• Membrane Journal
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• v.27 no.4
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• pp.291-312
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• 2017

Seawater desalination is currently considered to be one of the primary technologies to resolve the global water scarcity problem. A basic understanding of membrane filtration phenomena is significant not only for further technological development but also for integrated design, optimal control, and long-term maintenance. In this vein, the present work reviews the major transport and filtration models, specifically related to reverse osmosis phenomena, provides theoretical insights based on statistical mechanics, and discusses model-based physical meanings as related to their practical implications.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.2
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• pp.169-175
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• 2017

This study applied microbubbles to reduce membrane fouling in wastewater reuse membrane processes, evaluated and compared the transmembrane pressure with or without the application of microbubbles and the cleaning efficiency with the application of aeration and microbubbles. In addition, this study analyzed foulants removed from the membrane surface. Changes in the transmembrane pressure of membranes with the presence or absence of microbubbles were observed. As a result, transmembrane pressure (TMP) increasing rate decreased twofold when applying microbubbles to realize stable operations. This study compared and evaluated cleaning efficiency applying aeration and microbubbles. As a result, the cleaning efficiency was 5% higher on average when applying microbubbles. In turbidity and total organic carbon (TOC), foulants were discharged when applying microbubbles twice as much as applying aeration. It is thought that particulate foulants precipitated on the membrane surface were more likely to desorb because the adhesion between the membrane surface and particle was weakened by microbubbles. Therefore, it is considered possible to effectively control membrane fouling because of the increase in cleaning efficiency when applying microbubbles to wastewater reuse membrane processes.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1175-1182
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• 2002

The commercial viability of heat exchanger is mainly dependent on its long-term fouling characteristic because the fouling increases the pressure loss and degrades the thermal performance of a heat exchanger. An experimental study was performed to investigate the characteristics of fluid flow and heat transfer in a fluidized bed heat exchanger with circulating various solid particles. The present work showed that the higher densities of particles had higher drag force coefficients, and the increases in heat transfer were in the order of sand, copper, steel, aluminum, and glass below Reynolds number of 5,000.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.5
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• pp.240-246
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• 2014

A fault detector was developed for heat exchangers of a hybrid heat pump (HP) for household. The proposed detector can be applied directly to raw operating data. It is to monitor a tracking error between a measured saturation temperature and its state observer. The observer was estimated from a state-space model simulating dynamics of a heat exchanger. The real hybrid HP was substituted with a dynamic simulator that implemented two-phased heat transfer and was validated by experimental data. And artificial fault data were generated using the simulator. Diagnosing the data showed the following. The residual calculated from the state observer error shows a relatively robust consistency with respect fouling level. The fault detector is practically useful because it detects a threshold fouling beyond which the performance starts to deteriorate significantly.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.441-445
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• 2010

The ouput power of wave energy system in buoy is determined according to the inner diameter of oscillating water column and flow resistance. The increase of adhered shellfish inside the water column leads to decrease the inner diameter of wave energy converter. Influx loss of seawater reduces the efficiency of output power in the wave generation system. In this paper, the test result of AFS characteristic is described for preventing the deposition with shellfish and etc. The current of anode is controlled by buck converter, and the control algorithm developed for AFS in buoy. The experimental results is shown excellent preventing capapbility of AFS in buoy.

• Environmental Engineering Research
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• v.20 no.3
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• pp.223-229
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• 2015

