• 한국가시화정보학회지
• /
• 제7권2호
• /
• pp.47-55
• /
• 2010

In this study, we optimized the shape of the surface aerator that will be installed in a biological reactor using the response surface method. Response surfaces of mass flow rate, impeller torque, mass flow rate per impeller torque are generated and used to track the optimum shape of the aerator. MOGA(Multi-Objective Genetic Algorithm)method is adopted to find the optimum results. By increasing the mass flow rate per impeller torque, increase of oxygen supply efficiency to a reactor is anticipated. To verify the usability of the surface aerator, PIV measurements on flow fields inside a scale-downed biological reactor model are carried out.

• 대한조선학회논문집
• /
• 제42권3호
• /
• pp.183-189
• /
• 2005

A modeling of a hydraulic-gun-aerator is proposed to set up a design procedure for such devices. The aerators are used to destroy any thermal stratification that are responsible for the degradation of water qualify of lakes. The aerator produces ascending flow by using air bubbies released instantly near the bottom of the lake into a cylindrical pipe installed vertically. Differently form the diffuser-aerators, they can pull up the cold, oxygen depleted water directly to the region of the free surface, and they are believed to work effectively especially for relatively deeper lakes. Their design procedure has not been established yet though, and we propose a model focusing on the exit flow velocity at the top of the aerator through the examination of presently operating devices.

• 대한토목학회논문집
• /
• 제41권5호
• /
• pp.493-504
• /
• 2021

와류에 의해 물과 산소의 충돌을 반복적으로 일으켜 산소를 용존시키는 Multistage Vortex Aerator를 하천 정화에 적용하였다. 본 연구의 대상 현장인 괴정천은 부산시 사하구 도심을 흘러 낙동강 하구로 연결되는데, 우천 시에는 비점 오염물질이 유입되고 평시에도 하수 슬러지가 일부 유입되어 퇴적을 반복함에 따라 하천수의 용존산소 농도가 혐기성 상태에 가까웠다. 산소농도가 최소 0.1 ppm인 하천수를 흡입하여 22 ppm 이상으로 산소를 용존시켜 분당 1 m³을 순환시켰을 때, 하천에 나타나는 수질과 악취 변화를 2개월간 모니터링하였다. 운영 결과, 용존산소가 하천 전체적으로 약간 나쁨(4)~나쁨(5)에서, 좋음(1b)~보통(3) 등급으로 개선되었고, 총인 농도는 평균 76 % 감소되었다. 복합악취는, 하천 전체가 혐기화된 측정일에 최대 84.5 % 저감을 관찰할 수 있었다.

• 한국환경과학회지
• /
• 제17권1호
• /
• pp.107-112
• /
• 2008

A study on the enhancement of environmental durability of EPDM rubber materials for the aerator membrane was performed using a butyl rubber as a modifier. A conventional EPDM rubber formulation was evaluated as having about 26.0 wt% or more oil content from the chloroform immersion test. These oils would be gradually and continuously deleted from the aerator membrane when directly exposed to a waste-water or chemically corrosive fluids, making the membrane less flexible and the performance worse. To improve this, a butyl rubber (IIR) was utilized as the modifier for a low-ENB type of EPDM rubber formulation with low-oil content. The environmental durability of the IIR-modified EPDM rubber material was expected to be greatly enhanced compared to the conventional one. However, the mechanical and performance properties such as elongation, tensile strength, and air bubble size, etc. were still maintained as good as in the conventional one. Furthermore, TGA analysis of the IIR-modified EPDM material showed that there would be partially compatible between IIR and EPDM. It also showed that the initial degradation temperature of the IIR-modified EPDM could be somewhat increased, exhibiting the enhanced compatibility among the components and, thereby, more enhanced environmental durability.

