• Membrane Journal
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• 제13권2호
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• pp.65-72
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• 2003

This study was focused on the investigation of filtration characteristics of membrane-coupled fermentor system for dissolved organics recovery from liquid organic sludge. On the filterability of MF over the range of $0.1{\sim}5 {\mu}m,$ the magnitude of total membrane resistance ($R_t$) is ranged as follows in the order; $0.1 {\mu}m>0.2{\mu}m>0.5 >1{\mu}m>2{\mu}m>5{\mu}m$. The cake layer resistance ($R_c$) occupied about 68~88% of total resistance with fermented sludge. Permeation flux decline was mainly attributed to the $R_c$, which was formed by a strong deposition from physico-chemical interactions of solids on membrane surface. Higher suspended solids (SS) concentration of suspension caused lower permeation flux. However, there was not a proportion relation beyond a certain SS concentration. The cross-flow velocity on the membrane surface was faster, which resulted in the higher permeation flux and also more efficient with low trans membrane pressure (TMP) in viewpoint of energy efficiency. The appropriate pH of suspension was over the range of 5.0~6.0 for dissolved organics recovery as well as the permeation flux. It is possible f3r bacteria to be separated perfectly with $0.1{\mu}m\; and \;0.2{\mu}m$ membrane pore size. Based on experimental results, most appropriate membrane pore size for the recovery is believed to around $1{\mu}m$.

• Proceedings of the Membrane Society of Korea Conference
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• 한국막학회 2003년도 The 4th Korea-Italy Workshop
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• pp.65-68
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• 2003

The paper discusses the use of stable emulsion, prepared by membrane emulsification technology, to improve the enantiocatalytic performance of immobilised lipase in multiphasic membrane reactors. The production of optical pure (S)-naproxen from racemic naproxen methyl ester has been used as model reaction system. The enzyme was immobilised in the sponge layer (shell side) of capillary polyamide membrane with 50 kDa cut-off, The O/W emulsion, containing the substrate in the organic dispersed phase, was fed to the enzyme membrane reactor from shell-to-lumen. The results evidenced that lipase maintained stable activity during all the operation time (more than 250 hours), showing an enantiomeric excess (96 $\pm$2%) comparable to the free enzyme (98 $\pm$ 1%) and much higher compared to similar lipase-loaded membrane reactors used in two-separate phase systems (90%). The study showed that immobilised enzymes can achieve high stability as well as high catalytic activity and enantioselectivity.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제12권8호
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• pp.3532-3540
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• 2011

In order to improve flux of PTMSP/PDMS dense membrane, PTMSP/PDMS-PEI composite membrane with PEI support was prepared by phase inversion process and dip coating. These membranes were evaluated in terms of the removal of volatile organic compounds such as PCE, TCE, chloroform, 1,1,1-trichloroethane from wastewater by pervaporation. The selectivity and flux of PTMSP/PDMS dense membranes was in the range of 216.2 to 2394.4 and 244.3 to 428.2g/m2h, respectively. And pervaporation property of PTMSP/PDMS-PEI composite membrane was in the range of 215.5 to 2404.2 and 390.4 to 728.6g/m2h, respectively. PTMSP/PDMS-PEI composite membrane has remarkably greater flux than dense membranes with similar selectivity. It was possible for polymeric membranes used in this study to remove PCE selectively which is dissolved small quantity in water among other separable solutes. PTMSP/PDMS-PEI composite membrane showed the best performances among the silicone polymeric membranes, and has better durability and mechanical strength than dense membranes. PTMSP/PDMS-PEI composite membrane should be a useful candidate for the removal of volatile organic compounds dissolved in wastewater.

• Journal of Korean Society of Environmental Engineers
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• 제28권6호
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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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• 제12권4호
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• pp.226-239
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• 2002

A process simulation model of pervaporation process has been developed as a design tool to analyse and optimize the dehyhration of organic solvents through a commercial scale of pervaporative plate-and-frame modules that contain a stack of membrane sheets. In the simulation model, the mass balance, the heat balance and the concentration balance are integrated in a finite elements-in-succession method to simulate the overall process. In the integration method, a feed channel between membrane sheets in the modules was taken as differential unit element volume to simplify calculation procedure and shorten computing time. Some of permeation parameters used in the simulation model, were quantified directly from the dehydration experiment of ethanol through $AzeoSep^{TM}$-2002 membrane which is a commercial pervaporation membrane. The simulation model was verified by comparing the simulated values with experimental data. Using the model, continuous and batch pervaporation processes were simulated, respectively, to acquire basic data for analysing and optimizing in the dehydration of ethanol through the membrane. Based on the simulation results, a comparison between the continuous and the batch pervaporation processes would be discussed.

