• KSBB Journal
• /
• v.4 no.3
• /
• pp.281-287
• /
• 1989

The experimental study reported herein was to investigate to separation characteristics of a tangential flow membrane in a continuous recycle situation. Physical and dynamic analyses are performed on the membrane system in order to relate relevant variables to the capacity of separation. The results of separation process may be summarized by a proposed equation:Sh=A(Re.Sc.dh/L)1/3. It was shown also by the analyses that effective separation of sugar and cell was attainable by means of tangential membranes, thereby enhancing ethanol productivity in fermentation with continuous cell and substrate recycle.

• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.5
• /
• pp.619-627
• /
• 2004

Purposes of this study were to examine closely the extracellular polymeric substances (EPS) which was a membrane fouling contaminant, to control detected EPS by powdered activated carbon (PAC) dosage etc. and to evaluate the possibility of practical reuse facility. With high removal efficiency of general pollutants, when the PAC is added to MBR, improvement of removal efficiency of $COD_{cr}$, and color was expected and treated wastewater can be reused. It was judged that the correlation between EPS and membrane fouling was very high. Carbohydrate and DNA in the EPS were judged to be cause of membrane fouling. If EPS could be controled, not only membrane fouling would be decreased but also operation time would be extended. In experiment of powdered activated carbon (PAC), characteristics of the best PAC for membrane fouling control were the particle size of $7{\mu}m$, lodine Number of 1,050, surface area of peat of $1,150m^2/g$. In lab test, operation time of MBR by PAC dosage of 200mg/gVSS was longer than one of MBR by without PAC dosage. Because EPS, especially carbohydrate and DNA, was controled successfully by PAC, membrane fouling in MBR could be decreased.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.10
• /
• pp.67-75
• /
• 2011

Although membrane technologies are widely applied to the water and wastewater treatment processes, strategy for the control of membrane biofouling is strongly required. In this study, a possibility of control of membrane biofouling using HVI(High Voltage Impulse) was verified based on the inactivation of microorganisms by the HVI. The HVI system was consisted of power supply, voltage amplifier, impulse generator and disinfection chamber and the model microorganism was E. coli. When 15[kV/cm] of electric fields was applied to the E. coli solution, inactivation of the microorganism was found. A possibility of the control of membrane biofouling using HVI was verified with experiments of membrane filtration with and without exposure of the HVI to biomass solution. Another membrane filtration experiments with the contaminated membranes by E. coli solution were carried out and indicate that the HVI could be used as an alternative method for membrane biofouling control. A series of simulation of the electric fields between electrodes and microorganisms was carried out for the visualization of the disinfection that showed where the electric fields are formed.

• Membrane Journal
• /
• v.30 no.6
• /
• pp.443-449
• /
• 2020

In this study, CO2 separation experiment was performed on a CH4/CO2 mixed gas using a ceramic hollow fiber membrane contactor module (HFMC). In order to fabricate high-durability HFMC, a high-durability hollow fiber membrane was prepared and evaluated. HFMC was fabricated using the prepared hollow fiber membrane, and the experiment used a mixture of CH4/CO2 (30% CO2, CH4 balance) and monoethanolamine (MEA). During HFMC operation, the effect of gas and absorbent pressure on the CO2 removal efficiency was evaluated. The CO2 removal efficiency increased as the gas pressure increased, and the CO2 absorption flux also showed a tendency to increase with the liquid flow rate. In addition, when the CO2 absorption rate was less than 40%, LTS-1, a counter-current form where the absorbent enters from the bottom, has higher CO2 removal performance than LTS-2, a countercurrent form in which the absorbent enters from the top. and when the absorption rate was 40% or higher, LTS-2 had higher performance than LTS-1.

