• Journal of Environmental Science International
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• v.11 no.12
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• pp.1243-1252
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• 2002

This paper aims to find the characteristics of concentration distribution of coastal urban air pollutants. For this purpose, It was used the daily meteorological data and the hourly concentration data for $O_3$and NO$_2$ in Busan metropolitan city from 1994 to 1996. It was investigated the annual and monthly distribution of ozone and nitrogen dioxide concentration at each site in Busan, and also investigated the characteristics of concentration change of air pollutants with time under the sea breeze. As a results, the concentration of nitrogen dioxide and ozone tend to be increased every year and nitrogen dioxide concentration is higher than ozone concentration at all sites in Busan. The concentration of ozone is high in summer season and low in winter season, but the concentration of nitrogen dioxide have a reversed trend. The monthly peak concentration of ozone occurred in April and September, while the monthly minimum concentration of nitrogen dioxide occurred in August. Their trend were identified by sites near the coastline than sites stands apart from the coastline. The sea breeze occurred annual mean 81 day in Busan from 1994 to 1996. The main wind direction of sea breeze was classified into southwesterly and southeasterly. In case of southwesterly, It was pronounced the south wind and southwest wind. In case of southeasterly, the occurrence frequency of east wind was high. Especially, the concentrations of urban air pollutants, such as ozone and nitrogen dioxide, were high on time which the sea breeze flow, and the areas that ozone concentration was high moved from outside part to central part of city with time. In costal urban such as Busan, the wind direction of sea breeze is influenced the change of ozone and nitrogen dioxide concentration on time which the sea breeze flow at each site and also influenced the change of air pollutants concentration of sites on the pathway of sea breeze.

• Journal of Animal Environmental Science
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• v.6 no.2
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• pp.65-72
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• 2000

This study was conducted to investigate the effects of artificial filaments equipped in the aeration tank of aerobic·fermentation system on the removal efficiency of swine wastes which were fermented an aerobically and thus containing high nitrogen. Two aerobic fermentation system each consist4s of 4 tanks ; storage tank, 1st and 2nd aeration tank and settling tank were run before and one or three weeks after equipment of artificial filament in the aeration tanks. Total solids concentration tended to increase by aerobic fermentation in all running periods. However, decreased(P<0.05) total nitrogen concentration was shown three weeks after the equipment of artificial filament. Ammonia nitrogen concentration also largely decreased(p<0.05) in both running periods of one and three weeks after equipment of artificial filaments. These results suggest that the artificial filaments may improve the removal efficiency of nitrogen in swine wastewater containing high nitrogen during aerobic fermentation.

• Journal of the Semiconductor & Display Technology
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• v.21 no.1
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• pp.103-107
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• 2022

Scaffolds are the structures that safely protect sensors in various parts of the body. Because of scaffolds must protect sensors from load, the tensile strength of the scaffolds must be higher than 750 kgf/cm². Currently, the tensile strength of scaffolds made with the 3d printer is 714 kgf/cm². We confirm that the tensile strength of the scaffolds increase using air with high nitrogen concentration. In this study, we conducted experiments to find nitrogen concentrations in which the tensile strength of the specimen is higher than 750 kgf/cm². The nitrogen control device and the nitrogen concentration sensor were installed in the chamber type 3d printer. The nitrogen concentration inside the 3d printer was changed by 5 % from 80 % to 100 %. Specimens of ASTM D 638 standard were produced under changed nitrogen concentration. We measured the tensile strength of specimens. We compared the tensile strength of specimens produced under each nitrogen concentration. We confirmed that when air with nitrogen concentration of 90 % was used, the tensile strength of scaffolds were 762 kgf/cm².

