• 상하수도학회지
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• 제14권4호
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• pp.343-349
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• 2000

Techniques such as dissolved air flotation and electroflotation, which utilize micro bubbles, are increasingly used for water and wastewater treatment. Most studies have concentrated on particle characteristics. Pretreatments that manipulate particle size and zeta potential were considered important. A recent study, which modeled the collision mechanism between micro bubbles and particles in dissolved air flotation, suggested bubble characteristics should also be important. Hydrogen micro bubbles were generated electrolytically and their zeta potentials measured under various conditions using a novel electrophoresis method. Effects of several parameters were investigated. Bubble zeta potentials were found to be pH dependent, and to have a negative value around neutral pH, becoming zero or positive at lower pH. The pH at zero zeta potential was 5.0 under study conditions. Using artificial solution and tap water, at fixed pH, bubble zeta potentials varied with solution composition. Zeta potentia]s of bubbles were affected by the types of cations and anions in solution but not by the voltage applied. These findings will help improve efficiencies of particle removal processes that utilize micro bubbles. As bubble zeta potential varies with solution composition, it needs to be measured for each composition to understand those effects, which increase removal efficiency.

• 한국습지학회지
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• 제20권1호
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• pp.63-71
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• 2018

강우유출 조건에서 침투도랑의 여과기작은 수리학적 조건에 따라 변화할 수밖에 없다. 침투도랑에서 유출시간에 따른 다양한 여과조건이 입자상 물질의 제거에 미치는 영향을 이해하는 것은 매우 중요하다. 본 연구에서는 도로강우 유출수 처리를 위해 설치된 우드칩 충진 침투도랑에서 일어나는 여과기작을 조사 분석하였다. 유출수문곡선을 몇 개의 영역으로 분리하고 각 영역에서의 여과 메커니즘을 분석한 결과 여과는 수직흐름과 수평흐름, 그리고 불포화 흐름, 부분 포화흐름, 그리고 포화흐름을 거치면서 진행되는 것으로 나타났다. 불포화 흐름조건에서는 입자상 물질의 제거효율은 55-76%를 나타냈으며 주요 기작은 물리적인 억류(trapping)로 나타났으며 유출유량이 크게 증가하여 침투도랑에서 포화흐름이 조성되었을 때 제거효율은 75-95%로 크게 증가하였는데 이는 확산기작의 작용 때문인 것으로 분석되었다. 강우 중단 후 유출량 감소로 침투도랑이 부분 포화흐름으로 전환되는 시점에는 음으로 하전된 공기와 물의 경계면의 존재로 여과효율이 감소한 것으로 추정된다. 강우시 급격히 변화하는 수리학적 조건에서 발생하는 흐름조건 및 여과 메커니즘과 이와 같은 인자가 여과효율에 미치는 영향을 도출하기 위하여 변수통제가 비교적 용이한 실험실 규모의 침투도랑에 대한 연구가 필요하다.

• 한국입자에어로졸학회지
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• 제14권3호
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• pp.81-88
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• 2018

The market for improving the indoor air quality is continuously increasing, and air cleaners are the representative products. As interest in indoor air quality increases, so are the ultrafine particle which are harmful to the human body. Despite its many advantages, electrostatic precipitators are less used in indoor air due to ozone production. In this study, the carbon fiber sheet was applied to the discharge electrode and compared with the conventional tungsten wire discharge electrode. The particle collection efficiency and the amount of ozone generation were measured for 10-100 nm particles. Furthermore, it was applied to commercial air purifier with electrostatic precipitator to compare particle removal performance. The carbon fiber sheet type discharge electrode generates a small amount of ozone, and thus it can be applied to improve indoor air quality.

• 한국환경과학회지
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• 제1권2호
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• pp.105.1-113
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• 1992

The present study was performed to develop the removal system of the offensive gases, including hydrogen sulfide of acid gas, ammonia or amice of base gas, from the nightsoil treatment plant. In order to remove the offensive gases, the Fe-EDTA system liquid phase catalytic oxidation method with the bubble lift column reactor was employed. From the results obtained, it was confirmed that the offensive gases can be deodorized simultaneously and also hydrogen sulfide of acid gas, ammonia of base gas completely removed at pH 6.45. In addition, as input gases feed rate the efficiency of acid gas did not change but the efficiency of base gases decreased to approximately 90 % at pH 6, 0. From the result of particle size analyzer, it was found that the particle sizes including sulfur and other impurites grew up to $21{\mu}m$ over 72hour reaction time.

