• Journal of the Korean Society of Industry Convergence
• /
• v.3 no.3
• /
• pp.237-243
• /
• 2000

최근에 경제성장과 생활향상에 따른 물수요량이 급증함과 동시에 소비자의 질적요구가 강화되고 있는 실정이다. 기존 상수원인 하천의 수질오염으로 인하여 소비자의 요구사항을 충족시키기 위해서는 기존 정수처리법의 개선이 요구된다. 따라서 본 연구에서는 기존 급속여과법의 전염소 처리공정 및 응집.침전 공정의 개선을 통하여 음용수 수질을 개선하고자 하였다. 전염소 대신에 적용한 생물막여과 공정(BAF)의 처리효과 및 응집.침전 공정의 경우는 교반강도에 따른 침전효과에 따른 수질특성을 조사하였다. BAF공정은 탁월한 $NH_4$-N의 제거를 통하여 후속공정에 대한 오염부하량을 저감시킬수 있었고, 응집.침전의 경우 본 연구에서 제안한 응집제 주입량에 따른 교반강도의 실험식인에 의하여 구한 최적교반강도용 용집공정에 적용시 응집.침전의 효과를 향상시킨 수 있어 음용수 수질 향상을 기대 할 수 있었다.

• Korean Chemical Engineering Research
• /
• v.45 no.5
• /
• pp.523-528
• /
• 2007

The objectives of this research are to investigate the mechanism of coagulation affecting UF, find out the effect of metal salt coagulant on membrane fouling. Either rapid mixing + UF or slow mixing + UF process caused much less flux decline. For PACl coagulant, the rate of flux decline was reduced for both hydrophilic and hydrophobic membrane than alum due to higher formation of flocs. In addition, the rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. In general, Coagulation pretreatment significantly reduced the fouling of the hydrophilic membrane, but did little decrease the flux reduction of the hydrophobic membrane. When an Al(III) salt is added to water, monomers, polymers, or solid precipitates may form. Different Al(III) coagulants (alum and PACl) show to have different Al species distribution over a rapid mixing condition. During the rapid mixing period, for alum, formation of dissolved Al(III) (monomer and polymer) increases, but for PACl, precipitates of $Al(OH)_{3(s)}$ increases rapidly. This experimental results pointed out that precipitates of $Al(OH)_{3(s)}$ rather than dissolved Al(III) formation is major factor affecting flux decline for the membrane.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1991.11a
• /
• pp.34-37
• /
• 1991

Al계 베어링합금은 소착저항력등의 베어링특성이 우수하여 최근에 자동차의 엔진부품에 많이 사용되고 있다. Al계 베어링합금으로는 Al-Sn계, Al-Pb계, Al-Si계 합금이 개발되어 사용되어 왔다. Al-Si계 합금은 높은 강도, 우수한 부식성, 주조성이 향상되는 장점등을 갖고 있다. 또한 Al-Pb계 합금은 Pb가 고체윤활제로 작용하여 소착저항성이 높으며 가격도 저렴한 장점을 갖고 있다. Al과 Pb는 용융상태에서 넓은 용융간극을 갖어 중력편석을 일으키기 때문에 일반적인 주조방법으로 Al계 베어링합금을 제조할 수없다. 또한 Al에 Si이 첨가됨에 따라 높은 경도등의 기계적성질의 향상이 얻어지지만 Al 기지에 Si의 함량이 증가할 수록 편석이 심해져 조대한 Si-rich상이 미세조직에 존재하여 합금이 취약해지는 단점을 갖고 있다. 따라서 본 연구에서는 Al 기지에 Pb의 중력편석을 최소화하고 Al 기지에 조대한 Si-rich상이 생성되는 것을 막기 위하여 Al과 Pb가 공존하는 온도구역에서 높은 교반속도로 용탕을 강제교반하여 액상에서 Pb와 Si을 미세하게 분산시킨 후 수냉되는 동주형에서 급속응고시켜 Pb와 Si-rich 상이 균일하게 분포된 Al계 베어링합금을 제조하였다. 본 연구에서는 Pb의 양을 0%에서 35%까지 변화시켰으며, Si의 양을 0%에서 20%까지 변화시켜서 베어링합금을 제조하였으며, 강제교반속도는 500rpm에서 2500rpm 까지 변화시켜 베어링합금을 제조하였다.

