• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.101.2-101.2
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• 2010

현재 forward osmosis(FO)에 대한 관심이 증가하고 있다. 하지만 FO에 대한 안정성 평가는 전무한 실정이다. 본 연구는 많은 연구로 안정성을 인정받고 있는 RO와 직접 비교를 통하여 FO의 붕소에 대한 안정성을 평가하였다.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.2
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• pp.21-27
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• 2013

The present study explored the way to desalinate seawater for agricultural irrigation using forward osmosis (FO) process using liquid fertilizer as draw solution. FO experiments were performed in a cross flow mode using flat sheet FO membrane. The effect of membrane orientation, flow rate, and draw solution concentration on the performance of forward osmosis was investigated by measuring water flux of forward osmosis membrane. The water flux when the draw solution was placed against the membrane active layer was lower than the water flux when the feed solution was placed against the membrane active layer. This results indicated that the decrease of effective osmotic pressure by dilutive internal concentration polarization was less than that by concentrative internal concentration polarization. Increasing flow rate from 66.7 to 133.1 $cm^3$/min resulted in increase of the water flux when the membrane active layer orient to draw solution and feed solution, respectively. The reduction of resistance to water flow increased water flux at higher flow rate. The water flux of FO membrane increased with increasing draw solution concentration from 10000 to 30000 mg/L. The water flux for $KH_2PO_4$ draw solution was similar to that for commercial fertilizer. Optimization of FO process would contribute to economically desalinate brackish water for agricultural use.

• Membrane Journal
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• v.29 no.6
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• pp.339-347
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• 2019

Forward osmosis (FO) is operated at a lower pressure than reverse osmosis (RO), which has great advantages in terms of fouling control, maintenance, membrane cleaning, and potential energy reduction. In particular, since the membrane fouling layer of the forward osmosis process has a relatively loose and dispersed property, it is possible to control the membrane fouling by physical cleaning, unlike the reverse osmosis process. However, existing studies do not apply the proper cleaning flow rate for forward osmosis physical cleaning, and thus there is a limit that the optimal operation can not be performed. Therefore, this study aims to evaluate the justification of proper flow rate that can show high efficiency cleaning with economical energy amount. The membrane fouling experiments of the forward osmosis process were maintained at a circulating flow rate of 8.54 cm/s and the recovery rates were compared with the three cleaning flow rates. As a result of this experiment, it was confirmed that the 2 × speed cleaning showed the same efficiency as the water permeability recovery rate of the 3 × speed cleaning, and it was confirmed that the 2 × speed cleaning was an appropriate flow rate with high cleaning efficiency and economical SEC.

• Membrane and Water Treatment
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• v.10 no.6
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• pp.417-429
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• 2019

Poly Sulfone nanofibers were electrospun to fabricate membranes of different characteristics. To fabricate the fiber mats, polymer concentration, flowrate, and current density were determined as the most influencing factors affecting the overall performance of the membranes and studied through Response Surface Methodology. The Box-Behnken Design method (three factors at three levels) was used to design, analyze, and optimize the parameters to achieve the best possible performance of the electrospun membranes in forward osmosis process. Also, internal concentration polarization that characterizes the efficiency of the forward osmosis membranes was determined to better assess the overall performance of the fabricated electrospun membranes. Water flux to reverse salt flux was considered as the main response to assess the performance of the membranes. As confirmed experimentally, best membrane performance with the minimal structural parameter value could be achieved when predicted optimal values were used to fabricate the membranes through electrospinning process.

• Membrane Journal
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• v.26 no.4
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• pp.273-280
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• 2016

Pressure assisted forward osmosis (PAFO) is recently introduced because of its improved process efficiency to overcome drawbacks of forward osmosis (FO) such as low water flux and reverse solute diffusion. However, it is known that membrane fouling becomes deteriorated by additional hydraulic pressure applied in PAFO compared to FO. This study was performed to investigate possibility of intermittent pressure-assisted forward osmosis (I-PAFO) operation for fouling mitigation using colloidal silica particles as model foulants. FO, PAFO were operated as well to compare with. Two different solution pH conditions (pH 3, 10) were applied to see the effect of electrostatic interactions between the membrane and silica particles on fouling tendency. In the results, higher water flux was observed during pressurization and pressure relaxation periods in I-PAFO than water flux of PAFO, and FO on both pH conditions. Water flux decreased less in I-PAFO than PAFO after fouling. It resulted in higher water flux recovery in I-PAFO than PAFO after physical cleaning.

