but more increased in the treatments containing NH$_4$-N. The stem-base circumference, plant height, root weight, shoot weight, and yields of leaves were by far the highest in NO$_3$-N:NH$_4$-N=6 : 6 treatment and the lowest in NO$_3$-N:NH$_4$-N= 12 : 0 treatment. Among the mineral contents of leaves, N, K, Fe and P were higher in the treatments containing NH$_4$-N. Ca, Mg and Mn were higher in NO$_3$-N :NH$_4$-N= 12 : 0 treatment.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.265-277
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• 2000

Laboratory experiments were conducted to investigate characteristics for removing ammonia-nitrogens by electrolysis methods. A stainless steel plate is used as the cathode and either $IrO_2{\backslash}Ti$ plate serves as the anode. Experiments were conducted to examine the effects of the operating conditions, such as the current density, retention time, electrode gap, $Cl^-/NH_4{^+}-N$ on the $NH_4{^+}-N$ removal efficiency. Possible optimum range for these operating variables are experimentally determined. The $NH_4{^+}-N$ removal efficiencies between plate type anode and net type anode were about same effect, but electrolytic power using net type anode is low than plate type anode. The $Cl^-/NH_4{^+}-N$ ratio was about $20.0kgCl^-/kgNH_4{^+}-N$ when $NH_4{^+}-N$ removal obtained 73 %, $Cl^-/NH_4{^+}-N$ ratio needs $27.6kgCl^-/kgNH_4{^+}-N$ so as to $NH_4{^+}-N$ completely remove. The removal efficiency of $NH_4{^+}-N$ increase with current density, retention time and $Cl^-/NH_4{^+}-N$ ratio, but decreased with increasing electrode gap. The relationship of operating conditions and $NH_4{^+}-N$ removal efficiencies are $$NH_4{^+}-N_{re}(%)=14.5364(Current\;density)^{0.7093}{\times}(HRT)^{1.0060}{\times}(Gap)^{-0.9926}{\times}(Cl^-/NH_4{^+}-N)^{1.0024}$$ With adding COD or/and alkalinity, relationships are $$NH_4{^+}-N_{re}(%)=9.8408(Current\;density)^{0.6232}{\times}(HRT)^{1.0534}$$ There existed a competition between the removals for $NH_4{^+}-N$ and $COD_{Cr}$ during electrolysis, the removal of $NH_4{^+}-N$ was shown to be dominant. $NH_4{^+}-N$ removal was high as addition of glucose and alkalinity.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.517-521
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• 2008

Struvite의 최적 생성조건은 NH$_4$-N의 초기농도에 관계없이 모두 NH$_4^+$, PO$_4^{3-}$ 및 Mg$^{2+}$가 등몰비이고 pH 10.5이었다. Struvite 침전반응에서 NH$_4$-N 및 PO$_4$-P 제거율에 미치는 struvite seeding 효과는 습윤상태의 struvite를 seeding할 경우 그 효과가 거의 없었으나 건조된 struvite를 seeding할 경우 NH$_4$-N의 제거율은 증가되지만 PO$_4$-P의 제거율은 감소되는 경향을 나타냈다. 이는 건조과정에서 struvite의 NH$_4$-N가 휘산되어 소실되었기 때문이다. Mg와 P원으로서 struvite의 재이용을 위한 적정 건조온도는 100$^{\circ}C$ 이하였으며 그 이상 온도에서는 struvite가 $NH_4MgPO_4\cdot6H_2O$형에서 MgPO$_4$형으로 상전이점에 따라 struvite seeding에 의한 NE$_4$-N의 제거율이 현저히 감소되었다. 건조된 struvite는 초기 NH$_4$-N의 몰농도 대비 50%를 seeding할 경우 60% 이상의 NH$_4$-N를 제거하였으며, seeding량을 150%로 증가시킬 경우 90% 이상의 NH$_4$-N 제거율을 얻을 수 있었다. 그러나 struvite를 반복 재사용할 경우 재사용 횟수에 비례하여 NH$_4$-N의 제거율은 감소하는 경향을 보여 재사용 횟수가 제한적임을 알 수 있었다.

