• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.755-764
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• 2016

Pressure retarded osmosis (PRO) processes can be implemented on a number of water types, using different technologies and achieving various power outcomes. In this study, Sewage facility effluent was used for feed solution of PRO and synthetic NaCl water for draw solution. This study was conducted to investigate effect of water quality of pretreatment on power density and flux decline in PRO process. The results show that organic and particulate foulants have to be removed for more stable operation. Flourescence technique with EEM enables to investigate the chemical properties of aquatic organic matter by extracting spectral information. Humic/fulvic matters and soluble microbial by-products were analyzed as the most affecting factors on the PRO performance. As a result of analyzing the whole system based on the energy consumption of the unit process, specific energy consumption(SEC) of the applicable technology for PRO pre-treatment should be about $0.2kWh/m^3$ or less.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.227-238
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• 2013

The purpose of this study is to develop a process technology to produce high hardness drinking water which meet drinking water standard, remaining useful minerals like magnesium and calcium in the seawater desalination process while removing the sulfate ions and chloride ions. Seawater have been separated the concentrated seawater and desalted seawater by passing on Reverse Osmosis membrane (RO). Using Nano-filtration membrane (NF), We were prepared primary mineral concentrated water that sodium chloride were not removed. By the operation of electro-dialysis (ED) having ion exchange membrane, we were prepared concentrated mineral water (Mineral enriched desalted water) which the sodium chloride is removed. We have produced the high hardness water to meet the drinking water quality standards by diluting the mineral enriched desalted water with deionized water by RO. Reverse osmosis membranes (RO) can separate dissolved material and freshwater from seawater (deep seawater). The desalination water throughout the second reverse osmosis membrane was completely removed dissolved substances, which dissolved components was removed more than 99.9%, its the hardness concentration was 1 mg/L or less and its chloride concentration was 2.3 mg/L. Since the nano-filtration membrane pore size is $10^{-9}$ m, 50% of magnesium ions and calcium ions can not pass through the nano-filtration membrane, while more than 95% of sodium ions and chloride ions can pass through NF membrane. Nano-filtration membrane could be separated salt components like sodium ion and chloride ions and hardness ingredients like magnesium ions and calcium ions, but their separation was not perfect. Electric dialysis membrane system can be separated single charged ions (like sodium and chloride ions) and double charged ions (like magnesium and calcium ions) depending on its electrical conductivity. Above electrical conductivity 20mS/cm, hardness components (like magnesium and calcium ions) did not removed, on the other hand salt ingredients like sodium and chloride ions was removed continuously. Thus, we were able to concentrate hardness components (like magnesium and calcium ions) using nano-filtration membrane, also could be separated salts ingredients from the hardness concentration water using electrical dialysis membrane system. Finally, we were able to produce a highly concentrated mineral water removed chloride ions, which hardness concentration was 12,600 mg/L and chloride concentration was 2,446 mg/L. By diluting 10 times these high mineral water with secondary RO (Reverse Osmosis) desalination water, we could produce high mineral water suitable for drinking water standards, which chloride concentration was 244 mg/L at the same time hardness concentration 1,260 mg/L. Using the linked process with reverse osmosis (RO)/nano filteration (NF)/electric dialysis (ED), it could be concentrated hardness components like magnesium ions and calcium ions while at the same time removing salt ingredients like chloride ions and sodium ion without heating seawater. Thus, using only membrane as RO, NF and ED without heating seawater, it was possible to produce drinking water containing high hardness suitable for drinking water standard while reducing the energy required to evaporation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.179-184
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• 2019

In many countries, such as developing countries where electricity is scarce, small wind turbines in the form of Off Grid are an effective solution to solve power supply problems. In some countries, the expansion of power systems and the decline of electricity-intensive areas have led to the use of small wind power in urban road lighting, mobile communications base stations, aquaculture and seawater desalination. With this change, the size of the small wind power industry is expected to have greater potential than large-scale wind power. In the case of small wind power generators, the generator is controlled at a variable speed, and the voltage and current generated by the generator have many harmonic components. To solve this problem, the AC to DC converter to be studied in this paper is a three-phase step-up type converter with a single switch. The inductor current is controlled in discontinuous mode, and has a characteristic of having a unit power factor by eliminating the harmonic of the input current. The proposed converter is composed of LCL filter and three phase rectification boost converter at the input stage and a single phase full bridge for grid connection. It is a control system with energy storage system(ESS) that the system stabilization can be pursued against the electric power.

• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.249-255
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• 2015

Functional nanochannels were fabricated in order to control selective ion transportation with high permeability and low energy consumption. In this research, nanochannel platform fabrication process and surface functionalization process were developed. In addition, selective ion transportation and concentration measurement system was also set-up. By using fabricated multilayer metal membrane with electrical bias, 95% of ion ($Cl^-$) was blocked. This developed process is new-conceptional membrane fabrication technology and is expected to be applied to next-generation water purification/desalination, portable artifical kidney, and artificial sense organ.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1114-1119
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• 2004

The biofilms on pipe walls in water distribution systems are of interest since they can lead to chlorine demand, coliform growth, pipe corrosion, and water taste and odor problems. As such, the study described in this paper is part of an AWWARF and Tampa Bay Water tailored collaboration project to determine the effect of blending different source waters on the water quality in various distribution systems. The project was based on 18 independent pilot distribution systems (PDS), each being fed by a different water blend (7 finished waters blended in different proportions). The source waters compared were groundwater, surface water, and brackish water, which were treated in a variety of pilot distribution systems, including reverse osmosis (RO) (desalination), both membrane and chemical softening, and ozonation-biological activated carbon (BAC), resulting in a total of 7 different finished waters. The observations from this study consistently demonstrated that unlined ductile iron was more heavily colonized by a biomass than galvanized steel, lined ductile iron, and PVC (in that order) and that the fixed biomass accumulation was more influenced by the nature of the supporting material than by the water quality (including the secondary residual levels). However, although the bulk liquid water cultivable bacterial counts (i.e. heterotrophic plate counts or HPCs) did not increase with a greater biofilm accumulation, the results also suggested that high HPCs corresponded to a low disinfectant residual more than a high biofilm inventory. Furthermore, temperature was found to affect the biofilms, plus the AOC was important when the residual was between 0.6 and 2.0 mg $Cl_2/l$. An additional aspect of the current study was that the potential of the exoproteolytic activity (PEPA) technique was used along with a traditional so-called destructive technique in which the biofilm was scrapped off the coupon surface, resuspended, and cultivated on an R2A agar. Both techniques indicated similar trends and relative comparisons among the PDSs, yet the culturable biofilm values for the traditional method were several orders of magnitude lower than the PEPA values.

• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.53-57
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• 2013

For the purpose of development of the extraction process of lithium ion from concentrated water eliminated from desalination process, an experimental research on the solvent extraction of lithium ion from aqueous solutions was performed. The effects of operating parameters, such as concentration of extractant, ratio of extracting solution/aqueous solution, pH of aqueous solution, were examined. The effect of sodium chloride, the major component of sea water, was also examined. Lithium ion in aqueous solutions of pH=10.2~10.6 adjusted by ammonia solution was most effectively extracted by extracting solution composed of 0.02 M TTA and 0.04 M TOPO in kerosine. The addition of sodium chloride in lithium aqueous solution significantly interfered the extraction of lithium ion.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.279-284
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• 2016

Membrane distillation (MD) is the thermally driven water separation process based on the vapor pressure difference across the membrane. In order to increase the water recovery of the conventional RO process, the additional MD-PRO pocess was suggested. In this study, the syntheric RO brine was used as a feed solution of the MD process. Due to the high salinity of the RO brine, the MD membrane could be fouled by the scalants. In order to mitigate the scaling on the MD membrane surface, the pre-treatment process using the column filled by natural zeolite was applied. The roughing filter was installed between the pre-treatment process and MD system in order to prevent possible particulate fouling by the debries of the natural zeolite. Moreover, in order to enhance the CEC of the natural zeolite, the NaCl soaking was conducted. The flux and electronic conductivity were monitored under given experimental conditions. And the membrane morphology and the chemical compositions were analyzed by using the SEM-EDX.