• Journal of the Korean Ceramic Society
• /
• v.40 no.7
• /
• pp.696-701
• /
• 2003

The grinding efficiencies of silica powder in a small scale stirred ball mill were investigated by energy consumption estimate. Comparing with a non-treated silica powder and a heating treated silica powder, it was found that a silica powder cooled in room temperature after heating treatment at 600∼900$^{\circ}C$ consumed lower grinding energy than non-treated silica powder, and a silica powder quenched after heating treatment consumed lower grinding energies about 52∼62%, in case of dry grinding. Additionally, if heating treated silica powder grind in wet method, energy consumption will be decreased about 40% than in dry grinding, and the dependency of the particle size to the grinding efficiency, quenching significantly improved it.

• Korean Chemical Engineering Research
• /
• v.55 no.6
• /
• pp.816-821
• /
• 2017

An integrated slow mixing/sedimentation and net fit fiber filtration system has been developed to reduce the high concentrations of suspended solid (SS) and total phosphorus (T-P) in the reject water from sewage/wastewater. A filtration device used in this experiment consists of coagulation, in-line mixing, air injection, slow mixing/sedimentation, and filtration processes. The performance test using this device was carried out with six operational modes for reject water from sewage treatment plant. Experimental conditions used were 16.7, 33.3, 41.7 and 50.0 ton/day of flow rate and 2~4 of Al/P molar ratio. By injection of coagulant in each operational mode, the high removal efficiencies of SS and T-P were obtained, but continuous operation time was decreased to 7.8~11.4 min in most modes. However, when the Mode 5 of the developed filtration device was applied, the continuous operation time was maintained up to 88.2 min. Also, it was found that the continuous operation time in the Mode 5 using the developed system was increased from 8 to 11.3 times longer than those in other modes. Backwashing flow rate was also very low at 5.4% of total filtered water. Therefore, it can be concluded that the Mode 5 of the developed filtration system was the most efficient treatment method for the removal of high concentrations of SS and T-P.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.2
• /
• pp.243-252
• /
• 2007

Effects of alum dosage on the particle growth were investigated by monitoring particle counts in a rapid mixing process. Kaolin was used for turbid water sample and several other chemicals were added to adjust pH and ionic strength. The range of velocity gradient and mixing time applied for rapid mixing were $200{\sim}300sec^{-1}$ and 30~180 sec, respectively. Particle distribution in the synthetic water sample was close to the natural water where their turbidity was same. The number of particles in the range of $10.0{\sim}12.0{\mu}m$ increased rapidly with rapid mixing time at alum dose of 20mg/L, however, the number of $8.0{\sim}9.0{\mu}m$ particles increased at alum dose of 50mg/L. The number of $14.0{\sim}25.0{\mu}m$ particles at alum dose of 20mg/L was 10 times higher than them at alum dose of 50mg/L. Dominant particle growth was monitored at the lower alum dose than the optimum dose from a jar test at an extended rapid mixing time(about 120 sec). The number of $8.0{\sim}14.0{\mu}m$ particles was lower both at a higher alum doses and higher G values. At G value of $200sec^{-1}$ and at alum dose of 10-20mg/L, residual turbidity was lower as the mixing time increased. But at alum dose above 40mg/L and at same G value, lower residual turbidity occurred in a short rapid mixing time. Low residual turbidity at G value of $300sec^{-1}$ occurred both at lower alum doses and at shorter mixing time comparing to the results at G value of $200sec^{-1}$.

