• Journal of Ocean Engineering and Technology
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• v.22 no.5
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• pp.39-43
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• 2008

For a partially filled and deeply submersed membrane container, an analytic solution for similarity shape was studied. The static shape of a membrane container can be expressed as a set of nonlinear ordinary differential equations. These equations are combined into an integrable equation. The solution of the equation is derived in terms of elliptic integrals, the arguments of which contain an unknown at the point of inflection. The point of inflection is determined by using the boundary condition at a separating point. Some characteristic values of the similarity shape were evaluated and the shapes are illustrated.

• Journal of Ocean Engineering and Technology
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• v.16 no.5
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• pp.7-14
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• 2002

in the present paper, the hydrodynamics properties of a Rahmen type flexible porous breakwater interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged at th side edges of a submerged horizontal membrane. The dual vertical membranes are extended downward and hinged at seabed. The effects of permeability, Rahmen type membrane breakwater geometry pre-tensions on membranes, relative dimensionless wave number, and incident Wave headings are thoroughly examined.

• Membrane Journal
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• v.28 no.4
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• pp.279-285
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• 2018

The pervaporation separation of isopropanol/water mixture was carried out on a series of chemically cross-linked poly(vinyl alcohol)(PVA) composite membranes. The membranes were prepared by casting three kinds of PVA solutions with varying concentrations of PVA and GA onto polyacrylonitrile (PAN) support followed by thermal cross linking. As the PVA concentration increased, the flux decreased but separation factor was increased. It was confirmed that the composite membrane coated with PVA-3 (98~99% hydrolyzed) at a concentration of 7 wt% PVA and 20 wt% glutaraldehyde (GA) exhibited a flux of $209g/m^2h$ and a separation factor of more than 100. The submerged module test was carried out with controlled feed tank temperature and IPA concentration of the feed solution. The continuous concentration of IPA solution was increased from 90% to 99% after 60 h.

• Membrane Journal
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• v.26 no.2
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• pp.166-172
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• 2016

In this study critical permeation flux was measured by the flux-step method with respect to aeration rate. The hollow fiber membrane module which has $85cm^2$ of effective area and $0.4{\mu}m$ nominal pore size was submerged in the activated sludge solution of MLSS 5,000 mg/L. The critical flux for without aeration was measured of $15.2L/m^2{\cdot}h$. However, the critical flux increased from 20.6 to $32.5L/m^2{\cdot}h$ as the aeration rate increased from 100 to 1,000 mL/min.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.7-10
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• 2003

Factors affecting filtration performance were investigated in a Sequencing Batch Reactor (SBR) coupled with a submerged microfiltration module. Special bioreactors for aerobic and anoxic phases, respectively, were specifically designed in order to differentiate tile effect of Dissolved oxygen (DO) from that of mixing intensity on membrane filterability. DO concentration as well as mixing intensity proved to have a major influence on the membrane performance regardless of the SBR phase. A higher DO concentration resulted in a slower rise in TMP, corresponding to less membrane fouling.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.235-241
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• 2011