• Korean Journal of Microbiology
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• v.39 no.1
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• pp.21-26
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• 2003

Ninety strains of photosynthetic bacteria were isolated from a local stream at Kyonggi-do, Korea and were further screened. Using these isolated strains, experiments were performed under various light and oxygen conditions in order to select strains with high nitrogen $(NH_3-N,\; NO_3^--N)$ removal efficiencies. Results showed that all the strains screened removed $NH_3-N$, the light had no effect on nitrogen removal, and the nitrogen removal rate was higher aerobically than anaerobically. The removal of $NO_3^--N$ was showed up to 35.3% in some specific strains. Results of batch experiments using Rhodocyclus gelatinosus, an isolated strain with a superior removal rate of $NH_3--N$ and $NH_3-N$, under the anaerobic condition, showed that the removal rate of organics and $NH_3-N$ was the highest (98.2 and 89.0%, respectively) at the CODcr (mg/L)/biomass (mg/L) ratio of 0.2, and the $NH_3-N$ concentration did not increase with the decreasing $NH_3-N$ concentration. Experimental results from various C/N ratios confirmed that the effective removal rate (75.8%) of $NH_3-N$ occurred even at the low (5:1) C/N ratio as well as high ratios, and the simulataneous removal of $NO_3^--N$ (96.0%).

• Journal of Bio-Environment Control
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• v.3 no.2
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• pp.99-105
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• 1994

The objective of this study was conducted for elucidation of effects of the NO$_3$$^{[-10]}$ -N. NH$_4$$^{+}$-N ratio in the nutrient solution on the growth and quality of welsh onion(Allium fistulosum L.). The pH of nutrient solution increased in NO$_3$$^{[-10]}$ -N : NH$_4$$^{+}$-N ratio of 9 : 1 treatment, decreased in 1 : 1, 1 : 3 treatment, but was stable in 3 : 1 treatment during cultivation. The apparent growth of welsh onion was best in the treatment of 9 : 1(NO$_3$$^{[-10]}$ -N : NH$_4$$^{+}$-N ratio), however the treatment of 1 : 3 resulted in poor growth. The NO$_3$$^{[-10]}$ -N content of the plants increased in proportion to that content of nutrient solution. Pyruvic acid content of welsh onion was highest at 9 : 1, 3 : 1 treatment, and lowest at 1 : 3 treatment.tment.

• Journal of environmental and Sanitary engineering
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• v.12 no.3
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• pp.61-71
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• 1997

This study was conducted to examine the adsorption capacity of $NH_{3}-N$ by natural zeolite for the purpose of investigating the possibility for $NH_{3}-N$ eliminator of korea natural zeolite. The dominant clay minerals of zeolite was clinoptiloite. The amount of $NH_{3}-N$ adsorption by zeplite was not significantly affected by the particle size of zeolite and increased with increasing the ratio of zeolite to the volume of solution. Removal ratio of 100% of NH$_{3}$-N by non, 1st, 2nd regenerated cloumn was continued separately during 4.5, 18, 30hr and this amount was each 0.081, 0.324, 0.540g $NH_{3}-N/zero$.100g. The eluenting amount of K, Ca, Mg was increased on the zeolite cloumn according to that of Na decreased. The amount of 74% of $NH_{3}-N$ was desorved on the zeolite cloumn for regenerating treatment during 8hr. The perfect removal amount was $0.216gNH_{3}-N/zero$.100g on the zeolite cloumn with field sample.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.661-672
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• 1998

Two experiments were conducted to examine the effects of a range of concentrations of ruminal fluid ammonia ($NH_3$-N) on forage digestibility, microbial growth efficiency and the mix of microbial species. Urea was either continuously infused directly into the rumen of sheep fed 33.3 glh of oaten chaff (Exp. I) or sprayed onto the oaten chaff (750 g/d) given once daily (Exp. 2). Concentrations of $NH_3$-N increased with incremental addition of urea (p < 0.01). Volatile fatty acids (VFA) concentrations and 24 h in sacco organic matter digestibility in the rumen were higher when supplemental urea was given (p < 0.01). The (C2 + C4) : C3 VFA ratio was lower (p < 0.05) when $NH_3$-N was above 200 mgN/I. The fungal sporangia appearing on oat leaf blades were significantly higher when urea was supplemented, indicating that $NH_3$-N was a growthlimiting nutrient for fungi at levels of $NH_3$-N below 30 mgN/l. The density of protozoa was highest when $NH_3$-N concentrations were adjusted to 30 mgN/I for continuously fed ($4.4{\times}10^5/ml$) and to 168 mgN/1 for once daily feeding ($2.9{\times}10^5/ml$). Thereafter increasing concentrations of $NH_3$-N, were associated with a concomitant decline in protozoal densities. At the concentration of $NH_3$-N above 200 mgN/l, the density of protozoa was similar to the density of protozoa in ruminal fluid of the control sheep ($1.8{\times}10^5/ml$). The efficiency of net microbial protein synthesis in the rumen calculated from purine excretion was 17-47% higher when the level of $NH_3$-N was above 200 mgN/1. The possibilities are that 1) there is less bacterial cell lysis in the rumen because of the concomitant decrease in the protozoal pool and/or 2) microbial growth per se in the rumen is more efficient with increasing $NH_3$-N concentrations.