• Membrane Journal
• /
• v.32 no.3
• /
• pp.173-180
• /
• 2022

Presence of ammonia in drinking water is very toxic to human health. Soluble ammonia contaminates ground water due to activities such as the use of fertilizer in crop, industrial effluents and burning of fossil fuel. Even low concentration of ammonia present in water will damage aqua environment such as marine organism. Membrane technology is an important process to remove ammonia from effectively from water. Flat sheet membrane, membrane contactor and membrane distillation are some of the methods used for water purification from ammonia. Membrane contractor is an efficient process in which ammonia is removed through liquid-gas or liquid-liquid mass transfer without change of phase unlike membrane distillation. However, the cost of ammonia removal in this method is high due to maintenance of very high pH. Zeolite has excellent ion exchange ability that enhances its ability to interact with ammonia and adsorb from wastewater. Mixed matrix membranes containing zeolite enhance the efficiency of ammonia adsorption and separation from wastewater. In this review the above discussed issues are summarized in detail.

• KSBB Journal
• /
• v.6 no.4
• /
• pp.379-383
• /
• 1991

Pervaporation can be successfully utilized to recover alcohol from fermentation broths and dilute process streams. Polydimethylsiloxane (thickness: $60\mu$m), such as hydrophobic membrane have been employed in this application to produce an enriched product. The fermented alcohol was continuously extracted, and simultaneously concentrated by pervaporation, from the membrane bioreactor, and the extracted alcohol concentration was 6 to 10 times higher than in the broth. This experimental conditions were 6-10 Torr vacuum line, pH=5, $32^{\circ}C$, 3.5 liters of working volume, 200rpm of agitator speed, and 0.14 wm aeration flow rate.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.9
• /
• pp.948-954
• /
• 2008

Membrane bioreactor(MBR) processes have been widely applied to wastewater treatment for last decades due to its excellent capability of solid-liquid separation. However, membrane fouling was considered as a limiting factor in wide application of the MBR process. Excess aeration into membrane surface is a common way to control membrane fouling in most MBR. However, the excessively supplied air is easily dissipated in the reactor, which results in consuming energy and thus, it should be modified for effective control of membrane fouling. In this study, cylindrical tube was introduced to MBR in order to use the supplied air effectively. Membrane fibers were immersed into the cylindrical tube. This makes the supplied air non-dissipated in the reactor so that membrane fouling could be controlled economically. Two different air supplying method was employed and compared each other; nozzle and porous diffuser which were located just beneath the membrane module. Transmembrane pressure(TMP) was monitored as a function of airflow rate, flux, and ratio of the tube area and cross-sectioned area of membrane fibers(A$_m$/A$_t$). Flow rate of air and liquid was regulated to obtain slug flow in the cylindrical tube. With the same flow of air supply, nozzle was more effective for controlling membrane fouling than porous diffuser. Accumulation of sludge was observed in the tube with the nozzle, if the air was not suppled sufficiently. Reduction of membrane fouling was dependent upon the ratio, A$_m$/A$_t$. For diffuser, membrane fouling was minimized when A$_m$/A$_t$ was 0.27, but 0.55 for nozzle.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2007.05a
• /
• pp.375-379
• /
• 2007

폐비닐 여재(Synthetic Waste Polyethylene Media)를 적용한 부착성장식 공정의 유기물 및 질소${\cdot}$인 제거특성에 관한 Pilot Plant 실험 결과 다음과 같은 결론을 얻을 수 있었다. 1) 제거효율은 $RUNI1{\sim}3$에서 $COD_{cr}$ 91.4, 92.4, 93.9%, T-N 56.9, 61.4, 65.1%, T-P는 모든 단계에서 약 45%이상 제거되어 부하변동시에 강한 대처능력을 나타내었다. 2) BOD용적부하 $0.18{\sim}0.40kg/m^3{\cdot}d$, COD용적부하 $0.28{\sim}0.53kg/m^3{\cdot}d$, ${NH_4}^{+}-N$용적부하 $0.12kg/m^3{\cdot}d$을 나타내었다. 3) 도시하수 처리를 위한 생물학적 질소 및 인 제거공법을 본 여재를 이용하여 공정설계시 고려할 사항들과 적절한 대처방법을 다음과 같이 제시할 수 있다. - 1차 침전지에서 유기질소 및 유기인 농도가 높다면 유기질소 및 인 부하량을 감소시키기 위하여 1차 침전지를 설치하되 질소 및 인제거에 유리한 $BOD_5/T-N$, $BOD_5/T-P$를 유지할 수 있도록 체류시간을 1시간미만으로 설계하는 것이 경제적이라고 판단된다. 만일 유기질소와 유기인의 함량이 낮다면 1차 침전지는 제외하는 것이 유리할 것이다. - 여재의 배치는 폭기조에서 용존산소의 균일분포와 슬러지의 적정탈리를 위해 여재를 상하로 배치하거나 또는 여재끼리 일정 간격을 두어 배치하는 것이 바람직하다. 농촌에서의 처분이 문제시 되고 있는 폐비닐을 적용한 본 연구에서의 수처리특성은 기존 하수처리공정에서의 제거효율에 상응하는 처리특성을 나타내었다. 또한 폐비닐 처분의 문제를 해결할 수 있을뿐만 아니라 하수처리시에도 부하변동 등에 강한 대처능력을 나타내어 기존의 하수처리공정에 대체가능성을 나타내었다.

