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The most commonly used Thin-Film Composite (TF) is three-layered.
The reverse osmosis membrane is composed of Polyester Support Web (120Л), Microporous Polysulfone Interlayer (40Л), and Ultra thin barrier layer (0.2Л) made of Polyamide. It is a membrane to separate a solute (salt) from a solvent (water) using the reverse osmosis.
When solutions with different concentrations are separated by the semi-permeable membrane, it is found that the solvent (water) of lower concentration solution moves to the solution with higher concentration after some time, which leads to a difference in water levels. It is not that the solution itself goes through the membrane. The semi-permeable membrane prevents the solute (salt, ion, etc.) from passing through but, lets the solvent (water) pass. Examples include cell walls and kidney dialysis.
When the semi-permeable membrane separates two solutions with different concentrations, the solutions move to have equal concentrations. In such case, the membrane does not let the solute move through while the solvent (water) passes through the membrane to homogenize the concentrations.
The phenomenon is called osmosis and the difference in water level is osmotic pressure.
The reverse osmosis is the opposite movement of solvents from higher concentration solution to lower concentration solution when a higher pressure than the osmotic pressure is applied to the higher concentration solution. The solute (salt, ion, etc.) in higher concentration solution cannot move through the semi-permeable membrane while the solvent passes through the membrane toward the lower concentration solution, further increasing the concentration of higher concentration solution.
The system using this reverse osmosis is called reverse osmosis facility.
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| Types of reverse osmotic membranes
The membranes are classified by material and structure. When applying in the field, the characteristics of membrane material and structure shall be thoroughly studied.
⒑ Classification by material
Membrane materials include Cellulose Acetate (CA), Polyamide (PA), Polysulfonate, etc.
CA and PA membranes are most common.
1) CA(Cellulose Acetate) membrane - Asymmetric Membrane
2) PA(Polyamide) membrane - Composite Membrane
⒑ Classification by type
1) SPRIAL-WOUND MODULES
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| 2) HOLLOW-FIBER MODULES |
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| 3) PLATE-AND-FRAME MODULES |
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| 3) PLATE-AND-FRAME MODULES |
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1) Inorganic matters are easier to separate than organic matters.
2) Electrolyte is easier to separate than nonelectrolyte.
3) For electrolyte, the higher electric charge the higher the separability.
(+3 ion > +2 ion > +1 ion)
4) The removal rates of inorganic ions depend on ion-specific hydration water and the radius of hydration water ion. The bigger water ion can be more easily removed.
Cation: Mg+2 > Li+ > Na+ > K+
Anion: F- > Cl- > Br- > NO3-
5) For nonelectrolyte, the bigger the molecule, the more easily removed.
6) Gas flames are easily permeable to the membrane and removal rates of ammonium, chloride, carbon dioxide, oxygen and hydrogen sulfide are low.
7) The removal rate of weak acid is low. The removal rate of citric acid is the highest, followed by tartaric acid. Acetate acid has the lowest removal rate among the three acids.
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1) Water treatment
Seawater Desalination, Brackish Water Desalination, Pretreatment of portable water, Desalination, Ultra pure water production
2) Dairy, Fisheries and Husbandry
Retrieval of lactose from Cheese Whey, Separation of amino acid from fish processing wastewater
3) Food processing
Treatment of bean whey wastewater, enrichment of vegetable and fruit juice, winery, refinement and enrichment of sugar water, treatment of wastewater for starch processing facilities, enrichment of coffee extracts
4) Medical supplies industry
Removal of Pyrogen, enrichment and refinement of herbal medicine, manufacturing of medical and pharmaceutical water
5) Chemical industry
Treatment of wastewater for petrochemical facilities, retrieval of effective elements from photo development discharge water, retrieval of lignin from pulp wastewater
6) Textile and dye industries
Retrieval of dyes from wastewater
7) Surface treatment and machinery industries
Treatment of metal-containing wastewater, retrieval of aluminum Electrodeposition paints, retrieval of effective metals from paint wastewater
8) Water treatment and discharge water treatment
Treatment of sewage and discharge water from buildings, treatment of ion exchange recycle wastewater, wastewater of radioactive laundry, treatment of discharged water from hospitals and research centers
⒚ Factors and their handling that damage the membrane Note) Please contact the Engineering Department for the detailed information on "Factors and their handling that damage the membrane".
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| ⒑ Comparison of 1st R/O with 2nd R/O |
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1'st
R/O |
2'nd
R/O |
| Main Purpose |
Ion Removal |
TOC, Particle Removal |
| Feed Water TDS |
50~500ppm |
0.1~10ppm |
| Feed Water SDI |
3~5 |
0.5~3 |
| Recovery |
~75% |
~90% |
| CIP Period |
2~6 Times/Year |
1 Time/Year |
| Sterilization Method |
NaClO, Chloramine T |
H2O2,
UV |
| Operation Factor |
Product Flowrate
Operating Pressure
Ion Rejection |
Product Flowrate
Operating Pressure
TOC, Particle Rejection |
| Membrane Type |
Low Pressure TF
Medium Pressure
Fouling-Resistant Membrane |
Low Pressure TF
High rejection Membrane
Semiconductor-Grade Membrane |
| Applications |
Purification, desalinization of sea water, advanced treatment of leachate
Reclamation and reusing of wastewater, pretreatment system of demineralized water, |
Second desalinization of demineralized water, ultra pure water and leachate |
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| ⒑ 1'st
R/O |
| · |
KOReD has adopted the cost-effective design for its Reverse Osmosis units which is highly effective in removing ionized matters, the main function of 1st R/O. The company has design and construction records in various sectors including purification system, pretreatment system of demineralized water and ultra pure water, reusing of wastewater and advanced treatment of leachate. |
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| ⒑ 2'nd
R/O |
| · |
The main function of 2nd R/O is to eliminate TOC and particles. The company offers designing and construction services for optimized R/O units, backed by ample field experiences.
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To eliminate TOC and particles in the demineralized and ultra pure water processes |
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| ⒑ 2
Pass R/O |
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The benefit of 2 Pass R/O is to construct 1st & 2nd R/O Units at low cost.
It requires extra care for designing and construction compared with 1 Pass R/O Unit. KOReD has know-how and technology in designing, manufacturing, and operation. It has a variety of track records in the cost-effective construction of R/O units.
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Major components of demineralized water and ultra pure water systems |
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