• Biotechnology and Bioprocess Engineering:BBE
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• v.4 no.1
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• pp.46-50
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• 1999

The application of pulsed electric field was investigated in the crossflow ultrafiltration of BSA (bovine serum albumn) to economize the application time of electric current as well as to avoid inherent problems of long-term application of electric field. During the application of various cyclic patterns of pulsed electric current, the averaged filtration flowrate and the degree of concentration were maintained higher than those obtained in the absence of electric current application. The temperature increase, pH change, and BSA loss by electrodeposition were all negligible during the operation. The averaged filtration flowrate increased as the ON/OFF duration ratio of electric current was higher and as the period of ON/OFF cycle was shorter. The re-establishment of concentration polarization was dependent to the duration of current OFF state and, therefore, a longer duration of OFF state was not favorable in maintaining higher filtration flow rate. Although the averaged filtration flowrate was enhanced as the magnitude of electric current increased, the flowrate enhancement became smaller as the magnitude of current value above which the degree of electrokinetic depolarization is no further improved.

• Membrane Journal
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• v.17 no.3
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• pp.191-196
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• 2007

In the study, excess of lime-soda ash(L-S) was added to groundwater for chemical precipitation of hardness ions. After formation of the coagulated flocs, sedimentation step was replaced with crossflow ultrafiltration(UF) process using tubular ceramic membrane. As results, our treated water was below total hardness(TH) 10 mg/L as $CaCO_3$ from groundwater using washing water in a soymilk factory. Then, we investigated the change of permeat flux(J) and dimensionless permeate flux($J/J_0$) during experiments for variations of TMP(Trans-membrane pressure) or flow rate, to see effect of TMP or flow rate on membrane fouling by the coagulated Inorganic flocs. In the result, membrane fouling and rejection rate of total hardness were not affected by TMP and flow rate variations in the range of our experiments.

• KSBB Journal
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• v.6 no.2
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• pp.135-141
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• 1991

This study thus looks into two treatment processess : i) Anaerobic digester coupled with hollow fibre membrane unit. Treatment of starch waste with anaerobic digester-membrane system was studied. $0.17\m^2$ area of hollow fibre membrane unit of known pore size was immersed into laboratory-scale anaerobic digestion system. The pore size of membrane was varied from 0.03 to $\0.15mu$m. The hydraulic retention time of anaerobic digester was varied from 1.5 to 10 days. The effect of hydraulic retention time on treatment efficiency was significant while effect of membrane size was not significant. The gas production was about 0.74㎥/kg COD treated. The COD removal efficient was about 80-95% depending on the hydraulic retention time. ii ) Crossflow ultrafiltration as post treatment to anaerobic filter. The effluent from anaerobic filter, which had a total COD in the range of 4,500-5,200 mg/L was treated by crossflow ultrafiltration units. The study conducted with different membrane pore size indicated that membrace with 1,000,000 molecular weight cut-off size gave a higher COD removal efficiency in the range of 83-87% while giving a study flux of $120-130 L/\m^2$.h. A study was conducted to see the long term clogging effect of membrane also.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.403-409
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• 2000

The permeation characteristics and reclamation efficiency of waste lubricating oil were studied as a function of the types of ceramic composite membranes and the membrane separation process variables. The oil permeability of the TiO2 composite membrane(pore size 0.015 $\mu\textrm{m}$) was directly proportional to the crossflow velocity(0.22∼0.9 m/s) and temperature(150$^{\circ}C$∼200$^{\circ}C$). In the batch concentration process, as the concentration factor increased, both the permeability and the ash content of the permeate decreased. The average ash contents of the total permeate through the A6 alumina membrane(average pore size 0.8$\mu\textrm{m}$), Z1/A6 and Z1/A4(pore size 0.23$\mu\textrm{m}$)/A7(pore size 6$\mu\textrm{m}$) zirconia composite membrances(average pore size 0.07$\mu\textrm{m}$) were about 0.063 wt%, 0.045wt% and 0.08wt% in the region of 1∼2 concentration factor, respectively. The ash content of the mixed permeate through the A6 alumina and zirconia composite membrane was about 0.06 wt% and it can be also reduced to 0.06 wt% in the Z1/A6 membrane and below 0.003 wt% in the TiO2/Z1/A6 membrane. It was concluded that the treated oil obtained from the multi-step membrane separation process could be used as reclaimed lubricating oil as well as reclained fuel oil.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.11-14
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• 1998

