• Membrane and Water Treatment
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• v.6 no.1
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• pp.53-75
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• 2015

This paper provides an overview of the role of membranes in bioelectrochemical systems (BESs). Bioelectrochemical systems harvest clean energy from waste organic sources by employing indigenous exoelectrogenic bacteria. This energy is extracted in the form of bioelectricity or valuable biofuels such as ethanol, methane, hydrogen, and hydrogen peroxide. Various types of membranes were applied in these systems, the most common membrane being the cation exchange membrane. In this paper, we discuss three major bioelectrochemical technology research areas namely microbial fuel cells (MFCs), microbial electrolysis cells (MECs) and microbial desalination cells (MDCs). The operation principles of these BESs, role of membranes in these systems and various factors that affect their performance and economics are discussed in detail. Among the three technologies, the MFCs may be functional with or without membranes as separators while the MECs and MDCs require membrane separators. The preliminary economic analysis shows that the capital and operational costs for BESs will significantly decrease in the future due mainly to differences in membrane costs. Currently, MECs appear to be cost-competitive and energy-yielding technology followed by MFCs. Future research endeavors should focus on maximizing the process benefits while simultaneously minimizing the membrane costs related to fouling, maintenance and replacement.

• Membrane and Water Treatment
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• v.5 no.3
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• pp.207-219
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• 2014

Fouling is one of the critical factors associated with the application of membrane technology in treating palm oil mill effluent (POME), due to the presence of high concentration of solid organic matter, oil, and grease. In order to overcome this, chemical cleaning is needed to enhance the effectiveness of membranes for filtration. The potential use of sodium hydroxide (NaOH), sodium chloride (NaCl), hydrochloric acid (HCl), ethylenediaminetetraacetic acid (EDTA), and ultrapure water (UPW) as cleaning agents have been investigated in this study. It was found that sodium hydroxide is the most powerful cleaning agent, the optimum conditions that apply are as follows: 3% for the concentration of NaOH, $45^{\circ}C$ for temperature solution, 5 bar operating pressure, and solution pH 11.64. Overall, flux recovery reached 99.5%. SEM images demonstrated that the membrane surface after cleaning demonstrated similar performance to fresh membranes. This is indicative of the fact that NaOH solution is capable of removing almost all of the foulants from PES membranes.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.1
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• pp.15-24
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• 2010

Coagulation can be used for pretreatment of NF membrane filtration. Foulants such as organic matter and particulate can be removed effectively with the process while high flux recovery is maintained. Recently various types of polyaluminium coagulants including polyaluminium chloride(PAC) are commercially available for water treatment. This study examines effects of polymeric Al and hydrolysis products of PAC on nanofiltration membrane performance. Dominant hydrolysis products were polymeric Al, $Al(OH)_3$, and ${Al(OH)_4}^{-1}$ at acidic, neutral, and alkaline pH conditions, respectively. Under acidic pH condition, flux decline was increased with increasing PAC concentrations, possibly due to polymeric Al adsorption on membrane pore and/or surfaces. For neutral and alkaline pH conditions, little flux decline was observed with increasing PAC concentrations except the highest ${Al(OH)_4}^{-1}$ concentration, with which rapid flux decline was shown. Removal of ionic matters was also varied with pH conditions in this study. Especially, conductivity removal was substantially low and $Ca^{2+}$ concentration in the permeate was quite high at neutral pH condition.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.613-619
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• 2006

The objectives of this research are to evaluate the effect of membrane materials, particulate matter and membrane pore size on permeate flux. It was shown that the removal efficiency of high MW organic matter more than 10 kDa was lower than that of low MW organic matter for $MIEX^{(R)}$ process. For the change of permeate flux by the pretreatment process, $MIEX^{(R)}+UF$ process showed high removal efficiency of organic matter as compared with coagulation+UF processes, but high reduction rate of permeate flux was presented through the reduction of removal efficiency of high MW organic matter. The pretreatment of the raw water significantly reduced the fouling of the hydrophilic membrane, but did not decrease the flux reduction of the hydrophobic membrane. Flux decline on MF process increased due to the pore clogging, while the permeate flux decline of UF process decreased due to the formation of cake layer. It was shown that particle matter was not effect on MIEX+membrane process. But, for coagulation+membrane process, particle matter was important factor on permeate flux.

• Membrane Journal
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• v.19 no.1
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• pp.7-18
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• 2009

In this study, we used the hybrid module that was composed of granular activated carbons (GAC) packing between module inside and outside of tubular ceramic microfiltration membrane for advanced drinking water treatment. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, modified solution was prepared with humic acid and kaolin. We were investigated effect of water-back-flushing time (BT) and water-back-flushing period (FT) to minimize membrane fouling and to enhance permeate flux (J) in the hybrid process, and tried to find the optimal operating conditions. As a result, resistance of membrane fouling ($R_f$) was slightly decreased according to increasing BT. Also, the shorter FT was the more effective to reduce $R_f$ and to enhance J because of frequent water-back-flushing. However, the optimal BT and FT conditions were 10 sec and 8 min respectively when operating costs were considered. Then, the optimal conditions derived from our experiments of modified solution were applied to lake water treatment. As a result, average treatment efficiencies of turbidity, $UV_{254}$ absorbance, and $COD_{Mn}$ were very high as 99.11%, 91.40% and 89.34%, respectively, but that of TDS was low as 30.05%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.224-231
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• 2019