This study was performed to investigate the characteristics of nutrient removal of municipal wastewater in the submerged membrane bioreactor by addition of alum directly into aerobic tank. Membrane bioreactor consists of three reactors such as two intermittent anaerobic tanks and the aerobic tank with hollow fiber membrane. The removal efficiencies of $COD_{cr}$, BOD, SS, TN and TP on the membrane bioreactor were 94.0%, 99.1%, 99.9%, 66.9%, and 58.9%, respectively. In addition, The removal efficiencies of $COD_{cr}$, BOD, SS, TN and TP on the membrane bioreactor with alum addition were 93.4%, 99.0%, 99.9%, 63.2%, and 96.8%, respectively. There was little difference between them on the nutrient removal efficiencies except phophorus removal. The estimated sludge production, specific denitrification rate, specific nitrification rate and phosphorus removal content on the membrane bioreactor were 1.76 kgTSS/d, $0.055mgNO_3-N/mgVSS{\cdot}d$, $0.031mgNH_4-N/mgVSS{\cdot}d$, and 0.095 kgP/d, respectively. And The estimated sludge production, specific denitrification rate, specific nitrification rate and phosphorus removal content on the membrane bioreactor with alum addition were 2.90 kgTSS/d, $0.049mgNO_3-N/mgVSS{\cdot}d$, $0.030mgNH_4-N/mgVSS{\cdot}d$, and 0.160 kgP/d, respectively. The alum content added was 1.7 molAl/molP on an average. The increasing ratio of tran-membrane pressure on the membrane bioreactor was $0.0056kgf/cm^2{\cdot}compared$ to $0.0033kgf/cm^2{\cdot}d$ on the membrane bioreactor with alum addition. There was a slightly reduction effect on membrane fouling by alum addition.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2004.08a
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• pp.150-159
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• 2004

In the present paper, the hydrodynamics properties of a Rahmen type flexible porous breakwater with dual fixed-pontoon system interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged a the side edges of dual fixed pontoons, and a submerged horizontal membrane that both ends are hinged at the steel frames mounted pontoons. The dual vertical membranes are extended downward and hinged at bottom steal frame fixed into seabed. The wave blocking and dissipation mechanism and its effects of permeability, Rahmen type membrane and pontoon geometry, pre-tensions on membranes, relative dimensionless wave number, and incident wave headings are thoroughly examined.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.105-112
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• 1999

The removal characteristic of BOD, COD,T-N, and T-P was investigated in municipal wastewater treatment with anoxic and membrane submerged aerobic reactor. It was found that BOD and COD removal rate were obtained 90% and 92%, respectively, for 90 days operation. BOD and COD loading rate did not affect to the removal efficiency because MLSS concentration in aerobic tank was highly maintained.In the case of first reactor operated with anoxic and second reactor operated as aerobic, T-N, T-P removal rate were obtained 93% and 99% respectively.It was shown that removal efficiency could be maintained stable due to the complete removal of SS and sludge production decreased with increasing of sludge retention time.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.85-89
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• 2004

The wave interactions with fully submerged and floating dual buoy/vertical porous membrane breakwaters has been investigated in experimentally to validate the developed theory and numerical method in the previous study, in which multi-domain hydro-elastic formulation was carried out in the context of linear wave-body interaction theory and Darcy's law. It is found that the experimental results agrees well with the numerical prediction. Transmission and reflection can be quite reduced simultaneously especially in the region of long waves. The properly tuned system to incoming waves can effectively dissipate wave energy and also offset each other between incident and scattered waves using its hydro-elasticity and geometry.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.47-52
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• 2005

This study was conducted to evaluate the performance of submerged hollow fiber MF processes to treat secondary wastewater for water reuse. Specifically, membrane productivity and filtrate water quality were investigated under various operating conditions (i.e. flux, recovery, and backwash rate) at pilot-scale. Membrane fouling became more severe with increasing flux and recovery, suggesting that low flux operation (< 25 LMH) was desirable. At high flux operating(> 37.5 LMH), increasing backwash rate showed only limited success. The biofouling, quantified by PEPA and BFHPC, was also significant in wastewater reclamation, and biogrowth control by chlorine, were necessary to improve membrane productivity. Filtrate water qualities are in good compliance with water reuse regulations regardless of operating conditions (flux, recovery and backwash rate). Particle (e.g. turbidity) removal ranged from 89 to 98%, while only 11 to 21% of organics (e.g. NPDOC) were removed by MF membrane. Only small improvement in biostability (e.g. AOC) was achieved by MF system, and thus, without post disinfection, significant microorganisms might be present in the filtrate due to regrowth. Lastly, in order to further investigate pathogen removal, controlled microbial challenge tests were performed by monitoring Giardia, Cryptosporidium, bacteria and virus, and showed relatively good microbial removal.