• Proceedings of the Korean Environmental Sciences Society Conference
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• 2000.05a
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• pp.195-200
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• 2000

Chitin과 탈아세틸화된 chitosan은 중금속 제거에 효과적인 생물흡착제로 잘 알려져 있다. 그러나 본 연구의 결과 crab shell에 있어서의 중금속 제거효율이 순수 chitin과 chitosan에서 보다 더 뛰어남을 알 수가 있었다. 납, 카드뮴, 망간이온 제거실험에서 crab shell은 초기 2시간 이내에 모두 제거되었으나, chitin과 chitosan의 흡착 실험에선 14시간이 경과되어도 이들 중금속의 대부분 수용액 내에서 거의 제거되지 않았다. 구리의 경우 염의 형태에 따른 흡착의 영향을 chitosan에선 제거된 량이 Cu($SO_{4})_{2}$ > Cu($NO_{3})_{2}$ > Cu($Cl_{2}$)의 순으로 나타났으나 chitin에선 모두 흡착이 거의 안된 상태로 나타났다. 주사현미경 분석 결과 crab shell의 표면에 납이 축적되어 있는 상태를 확인하였다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.239-243
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• 1997

A continuous foam separator has been used to remove TSS, $NH_3\;and\;NO_2^-$ from the recirculating water in aquaculture. Experimental runs were carried out to determine the foam separation variables, such as, hydraulic retention time, superficial air velocity and foam .height. The removal efficiency of TSS, $NH_3\;and\;NO_2^-$ was increased with hydraulic retention time and superficial air velocity, and removal efficiency of $NH_3$ was increased steadily with foam height. As DO concentration was increased with superficial air velocity and foam height, foam separator is also used for oxygen addition. It was concluded that foam separator might offer better perspective for removal of harmful components in fish culture water.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.600-605
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• 2022

In this study, nitrogen oxide (NO_x) removal experiments were performed using a graphene based ceramic filter coated with a V₂O₅-WO₃-TiO₂ catalyst. Graphene oxide (GO) was prepared by Hummer's method using graphite, and the reduced graphene oxide was produced by reducing with hydrazine (N₂H₄). Vanadium (V), Tungsten (W), and Titanium (Ti) were coated by the sol-gel method, and then a metal oxide-supported filter was prepared through a calcination process at 350 ℃. A NO_x removal efficiency test was performed for the catalytic ceramic filters with UV light in a humid condition. When graphene oxide (GO) and reduced graphene oxide (rGO) were present on the filter, the NOx removal efficiency was superior to that of the conventional ceramic filter. Most likely, this is due to an improvement in the adsorption properties of NOx molecules on graphene coated surfaces. As the concentration of graphene increased, higher NO_x removal efficiency was confirmed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.2
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• pp.35-44
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• 1986

This paper is a basic study of the experimental results for the treatment of ammonia-nitrogen in the septic tank effluent. The substrates in this experiment are actual septic tank effluent and synthetic waste-water which is similar to septic tank effluent containing a considerable amount of nitrogenous component. Experiments were conducted for organic removal and nitrification using various recycle ratio and hydraulic retention time at each stage. The results obtained show that organic removal rate was above 80% in the 1st and 2nd stage, but as nitrification process was proceeded, above 90% of ammonia-nitrogen was removed in the 3rd and 4th stage. In these cases, the recycle ratio and HRT were found 30 and 7 hrs respectively. In the relation of $NH_4{^+}-N$ removal to $NO_3{^-}-N$ formation in the synthetic waste-water and septic tank effluent, when $1mg/{\ell}$ of $NH_4{^+}-N$ was removed, $NO_3{^-}-N$ formations were $0.95mg/{\ell}$ and $0.82mg/{\ell}$ respectively. And kinetics of nitrification using Biological Fluidized Bed was discussed also.

• Journal of Wetlands Research
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• v.23 no.1
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• pp.60-66
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• 2021

As the concentration of nitrogen in the sewage flowing into the sewage treatment plant increases due to urbanization and industrialization, the degree of adverse effects such as eutrophication and toxicity to the aquatic ecosystem is also increasing. In order to treat sewage containing high concentration of nitrogen, various studies on the biological nitrogen removal process are being conducted. Existing biological nitrogen removal processes require significant costs for supplying oxygen and supplementing external carbon sources. In this respect, as a high-level nitrogen removal process with economic improvement is required, an anaerobic ammonium oxidation process (ANAMMOX), which is more efficient and economical than the existing nitrification and denitrification processes, has been proposed. The purpose of this study is to confirm the stability of the ANAMMOX process in the water treatment process and to derive the ratio of ammonia nitrogen (NH4+) to nitrite nitrogen (NO2-) for the implementation of the mainstream ANAMMOX process. A laboratory-scale Mainstream ANAMMOX reactor was operated by applying the ratio calculated based on the substrate ratio suggested in the previous study. In the initial range, the removal efficiency of NH4+ was 58~86%, and the average removal efficiency was 70%. In the advanced range, the removal efficiency of NH4+ was 94~99%, and the average removal efficiency was 95%. As a result of the study, as the NH4+/NO2- ratio increased, the stability of the mainstream ANAMMOX process was secured, and it was confirmed that the NH4+ removal efficiency and the total nitrogen (TN) removal efficiency increased. As a result, the results of this study are expected to be used as basic data in the application of the ANAMMOX process in the mainstream.

