• Journal of Environmental Science International
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• v.17 no.11
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• pp.1235-1241
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• 2008

Membrane separation is extensively used for water/wastewater treatment because of its efficiency separation processes. However, particles in the feed water can deposit and accumulate on the membrane surface to created cake layer. As a consequence, the selectivity of the membrane and flux through the membrane are decreased, which is called fouling/blocking phenomenon. In order to solve fouling problem, we developed a novel membrane named Carbon Whisker Membrane (CWM) which contains vapor-grown carbon fibers/whiskers on the surface of the membrane and a layer of carbon film coated on the ceramic substrate. We firstly employed polymethyl methacrylate (PMMA) as a testing material to investigate the fouling mechanism. The results suggested that Carbon Whiskers on the surface of the membrane can prevent the directly contact between the membrane body and particles so that the fouling/blocking could not occurred easily compared to the membrane without carbon whiskers. We also researched the relationship with the diameter, density of carbon whisker on the membrane surface and total flux of solutions. Finally, we will be able to control the diameter and density of carbon whiskers on the membrane and existence of carbon whiskers on the membrane, it is important factor, might be prevent fouling/blocking in the water treatment.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.133-138
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• 2015

Pressure retarded osmosis (PRO) process is one of membrane processes for harvesting renewable energy by using salinity difference between feed and draw solutions. Power is generated by permeation flux multiplied by hydraulic pressure in draw side. Membrane fouling phenomena in PRO process is presumed to be less sever, but it is inevitable. Membrane fouling in PRO process decreases water permeation through membrane, resulting in significant power production decline. This study intended to investigate the effect of hydraulic pressure in PRO process on alginate induced organic fouling as high and low hydraulic pressures (6.5 bar and 12 bar) were applied for 24 h under the same initial water flux. In addition, organic fouling in draw side from the presence of foulant (sodium alginate) in draw solution was examined. As major results, hydraulic pressure was found to be not a significant factor affecting in PRO organic fouling as long as the same initial water flux is maintained, inidicating that operating PRO process with high hydraulic pressure for efficient energy harvesting will not cause severe organic fouling. In addition, flux decline was negligible from the presence of organic foulant in draw side.

• The KSFM Journal of Fluid Machinery
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• v.16 no.4
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• pp.35-43
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• 2013

Most of the nuclear power plants(NPPs) adopts pressure difference type flow meters such as venturi and orifice meters for the measurement of feedwater flow rates to calculate reactor thermal power. However, corrosion products in the feedwater deposits on the flow meter by fouling as operating time goes. These effects lead to severe errors in the flow indication and then determination of reactor thermal power. The averaging BDFT, which has developed by Yun et al., has a potentiality to minimize this problem thanks to its inherent measurement principle. Therefore, it is expected that the averaging BDFT can replace the venturi meter for the feedwater pipe of steam generator of NPPs. The present work compares the amplification factor, K, based on CFD calculation against the K obtained from experiments in order to confirm whether a commercial CFD code can be applicable to the evaluation of characteristic for the averaging BDFT. In addition to this, the simulations to take into account of fouling effect are also carried out by rough wall option. The results show that the averaging BDFT is a promising flow meter for the accurate measurement of flow rates in the fouling condition of the NPPs.

• Membrane and Water Treatment
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• v.11 no.2
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• pp.97-109
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• 2020

Membrane fouling is the main drawback of membrane technology. Frequent membrane cleaning and membrane replacement are, therefore, required to reduce membrane fouling that causes permeate flux reduction, lower rejection, or higher operating pressure. Studies have proved that the alteration of membrane properties is the key controlling factor in lessening membrane fouling. Among stimuli-responsive membranes, thermo-responsive membrane is the most popular, with a drastic phase transition and swelling-shrinking behavior caused by the temperature change. In this study, the thermo-responsive ability of two commercial membranes, PolyCera® Titan membrane and PolyCera® Hydro membrane, at different temperatures was studied on the antifouling function of the membrane in palm oil mill effluent (POME) treatment. The evaluation of the membrane's thermo-responsive ability was done through three cycles of adsorption (fouling) and desorption (defouling) processes in a membrane filtration process. The experimental result depicted that PolyCera® Hydro membrane had a higher membrane permeability of 67.869 L/㎡.h.bar than PolyCera® Titan membrane at 46.011 L/㎡.h.bar. However, the high membrane permeability of PolyCera® Hydro membrane was compensated with low removal efficiency. PolyCera® Titan membrane with a smaller mean pore size had better rejection performance than PolyCera® Hydro membrane for all tested parameters. On the other hand, PolyCera® Titan membrane had a better hydrodynamic cleaning efficiency than PolyCera® Hydro membrane regardless of the hydrodynamic cleaning temperature. The best hydrodynamic cleaning performed by PolyCera® Titan membrane was at 35℃ with the flux recovery ratio (FRR) of 99.17 ± 1.43%. The excellent thermo-responsive properties of the PolyCera® Titan membrane could eventually reduce the frequency of membrane replacement and lessen the use of chemicals for membrane cleaning. This outstanding exploration helps to provide a solution to the chemical industry and membrane technology bottleneck, which is the membrane fouling, thus reducing the operating cost incurred by the membrane fouling.

