• Applied Chemistry for Engineering
• /
• v.3 no.4
• /
• pp.730-738
• /
• 1992

Filtration characteristics according to membrane materials were studied In the ultrafiltration of anaerobic digestion broth as a post treatment method. A series of resistances for different membranes were quantitatively assessed on the basis of the resistance-in-series model. Flux behavior observed with the digestion broth was irrelevant to initial water permeabilities of each membrane. The fluoro polymer membrane showed the most significant improvement of flux with increase of cross-flow velocity, which suggests that the cake layer formed on this membrane is more weakly attached to the membrane surface than those on the other membranes. Flux reduction during longtime running was attrib-used to the polarization layer resistance ($R_p$) as well as the fouling layer resistance($R_f$). Continuous increase of $R_p$ may reflect the variation in the characteristics of cake layers, which could result from size, shape, and structure changes due to lysis and growth of biomass. Hydrophilic cellulosic membrane had a much lower fouling tendency than hydrophobic polysulfone membrane. The depressurization method induced a small increase in flux of $5-10L/m^2/h$. During washing and cleaning, filtrability of each membrane was rapidly recovered within 15 minutes until a stationary value was reached.

• Membrane Journal
• /
• v.29 no.6
• /
• pp.329-338
• /
• 2019

The constant-pressure and constant-flux membrane filtration experiments of alumina colloidal solution are performed to investigate defouling effect of the natural convection instability flow (NCIF) induced in membrane module. The permeate flux at constant-pressure and the transmembrane pressure (TMP) at constant-flux experiments are measured by changes the inclined angle (0, 90 and 180°) of membrane module to the gravity, and flux results are analyzed by using the blocking filtration model. NCIF are more induced as the inclined angles increased from 0° to 180°, and the maximum induced NCIF at 180° angle enhances flux to 2.8 times and reduces TMP to 85% after two-hour operation. As a result of analyzing flux data by applying the blocking filtration model, it is more reasonable to analyze them by using the intermediate blocking model within 15-minute operation time and then thereafter times by using the cake filtration model. The induced NCIF at 180° angle reduces the intermediate blocking fouling at 52% in the early operation time of 15-minute and thereafter the cake layer fouling at 93%. The main membrane fouling control mechanism of NCIF induced in membrane module is evaluated as suppressing the formation of the cake layer of particulate colloidal materials on membrane surface.

• Resources Recycling
• /
• v.18 no.3
• /
• pp.55-61
• /
• 2009

Dewatering process to remove water from pigment sludge was important in the diverse aspects of the improvement of product quality, curtailment of the drying cost and the transportation. It was difficult to dewater pigment particles with the mechanical forces because the size was fine under $5{\mu}m$. Thermal filter press dewatering equipment composed of squeezing plate and a fixed heating plate was developed to improve the dewaterability of pigment the sludge as supplying the heat from the fixed heating plate to the cake. Several tests that estimate the dewaterability for pigment sludge as with or without squeezing process and the difference of dewatering time was conducted with this equipment. Dewaterability of thermal dewatering under squeezing process was increased about 20% compared with non squeezing process. Under squeezing process, thermal dewatering tests changing dewatering time with 70 and 80 minute were conducted respectively. The water content of cake was more reduced at dewatering time of 80 minute compared with 70 minute, and dewatering velocity was also decreased, which caused the productivity of thermal filter press to drop. It was observed that clogging of filter cloth didn't almost occur because the liquid was discharged from cake layer easily. In this research, it was resulted that the squeezing process and long dewatering time were effective to improve the dewaterability of pigment sludge. So, this thermal filter press equipment was useful for dewatering the fine particle sludge like pigment.

• Membrane Journal
• /
• v.29 no.1
• /
• pp.18-29
• /
• 2019

The dead-end ultrafiltration (UF) of BSA protein solution was performed to investigate the defouling effects of natural convection instability flow (NCIF) induced in membrane module. The permeate fluxes were measured according to the inclined angles ($0{\sim}180^{\circ}$) of membrane module with respect to gravity, and analyzed using the blocking filtration model. NCIF are more induced as the inclined angles increased from $0^{\circ}$ to $180^{\circ}$, and the induced NCIF enhances flux. Comparing the fluxes at $0^{\circ}$ inclined angle (no NCIF induction) and $180^{\circ}$ (maximum NCIF induction), the flux enhancements by NCIF induction are increased about 5 times in the short-term UF operation (2 hours) and about 17 times in the long-term operation (20 hours). As applying the blocking filtration model, it is more suitable to analyze the flux results by using the intermediate blocking model in the early times of UF operation within 15 minutes and then thereafter times by using the cake filtration model. NCIF induced at $180^{\circ}$ inclined angle reduces the intermediate blocking fouling at about 67% in the early times operation and thereafter the cake layer fouling at about 99.9%. The main defouling mechanism of NCIF induced in the membrane module is suppress the formation of protein cake layer.