• Journal of agriculture & life science
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• v.46 no.2
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• pp.169-178
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• 2012

This study was aimed at providing optimal water treatment processes based on various required water quality for utilization of the Saemangeum lake water as water supply alternatives to this area. Various water treatment methods were considered for investigation there characteristics, pollution removal rate, pros and cons in order to select appropriate water treatment processes satisfying the required water quality for different purposes. As results, the FDA system for SS, turbidity, BOD removals, UV treatment for coliform, BOD removals, FNR process for T-N, T-P removals, and ECRS process for desalination purpose were found to be better methods in senses of removal efficiency, operation and maintenance. Case studies were provided with cost analysis for field applications in the Saemangeum area.

• Membrane and Water Treatment
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• v.10 no.4
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• pp.277-286
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• 2019

In 2014, the first demineralization plant, using nanofiltration (NF) membrane coupled with renewable energies was realized at Al Annouar high school of Sidi Taibi, Kenitra, Morocco. This project has revealed difficulties related to the membrane performances loss (pressure increase, flux decline, poor water quality of the produced water and increase of energy consumption), as consequences of membrane fouling. To solve this problem, an autopsy of the membrane was done in order to determine the nature and origin of the fouling. The samples of membrane and fouling were then analyzed by scanning electron microscopy using a scanning electron microscope (SEM) connected with an energy dispersive X-ray (EDX) detection system and X-ray diffractometer (XRD). Moreover, three cleaning solutions (hydrochloric acid, nitric acid and sulfuric acid) were tested and assessed in a single cleaning step to find the suitable one for the fouled membrane to regain its initial permeability and performances. The analysis of the experimental results showed that the fouling layer is mainly composed of calcium carbonate (inorganic fouling). Results showed also that the permeability is improved by the hydrochloric acid cleaning (pH=3) with a cleaning efficiency of 93%. Cleaning efficiency did not exceed 75 % with nitric acid (pH=3) and 40 % with sulfuric acid (pH=3).

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.522-522
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• 2016

우리나라의 488개 유인도 중 강수량 부족 혹은 지하수의 수질문제 등으로 상습적 식수난을 겪고 있는 도서지역은 237개에 이르고 있다. 이들 도서지역은 생활용수를 우물, 간이상수도, 운반급수 등에 의존하고 있지만 이중 47%의 도서는 간이급수시설이 전무한 실정이다. 2015년에는 인천시 옹진군의 소청도, 대청도에 장기간 지속된 가뭄으로 식수원이 고갈되어 3일에 1시간으로 급수를 제한하였고 이로 인해 식수난 문제 외 관광산업의 소득저하 등의 문제가 발생되어 원활한 물공급문제가 해결되지 않으면 도서지역의 위기는 심각할 것으로 우려된다. 도서지역의 기본권인 먹는 물 문제를 해결하기 위해 정부 및 지자체에서는 소규모 유인도서에 해수담수화시설을 설치하여 유지관리 및 운영을 위한 인력을 배치하고 수동으로 조작하거나 단순 자동운전에 의해 운영 및 관리되고 있는 실정이다. 본 연구에서는 해수담수화시설의 안정적이고 효율적인 운영을 위해 지능적 수운영 알고리즘을 개발하였다. 제어시스템, 감시시스템, 계측시스템 등의 ICT 기술과 연계하여 수요를 정확히 예측하고, 실시간 전력비용과 저류량, 사용량 등을 통합적으로 고려하였으며 적시정량을 생산하여 저장 및 공급하며, 목표수질과 수량을 원활하고 안정적으로 공급할 수 있도록 제어 및 감시를 통한 지능적 수운영을 목적으로 연구하였다. 데이터의 수집과 전송, 분석, 제어, 감시 활동이 유기적으로 결합되어 용수의 생산과 분배, 공급활동을 자동화함으로 운영상의 리스크를 줄여주며, 필요시 통합운영센터에서의 의사결정을 지원할 수 있도록 개발하였다. 향후, 해수담수화시설뿐이 아닌 일반 상수도 수운영에 있어서의 취수, 도수, 정수, 배수지관리, 송수, 관망관리까지 자동화된 시스템을 개발하여 지능적 운영관리가 가능하도록 알고리즘 모델 및 프로그램을 제시하고자 한다.