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.379-384
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• 2005

In this research, coagulation was employed as the pretreatment for membrane process. The effective coagulation conditions were decided after the discussion of different coagulant doses and mixing conditions, etc. Raw water was taken from Nakdong River. The best operation occurred when G value was $230s^{-1}$ and the slow mixing lasted around 5 minutes at G value was $23s^{-1}$. To investigate the optimum coagulant dosage, the optimum organics removal was target as organic removal reduces membrane fouling effectively than particle removal. This result indicated that organics are more important causes than turbidity for membrane fouling. However, turbidity becomes an important factor after certain amount of organic matters is removed.

• Journal of Navigation and Port Research
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• v.33 no.7
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• pp.501-504
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• 2009

There are many difficulties to supply constant power to marine facilities which operate in the sea. Especially, there is a limit to stand alone power supply systems due to the influence of weather conditions. That's why a hybrid power supply system is required to overcome these problems. This paper will describe an Electronic Anti-Fouling System (EAFS) to maximise the power efficiency for a solar - wave hybrid power generation system. A main factor reducing the efficiency of a Wave Energy Converter (WEC) is due to the attachment of aquatic life forms. Therefore the aim of this research is to develop a simulation programme to enable the design of more efficient EAFS for hybrid power generation systems and to provide valuable data for production of more efficient EAFS.

• Journal of the Korean Society of Marine Environment & Safety
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• v.4 no.1
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• pp.49-56
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• 1998

The Microfiltration and Ultrafiltration were used to treat effluent of secondary municipal wastewater treatment system(Sequencing Batch Reactor). The cross-flow hollow fiber, UF 500,000(NMWC) and MF 0.65$\mu$ membrane were selected as suitable membrane. Short term and long term fouling effect were measured as a factor of flux decrease and the fouling removal effect of mixing air bubble in the penetrant was studied. The removal of anionic sulfactants before and after formation of micelle with several kinds of oil were checked. The test results show that removal of TOC was 70~80%, TN 28% and TP 16%. The decrease of flux due to fouling were 85%(UF) and 90%(MF) after running of 100hrs. The removal of anionic sulfactants were 60~70% notwithstanding micelle or not.

• Membrane and Water Treatment
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• v.7 no.1
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• pp.1-10
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• 2016

Ultrafiltration is known to be one of the most commonly applied techniques in water treatment. Membrane fouling is the main limiting factor in terms of process efficiency and restricting it to the manageable degree is crucial. Natural organic matter is often found to be a major foulant in surface waters. Among many known fouling prevention techniques, the membrane chemical cleaning is widely employed. This study focuses on evaluating the cleaning efficiency of polymeric and ceramic membranes with the use of various chemicals. The influence of cleaning agent type and its concentration, membrane material and its MWCO, and cleaning process duration on the recovery of membrane flux was analyzed. Results have shown that, regardless of membrane type and MWCO, the most effective cleaning agent was NaOH.

• Korean Membrane Journal
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• v.11 no.1
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• pp.21-28
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• 2009

We investigated the effect of organic materials on membrane fouling in advanced drinking water treatment by a hybrid module packed with granular activated carbon (GAC) outside multi-channel ceramic microfiltration membrane. Synthetic water was prepared with humic acid and kaolin to simulate natural water resouces consisting of natural organic matter and inorganic particles. Kaolin concentration was fixed at 30 mg/L and humic acid was changed as 2~10 mg/L to inspect the effect of organic matters. Periodic back-flushing using permeate water was performed for 10 sec per filtration of 10 min. As a result, both resistance of membrane fouling (Rf) and permeate flux (J) were influenced highly by concentration of humic acid. It proved that NOM like humic acid could be an important factor on membrane fouling in drinking water treatment. Turbidity and UV254 absorbance were removed up to above 97.4% and 59.2% respectively.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.263-271
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• 2018

The objective of this work was to analyze organic matter removal, nitrification, biomass growth and membrane fouling in a submerged flat-sheet membrane bioreactor, fed with synthetic wastewater, of similar composition to the effluents generated in a fish meal industry. After biomass acclimatization with saline conditions of 12 gNaCl/L and COD/N ratio of 15 in the bioreactor, results showed that the organic matter removal was higher than 90%, for all organic loading rates (0.8, 1, 1.33 and $2gCOD/L{\cdot}d$) and nitrogen loading rates (0.053, 0.067, 0.089 and $0.133gN/L{\cdot}d$) tested during the study. However, nitrification was only carried out with the lowest OLR ($0.8gCOD/L{\cdot}d$) and NLR ($0.053gN/L{\cdot}d$). An excessive concentration of organic matter in the wastewater appears as a limiting factor to this process' operating conditions, where nitrification values of 65% were reached, including nitrogen assimilation to produce biomass. The analysis of membrane fouling showed that the bio-cake formation at the membrane surface is the most impacting mechanism responsible of this phenomenon and it was demonstrated that organic and nitrogen loading rates variations affected membrane fouling rate.