The application of coagulation for feed water pretreatment prior to microfiltration (MF) process has been widely adopted to alleviate fouling due to particles and organic matters in feed water. However, the efficiency of coagulation pretreatment for MF is sensitive to its operation conditions such as pH and coagulant dose. Moreover, the optimum coagulation condition for MF process is different from that for rapid sand filtration in conventional drinking water treatment. In this study, the use of response surface methodology (RSM) was attempted to determine coagulation conditions optimized for pretreatment of MF. The center-united experimental design was used to quantify the effects of coagulant dose and pH on the control of fouling control as well as the removal organic matters. A MF membrane (SDI Samsung, Korea) made of polyvinylidene fluoride (PVDF) was used for the filtration experiments. Poly aluminum chloride (PAC) was used as the coagulant and a series of jar tests were conducted under various conditions. The flux was $90L/m^2-h$ and the fouling rate were calculated in each condition. As a result of this study, an empirical model was derived to explore the optimized conditions for coagulant dose and pH for minimization of the fouling rate. This model also allowed the prediction of the efficiency of the coagulation efficiency. The experimental results were in good agreement with the predictions, suggesting that RSM has potential as a practical method for modeling the coagulation pretreatment for MF.

• Membrane Journal
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• v.26 no.3
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• pp.205-211
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• 2016

Performance of pyrophyllite-based ceramic membranes newly developed were investigated. Membrane fouling caused by microbial suspensions taken from a full-scaled MBR system at domestic wastewater treatment plant was observed at different airflow rate and distance between each membrane. For the pyrophyllite support, pore size was about $1.0{\mu}m$, but surface coating with $Al_2O_3$ solution decreased the pore size with the reduction of the pure water permeability. With the MLSS taken from the full-scaled MBR system (6 g/L), the fouling rate was decreased by increasing airflow rate under $20L/m^2{\cdot}hr$ of setpoint flux. However, the effectiveness of the airflow rate on the fouling control depends strongly upon the gap between each membrane. At fixed airflow rate, the fouling rate was decreased by increasing the gap between each pyrophyllite membrane. Nevertheless, further increasing the membrane distance from 3.5 to 5.4 cm resulted in higher fouling rate. Similar result was observed with the $Al_2O_3$ coated-pyrophyllite membrane. Nevertheless, the fouling rate was lower with the coated membrane than that observed with the uncoated pyrophyllite support. Regardless of surface coating, the suspended solids were removed almost completely and the surface coating on the pyrophyllite support improved organic rejection with PEG solution (MW : 8000 kDa) tested.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.35-41
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• 2007

An International Convention on the control of harmful anti-fouling system on ships(AFS Convention) was adopted on 5 October 2001 at Diplomatic Conference in London, and is expected to be presently effectuated with ratification of more than 25-member nations possessing about 25% of total world tonnage. This convention regulates the operation of harmful anti-fouling system and especially prohibits the use of organotin compounds contained in anti-fouling paint. Organotin compounds have a tendency to be easily extracted by specific solvents and have high polarity and low volatility as specific characteristics. This drives us to attempt of going through the process named derivatization that is required in analysis using a gas chromatography(GC). This study was conducted to determine the proper pre-treatment method, ethylation in comparison with hydridization on the analysis of tributyltin in organotin compounds and to verify the application of the method through the experimental analysis practically used anti-fouling paint and painted layer sample of the served ship.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.5
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• pp.605-612
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• 2016

Membrane bioreactors (MBRs) employ a process of biological treatment that is based on a membrane that has the advantages of producing high-quality treated water and possessing a compact footprint. However, despite these advantages, the occurrence of "fouling" during the operation of these reactors causes the difficulty of maintenance. Hence, in this study, three physical cleaning methods, namely, backwashing, air scrubbing, and mechanical cleaning ball was performed to identify optimum operating conditions through laboratory scale experiments, and apply them in a pilot plant. Further, the existing MBR process was compared with these methods, and the field applicability of a combination of these physical cleaning methods was investigated. Consequently, MCB, direct control of cake fouling on the membrane surface was found to be the most effective. Moreover, as a result of operating with combination of the physical cleaning process in a pilot plant, the TMP increasing rate was found to be - 0.00007 MPa/day, which was 185% higher than that obtained using the existing MBR process. Therefore, assuming fouling only by cake filtration, about one year of operation without chemical cleaning is considered to be feasible through the optimization of the physical cleaning methods.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.04a
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• pp.94-96
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• 1999