• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.6
• /
• pp.403-410
• /
• 2020

The difficulty of securing freshwater sources is increasing with global climate change. On the other hand, seawater is less affected by climate change and regarded as a stable water source. For utilizing seawater as freshwater, seawater desalination technologies should be employed to reduce the concentration of salts. However, current desalination technologies might accelerate climate change and create problems for the ecosystem. The desalination technologies consume higher energy than conventional water treatment technologies, increase carbon footprint with high electricity use, and discharge high salinity of concentrate to the ocean. Thus, it is critical to developing green desalination technologies for sustainable desalination in the era of climate change. The energy consumption of desalination can be lowered by minimizing pump irreversibility, reducing feed salinity, and harvesting osmotic energy. Also, the carbon footprint can be reduced by employing renewable energy sources to the desalination system. Furthermore, the volume of concentrate discharge can be minimized by recovering valuable minerals from high-salinity concentrate. The future green seawater desalination can be achieved by the advancement of desalination technologies, the employment of renewable energy, and the utilization of concentrate.

• Environmental Engineering Research
• /
• v.20 no.1
• /
• pp.99-104
• /
• 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 Energy Engineering
• /
• v.25 no.4
• /
• pp.1-6
• /
• 2016

Seawater desalination plants generally have two inherent problems which stem from energy inefficiency and desalination concentrate management. The former has been somewhat resolved thanks to the innovative methods in utilizing new and renewable energy resources whereas the latter still has much issues to be dealt with. This paper introduces the application of a desalting process for the disposal of desalination concentrate (especially, Mg) and to improve its cost effectiveness of a MVR seawater desalination plant built in Jeju. Principal component analysis on the desalination concentrate has revealed a steady reduction of Mg with the application of the desalting process verifying its functional reliability. Also, it was found that our MVR seawater desalination plant is not only energy efficient but also could be effectively applied for the dual purpose of fresh water production and concentrate management.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.41 no.3
• /
• pp.163-169
• /
• 2008

This study investigated the quality of salted mackerel prepared with deep seawater concentrate and salt. The quality of the salted mackerel product prepared with deep seawater was compared to that prepared with surface and intermediate seawater salts, sun-dried salt, and refined salt. After preparing the salted mackerel products using the five salts, the products were stored at $4^{\circ}C$ for 35 days. Quality characteristics compared were the acid value (AV), peroxide value (POV), lipophilic browning, volatile basic nitrogen (VBN), pH, viable cell count, and sensory factors. The deep seawater salted mackerel product had the lowest AV, POV, browning value, and viable cell counts, compared to the others, while it had the highest score in the sensory evaluation.

• Nuclear Engineering and Technology
• /
• v.41 no.8
• /
• pp.1101-1108
• /
• 2009

The ocean contains around eighty elements of the periodic table and uranium is also one among them, with a uniform concentration of 3.3 ppb and a relative abundance factor of 23. With a large coastline, India has a large stake in exploiting the 4 billion tonnes of uranium locked in seawater. The development of radiation grafting techniques, which are useful in incorporating the required functional groups, has led to more efficient adsorbent preparations in various geometrical configurations. Separation based on a polymeric adsorbent is becoming an increasingly popular technique for the extraction of trace heavy metals from seawater. Radiation grafting has provided definite advantages over chemical grafting. Studies related to thermally bonded non woven porous polypropylene fiber sheet substrate characterization and parameters to incorporate specific groups such as acrylonitrile (AN) into polymer back bones have been investigated. The grafted polyacrylonitrile chains were chemically modified to convert acrylonitrile group into an amidoxime group, a chelating group responsible for heavy metal uptake from seawater/brine. The present work has been undertaken to concentrate heavy metal ions from lean solutions from constant potential sources only. A scheme was designed and developed for investigation of the recovery of heavy metal ions such as uranium and vanadium from seawater.

• Membrane Journal
• /
• v.12 no.3
• /
• pp.182-191
• /
• 2002

Polyamide reverse osmosis (RO) membrane with thin film composite structure was commercialized for seawater desalination process. Recently, it has been reported that some RO processes for high pressure and recovery leads to reducing in energy cost and pretreatment scale compared with earlier process. The development of energy recovery, pumping device and RO elements with high pressure and rejection made high pressure and recovery process possible. In this study, permeation properties of commercialized seawater RO membrane were investigated under the condition of high pressure and recovery. In the RO sheet membrane test 3.5% NaCl of synthetic seawater was used. The synthetic seawater contained only sodium chloride. In the RO module test, natural seawater was used at Happo Bay, Masan city. As the results, RO membrane with high durability of pressure was better than that with high rejection of seawater for high pressure and recovery process. Seawater rejection of high concentrate tends to be improved by high pressure operation.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.18 no.1
• /
• pp.9-14
• /
• 2015

There are various ions in seawater. In order to use seawater as the drinking water, some elements are to be concentrated and other elements are to be removed. To obtain these characteristics using seawater, it is necessary to adjust seawater quality. Because calcium and magnesium are especially healthful to human bodies, it is required to concentrate these elements. In this study, the technology to obtain the hard water from seawater by electerodialysis was investigated. After concentrated water was produced using nanofiltration membranes, sodium chloride was eliminated from the concentrated water by electrodialysis. The hard water production from seawater was successfully achieved using electrodialysis in this study.

• Analytical Science and Technology
• /
• v.33 no.4
• /
• pp.186-196
• /
• 2020

A simple and rapid preconcentration method of actinide from seawater using Actinide resin was developed and tested with the seawater spiked with a known U and Th. The developed method of Actinide resin based on column chromatography is less time-consuming and requires less labor compared with a typical co-precipitation technique for preconcentration of actinides. U and Th, which are relatively weak-bonded with Actinide resin among actinides, were used to determine the optimum flow rate of seawater sample and evaluate the capacity of Actinide resin to concentrate actinides from seawater. A flow rate of 50 mL min^-1 was available with Actinide resin 2 mL (BV, bed volume). When 5 or 10 L of seawater containing U were loaded on Actinide resin (2 mL, BV) at 50 mL min^-1, the recovery of U was 93 % and 86 %, respectively. For extraction of actinides bound with Actinide resin, we compared three methods: solvent extraction, ashing-acid digestion, and ashing-microwave digestion. Ashing-microwave digestion method shows the best performance of which is the recovery of 100 % for U and 81 % for Th. For the preconcentration of actinides in 200 L of seawater, a typical coprecipitation method requires 2-3 days, but the developed method in this study is achieved the high recovery of actinides within 12 h.

• Journal of Korean Society of Water and Wastewater
• /
• v.31 no.6
• /
• pp.599-609
• /
• 2017

Desalination plants have been recently constructed in many parts of the world due to water scarcity caused by population growth, industrialization and climate change. Most seawater desalination plants are designed with a submarine pipeline for intake and discharge. Submarine pipelines are installed directly on the bottom of the water body if the bottom is sandy and flat. Intake is located on a low-energy shoreline with minimal exposure to beach erosion, heavy storms, typhoons, tsunamis, or strong underwater currents. Typically, HDPE (High Density Polyethylene) pipes are used in such a configuration. Submarine pipelines cause many problems when they are not properly designed; HDPE pipelines can be floated or exposed to strong currents and wind or tidal action. This study examines the optimal design method for the trench depth of pipeline, analysis of on-bottom stability and dilution of the concentrate based on the desalination plant conducted at the Pacific coast of Peru, Chilca. As a result of this study, the submarine pipeline should be trenched at least below 1.8 m. The same direction of pipeline with the main wind is a key factor to achieve economic stability. The concentrate should be discharged as much as high position to yield high dilution rate.