• 유체기계공업학회:학술대회논문집
• /
• 2003.12a
• /
• pp.508-513
• /
• 2003

A quick injection agitator is used to mix working fluids. In this study, numerical analyses are carried out to investigate the performance of a quick injection agitator with different gaps between the impeller and vacuum enhancer. A commercial CFD code is used to compute the 3-D viscous flow field within the impeller of agitatior. Numerical results are graphically depicted with different gaps. Special attention is paid to the following topics: pressure distribution, velocity gradient, volume fraction.

• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.2
• /
• pp.128-136
• /
• 2004

The overall objective of this research was to find out the role of rapid mixing conditions in the species of hydrolyzed Al(III) formed by different Al(III) coagulants. When an Al(III) salt is added to water, monomers, polymers, or solid precipitates may form. Different Al(III) coagulants (alum and PACl) show to have different Al species distribution over a rapid mixing condition. During the rapid mixing period, for alum, formation of dissolved Al(III) (monomer and polymer) increases, but for PACl, precipitates of $Al(OH)_{3(s)}$. increases rapidly. Also, for alum, higher mixing speed favoured Al(III) polymers formation over precipitates of $Al(OH)_{3(s)}$ but for PACl, higher mixing speed formed more precipitates of $Al(OH)_{3(s)}$. At A/D and sweep condition, both $Al(OH)_{3(s)}$ and dissolved Al(III) (monomer and polymer) exist, concurrent reactions by both mechanism appear to cause simultaneous precipitation.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.197-197
• /
• 2017

본 연구에서는 입자성 오염물질을 다량 함유하고 있는 초기강우 유출수를 처리하기 위한 수처리 시설로 고속복합응집장치를 개발하였다. 고속응집복합장치의 요소기술은 마이크로 버블, 급속교반장치(인라인믹서), 전기촉매를 이용한 부상촉진장치, 볼텍스 흐름 등으로 구성되며, 기술 원리는 응집제에 의해 오염물질을 응결, 응집, 부상시켜 스컴을 제거하는 일반 응집 원리와 유사하다. 본 기술의 특징은 교반, 혼화조, 응집제를 1개의 조에 컴팩트하게 구성하여 체류시간을 10분 이내로 단축하였고, 볼텍스(voltex) 흐름을 이용한 선회류와 루버홀 형태의 스크린을 적용하여 응집효과를 극대화하였으며, 플럭에 의한 막힘이 없이 스크리닝이 이루어질 수 있도록 하였다. 또한, 부상촉진장치(전기유도)를 이용해 응집 플럭의 부상효과를 상승시켰고, 감속기와 일체화된 내통스크린이 선회류와 반대 방향으로 회전하면서 볼텍스 흐름의 가속효과에 의한 스크린 폐색 방지 및 응집부상 효율을 향상시킬 수 있도록 설계하였다. 부상슬러지는 별도의 플럭 제거 설비 없이 스크린 내통 회전에 이용되는 감속기에 부착된 스컴 제거기에 의해 동시 제거가 가능하며, 응집부상 처리수는 장치 가장 바깥 외곽에 충진된 필터층에서 최종 여과되어 방류되도록 구성함으로서 모든 처리공정이 단일 장치 내에서 이루어지도록 구성하였다. 본 고속복합응집장치는 전체 규격 ￠ $1000{\times}2,000mmH$의 시제품이 제작되어 현재 시흥소재 매화저수지에서 성능평가를 실시하고 있다.

• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.6
• /
• pp.799-810
• /
• 2009

With time, the stable management of turbidity is becoming more important in the water treatment process. So optimization of coagulation is important for the improvement of the sedimentation efficiency. we evaluated the mixing and hydrodynamic behavior in the coagulation basin using Computational Fluid Dynamics (CFD). The items for evaluation are a location and the speed of agitator and angle of an injection pipe. The results of the CFD simulation, the efficacy of mixing in the coagulation basin was not affected according to one or two injection pipe and angle of an injection pipe. If there is a agitator near outlet of coagulation basin, the efficacy of mixing don't improve even though the speed of agitator increase. So location of agitator is perfect when it locate center at the inlet stream. The coagulation basin at this study, the proper speed of agitator is form 20rpm to 30rpm.