1. Introduction : Research progresses in Chemistry and Chemical Engineering have been made during the last decades with important contributions to the industrial development and to the quality of our life. An interesting case is related to the membrane science and technology continuous impact to innovative processes and products, particularly appropriate for a sustainable industrial growth. Membrane operations have been familiar for many years to biologists and chemists working in their laboratorier or studying biological phenomena. Only recently engineers started to operate in' this area. The preparation of asymmetric CA membranes at University of California, Los Angeles in the early 60s is generally recognized as a crucial moment for membranology (1). Loeb and Sourirajan with their discovery of how to increase significantly the permeability of polymeric membranes without significant changes in their selectivity, made realistic the possibility of their use in large scale operations for desalting brackish and sea water by reverse osmosis and for various other molecular separations in different industrial areas. Reverse osmosis is today a well recognized basic unit operations, togheter with ultrafiltration, crossflow microfiltration,. nanofiltration, all pressure driven membrane processes. Already in 1992 more than 4 milIions m$^3$/day were the total capacity of RO desalination plants and in 1995 more than 180.000 m$^2$ of ultrafiltration membranes were installed for the treatment of wheys and milk (2) (3).

• Membrane Journal
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• v.8 no.2
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• pp.94-101
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• 1998

The oil separation is effectively performed from the oil containing alkaline cleaner solution by using a backflushed ultrafiltration system, where hollow fibers commercially made by polyacrylonitrile copolymer are bundled. Backflushing to reduce membrane fouling during crossflow ultrafiltration is investigated. Experimental observations allow us to understand the behavior of permeate flux according to the relative operating conditions, and determine the optimum condition of normal operation and backflushing. The maximum improvement of net permeate flux owing to backflushing was found to be about 23 % with the condition of 10 min/40 sec for the cycle of normal/backflushing operations. Note that, however, the maintenance of stable permeate flux is lost as the duration of normal operation is increased. The permeate flux depends on both the backflushing pressure and the feed flow rate. It is obvious that there is a critical velocity of feed flow, in which permeate flux is practically independent of backflushing pressure. Above this critical value, the permeate flux is proportional to an appropriate power of the backflushing pressure, $\Delta P_{back}^n$, where exponent n is enhanced with increasing feed velocity.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.745-748
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• 2000

Anaerobic digester coupled with hollow fiber membrane unit. Treatment of starch waste with anaerobic digester-membrane system was studied. $0.17\;m^2$ area of hollow fiber membrane unit of known pore size was immersed into laboratory-scale anaerobic digestion system. The gas production was about $0.74\;m^3/kg$ COD treated. The COD removal efficient was about 80-95% depending on the hydraulic retention time. Crossflow ultrafiltration as Post treatment to anaerobic filter. The study conducted with different membrane pore size indicated that membrane with 1,000,000 molecular weight cut-off size gave a higher COD removal efficiency in the range of 83-87% while giving a study flux of $120-130\;L/m^2\;{\cdot}\;h$. A study was conducted to see the long term clogging effect of membrane also.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.06a
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• pp.113-133
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• 1998

