• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.639-645
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• 2008

The objectives of this research are to (1) observe changes in particle size distribution due to formation of microflocs during coagulation process (2) identify the membrane fouling potential on cross flow system (3) investigate the mechanism of membrane fouling. The rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. The pretreatment of the raw water significantly reduced the fouling of the UF membrane. Also, the rate of flux decline for the hydrophobic membrane was considerably greater than for the hydrophilic membrane. Applying coagulation process before membrane filtration showed not only reducing membrane fouling, but also improving the removal of dissolved organic materials that might otherwise not be removed by the membrane. That is, during the mixing period, substantial changes in particle size distribution occurred under rapid and slow mixing condition due to the simultaneous formation of microflocs and NOM precipitates. Therefore, combined pretreatment using coagulation not only improved dissolved organics removal efficiency but also flux recovery efficiency.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.467-468
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• 1999

여과집진장치는 기존의 집진장치 중에서 집진효율이 가장 우수하나, 여과집진에서 필연적으로 발생하는 높은 압력손실과 탈진에 따른 여과포의 마모, 그리고 고온조건에서의 성능저하 등은 여과집진장치의 광범위한 적용을 저해하는 요인으로 작용해왔다. 탈진에 따른 여과포의 손상을 막고, 먼지입자의 표면여과를 극대화시키는 방법으로 기존의 여과포에 박막을 입히는 방법이 많은 연구자들에 의해 개발되어 왔다.(중략)

• Membrane and Water Treatment
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• v.7 no.4
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• pp.313-325
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• 2016

South Africa recognises piped water as the main source of safe drinking water supply. Remote areas do not have access to this resource and they rely solely on surface water for survival, which exposes them to waterborne diseases. Interim point of use solutions are not practiced due to their laboriousness and alteration of the taste. Bio-ultra low pressure driven membrane system has been noted to be able to produce stable fluxes after one week of operation; however, there is limited literature on South African waters. This study was conducted on three rivers namely; Umgeni, Umbilo and Tugela. Three laboratory systems were setup to evaluate the performance of the technology in terms of producing stable fluxes and water that is compliant with the WHO 2008 drinking water guideline with regards to turbidity, total coliforms and E.coli. The obtained flux rate trends were similar to those noted in literature where they are referred to as stable fluxes. However, when further comparing the obtained fluxes to the normal dead-end filtration curve, it was noted that both the Umbilo and Tugela Rivers responded similarly to a normal dead-end filtration curve. The Umgeni River was noted to produce flux rates which were higher than those obtainable under normal dead-end. It can be concluded that there was no stabilisation of flux noted. However, feed water with low E.coli and turbidity concentrations enhances the flux rates. The technology was noted to produce water of less than 1 NTU and 100% removal efficiency for E.coli and total coliforms.

• Clean Technology
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• v.5 no.2
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• pp.25-35
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• 1999

Behavior of permeate flux decline was examined through the hollow fiber membrane in ultrafiltration system for Si colloidal solution. Flux decline with time was due to the growth of Si cake deposited on the membrane surface and the pore blocking by Si particles for the hollow fiber membrane. At the pseudo steady state of operation, the permeate flux of dead-end flow was 60 % to that of the cross flow. The ratio of permeate flux to the pure water flux, $J/J_w$, decreased with increasing the trans-membrane pressure, from 64.2 % for $0.5kg_f/cm^2$ to 45.7 % for $2.0kg_f/cm^2$. When the feed flow rate was 3 L/min, the pore blocking model was dominant at the initial period of filtration and was followed by the cake filtration model. And with increasing the feed flow rate from 1 L/min to 3 L/min, $R_c$ was $1.79{\times}10^{12}{\sim}2.34{\times}10^{12}m^{-1}$ which was the about 40 % decreased value to that of the 1 L/min while $R_p$ was not changed and was $1.71{\times}10^{12}m^{-1}$ approximately.

• KSBB Journal
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• v.5 no.1
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• pp.69-74
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• 1990

Dynamic characteristics of separation in membrane filtration system of tangential flow was investigated to find the functional relationship among the filtrate flux, transmembrane pressure, inulin concentration and recirculation rate. In case that NMWL is 1000, tracts-membrane pressure $0.4kgf/\;{\textrm{cm}^2}$ to $3.2kgf/\;{\textrm{cm}^2}$, inulin concentration lwt% to 5wt%, and recirculation rate 4ml / sec, mathematical model for the function among filtrate flux, transmembrane pressure, and inulin concentration was deduced and expressed as follows.Jv = (0.0022p + 0.0003) ln \frac{3p\;+\;2.1}{C_b}$ The values calculated by the above equation and those measured were compared to find to be nicely in accord with each other. Especially the agreement was enhanced in the region of higher concentration of inulin.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.1
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• pp.27-34
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• 2006

This study was conducted to evaluate the performance of a membrane bioreactor filled with high concentration of powdered activated carbon (HCPAC-MBR) to reduce DBPs at the drinking water treatment. The pilot system was installed after the rapid sand filtration process whose plant was the conventional treatment process. The removal efficiencies of DBPs were measured during pilot operation period of 2 years. HAA and THM removal rates could be maintained around 80~90% without any troubles and then tremendous reduction of HAA and THM reactivity were observed more than 52%. The average removal rate of HAA formation potential (FP) and THM formation potential (FP) were 70.5% and 67.6% respectively. It is clear that the PAC membrane bioreactor is highly applicable for advanced water treatment to control DBPs.