• Journal of Korean Society of Water and Wastewater
• /
• v.19 no.6
• /
• pp.720-727
• /
• 2005

This study was performed to advance nitrogen removal efficiency by employing an single biofilter packed with granular sulfur, which consists of nitrification occurring at upper part and denitrification at lower part of the reactor. Continuos nitrification/denitrification was carried out with different alkalinity sources, which were $NaHCO_3$ and $CaCO_3$(limestone). In the downflow nitrification/denitrification biofilter packed with granular sulfur, first, terms for nitrogen removal was decided. As results, nitrification and denitrification rate with NaHCO3 at 0.85 kg $NH_4^+-N/m^3{\cdot}d$ were accomplished $0.80kg\;N/m_3{\cdot}d$, $0.43kg\;N/m^3{\cdot}d$, respectively. In the sulfur/limestone packed downflow nitrification/denitrification biofilter, sulfur and limestone were mixed packed, preliminary test showed sulfur/limestone mixing ratio was 3:1 and that was ideal. In the result, nitrification and denitrification rate at $0.7kg\;NH_4^+-N/m^3{\cdot}d$ were accomplished$0.65kg\;N/m^3{\cdot}d$, $0.34kg\;N/m^3{\cdot}d$, respectively. In general, employing granular sulfur can be implemented for only denitrification, but this system can accomplish nitrification as well as denitrification in a single reactor even though low carbon concentration was present in influent limiting to nutrient removal process. This biofilter system of limestone and granular sulfur packed together can successfully apply for nutrient removal effectively.

• Clean Technology
• /
• v.29 no.1
• /
• pp.31-38
• /
• 2023

Due to water shortages caused by water pollution and climate change, total organic carbon (TOC) standards have been implemented for wastewater discharged from public sewage treatment facilities. Furthermore, there is a growing interest and body of research pertaining to the reuse of sewage treatment water as a secure alternative water resource. The membrane bio-reactor (MBR) method is commonly used for advanced wastewater treatment because it can remove organic and inorganic ions and it does not require or emit any chemicals. However, the MBR process uses a separation membrane (MF), which requires frequent film cleaning due to fouling caused by a high concentration of mixed liquor suspended solid (MLSS). In this study, process improvement and microbubble cleaning efficiency were evaluated to improve the differential pressure, water flow, and MF fouling, which are the biggest disadvantages of operating the MF. The existing MBR method was improved by installing a precipitation tank between the air tank and the MBR tank in which raw water was introduced. Microbubbles were injected into a separation membrane tank into which the supernatant water from the precipitation tank was introduced. The microbubble generator was operated with a 15 day on, 15 day off cycle for 5 months to collect discharged water samples (4L) and measure TOC. As the supernatant water from the precipitation tank flowed into the separation membrane tank, about 95% of the supernatant water MLSS was removed so the MF fouling from biological contamination was prevented. Due to the application of microbubbles to supernatant water from the precipitation tank, the differential pressure of the separation membrane tank decreased by 1.6 to 2.3 times and the water flow increased by 1.4 times. Applying microbubbles increased the TOC removal rate by more than 58%. This study showed that separately operating the air tank and the separation membrane tank can reduce fouling, and suggested that applying additional microbubbles could improve the differential pressure, water flow, and fouling to provide a more efficient advanced treatment method.