• 유통과학연구
• /
• 제19권4호
• /
• pp.53-60
• /
• 2021

Purpose: This study focuses on exploring ways to improve the distribution method of shrimp farming so that it is eco-friendly and increases the distribution of shrimp. Research design, data and methodology: The experimental device installed in a biofloc shrimp culture in one area tested 10 times. Complex odor, concentration of H2S, water quality improvement effected by decomposition of organic substances, and degree of microbial activation measured. The data of the experimental results verified using the T-test technique, and the p value was determined based on the significance probability of 0.05. Results: This experimental device was effective in reducing odor and hydrogen sulfide in shrimp farms. With the improvement of water quality, dissolved oxygen increased due to the microbubble and cavitation action of air ejector and ultrasonic waves. In addition, the cultured microorganisms in the cultured water treated by the experimental device were remarkably proliferated compared to the raw water. Conclusions: The biofloc distribution method has a significant effect on improving water quality and reducing odor substances and will become a new eco-friendly and efficient distribution method for shrimp farming in the future.

• Membrane and Water Treatment
• /
• 제13권1호
• /
• pp.1-6
• /
• 2022

The regulations of the International Maritime Organization (IMO) have been steadily strengthened in ship emissions. Accordingly, there is a growing need for development of related technologies for the removal of contaminants that may occur during the treatment of SOx and NOx using a wet scrubber. However, this system also leads to wastewater production when the exhaust gas is scrubbed. In this research, we evaluated the performance of an ion selective resin process in accordance with scrubber wastewater discharge regulations, specifically nitrate discharge, by the IMO. Accelerated real and synthetic wastewater of wet scrubbers, contained high amounts of TDS with high nitrate, is used as feed water in lab scale systems. Furthermore, a pilot scale dissolved air flotation (DAF) using microbubble generator with ion exchange resin process was combined and developed in order to apply for the treatment of wet scrubber wastewater. The results of the present study revealed that operating conditions, such as resin property, bed volume (BV), and inlet wastewater flow rate, significantly affect the removal performance. Finally, through a pilot test, DAF with ion exchange resin process showed a noticeable improvement of the nitrate removal rate compared to the single DAF process.

• 자원리싸이클링
• /
• 제19권2호
• /
• pp.35-44
• /
• 2010

신흥개발국과 선진국의 해외자원 확보 경쟁이 심화되는 가운데 대부분의 광물자원을 수입하고 있는 우리나라는 안정적인 자원확보 및 외화지출을 줄이기 위해 국내에 부존되어 있는 몰리브덴광 등을 재개발하기 시작하였다. 본 연구에서는 현재 국내에서 유일하게 몰리브덴광을 생산하고 있는 (주)동원NMC의 최종정광(Mo 50.4%)을 대상으로 XRD 및 성분분석 결과 석영과 Grossular, Hedenbergite 등이 불순문로 존재하였으며, 입도분석 결과 60~140 mesh의 비교적 조립질 구간에 Mo 57% 이상의 고품위로 구성되어 있음을 확인하였다. 또한, (주)동원NMC의 최종정광(Mo 50.4%)의 고품위 가능성 및 실수율 향상 가능성을 확인하기 위해 실험을 실시하였다. 그 결과 마광시간 15분, 포수제 Kerosene 0.1 l/ton, 기포제 AF 65 7.2 l/ton, 세척수량 630 ml/min., air flow rate 1,197 ml/min.의 조건에서 Mo 58.6% ($MoS_2$ 97.83%)의 산물을 87.47%의 실수율로 얻을 수 있었다.

• 한국가시화정보학회지
• /
• 제4권2호
• /
• pp.69-75
• /
• 2006

The microbubbles were used in various fields, such as turbulent control, drag reduction, material science and life science. The X-ray PTV using X-ray micro-imaging technique was employed to mea-sure the size and velocity of micro-bubbles moving in an opaque tube simultaneously. Micro-bubbles of $10{\sim}60{\mu}m$ diameter moving upward in an opaque tube (${\phi}$=2.7mm) were tested. Due to the different refractive indices of water and air, phase contrast X-ray images clearly show the exact size and shape of over-lapped microbubbles. In all of the working fluids tested (deionized water, tap water, 0.01 and 0.10M NaCl solutions), the measured terminal velocity of the microbubbles rising through the solution was proportional to the square of the bubble diameter. The rising velocity was increased with increasing mole concentration. The microbubble can be useful as contrast agent or tracer in life science and biology. The X-ray PTV technique should be able to extract useful information on the behavior of various bio/microscale fluid flows that are not amenable to analysis using conventional methods.

