• Journal of Korean Society of Water and Wastewater
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• v.18 no.6
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• pp.770-777
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• 2004

Three pilot-scale membrane systems were operated using lake water as influent in this study. Microfiltration (MF) membrane with pore size of 0.01 m was used in Systen I of which filtration mode was set at constant pressure of $1kgf/cm^2$. Ultrafiltration (UF) membranes with molecular cutoff (MWCO) of 80,000 and 13,000 were used in System II-1 and II-2, respectively. Constant flow mode was applied at the range between 0.7 and $1.5m^3/m^2{\cdot}d$ (average of $1.1m^3/m^2${\cdot}d) for System II-1 and between 0.37 and $1.65m^3/m^2{\cdot}d$ (average of $1.18m^3/m^2{\cdot}d$) for System II-2. In System I, the flux changed from $1m^3/m^2{\cdot}d$ to $0.2m^3/m^2{\cdot}d$ during the operation time of 5 months. System II showed recovery of 94% under the allowable maximum pressure of $3kgf/cm^2$ during the same operation period. From these results, the efficient operation was observed in constant flow mode with respect to filtration time and recovery. Average filtrate turbidity showed 0.0071 NTU in System I and 0.0054 NTU in System II, which implied that high turbidity removal was obtained in both MF and UF systems with no significant difference between MF and UF. From the fact that membrane flux depends largely on membrane type and operation mode, a guideline of optimum design and operation should be suggested for application of membrane systems to full scale water treatment.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.4
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• pp.535-543
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• 2006

The Ozone oxidation process was applied to increase the efficiency of reuse process when treating the secondary effluent by the membrane system. This paper focus on decreasing efficiency of membrane fouling, because of membrane fouling reduction by ozone and evaluation of application of the ozone oxidation. The feed water was secondary effluent from BNR process. The result shows that the ozone pretreatment can reduce membrane fouling effectively. Also, the improvement of treated water quality was obvious. The reduction of the membrane fouling led decrease of following pollutant and increase of lnner adsorptive ability of hydrophilic organic matter and decrease of molecular weight. MF membrane process alone can meet the domestic reuse water standards. And ozone pretreatment process also can increase the removal rates of turbidity, COD, nitrogen, and color.

• Membrane and Water Treatment
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• v.4 no.2
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• pp.143-155
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• 2013

Four membranes were used to separate Chlorella sp. from their culture medium in cross-flow microfiltration (MF) experiments: cellulose acetate (CA), cellulose nitrate (CN), polypropylene (PP) and polyvinylidenefluoride (PVDF). It was found that the hydrophilic CA and CN membranes with a pore size of 1.2 ${\mu}m$ exhibited the best performances among all the membranes in terms of permeation flux. The hydrophobicity of each membrane material was determined by measuring the angle between the water (liquid) and membrane (solid). Contact angle measurements showed that deionized (DI) water had almost adsorbed onto the surfaces of the CA and CN membranes, which gave $0.00^{\circ}$ contact angle values. The PP and PVDF membranes were more hydrophobic, giving contact angle values of $95.97^{\circ}$ and $126.63^{\circ}$, respectively. Although the pure water flux increased with increasing pore diameter (0.8 < 1.2 < 3.0 ${\mu}m$) in hydrophilic CA and CN membranes, the best performance in term of filtration rate for filtering a microalgae suspension was attained by membranes with a pore size of 1.2 ${\mu}m$. The fouled membrane pore sizes and pore blocking were inspected using a scanning electron microscope (SEM). MF with large pore diameters was more sensitive to fouling that contributed to intermediate blocking, where the size of the membrane pores is almost equivalent to that of cells.

• Membrane Journal
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• v.24 no.1
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• pp.31-38
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• 2014

Rainwater harvesting is a process by which rainwater collected from rooftop or other catchment is purified so that the water can be directly or indirectly used by human beings for beneficial uses. As rainwater is increasingly considered for high quality purposes, membranes have gained an important place in rainwater treatment. It has advantages such as the production of high quality water, small footprint, and affordable energy consumption. Nevertheless, membrane fouling is regarded as a serious problem similar to the cases of water treatment and wastewater reclamation. In this study, we applied microfiltration (MF) membranes for rainwater treatment. In addition, a low pressure ultraviolet (UV) process was also use as a pretreatment to control notonly. To quantify the effect of UV on organic matters, both total organic carbon (TOC) and UV absorbance (UVA) were measured. Moreover, the effect of UV pretreatment on membrane fouling was investigated. Experimental results indicated that the pretreatment of membranes using LPUV was effective to control fouling of MF membranes only when the rainwater was contaminated by algae. This was attributed the reduction and modification of organics after UV treatments. It is likely that the UV/MF process is a promising option for water treatment in decentralized water treatment such as micro water grid systems.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.06a
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• pp.39-50
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• 1995

The membrane processes that are commonly uscd in water and wastewater treatment are reverse osmosis (Ro), ultrafiltration (UF) and microfiltration (MF), which utilize pressure differentials. There is also nano-filtration (NF), or low-pressure reverse osmosis, which is positioned midway between conventional reverse osmosis and ultrafiltration. Reverse osmosis membranes reject dissolved ions, while ultrafiltration can be used to reject relatively larger molecules, such as protein, polysacchalides and so on. Microfiltration is capable of eliminating particles at submicron level. This paper summarizes the characteristics of MSAS process first, as it is the main membrane process applied to wastewater treatment. Two successful examples of the applications, the cases of individual building reuse system and nightsoil treatment, are then shown. The latest trend of new membrane applications, i.e., immersed-type MSAS is also introduced.