• Clean Technology
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• v.27 no.4
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• pp.341-349
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• 2021

In combustion facilities, the nitrogen and sulfur in fossil fuels react with oxygen to generate air pollutants such as nitrogen oxides (NO_X) and sulfur oxides (SO_X), which are harmful to the human body and cause environmental pollution. There are regulations worldwide to reduce NO_X and SO_X, and various technologies are being applied to meet these regulations. There are commercialized methods to reduce NO_X and SO_X emissions such as selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and wet flue gas desulfurization (WFGD), but due to the disadvantages of these methods, many studies have been conducted to simultaneously remove NO_X and SO_X. However, even in the NO_X and SO_X simultaneous removal methods, there are problems with wastewater generation due to oxidants and absorbents, costs incurred due to the use of catalysts and electrolysis to activate specific oxidants, and the harmfulness of gas oxidants themselves. Therefore, in this research, microbubbles generated in a high-pressure disperser and reducing agents were used to reduce costs and facilitate wastewater treatment in order to compensate for the shortcomings of the NO_X, SO_X simultaneous treatment method. It was confirmed through image processing and ESR (electron spin resonance) analysis that the disperser generates real microbubbles. NO_X and SO_X removal tests according to temperature were also conducted using only microbubbles. In addition, the removal efficiencies of NO_X and SO_X are about 75% and 99% using a reducing agent and microbubbles to reduce wastewater. When a small amount of oxidizing agent was added to this microbubble system, both NO_X and SO_X removal rates achieved 99% or more. Based on these findings, it is expected that this suggested method will contribute to solving the cost and environmental problems associated with the wet oxidation removal method.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.35-39
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• 1999

현재 NO제거에 주로 사용되는 환원제로서 NH$_3$가 있는데 이는 NO에 대한 선택도가 우수하기 때문이다. 그러나, NH$_3$는 독성이 강하고 부식성이 있어 저장 및 수송에 많은 비용이 든다는 단점이 있다. 따라서 본 연구에서는 SOx/NOx 동시 제거 공정에 효과적으로 알려진 fresh and sulfated CuO/${\gamma}$-A1$_2$O$_3$촉매상에서 독성이 강한 NH$_3$를 대신하는 새로운 환원제로서 urea용액을 이용하여 유동층 반응기에서 SCR을 수행해 보고자 한다.(중략)

• Clean Technology
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• v.28 no.4
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• pp.309-315
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• 2022

Research was conducted to derive the optimal operation conditions and the optimal cathode for using a DSA electrode as an anode to minimize electrode consumption during the removal of nitrogen from wastewater by the electro-chemical method. Of the various electrodes tested as cathodes, brass was determined to be the optimal electrode. It had the highest NO₃-N removal rate and the lowest concentration of residual NH₃-N, a by-product when Cl is present in the solution. Investigating the effect of current density found that when the initial concentration of NO₃-N was 50 mg L^-1, the optimal current density was 15 mA cm^-2. In addition, current densities above 15 mA cm^-2 did not significantly affect the NO₃-N removal rate. The effect of electrolytes on removing NO₃-N and minimizing NH₃-N was investigated by using Na₂SO₄ and NaCl as electrolytes and varying the reaction times. When Na₂SO₄ and NaCl are mixed at a ratio of 1.0 g L^-1 to 0.5 g L^-1 and reacted for 90 min at a current density of 15 mA cm^-2 and an initial NO₃-N concentration of 50 mg L^-1, the removal rate of NO₃-N was about 48% and there was no residual NH₃-N. On the other hand, when using only 1.5 g L^-1 of NaCl as an electrolyte, the removal rate of NO₃-N was the highest at about 55% and there was no residual NH₃-N.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.725-728
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• 2002

A series of fabric filters including P-84, Nomex and PTFE were coated with a commercial $V_2O_5/TiO_2$ catalyst as an effort to develop a functional fabric filter of simultaneous removal of dust and NOx. The coating methods employed are sol-gel coating method, spray coating method and dip coating method, and the effects of coating method on NOx removal performance of functional fabric filter were investigated. Experimental conditions are as follows: the temperatures of $100-250^{\circ}C$ which are the normal operating temperature range of fabric filters, the space velocity of $5,000hr^{-1}$, the oxygen concentration of 6%, and the $NH_3/NO$ ratio of 1.0. Results showed that the sol-gel coating method gave the best NOx removal performance mainly due to its ability in controlling the amount of catalyst and uniform coating.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2004.11a
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• pp.451-452
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• 2004