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.43-53
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• 1997

In this research, the synthetic livestock wastewater was prepared to study the characteristics of organic matter removal, the change of VFA production, and the amount of gas production with respect to the change of ammonium nitrogen concentration in the waste using anaerobic fixed bed process, which is an anaerobic biofilm process. The HRT and operation temperature were 1 day and $35{\pm}1^{\circ}C$, respectively. Also, the characteristics of organic matter removal and the inhibitory effect on microorganism in the anaerobic process were studied on the organic loading and ammonium nitrogen concentration. The results obtained were as follows: For COD loading of $10kg/m^3$-day and five levels of ammonium nitrogen concentration ranging from 1,000 to 5,000 mg/L, organic removal efficiencies were about 81, 74, 67, 58, and 51%, and gas productions were 3,860, 3,520, 3,240, 3,020, and 2,790 ml/l-day, respectively. Average methane contents in the gas produced on COD loading of $10kg/m^3$-day was about 76%. Throughout the whole period of experiment, remaining VFA (as COD base) in the effluent was over 90% of remaining COD. This result indicated the inhibitory effect of high concentration of ammonium nitrogen through the facts that accumulated VFA was almost COD and organic removal efficiency decreased also with the increase of ammonium nitrogen. Especially, that implys which high concentration of ammonium nitrogen not only inhibits methane forming bacteria, but also acid forming bacteria.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.993-997
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• 2007

The upflow anaerobic sludge blanket (UASB) reactor can be effective for treating simple organic compounds containing high concentration of ammonia nitrogen. The chemical oxygen demand (COD) removal efficiency was about 80% at ammonia nitrogen concentration up to 6,000 mg-N/L. This result also showed that it would be possible to treat propionate effectively at free ammonia nitrogen concentration up to 724 mg-N/L if sufficient time was allowed for adaptation. However the specific methanogenic activity (SMA) of granule was lower than that of granule in the reactor with lower ammonia nitrogen concentration. At 8,000 mg-N/L, the inhibition of high ammonia concentration was observed with evidence of increase of the volatile suspended solids (VSS) concentration in the effluent. It might be ascribed to the decrease in the content of extracellular polymer (ECP), which resulted to the sloughing off of obligated proton-reducing acetogens and heterogenotrophic methanogens from the exterior of granular sludge. This caused a great portion of the finely sludge to be easily washed out. Therefore, failure to maintain the balance between these two groups of microorganism cause accumulation of the hydrogen partial pressure in the reactor, which could have inhibited the growth of acetate utilizing methanogens.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.5
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• pp.649-658
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• 2012

In this study, the influencing factors for efficient anaerobic digestion of high strength ammonia-nitrogen wastewater removal were investigated by testing biochemical methane potential test. In the influencing factors, the trace metals which could increase activity of anaerobic microorganisms, microbial concentration and types were evaluated. In the results, trace metals supplementation showed gas production amount higher than those without addition of trace metals. Among the tested trace metals, B, Ni, and Se were preferable to gas production. In the result of gas production according to the microbial concentration, the amount of gas production was proportional to the microbial concentration. In addition, the shortest lag time and the fastest gas production rate were achieved when the highest microbial concentration was tested. granule-type microorganism produced more gas than suspended-type microorganism. In conclusion, the efficient anaerobic digestion for high strength ammonia-nitrogen wastewater removal could be achieved by applying necessary trace metals injection and high concentration granule type microorganism.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.460-465
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• 2007

In this study, the removal characteristic of ammonia nitrogen and behavior of nitrogen was investigated using Leclercia adecarboxylata, which was derived from the culture contaminated by ammonia nitrogen of high concentration. The method of ammonia nitrogen removal was not biological nitrification and denitrification but elimination of nutrient salt with internal synthesis of microorganisms which use ammonia nitrogen as substrate. L. adecarboxylata(one of ammonia synthesis microorganisms) was highly activated and showed the most high removal efficiency in free salt condition but the removal efficiency decreased badly in salt concentration of more than 4%. About 80 mg/L of $NH_3-N$ was mostly removed within 20 hours and 500 mg/L of $NH_3-N$ showed less then removal efficiency of 50% because carbon source was not enough. However, ammonium nitrogen concentration was decreased again when the carbon source was inserted additionally thus, ammonium nitrogen removal efficiency by L. adecarboxylata, was related to amount of carbon source. pH decreased from 8.0 to 6.36 according to growth of L. adecarboxylata. Concentration of nitrite nitrogen and nitrate nitrogen did not increase and TKN concentration showed no variation while ammonia nitrogen was removed by L. adecarboxylata. In addition to, when content of protein in organic nitrogen was measured, protein was not detected at the beginning of microorganism synthesis but protein of 193.1 mg/L was detected after 48 hours. Hence, ammonium nitrogen was not decomposed as nitrate nitrogen and nitrite nitrogen but synthesized by L. adecarboxylata, which has excellent ability of nitrogen synthesis and can threat ammonia nitrogen of high concentration in wastewater.