• Journal of the Korean Society of Marine Environment & Safety
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• v.4 no.1
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• pp.49-56
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• 1998

The Microfiltration and Ultrafiltration were used to treat effluent of secondary municipal wastewater treatment system(Sequencing Batch Reactor). The cross-flow hollow fiber, UF 500,000(NMWC) and MF 0.65$\mu$ membrane were selected as suitable membrane. Short term and long term fouling effect were measured as a factor of flux decrease and the fouling removal effect of mixing air bubble in the penetrant was studied. The removal of anionic sulfactants before and after formation of micelle with several kinds of oil were checked. The test results show that removal of TOC was 70~80%, TN 28% and TP 16%. The decrease of flux due to fouling were 85%(UF) and 90%(MF) after running of 100hrs. The removal of anionic sulfactants were 60~70% notwithstanding micelle or not.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.517-522
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• 2008

This study aims at an assessment of the effectiveness of taste & odor removal and transmembrane pressure changes in a pilot membrane plant(500m3/day) by adding PAC to MF process, and at providing a basis for applying it to the advanced water treatment process. The transmembrane pressure showed, in low turbidity of raw water, a tendency to decrease when PAC was injected at the Flux of 1, $1.5m^3/m^2{\cdot}d$, while it increased in high Flux($1.5m^3/m^2{\cdot}d$) in high turbidity of raw water. in addtion, it is shown that the fouling could be reduced more when PAC is injected together with appropriate amount of coagulant, than when PAC is solely injected. Taste & Odor-causing 2-MIB may not be detected in membrane filtered water, if the amount of PAC injection is increased in accordance with the increasing concentration of 2-MIB. Hence, PAC injection, as a pre-treatment process in MF membrane filtering, is supposed to be a suitable process for reducing fouling as well as for improvement effectiveness of taste & odor treatment.

• Environmental Engineering Research
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• v.20 no.3
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• pp.223-229
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• 2015

The application of coagulation for feed water pretreatment prior to microfiltration (MF) process has been widely adopted to alleviate fouling due to particles and organic matters in feed water. However, the efficiency of coagulation pretreatment for MF is sensitive to its operation conditions such as pH and coagulant dose. Moreover, the optimum coagulation condition for MF process is different from that for rapid sand filtration in conventional drinking water treatment. In this study, the use of response surface methodology (RSM) was attempted to determine coagulation conditions optimized for pretreatment of MF. The center-united experimental design was used to quantify the effects of coagulant dose and pH on the control of fouling control as well as the removal organic matters. A MF membrane (SDI Samsung, Korea) made of polyvinylidene fluoride (PVDF) was used for the filtration experiments. Poly aluminum chloride (PAC) was used as the coagulant and a series of jar tests were conducted under various conditions. The flux was $90L/m^2-h$ and the fouling rate were calculated in each condition. As a result of this study, an empirical model was derived to explore the optimized conditions for coagulant dose and pH for minimization of the fouling rate. This model also allowed the prediction of the efficiency of the coagulation efficiency. The experimental results were in good agreement with the predictions, suggesting that RSM has potential as a practical method for modeling the coagulation pretreatment for MF.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.58-73
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• 1995

Membrane filtration is a promising technology for efficient solid/liquid separation in water purification. In FY 1991, the Ministry of Health and Welfare, Japanese Government launched a comprehensive research project "MAC 21" for development of membrane technology and its application to public water supply. The project was conducted by the Water Purification Process Association (WPPA), under the supervision of the Institute of Public Health. By the research project from FY 1991 to FY 1993, we confirmed that microfiltration (MF)/ultrafiltration (UF) technology was applicable to water purification and MF/UF was a effective method for the removal of such contaminants as particulate matter and coliforms. The Guideline Committee organized under the Technical Committee prepared a the guidelines on application of membrane system to small-scale public water supplies, based on the results as written above. The guidelines has been published in Dec., 1994 by WPPA.4 by WPPA.

• Korean Membrane Journal
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• v.9 no.1
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• pp.12-17
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• 2007

We performed periodic water-back-flushing using permeate water to minimize membrane fouling to enhance permeate flux in tubular ceramic microfiltration system for water treatment of high turbid source. The filtration time (FT) = 2 min with periodic 6 sec water-back-flushing showed the highest value of dimensionless permeate flux ($J/J_o$), and the lowest value of resistance of membrane fouling ($R_f$), and we acquired the highest total permeate volume $(V_T)\;=\;6.805L$. Also in the result of BT effect at fixed FT = 10 min and BT (back-flushing time) = 20 sec showed the lowest value of $R_f$ and the highest value of $J/J_o$, and we could obtain the highest $V_T\;=\;6.660\;L$. Consequently, FT = 2 min and BT = 6 sec could be the optimal condition in water treatment of high turbid source above 10 NTU. However, FT = 10 min and BT = 20 sec was superior to reduce operating costs because of lower back-flushing frequency. Then the average quality of water treated by our tubular ceramic MF system was turbidity of 0.07 NTU, $COD_{Mn}$ of 1.86 mg/L and $NH_3-N$ of 0.007 mg/L.