• Membrane Journal
• /
• v.28 no.2
• /
• pp.96-104
• /
• 2018

With the rapid increase in seawater desalination, the importance of boron rejection is rising. This study was conducted to investigate the effect of hydrophilic compounds on surface modification to maximize water flux and increase boron rejection. First, polyamide active layer was fabricated by interfacial polymerization of polysulfone ultrafiltration membrane with M-phenylenediamine (MPD) and trimesoyl chloride (TMC) to obtain Control polyamide membrane. Next, D-gluconic acid (DGCA) and D-gluconic acid sodium salt (DGCA-Na) were synthesized with glutaraldehyde (GA) and hydrochloric acid (HCl) by modifying the surface of Control polyamide membrane. XPS analysis was carried out for the surface analysis of the synthesized membrane, and it was confirmed that the reaction of surface with DGCA and DGCA-Na compounds was performed. Also, FE-SEM and AFM analysis were performed for morphology measurement, and polyamide active layer formation and surface roughness were confirmed. In the case of water flux, the membrane fabricated by the surface modification had a value of 10 GFD or less. However, the boron rejection of the membranes synthesized with DGCA and DGCA-Na compounds were 94.38% and 94.64%, respectively, which were 12.03 %p and 12.29 %p larger than the Control polyamide membrane, respectively.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.6
• /
• pp.735-741
• /
• 2010

A pilot test was carried out to investigate the long term operation characteristics of Microfiltration (MF) system as a pretreatment for seawater reverse osmosis (SWRO) processes for two years. A commercialized MF module with pressurized operation type was used to filter seawater to remove particles which can foul reverse osmosis (RO) membrane. Silt Density Index (SDI) values of filtered seawater by the MF system were ranged from 0.14 to 1.79, which meet the SDI standard for RO feed water as depicted in previous literatures. Although the tested seawater is quite clean (i.e., dissolved organic cabon (DOC) concentration and turbidity were about 1 mg/l and less than 1 NTU, respectively) enough not to foul the MF membrane, steep increase in trans-membrane pressure (TMP) with a constant flux were observed over a whole operation period. A set of operation and water analysis data implies that the steep increase in TMP was resulted from iron and maganese fouling by the combination of metal corrosion by seawater and oxidation state by aeration and residual chlorine.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.2
• /
• pp.177-184
• /
• 2011

Membrane fouling is an unavoidable phenomenon in operation of seawater reverse osmosis (SWRO) and major obstacle for economic and efficient operation. When fouling occurs on the membrane surface, the permeate flux is decreased, on the contrary, the trans-membrane pressure (TMP) is increased, therefore operation and maintaining costs and potential damage of membranes are able to the pivotal risks of the process. Chemical cleaning process is essential to prevent interruptions for effective RO membrane filtration process. This study focused on proper chemical cleaning condition for polyamide RO membranes of 4 companies. Several chemical agents were applied for chemical cleaning under numbers of operating conditions. Additionally, a monitoring tool of FEEM as autopsy analysis method is adapted for the prediction of organic bio-fouling.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.4
• /
• pp.573-579
• /
• 2011

As rapid advances in technologies continue, seawater reverse osmosis (SWRO) desalination systems are now more energy-efficient than conventional thermal processes. Some SWRO desalination plants can achieve the specific energy consumption (SEC) below 2 kWh/$m^3$. Along with the development of new membranes and high-performance pumps, energy recovery devices (ERD), which recover the hydraulic energy of brine, have been developed to enhance energy efficiency. In this work, we reviewed general aspects of ERD technologies and their market trends. The advantages and disadvantages of various EDR technologies were compared to explore the future directions of ERD development.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.3
• /
• pp.399-405
• /
• 2011

In a desalination technology using RO membranes, chemical cleaning makes damage for membrane surface and membrane life be shortened. In this research cleaning technology using direct osmosis (DO) was introduced to apply it under the condition of high pH and high concentration of feed. When the high concentration of feed is injected to the concentrate side after release of operating pressure, then backward flow occurred from treated water toward concentrated for osmotic pressure. This flow reduces fouling on the membrane surface. Namely, flux of DO was monitored under pH 3, 5, 10 and 12 conditions at feed concentrations of NaCl 40,000 mg/L, 120,000 mg/L and 160,000 mg/L. As a result, DO flux in pH 12 increased about 21% than pH 3. DO cleaning was performed under the concentrate NaCl 160,000 mg/L of pH 12 during 20 minutes. Three kinds of synthetic feed water were used as concentrates. They consisted of organic, inorganic and seawater; chemicals of SiO2 (200 mg/L), humic acid (50 mg/L) sodium alginate (50 mg/L) and seawater. As a result, fluxes were recovered to 17% in organic fouling, 15% in inorganic fouling and 14% of seawater fouling after cleaning using DO under the condition of concentrate NaCl 160,000 mg/L of pH 12.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.201-201
• /
• 2019