In activated sludge process, sludge settling condition is affected by organic loading rate or operation condition, and if settling condition is getting worse, it is common that overall process fails due to wash-out of biomass causing low concentration in the aeration tank. Also activated sludge process has such several problems as requiring large area, consuming a lot of power and producing large volume of sludge. Increased public concern over health and the environment combined with a strong desire to reduce capital, operating and maintenance costs, have created a need for innovative technologies for building new high quality effluents which vail meet 21st century crkeria. MBR(Membrane Bioreactor) process consists of a biological reactor and ultrafiltration(UF) membrane system that replaces the conventional clarifier of an activated sludge process. The main operating advantages of this system are that the quality of the effluent is independent of the settleability of the mixed liquor and that the effluent is free of suspended solids in any operating condition. It is possible to eliminate clarifier and to reduce the volume of aeration tank because it can afford to accumulate high biomass concentration in the bioreactor(20, 000~30, 000mg/L), which would not be possible in a conventional activated sludge process. Therefore, this process reduces overall treatment plant area. In addition to those advantages, Longer SRT condition enables higher sludge digestion in MBR process so the sludge volume produced is 50 to 70% lower than that of conventional activated sludge process There are two kinds of MBR process according to the allocations of membrane. One is cross flow type MBR of which module is located outside of the bioreactor and mixed liquor is driven into the membrane module. The other is submerged type MBR process of which module is submerged in the bioreactor and mixed liquor is generally sucked from the lumen side. addition to that the cake layer is often removed by the uplifting flow of bubbling air. A submerged MBR process is superior to a crossflow MBR in regard to the power consumption because suction pressure of a submerged MBR is generally lower than that of a crossflow MBR which has recirculation pump. A submerged MBR, therefore, has the potential to be applied to small wastewater treatment plants that need low cost treatment systems.

• Journal of Microbiology and Biotechnology
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• v.19 no.1
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• pp.108-112
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• 2009

A simplified method for the purification of cholera toxin was developed. The 569B strain of Vibrio cholerae, a recognized hyper-producer of cholera toxin, was propagated in a bioreactor under conditions that promote the production of the toxin. The toxin was separated from the bacterial cells using 0.2-${\mu}m$ crossflow microfiltration, the clarified toxin was passed through the membrane into the permeate, and the bacterial cells were retained in the retentate. The 0.2-${\mu}m$ permeate was then concentrated 3-fold and diafiltered against 10 mM phosphate buffer, pH 7.6, using 30-kDa crossflow ultrafiltration. The concentrated toxin was loaded onto a cation exchange column, the toxin was bound to the column, and most of the impurities were passed unimpeded through the column. The toxin was eluted with a salt gradient of phosphate buffer, pH 7.0, containing 1.0 M NaCl. The peak containing the toxin was assayed for cholera toxin and protein and the purity was determined to be 92%. The toxin peak had a low endotoxin level of $3.1\;EU/{\mu}g$ of toxin. The purified toxin was used to prepare antiserum against whole toxin, which was used in a $G_{M1}$ ganglioside-binding ELISA to determine residual levels of toxin in an oral inactivated whole-cell cholera vaccine. The $G_{M1}$ ganglioside-binding ELISA was shown to be very sensitive and capable of detecting as little as 1 ng/ml of cholera toxin.

• Membrane Journal
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• v.9 no.4
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• pp.193-201
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• 1999

The object of study were the development of membrane process and the optimization of operation condition for membrane system, which was used the pre-treatment system of tap water treatment in steady of conventional process such as coagulation, sedimentation. The higher steady flux is very important factor, by a suitable pre-treatment and optimization of operating condition such as fouling control, crossflow and backwashing method, in membrane system. So, we were observed the effect of flux decline for membrane used by 4 type ultrafiltration(UF) membrane pre-treatment process, and optimized the operation condition of filtration system under various MWCO(Molecular weight cut-off), operation pressure, linear velocity and temperature to maintain higher flux. From these experiment, we were identified that UF process showed a slower flux decline rate and a higher flux recovery than microfiltration(MF) membrane. The water quality of UF permeate was better than that of MF, and was not effected pre-treatment process. In the operation condition, the rate of flux decline was diminished by a higher linear velocity and operation temperature, lower pressure.