• Membrane and Water Treatment
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• v.5 no.2
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• pp.123-146
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• 2014

Safe water has becoming a competitive resource in many parts of the world due to increasing population, prolonged droughts, climate change etc. The development of economical and stable materials and methods for providing the fresh water in adequate amounts is the need of the water industry. Nanomaterials have unique characteristics e.g., large surface areas, size, shape, and dimensions etc. that make them particularly attractive for removing various contaminants from polluted waters. Nanotechnology based multifunctional and highly efficient membrane processes are providing affordable solutions in the new era that do not rely on large infrastructures or centralizes systems. The objective of the current study is to review the possible applications of the membrane based nanomaterials/composites for the removal of various contaminations from polluted waters. The article will briefly overview the availability and practice of different nanomaterials based membranes for removal of bacteria and viruses, organic compounds and inorganic solutes etc. present in surface water, ground water, seawater and/or industrial water. Finally, recommendations are made based on the current practices of nanofiltration membranes in water industry for a stand-alone membrane filtration system in removing various types of contaminants from polluted waters.

• Journal of Environmental Science International
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• v.20 no.6
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• pp.767-773
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• 2011

The objectives of this research are to investigate the proper coagulation conditions which are a type and doses of coagulants, mixing conditions (velocity gradients and mixing times), pH and so on through Jar-test, to evaluate the flux variations, permeate, backwashing according to characteristics of pretreatment of the wastewater by means of MF membranes for river maintenance water reuse. The effluent water from B-city K-sewage treatment plant are used for this research. Turbidity and suspended solids(SS) are 14.2 NTU and 10.4 mg/L respectively. This condition causes fouling for membrane process. The flux decline could be reduced when coagulation pretreatment was carried out. Optimal coagulations PAC which are commonly used in the sewage treatment plant was observed in this research. The results indicate that an optimal coagulation dose and pH are 80 ppm and pH of 7 respectively, but coagulation efficiency was lower at strong acid or strong base. Results showed that continuous and steady operations in membrane separation process by means of the effective removal of organic matter and turbidity with coagulation pretreatment of sewage secondary effluent were achieved.

• The Korean Journal of Physiology
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• v.30 no.2
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• pp.279-288
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• 1996

Chronic exposure to cadmium impairs various renal tubular functions, including organic acid (anion) secretion. To investigate the mechanism of cadmium-induced alterations in the organic anion transport system, kinetics of p-aminohippurate (PAH) uptake was studied in renal cortical basolateral membrane vesicles (BLMV) isolated from cadmium-intoxicated rats (adult male Sprague-Dawley). Cadmium intoxication was induced by subcutaneous injections of $CdCl_{2}$ (2 mg Cd/kg per day) for 3 weeks. The renal plasma membrane vesicles were prepared by Percoll gradient centrifugation. The vesicular uptake of $^{14}C$-PAH was determined by rapid filtration technique using Millipore filter. Cadmium intoxication resulted in a marked attenuation of $Na^{+}$-dependent, ${\alpha}$-ketoglutarate (${\alpha}$KG)-driven PAH uptake with no changes in $Na^{+}$ and ${\alpha}$KG-independent transport component. Kinetic analysis indicated that Vmax, but not Km, of the $Na^{+}$-dependent, ${\alpha}$KG-driven component was reduced. A similar reduction of $Na^{+}$-dependent, ${\alpha}$KG-driven PAH uptake was observed in normal membrane vesicles directly exposed to inorganic cadmium in vitro, and this was accompanied by an inhibition of both $Na^{+}$-dependent ${\alpha}$KG uptake and ${\alpha}$KG-PAH exchange activity. These results indicate that during chronic exposure to cadmium, free cadmium ions liberated in the proximal tubular cytoplasm directly interact with the basolateral membrane and impair the active transport capacity for organic anions, most likely due to an inhibition of both $Na^{+}$-dicarboxylate cotransporter and dicarboxylate-organic anion antiporter activities.

• Membrane Journal
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• v.8 no.3
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• pp.130-137
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• 1998

Membrane fouling characteristics in the membrane-coupled activated sludge system were investigated. The influence of the floc size variation on the filtration resistance was analyzed using resistance-in-series model and mixed liquor was fractionated into three components to verify which component would give rise to a major contribution to the total resistance. The microbial floc size was rapidly reduced during the initial 4~6 hours of operation, and then decreased slightly but steadily, followed by leveling off at the size of 20 $\mu$m. The specific resistance of activated sludge increased with operation time, and measured values of specific resistance were matched well with the values estimated on the basis of the mean particle size in the mixed liquor. The contribution of soluble organics and cells to the total resistance was relativdy small compared with that of the supematant. Colloidal particles in the supematant showed much higher specific resistance than that of microbial floc, and played the most important role in the cake resistance.