• Journal of Korean Society of Water and Wastewater
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• 제25권3호
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• pp.285-291
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• 2011

Membrane fouling is an unavoidable phenomenon and major obstacle in the economic and efficient operation under sea water reverse osmosis (SWRO). When fouling occurs on the membrane surface, the permeate quantity and quality decrease, the trans-membrane pressure (TMP) and operation costs increase, and the membrane may be damaged. Therefore, chemical cleaning process is important to prevent permeate flow from decreasing in RO membrane filtration process. This study focused on proper chemical cleaning condition for Shuaibah RO plant in Saudi Arabia. Several chemical agents were used for chemical cleaning at different contact time and concentrations of chemicals. Also autopsy analysis was performed using LOI, FT-IR, FEEM, SEM and EDX for assessment of fouling. Specially, FEEM analysis method was thought as analyzing and evaluating tool available for selection of the first applied chemical cleaning dose to predict potential organic fouling. Also, cleaning time should be considered by the condition of RO membrane process since the cleaning time depends on the membrane fouling rate. If the fouling exceeds chemical cleaning guideline, to perfectly remove the fouling, certainly, the chemical cleaning is increased with membrane fouling rate influenced by raw water properties, pre-treatment condition and the point of the chemical cleaning operation time. Also choice of cleaning chemicals applied firstly is important.

• Proceedings of the Membrane Society of Korea Conference
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• 한국막학회 1995년도 춘계 총회 및 학술발표회
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• pp.34-35
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• 1995

The unique feature of pervaporation is the mass transfer from a liquid phase to a vapor phase through a non-porous polymeric membrane. When a liquid mixture is brought into contact with a membrane at one side, it is sorbed into the membrane. Due to a driving force applied across the membrane, the sotbed liquid molecules permeate through the membrane and evaporate at the downstream side of the membrane. In pervaporation the permeated species are usually removed from the downstream side under a relatively low vapor pressure, for example by evacuation with a vacuum pump. As far as this condition is fulfilled, the evaporation step can be considered to be much faster than sorption or diffusion. Hence evaporation does not contribute to permselectivity. Therefore the separation by pervaporation results from the differences in the preferential sorption of the individual components of a mixture into the membrane together with the diffusion rates through the membrane. This postulation implies that both sorption and diffusion phenomena have to be accounted for to understand the physico-chemical nature of the pervaporation separation process.

• Journal of Korean Society on Water Environment
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• 제26권1호
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• pp.81-88
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• 2010

This study was conducted to find the capability of comparison of overall oxygen transfer coefficient in the membrane coupled high performance reactor (MPHCR) in treating high organic loading wastewater. Effluent quality had been analyzed while the influent organic loading rate was changed from 2 to $7kg\;COD/m^3{\cdot}day$. The oxygen transfer coefficients had been investigated using two-phase nozzle for operating variables which were internal circulation flowrate (5~8 L/min), air flow rate (0.0125~0.2 L/min), liquid temperature ($10{\sim}20^{\circ}C$), and pure-oxygen flow rate (0.0125~0.2 L/min). The overall oxygen transfer coefficient was increased with flowrate of internal circulation and air and high temperature. Especially, internal circulation flow rate showed distinct effect on overall oxygen transfer coefficient due to an increase of gas holdup and air-liquid contract area by two-phase nozzle. In the high range of organic loading rate from 4 to $7kg\;COD/m^3{\cdot}day$, the removable efficiency of COD was 91%. Conventional activated sludge process usually treat organic loading from 0.32 to $0.64kg\;COD/m^3{\cdot}day$ however, the MPHCR can treat 10 to 20 times higher if it would be compared to the conventional activated sludge process. Foaming problem often happened and caused biomass wash out of the reactor, therefore, the foaming should be controlled for the enhanced operation.

• Membrane Journal
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• 제14권2호
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• pp.149-156
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• 2004

This work focused on the degradation of natural organic matter (NOM) present in lake water using a combined pkotocatalysisimicrofiltration (MF) process. The system performances were investigated in terms of organic removal efficiency and membrane permeability. The addition of iron oxide particles (IOP) into the photocatalytic membrane reactor improved initial NOM removal by sorption, but during photocatalysis the removal efficiency was reversed, probably due to the scattering of UV light by IOP. The modification of TiO$_2$ surfaces by IOP deposition was conducted to enhance the photocatalytic NOM removal efficiency. A minimal amount of Impregnation of IOP on TiO$_2$ surfaces was required to prevent the light scattering effect as well. The coating of MF membranes with IOP helped to improve the NOM removal efficiency while sorbing NOM by IOP. Regardless of tile operating conditions and particles addition examined, no significant fouling was occurring at a flux of 15 L/$m^2$-h during entire MF operation.

• Journal of the Korean Chemical Society
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• 제34권4호
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• pp.377-383
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• 1990

Three kinds of hydrogel membranes were prepared by the copolymerization of 2-hydroxyethylmethacrylate (HEMA) with acrylamide, N, N-dimethylamide and methylmethacrylate in the presence of solvent and crosslinker respectively. The equilibrium water content, relative permeability and partition coefficient of the membranes for alcohol solutes were measured. It has been found that the permeation of organic solute occurs through the water-filled regions in the hydrogel membrane, and that the gpermeability coefficient of organic solute depends on the molecular size. But the permeability of organic solute was controlled by the interaction of solute-membrane at the low water content. By the partition data, it has been shown that the partition of solute is only controlled by hydrophobic interaction between solute and membrane. The diffusion coefficient data were interpreted on the basis of water-solute interaction. It has been found that the diffusion of organic solute is determined by the free volume of water in the membrane, and that hardly depends on polarity-polarizability and hydrogen bonding ability between water and solute.