• Journal of Wellbeing Management and Applied Psychology
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• v.6 no.3
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• pp.33-36
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• 2023

Purpose: Since the food wastewater contains a high concentration of nitrogen, it is very important to find a way to efficiently remove it. Research design, data and methodology: A total of four experiments were conducted under different conditions to remove ammonia nitrogen present in the food wastewater. The experiment was designed by adding sodium hypochlorite to the raw food wastewater and varying conditions such as pH control, aeration/precipitation, and stirring. Results: The ammonia nitrogen removal rate in Experiment 1 was about 12% (sodium hypochlorite added), ammonia nitrogen increased about 4.7% in Experiment 2 (sodium hypochlorite added after aeration/precipitation in a bioreaction tank, stirring), and decreased about 52.5% (sodium hypochlorite added after controlling and stirring). Conclusions: When the concentration of sodium hypochlorite was high, ammonia nitrogen was best removed, and the pH was adjusted to 12, and sodium hypochlorite was added after stirring, and the removal was the second best. If the method of this study is further studied and developed, it can be basic data for ammonia nitrogen removal in the future.

• Journal of environmental and Sanitary engineering
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• v.10 no.1
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• pp.66-75
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• 1995

This survey is executed about the water quality and improvement measure of Imjin- river. The results are summarized as follows; 1 ) Ammonia nitrogen concentration in tap water was two times higher than drinking water standard. 2) The concentration of BOD in textile wastewater was 235ppm which is higher than wastewater distribution standard and leather wastewater showed high nitrogen concentration. 3) Water quality of the Imjin- river upstream was not in problem but that of Shin- stream showed somewhat high concentration in BOD, COD, and ammonia nitrogen. Especially the detected Cynide compound on the lower of Shin- stream implied seriously polluted condition. 4) The heavy metal in soil of the river bed was not detected but iron, zinc was detected to high concentration. 5) It Is urgently suggested to build more municipal sewage and sanitary treatment plants, and run dredging and river bed rearrangement project. 6) The Construction of the wastewater treatment complexes of relevant industries shall be propelled as soon as possible.

• Journal of Bio-Environment Control
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• v.15 no.1
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• pp.84-90
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• 2006

This study was conducted to anticipate nitrate reduction state in tree through measurement of nitrate reductase activity (NRA) and investigate the effect of nitrogen concentrations (100, 200, 400, and 600 $mg\;L^{-1}$) on growth, the nitrogen content of various tissue, and NRA of pear (Pyrus pyrifolia cv. Niitaka) seedlings in sand culture. Nutrient solutions used in this experiment were adjusted to pH 6.5 and fixed the ratio of ammonium and nitrate to 1:3 and trickle-irrigated 3 times a day. Tree height and dry weight of various organs in seedlings were higher in low nitrogen concentration (100 and 200 $mg\;L^{-1}$) than in high nitrogen concentration (400 and 600 $mg\;L^{-1}$). The shoot growth in 600 $mg\;L^{-1}$ was extremely poor by nitrogen over supply. Increasing the nitrogen concentration, the concentration of nitrate-N in leaves and roots were insignificantly changed but that of stems increased. The accumulation of total and reduced nitrogen in all organs with increasing concentrations of nitrogen supply were increased at 30 days after treatment but those of all organs at 60 and 90 days after treatment were highest in 600 $mg\;L^{-1}$, whereas there were no significant changes among other nitrogen concentration. The in vivo (${+NO_3}^-$) NRA of all organs did not relate to nitrogen concentration but the in vivo (${-NO_3}^-$) NRA of leaves except roots increased with increasing the nitrogen concentration. Therefore, the proper nitrogen concentration to promote growth and nitrate reduction of pear tree was 200 $mg\;L^{-1}$.