• 보일러설비
• /
• 통권71호
• /
• pp.93-96
• /
• 1999

• 한국양식학회지
• /
• 제13권3호
• /
• pp.267-275
• /
• 2000

이 연구는 값싸고 높은 비 표면적을 제공할 수 있는 발포스티로폼 입자를 packed column 에어레이터의 산소전달 매질로 이용 가능성을 알기 위하여 매질의 깊이와 수리학적부하량에 따른 산소 전달 특성과 효율을 조사 하였다. 이용된 발포스티로폼 입자는 직경 2.5 mm의 구형이었으며, 비표면적이 1350 $m^2$/$m^3$으로 일반적으로 이용되는 매질에 비해 약 3.7~7.0배 더 넓은 비표면적을 제공할 수 있다. 이 매질을 직경 10 cm, 높이 1 m의 내부 관찰이 용이한 아크릴 관으로 제작한 packed column 에어 레이터에 0, 4.5, 9그리고 18 cm의 매질을 채워 넣고, 수온 20, 25 및 3$0^{\circ}C$에 대해 수리학적 부하량을 2, 4 및 5.6 $m^3$/$m^2$/min로 각각 달리하여 산소전달특성을 실험한 결과(Exp. 1),모든 실험 수온에서 수리학적 부하량이 증가함에 따라 표준산소전달률이 증가하였으나 매질의 깊이는 9 cm 까지는 증가하다가 18 cm에서는 감소하였다. 표준산소전달률은 매질 깊이 9 cm에서 수리학적 부하량이 5.6 $m^3$/$m^2$/min일 때 가장 높았다. 그러나 수리학적 부하량이 증가함에 따라 펌프의 소모 전력이 증가하여, 단위소모 전력당 표준에어레이션 효율은 매질의 깊이 9 cm에서 수리학적부하량 2 $m^3$/$m^2$/min일 때 가장 높았다. 따라서 모든 수리학적 부하량에서 매질의 깊이 9 cm 일 때 표준산소전달률과 표준에어레이션 효율이 가장 좋았다. 이 매질을 직경 20 cm, 높이 2 m의 PVC관으로 제작한 packed column 에어레이터에 깊이를 0, 9, 18, 27 및 36 cm로 넣고 순환여과식 시설 내에 실험실 규모의 적용실험을 통해 에어레이터의 효율을 조사하였는데 (Exp.2), 실험 수온 27$^{\circ}C$에서, Exp. 1에서와 동일한 3개의 수리학적 부하량에서 산소 전달률을 측정한 결과, Exp. 1에서와 같이 수리학적 부하량과 매질의 깊이의 증가에 따라 산소 전달률이 증가하였으며, 매질의 깊이가 가장 깊은 36 cm에 대해, 수리학적 부하량이 2 $m^3$/$m^2$/min 일때, 2 kg 02 kg $O_2$/kW-hr의 가장 높은 표준에어레이션효율을 나타내었다. 위의 두 실험 결과에 따라 packed column 에어레이터에서 발포스티로폼 입자를 산소전달 매질로 이용하여 산소 전달률을 증가시킬 수 있다는 것을 확인할 수 있었다.

• ALGAE
• /
• 제19권1호
• /
• pp.23-30
• /
• 2004

The purpose of this study is to assess the effects that hydraulic-gun-aerators have on cyanobactedial bloom in Sayeon Dam Reservoir in Ulsan City, Korea. A total of nine hydraulic-gun-aerators are in operation at the reservoir withe 100 m spacing between each aerator to control severe cyanobacterial bloom in the dam reservoir. The field studies were performed an total four times at two sampling stations in the reservoir from July to August in 2001. The standing crops of phytoplankton did not changed significantly by the operation. The cell concentration of the cyanobacteria at the surface layer were reduced about 10%, which is a poor result for the dispersing cyandobacteria deeper into the water. The average surface temperature during the study was reduced by 2.0$^{\circ}C$ by the hydraulic-gun-aerators. The effect of the operation on the vertical distribution of DO concentration was clear. However, the hydraulic-gun-aerators were not expected to have an effect in the lowest layer of the hypolimnion. In the study, it was proposed that installation distance between each hydraulic-gun-aerator would be proper when they are apart about 120 m based on DO depth profiles.

• 한국환경과학회지
• /
• 제13권6호
• /
• pp.571-579
• /
• 2004

There is a need to improve the efficiency of the existing sanitary treatment facilities, because the effluent standard becomes more stricter and septic sludge increased. Thus, operating processes of sanitary treatment system in M city changed with installation of additional facilities. Process modifications were as follows: Dilution water was added to the next process after primary aeration tank. Some secondary sedimentation sludge was recycled to primary aerator so that most of the organics were stabilized in primary aeration tank under automatic control of dissolved oxygen. The line of effluent from dewatering process flowing to the activated sludge tank was changed to the primary aerator. The primary sedimentation sludge line was linked to a thickener. Polymer was added to the activated sludge tank. The effluent of primary aerator and aerobic digester was recycled from the 5th to the 1st sector. As consequencies of above process modifications, the improvement of removal efficiency was achieved as BOD 54%, COD 42%, SS 61%, T-N 39%, and T-P 12%, respectively.

• 한국축산시설환경학회지
• /
• 제4권1호
• /
• pp.63-71
• /
• 1998

The dramatic increase in both swine and cattle production in Korea has presented problems related to protection of water resources. Animal wastes are a potentially valuable source of plant nutrients. Modern liquid waste management plans for a livestock housing need to focus on the slurry aeration and composting control methods and cost effective equipments. Recent developments in the animal manure liquid composting make it possible to improve the manure more easier to handle, reduce the odorous, labors and bedding materials, kill the weed seeds etc. However, there are some disadvantages, the aerator consumes much electrical power and initial cost is high. To solve these problems, this study is intended to develop a key points such as slurry aeration and dilution, liquid waste composting equipments.

• Journal of Mechanical Science and Technology
• /
• 제18권9호
• /
• pp.1661-1667
• /
• 2004

An experimental study is performed on atomization characteristics and stable operating conditions for the injection of high viscous waste vegetable oil using an effervescent atomizer with 2 aerator tubes. Consideration is given to the effects of ALR and liquid viscosity on the velocity and mean diameter of the injected droplet. It is found that (i) as ALR increases, the axial velocity of the droplet is increased, while half-velocity width and SMD are decreased regardless of the change in liquid viscosities, (ii) the rate of fine drop distribution occupied in the total spray field is increased with an increase in ALR, and (iii) the effect of viscosity on the atomization characteristics is minor. Consequently, it is expected that the effervescent atomizer will exhibit an excellent atomization performance at the high ALR condition, regardless of liquid viscosities.