세계적인 기상이변으로 가뭄발생 빈도 및 영향이 증가하고 있으며, 급속한 산업화로 사용 가능한 수자원이 점차 고갈되어 있어, 국내에서도 해수담수화(Seawater Desalination)는 새로운 대체수자원으로 많은 관심을 받고 있다. 해수담수에 필요한 에너지 약 50~70%는 역삼투(Reverse Osmosis) 공정에서 발생되며, 해수온도 및 염분도에 따라 많이 변동될 수 있으므로 국립해양조사원(KHOA)의 과거 20년 자료를 이용하여 해수담수화 시설물 위치에 따른 영향을 분석하였다. 해수담수화에 필요한 에너지는 막 제조사에서 제공하는 RO Projection Software를 적용하여 에너지 소모량을 평가하고, 이를 고려한 시설물 위치에 대한 평가 모델을 구축하였다. 기존 해수담수화 시설은 대규모 물 공급이 필요한 지역을 우선적으로 고려했기 때문에 시설물 위치에 대한 객관적인 평가기준 마련이 어려웠다. 그러나 해수담수화 플랜트는 한번 설치되면 장기적인 시설물 유지 및 관리가 필요함으로 경제성을 고려한 최적 입지의 선정은 매우 중요하다. 본 연구는 국립해양조사원의 수집된 자료를 바탕으로 해수담수화 시설물 입지선정을 정량적으로 평가함으로서, 시설물 위치에 대한 의사결정시 참고할 수 있는 기초자료로 활용될 것으로 기대한다.

• Journal of Korea Water Resources Association
• /
• v.44 no.10
• /
• pp.809-817
• /
• 2011

We analyzed various cost components for approximately 40 small-scale island desalination plants operated by K-water. A significant factor affecting desalination cost was found, and we proposed a way to reduce desalination costs. All plants considered were reverse osmosis (RO) facilities. TDS concentrations of feed water varied from less than 1,000 mg/L (practically considered freshwater) to over 30,000 mg/L (nearly seawater). Analysis of desalination costs from 2005 to 2009 indicated that maintenance, labor, and energy were the three biggest components that accounted for 50.6%, 36.9% and 7.8%, respectively. It was well known that TDS of feed water directly affected energy needed for RO process. In this study we found that maintenance cost was also directly related to feed water TDS. This finding indicated that lowering feed water TDS might result in significant desalination cost reduction.

• Membrane Journal
• /
• v.23 no.5
• /
• pp.343-351
• /
• 2013

This study is to investigate the effects of the draw solution concentration on forward osmosis desalination performance using blended fertilizer as draw solution. As the concentration of blended fertilizer solution (draw solution) increased, the water permeate flux increased nearly linearly, but PR (performance ratio) was reduced. Using sea water and deionized water as the feed solution, respectively, at the blended fertilizer solution of 600 g/L $H_2O$, the PR obtained were 5.39 and 6.50, respectively. And as the concentration of blended fertilizer solution increased, the reverse solute flux for nitrogen (N), phosphorus (P), and potassium (K) increased nearly linearly, but specific reverse solute flux for them was reduced. The reverse solute flux and specific reverse solute flux became higher in the order of N > K > P.

• Membrane Journal
• /
• v.17 no.4
• /
• pp.277-286
• /
• 2007

The technology of seawater desalination has been received much attentions to solve the problem of water shortage through all over the world. In this study, it attempts to confirm the use-possibility of cellulose triacetate (CTA) for preparation of reverse osmosis membranes which have been highlighted as high efficiency and low energy consumption process for seawater desalination. The effects of casting dope parameters like an acetyl content, solvent, additives on the membrane performance were investigated. It was possible to produce the membranes which have high water flow rate and salt rejection with the increase of acetyl content and dioxane content among various dioxane/acetone ratios. Acetic acid and maleic acid were preferred for additives to produce high performance membranes. It was verified that $HOLLOSEP^{(R)}$ module which is commercialized CTA membrane by TOYOBO Co. can produce stable water production and high-quality water for long-term operation in the practice plants without any chemical treatments.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.3
• /
• pp.351-357
• /
• 2022

A conventional seawater reverse osmosis (SWRO) and a forward osmosis (FO) and reverse osmosis (RO) hybrid process to produce 1,000 m³/d of fresh water, were designed and compared in terms of carbon emission. When FO was adapted for the osmotic dilution, the required pressure for RO decreases, and thus energy consumption decreases. The decrease in carbon emission by decreased energy consumption (up to -0.73 kgCO₂/m³ using coal as the energy source) was compared with the increase in carbon emission by the FO system (+0.16 kgCO₂/m³), which is a function of various factors such as the number of FO modules and energy consumption. The comparison revealed that the FO-RO process causes less carbon emission compared with the SWRO process when the energy sources are coal and oil. However, if energy sources with low carbon emission such as solar, wind, and nuclear energy are selected, the carbon emission of the FO-RO process becomes higher than that of the SWRO process. This implies that the type of energy source is a key factor to determine the necessity of the FO-RO process from the aspect of carbon emission.