• Environmental Engineering Research
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• v.20 no.1
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• pp.99-104
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• 2015

The purpose of this study is to evaluate the performance of forward osmosis (FO) system for harvesting microalgae cultivated in secondary sewage effluent. Microalgae species used in this study were chlorella sp. ADE4. The drawing agents used for forward osmosis system were seawater and concentrate of sea water reverse osmosis (SWRO) system. Chlorella sp. ADE4 cultured in secondary sewage effluent illustrated moderate efficiency in removal of total nitrogen (TN) (68%) and superior performance in total phosphorus (TP) removal (99%). Comparison of seawater and SWRO concentrate as drawing agent were made in FO membrane separation of the microalgae. The result from this study depicts that SWRO concentrate is strong drawing agent in FO membrane system providing an average dewatering rate of $4.8L/(m^2{\cdot}hr)$ compared to seawater with average dewatering of $2.9L/(m^2{\cdot}hr)$. Results obtained from this study indicated that FO system could be viable option for harvesting the microalgae for further biodiesel production. SWRO concentrate as a drawing agent could be very important finding in field of membrane technology for disposal of SWRO concentrate.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.2
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• pp.131-137
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• 2016

The development of alternative water resources has emerged as an effective method for solving drought of water resources due to extreme weather and increase in water consumption. Recently, in Korea, there has been active research on reverse osmosis desalination technology, wastewater reuse using forward osmosis membranes, and the forward osmosis(FO)-reverse osmosis(RO) hybrid process combining these two technologies. In this study, the basic performance of FO membranes manufactured by three domestic and international manufactures such as Microfilter Co., Ltd., Toray Chemical Korea Inc., and Hydration Technologies Inc., were investigated for wastewater reuse. In addition, as an experiment to select feed solution, the selected membranes were operated 48 consecutive hours using three secondary effluents pretreated by the UF membrane with a pore size of $0.1{\mu}m$ and auto strainer with pore sizes of $1{\mu}m$ and $100{\mu}m$ as feed solution. Although there was not much difference in the operating performance. Thus, the treated water using the $100{\mu}m$ auto strainer was selected as feed solution applied to the assessment.

• Membrane Journal
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• v.25 no.4
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• pp.367-372
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• 2015

In pressure-retarded osmosis (PRO) and forward osmosis (FO) processes, solvent (permeate) flux depends on which surface the draw solution faces. There are two operation modes. PRO mode indicates that the active layer faces the draw solution, and FO mode means that the porous substrate fronts the draw stream. It is often observed that the PRO mode produces higher flux than that of FO under the same operating conditions. The current work uses the method of proof by contradiction, and mathematically proves the intrinsic flux inequality between the two modes.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.5
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• pp.521-532
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• 2016

Seawater desalination market after global economic crisis has been stalled due to the market uncertainties and decreased demand in desalination. It is important to review the status of the market and to estimate the appropriate share of Forward osmosis-Reverse Osmosis (FO-RO) hybrid desalination technology by figuring out the outlook of the desalination market. Main part of the desalination market will still be MENA (Middle East and North Africa) in the near future due to the fast population increase and high dependency of fossil fuel in the region. The market for FO-RO hybrid technology, however, might be smaller than the conventional SWRO desalination market anyway because of aesthetic issues from using wastewater as raw water and higher costs associated with capex. Therefore, it is essential to improve FO membrane performance and system operation technologies in order to make the hybrid technology attractive compared to the conventional SWRO technology.

• Membrane Journal
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• v.26 no.3
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• pp.187-196
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• 2016

Pressure-assisted forward osmosis (PAFO) process has recently been under spotlight for its potential to improve forward osmosis (FO) process performance by applying low hydraulic pressure on the feed side. Structure parameter, one of the governing factors in estimating water flux and solute flux across FO membranes in the solution-diffusion model (S-D model), determines solute resistivity in FO and PAFO processes. This study aims to estimate the trend of structure parameter change with respect to varying additional hydraulic pressure condition in PAFO.