• 상하수도학회지
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• 제16권6호
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• pp.663-669
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• 2002

Electro-flotation (EF) has shown advantages, such as a high removal efficiency and easy control of bubble generation, over dissolved air flotation. However, the fundamental characteristics of the process have not been investigated in detail. According to recent modeling results from trajectory analysis, the size of the bubble is one of the most important factors that affect the efficiency of collision between bubble and particle. In this paper, the size characteristics of bubbles generated from EF under various conditions are measured using a new method for bubble size measurement, the Particle Counter Method (PCM). The size of the generated bubbles was found to be constant with respect to applied voltage but to vary with the electrode materials. These results and their implications are discussed.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.209-212
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• 2002

Main radionuclides of the soil waste stored in Korea Atomic Energy Research Institute are Co-60 and Cs-137. Moisture content of soil is 12%, pH of soil is 5.8, and content of organic matter is 2.2 %. Radioactive concentrations of the soil particle size of which is less than 0.063mm and soil in the drum surface of which is more than radiation dose rate 0.05mR/hr are higher. Meanwhile, radioactive concentration of soil in the drum surface of which is less than radiation dose rate 0.02 mR/hr are mostly lower. On using the mixing solution of ammonium sulfate and citric acid, 62% Co was removed from soil and 41% Cs was removed. Also, on using the mixing solution of ammonium nitrate and citric acid, 61% Co was removed from soil and 39% Cs was removed, and on using the mixing solution of ammonium potassium oxalate, 36% Co was removed and only 3% Cs was removed. And on using only water, removal efficiency is less than 5%.

• 펄프종이기술
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• 제40권2호
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• pp.16-22
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• 2008

The pilot scale ultrasonic deinking was carried out in order to confirm the commercialization possibility of ultrasonic deinking. White ledger was used as a raw material and the results were compared to the results obtained from the conventional deinking. The fraction of smaller ink particle was increased and the improved ink removal efficiency was also obtained by the ultrasonic treatment. The brightness and breaking length of ultrasonic deinked pulp were superior to those of the conventional deinked pulp. Most interesting findings in this study were that the significant improvement in effluent quality and the reduction of chemicals and energy cost were obtained by the ultrasonic deinking.

• 한국안전학회지
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• 제1권1호
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• pp.27-32
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• 1986

To remove sulfur dioxide from flue gas by the method of metal oxide, copper powder of average diameter $2.4\mu\textrm{m}$and $51\mu\textrm{m}$ were used in a fixed bed reactor over a, temperature range of $300^{\circ}C-500^{\circ}C$. Copper oxide reacts with sulfur dioxide producing cupric sulfate and it can be regenerated from the latter by using hydrogen or methane. Experimental results showed that the reaction rate was increased by the increase of reaction temperature in the range of $300^{\circ}C-422^{\circ}C$ and the removal efficiency of sulfur dioxide was high in case of small size copper particle. However the removal efficiency was decreased at higher temperature due to decomposition of cupric sulfate. The rate controlling step of this reaction was chemical reaction and deactivating catalysts model can be applied to this reaction. The rate constants for this reaction and deactivation are as follows ： k＝8,367exp(-10,298/RT) Kd＝2.23exp(-8,485/RT)

• 한국안전학회지
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• 제12권2호
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• pp.102-111
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• 1997

An In-line dry scrubbing FGD process was investigated. Calcium hydroxide was entrained in flue gas and the SO$_2$ removal efficiency by humidity and additives were examined. The range of reaction temperature was $200^{\circ}C$~$500^{\circ}C$ and the concentration of $SO_2$ was around 900ppm. By the increase of humidity in flue gas, the removal efficiency was increased. The effect of NaOH as a additive was very high and got high conversion of $Ca(OH)_2$, however in case of RH 90%, it was reverse. The effect of particle size and flow rate were examined. And the reaction rate constant and effective diffusivity also calculated.

• 상하수도학회지
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• 제18권2호
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• pp.201-207
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• 2004

Dissolved air flotation (DAF) is a solid-liquid separation process that uses fine rising bubbles to remove particles in water. Most of particle-bubble collision occurs in the DAF contact zone. This initial contact considered by the researchers to play a important role for DAF performance. It is hard to make up conceptual model through simple mass balance for estimating collision efficiency in the contact zone because coupled behavior of the solid-liquid-gas phase in DAF system is 90 complicate. In this study, 2-phase(gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. For the modeling of turbulent 2-phase flow in the reactor, the standard $k-{\varepsilon}$ mode I(liquid phase) and zero-equation(gas phase) were used in CFD code because it is widely accepted and the coefficients for the model are well established. Particle-bubble collision efficiency was calculated using predicted turbulent energy dissipation rate and gas volume fraction. As the result of this study, the authors concluded that bubble size and recycle ratio play important role for flow pattern change in the reactor. Predicted collision efficiency using CFD showed good agreement with measured removal efficiency in the contact zone. Also, simulation results indicated that collision efficiency at 15% recycle ratio is higher than that of 10% and showed increasing tendency of the collision efficiency according to the decrease of the bubble size.