• The KSFM Journal of Fluid Machinery
• /
• v.14 no.6
• /
• pp.35-44
• /
• 2011

Membrane filtration has become firmly established as a primary process for ensuring the purity, safety and efficiency of treatment of water or effluents. Several researches have been performed to develop and design membrane systems in order to increase the accuracy and performance of the processes. In this study, a lattice Boltzmann method for the cake layer has been developed using particle dynamics based on an immersed boundary method and the cake layer formation process on membrane has been numerically simulated. Case studies including various particle sizes were also performed for a microfiltration process. The growth rate of the cake layer thickness and the permeation flow rate along the membranes were predicted. The results of this study agreed well with that of previous experiments. Effects of various particle diameters on the membrane performance were studied. The cake layer of a large particle tended to be growing fast and the permeation flow going down rapidly at the beginning. The layer thickness of a small particle increased constantly and the flow rate was smaller than that of the large particle at the end of simulation time.

• Proceedings of the Membrane Society of Korea Conference
• /
• 2000.04a
• /
• pp.82-83
• /
• 2000

• Proceedings of the Membrane Society of Korea Conference
• /
• 1995.04a
• /
• pp.62-63
• /
• 1995

혐기성 소화는 고농도의 유기폐수를 최종적으로 메탄으로 전환하여 에너지원을 회수할 수 있는 효율적인 생물학적 폐수처리 공정 중의 하나이다. 그런데 이러한 혐기성 소화 공정에서 가장 큰 장애요인으로 작용하고 있는 요소 중의 하나가 매생물의 침강성 저하로 인한 고액분리의 문제이다. 이로인해 현재 고전적인 중력침강법, 부상법 대신에 분리막을 이용한 막결합형 혐기성 소화 공정이 대두되고 있으며 완전한 고액분리, 반응조내의 고농도 미생물 보유, 양질의 최종 유출수 획득 등 많은 장점들이 제시되고 있다. 그러나 이러한 장점에도 불구하고 시간에 따른 막오염 현상, 분리막 표면에서의 케이크층 형성 등으로 인한 막투과 유속 (flux)의 감소는 분리막의 응용에 있어 경제성을 저하시키는 주요한 부정적 요인으로 지적되고 있다. 그리고 막분리 성능은 분리막의 특성, 유체역학적 조건, 그리고 혐기성 소화 상태 등에 의해 영향을 받을 수 있다. 본 연구에서는 막결합형 혐기성 소화 공정의 십자흐름 (crossflow) 막분리 공정에서 유체역학적 조건 및 혐기성 소화조의 상태와 관련된 요인들이 어떻게 막투과도 및 배제율 등에 영향을 미치는 지 살펴보고자 한다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.1C
• /
• pp.17-25
• /
• 2010

Electrophoresis may offer a new technique to repair in service leaking geomembrane liner of municipal solid waste (MSW) impoundment. The method involves introducing a suspended clay particles, which are charged negatively, into the leakage in geomembrane liners by electrokinetic phenomena and formation of clay cake around leakage for prevention of leachate outflows. Therefore, the 3-dimensional leakage simulation experiments are conducted to evaluate the field applicability of sealing leaks of waste impoundment. In addition, the adequateness of optimum influence factors deduced from 1-dimensional experiments is evaluated. After the test, the total size (width, length) of clay cake formation around leak is increased with enlargement of leakage diameter and distance decrease detween anode and cathode.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.10
• /
• pp.1009-1015
• /
• 2006

The elcetrodewatering filter press(EDFP) which had anode and cathod plates to be set between filter plates was built for reducing the waterworks sludge and improving performance of dewatering equipment. Several tests to compare the dewaterability with conventional mechanical filter press dewatering(MDEP) and EDFP was conducted through this equipment. As test results, filtration amount discharged from EDFP measured 43.2 kg which increased against MDFP, and cake weight measured 4 kg which was two times against MDFP. The water content of dewatered cake from EDFP was 55wt% and dewatering velocity was 2.3 $kg/m^2{\cdot}cycle$. This water content decrease 20% and dewatering velocity increased 30% with compare to the MDFP. That is to say, EDFP constructed from electrodewatering mechanism increase filtrate discharging amount, which make dewatering velocity increase and produce the low water content dewatered cake against MDFP. Energy consumption of EDFP is analysed to 400 kwh/DS ton. The results to analysis the economical aspect considering the power consumption and the handling cost decline as sludge volume reduction due to producing the low water content cake showed that expenses to handle sludge of 1 ton by dry solid base cut down on 20,000 won. If considering several test aspects, it was analysed that EDFP was excellent in the side of performance as well as economical suitability.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.12
• /
• pp.47-55
• /
• 2009

As a conventional line-fitting method, the Bouwer and Rice method has been popularly adopted to estimate the hydraulic conductivity of an aquifer through a slug test. Because a vertical cutoff wall is usually very compressible and features a small wall thickness, the Bouwer and Rice method should be carefully applied to analyzing slug test results to estimate the hydraulic conductivity of vertical cutoff walls. In addition, a relatively impermeable layer, called a filter cake, formed at the interface between the cutoff wall and the natural soil formation makes it difficult to use the Bouwer and Rice method directly. In order to overcome such limitations, the original Bouwer and Rice method has been modified by incorporating the concept of the flow net method. In this modification, the geometry condition of cutoff walls including the filter cake is effectively considered in evaluating the hydraulic conductivity of a vertical cutoff wall.