• 환경영향평가
• /
• 제28권3호
• /
• pp.332-345
• /
• 2019

이 연구의 목적은 TPH 또는 $Cr^{6+}$이 함유된 오염 지하수의 처리 가능성을 평가하는 데 있다. 오일과 물의 분리, 용존 공기 부유 (DAF), 응고 및 침전, 모래와 활성탄으로 각각 여과를 위한 실험실 규모 테스트가 수행되었다. 총 40 분간의 분리 시간 동안 오일과 물의 분리 시험을 2 회 실시한 결과 TPH 제거율은 90.2 %였다. 높은 농도의 TPH 샘플에 대한 DAF 테스트의 경우, TPH 제거율은 미세 기포 크기의 변화에 따라 크게 변하지 않았다. 그러나 낮은 TPH 샘플에 대한 테스트는 미세 기포가 작을수록 TPH 제거율이 증가함을 보여준다. DAF 테스트를 위해 응집제를 샘플에 첨가했을 때 TPH 제거율은 12.3 % 증가했다. DAF에 의한 SS 제거율은 $16{\sim}40{\mu}m$에서 97.9 %였으며 미세 기포의 크기가 감소함에 따라 증가했다. 지하수에서 $Cr^{6+}$의 제거를 평가하기 위해 응집 및 침전 시험을 수행했다. $FeSO_4$ 투여량을 증가하였을때 응집 및 침전 공정에서 $Cr^{6+}$ 제거율이 증가하였다. 필터 매체에서 활성탄의 비율이 높을수록 여과공정에서 TPH 제거율이 증가한다. 여과에 의한 SS 제거율은 DAF 공정 시험 결과와 비슷한 96.7 %였다. 여과 과정은 TPH와 SS 농도가 감소하였다. 모래의 크기가 $425{\sim}850{\mu}m$이고 활성탄과 모래의 비율이 50:50일때 최적의 처리효율을 나타냈다.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2005년도 추계학술대회 논문집
• /
• pp.17-22
• /
• 2005

An experimental study was carried out to investigate the effect of local ultrasonic forcing on a turbulent boundary layer. Stereoscopic particle image velocimetry (SPIV) was used to probe the characteristics of the flow. A ultrasonic forcing system was made by adhering six ultrasonic transducers to the local flat plate. Cavitation which generates uncountable minute air-bubbles having fast wall normal velocity occurs when ultrasonic was projected into water. The SPIV results showed that the wall normal mean velocity is increased in a boundary layer dramatically and the streamwise mean velocity is reduced. The skin friction coefficient ($C_{f}$) decreases $60\%$ and gradually recovers at the downstream. The ultrasonic forcing reduces wall-region streamwise turbulent intensity, however, streamwise turbulent intensity is increased away from the wall. Wall-normal turbulent intensity is almost the same near the wall but it increases away from the wall, In tile vicinity of the wall, Reynold shear stress, sweep strength and production of turbulent kinetic energy were decreased. This suggests that the streamwise vortical structures are lifted by ultrasonic forcing and then skin friction is reduced.

• 한국유체기계학회 논문집
• /
• 제20권2호
• /
• pp.41-46
• /
• 2017

The flotation performance of the induced gas flotation (IGF) machine is considerably influenced by geometric configurations of rotor and stator. The interaction of rotor and stator, which are the most important components in IGF, serves to mix the air bubbles. Thus, the understanding of flow characteristics and consequential analysis on the machine are essential for the optimal design of IGF. In this study, two-phase (water and air) flow characteristics in the forced-air mechanically stirred Dorr-Oliver flotation cell was investigated using ANSYS CFX. In addition, the void fraction and the velocity distributions are determined and presented with different blade configurations.