Recently, the pollution of groundwater has become serious. In particular, the contamination of groundwater near livestock farms is becoming increasingly severe and it is difficult to drink with drinking water. In this paper, a groundwater purifier apparatus that can be installed in a community well was designed. The designed groundwater purifier apparatus enables a RO membrane filter and UV sterilization to remove pollutants, such as heavy metals, bacteria, and organic compounds. In addition, electrical conductivity, pressure, and flow sensors were added for remote monitoring. Remote monitoring of the system can determine the level of fouling and contamination of RO membrane filters through pressure and flow sensor data, and can record changes in the contamination and condition of groundwater through the electrical conductivity of the feed water. The designed groundwater purifier apparatus was installed at a farmhouse and remote monitoring. The result after 15 days of operating a groundwater purifier apparatus and analyzing the monitoring data revealed an average permeate water flow rate of 2.67L/min and an average water pressure of 7.09kgf/㎠, indicating that the RO Membrane filtered without fouling and clogging. The average electrical conductivity was 796.6 S/㎠ of the feed water and 55.6 S/㎠ of permeate water, which is similar to that of general tap water. Through this, it was confirmed that no pollutant occurred in the surroundings. Therefore, the designed groundwater purifier apparatus can confirm the replacement time of the RO membrane filter in advance through remote monitoring, and check the pollution state of the groundwater.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1391-1398
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• 2010

Reuse feasibility of MBR effluent of S Electronic Company's organic wastewater as a LCD process water was investigated by a $32m^3/d$ pilot-scale RO membrane process. The effects of operating pressure and permeate flux at constant 85% recovery of RO membrane process using MBR effluent were analyzed for transmembrane pressure and period for CIP by membrane fouling as well as rejection of TOC and conductivity. MBR effluent requires additional treatment to meet the LCD process water quality criteria of TOC<1 mg/L and conductivity<$100{\mu}S/cm$ which is stringent as compared with those of conventional reuse water quality criteria. The RO process operated at 85% recovery with stepwise increasing of permeate fluxes from 12.5 LMH to 22.0 LMH was able to meet LCD process water quality criteria. However, the transmembrane pressure increased and the period of CIP decreased as increasing permeability fluxes due to fouling of RO membrane. The optimum operational conditions of RO membrane process were permeate fluxes of 16.5~18.5 LMH with operating pressure of $6.7{\sim}12.4kgf/cm^2$ and CIP period of 20~25 days at constant 85% recovery.

• Membrane Journal
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• v.25 no.4
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• pp.301-309
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• 2015

Importance of pretreatment for seawater desalination is growing rapidly. Proper selection of pretreatment is critical for the successful, long-term operation in the seawater desalination plant such as seawater reverse osmosis (SWRO). The purposes of seawater pretreatment are to remove particulate, colloidal materials, organic, inorganic materials, microorganisms and their by-products present in the seawater, and thus to improve the performance of seawater desalination systems. However, pretreatment is most challenging for designing and operating seawater desalination plants because of fluctuations of water qualities, site specifications and wide ranges of target materials present in the seawater to be treated. In addition, it is also becoming evident increasingly that microscopic algae are a major cause of operational problems, for example, membrane fouling which is long-standing problem in SWRO process. Pretreatment strategies prior to the operation of seawater desalination technologies should be even more complicated by algae blooms and release of their harmful by-products in marine environment. This paper reviews the roles of various pretreatment methods in seawater desalination process. Benefits and drawbacks are described, which should be taken into account in future studies on selecting pretreatment for seawater desalination process.

• Membrane Journal
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• v.24 no.3
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• pp.201-212
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• 2014

This study was performed to discover the optimum operation conditions for the advanced water treatment using the ceramic membrane, introduced the first in the nation at the Y water treatment plant (WTP). The result of investigation to find the optimum operation conditions which can continue preserving the filtration performance as well as satisfying both the economics and the water quality is as follows. In the ordinary water quality condition of the Y WTP, the optimum filtration time(the backwash period), which can minimize the production of backwash waste and preserve the membrane performance was examined to be 4.0 hours on basis of institution capacity ($16,000m^3/day$). Examining the recovery rate of TMP from the chemical cleaning (CIP) discovered that the inorganic contaminants, which cause membrane fouling, such as iron, manganese, aluminum, were removed through the acidic cleaning using citric acid, whereas the membrane recovery rate was found to be low. But, on the other hand, the TMP was recovered to the initial value from the alkali cleaning using the NaOCl. Therefore, the main contaminant causing the fouling was determined to be hydrophilic organic compound( biopolymer). The membrane recovery rate is highly influenced by the temperature of the cleaning chemical. That is, the rate increased with increasing temperature.

• Membrane Journal
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• v.18 no.3
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• pp.191-197
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• 2008

In this study, we used hybrid module that was composed of packing granular activated carbon (GAC) between module inside and outside of ceramic microfiltration membrane for advanced drinking water treatment. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, synthetic water was prepared with humic acid and kaolin. Packing fraction of GAC was changed from 0 to 24.05% to see effect of packing fraction. As a result, changing curves of resistance of membrane fouling ($R_f$) and permeate flux (J) during 3 h operation were almost overlapped independent of packing fraction of GAC. Treatment efficiencies of turbidity were very high above 99.46% at all packing fractions of GAC. And treatment efficiency of NOM, which was measured by $UV_{254}$ absorbance, was the highest value of 99.43% at packing fraction of 24.05%. Then, we operated the hybrid process during 13 h at packing fraction of 24.05%. As a result, J was rapidly dropped according to increase of membrane fouling within initial 1 h of operation, and almost constant after 3 h. And treatment efficiencies of turbidity and NOM were stable and high values of 99.52% and 96.63%, respectively.