• 한국가시화정보학회지
• /
• 제19권3호
• /
• pp.84-91
• /
• 2021

Effervescent tablets generate gas bubbles when chemical reaction occurs between water and tablets. Most of previous studies have been focused on pharmaceutical characteristics of tablets. However, for their applications in disinfectants, cleaners, and pesticides, physical characteristics of bubbles released from the effervescent tablets when they are in water are important. In this study, we experimentally investigated the characteristics of microbubbles generated by an effervescent tablet made of sodium bicarbonate and tartaric acid using PDPA and high-speed camera. Microbubbles were generated using different weights of effervescent tablet as well as in different water temperature. The experimental study shows increase in reaction time, bubble concentration and rise velocity as the weight of effervescent tablet increases from 1 to 20 g. The decrease in average bubble diameter was observed when the temperature of water increased from 25 to 45 ℃. Further, reaction time varies inversely with increase in water temperature, while bubble rise velocity is directly proportional to increase in water temperature. Effervescent table continuously generates the bubble with approximately constant diameter (235 ㎛) in the water. However, bubble concentration and bubble rise velocity decreased over time.

• 현장농수산연구지
• /
• 제19권1호
• /
• pp.109-117
• /
• 2017

아직까지 많이 알려지지 않은 마이크로버블을 사용하여 우리나라 대표 작물인 인삼재배에 적용하였다. 고년근에 적용하여 결과를 확인하기 위해서는 비용과 시간 소요가 많아 종묘삼을 활용하여 생리적 변화를 측정하고 분석하였다. 최근 뿌리 작물에 기능성이 있다는 산소수 일반 재배농가에서 사용해보았지만 그 결과가 미미하고 오히려 해를 입는 경우도 생기게 되었다. 다른 작물의 선행결과와 본 연구결과를 볼 때 마이크로 버블을 사용한 인삼재배는 파급효과 있을 것으로 사료된다. 중화제 및 약제를 활용하여 만든 산소수와는 다른 개념으로 마이크로 버블은 공급 장치를 통해 우리가 이용하는 공기를 아주 작은 버블로 압축하여 인삼에 제공함으로써 저해 없이 특이성 성장을 이끌어 내었다. 연구결과로부터 설정된 종묘삼의 생장 특성 및 세분화별 적정범위 및 적정치를 결과와 비교하면, 그동안 이루어졌던 관행농법에서 사용되는 일반수와 마이크로 버블(Micro bubble)수를 사용하여 재배한 결과는 10%에서 15%의 인삼생장을 나타내었다. 이후로 마이크로 버블수를 생산할 때 시간별 용존 산소량을 측정하여 마이크로 발생장치의 최적 시간을 설정하고 최적화 설정을 위해서는 관계시간과 에너지 효율 및 토양의 영양환경에 대한 변화에 대해서도 더욱 많은 연구가 필요하고 사료되며, 더불어 생체 및 중량이 증가된 만큼 인삼의 주요 성분인 진세노사이드의 증감에 대한 분석 등 추가 연구가 활발하게 이루어져야 할 것이다.

• 상하수도학회지
• /
• 제31권2호
• /
• pp.169-175
• /
• 2017

This study applied microbubbles to reduce membrane fouling in wastewater reuse membrane processes, evaluated and compared the transmembrane pressure with or without the application of microbubbles and the cleaning efficiency with the application of aeration and microbubbles. In addition, this study analyzed foulants removed from the membrane surface. Changes in the transmembrane pressure of membranes with the presence or absence of microbubbles were observed. As a result, transmembrane pressure (TMP) increasing rate decreased twofold when applying microbubbles to realize stable operations. This study compared and evaluated cleaning efficiency applying aeration and microbubbles. As a result, the cleaning efficiency was 5% higher on average when applying microbubbles. In turbidity and total organic carbon (TOC), foulants were discharged when applying microbubbles twice as much as applying aeration. It is thought that particulate foulants precipitated on the membrane surface were more likely to desorb because the adhesion between the membrane surface and particle was weakened by microbubbles. Therefore, it is considered possible to effectively control membrane fouling because of the increase in cleaning efficiency when applying microbubbles to wastewater reuse membrane processes.