R O Intro


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R O Intro

  1. 1. Introduction to Reverse Osmosis
  2. 2. Principle of Reverse Osmosis <ul><li>The phenomenon of osmosis occurs when pure water flows from a dilute saline solution through a membrane into a higher concentrated saline solution. </li></ul><ul><li>The phenomenon of osmosis, a semi permeable membrane is placed between two compartments “Semi permeable” means that the membrane is permeable to some species and not permeable to other. </li></ul><ul><li>Assume that, the membrane is permeable to water, but not salt. </li></ul><ul><li>Place a salt solution in one compartment and pure water in the other compartment. </li></ul><ul><li>The membrane will allow water to permeate through it to other side, But salt cannot pass through the membrane. </li></ul><ul><li>As a fundamental rule of nature, this system will try to reach equilibrium. </li></ul><ul><li>The only possible way to reach equilibrium is for water to pass from the pure water compartment to the salt water compartment. </li></ul><ul><li>The Osmosis can cause a rise in the height of the salt solution. </li></ul><ul><li>This height will increase until the pressure of the column of water (Salt Solution) is so high that the force of this water column stops the water flow . </li></ul><ul><li>The equilibrium point of this water column height in terms of water pressure against the membrane is called Osmotic Pressure. </li></ul><ul><li>If the force applied to this column of water, the direction of water flow through the membrane can be reversed. </li></ul><ul><li>This is the basis of the term reverse osmosis. </li></ul><ul><li>This Reversed flow produced a pure water from the salt solution, Since the membrane is not permeable to salt. </li></ul>
  3. 3. Two Compartments A Semi-permeable membrane Placed in between Concentration Solution in Left side, Dilute Solution in Right Side Dilute Solution Concentrated Solution Pressure Equilibrium Case Applied Force in Concentration Side
  4. 4. How to use Reverse Osmosis <ul><li>With a high pressure pump, Pressurized saline feed water is continuously pumped to the module system. </li></ul><ul><li>With in the module consisting of a pressre vessel (housing) and a membrane element the feed water will be split into a low saline product, Called (Permeate) and high saline brine, Called (Reject). </li></ul><ul><li>A flow regulating valve controls the percentage of feed water that is going to the concentrate stream and the permeate which will be obtained from the feed. </li></ul><ul><li>A pressurized water flows into the vessel and through the channel between the spiral winding of the element. </li></ul><ul><li>Up to seven element are connected together within pressure vessel. </li></ul><ul><li>The feed water becomes more and more concentrated and will enter the next element. </li></ul><ul><li>The permeate of each element will be collected in the common permeate tube installed in the center of each spiral wound element and flows to a permeate collecting pipe outside of the pressure vessel. </li></ul>
  5. 5. Vessel Feed Water Feed Valve Permeate Water Reverse Osmosis Process
  6. 6. Reverse Osmosis Process Recovery (%) = Permeate Flow Feed Flow Salt Passage (%) = Permeate Salt Concentration Feed Salt Concentration Salt Rejection (%) = 100 – Salt Passage
  7. 7. Cross Flow Membrane Filtration <ul><li>There are four categories of cross flow membrane filtration: </li></ul>Micro filtration Ultra filtration Nano filtration Reverse Osmosis
  8. 8. Micro Filtration (MF) <ul><li>Micro filtration removed particles in range of approximately 0.1 to 1 micron. </li></ul><ul><li>Suspended particles and large colloids are rejected while macromolecules and dissolved solids pass through mf. </li></ul><ul><li>Transmembrane pressure are typically 0.7 bar (10 PSI). </li></ul>
  9. 9. Ultra Filtration (UF) <ul><li>Ultra filtration provide macromolecules separation for particles in the 20 to 1000 Angstrom range (Up to 0.1 micron) . </li></ul><ul><li>All dissolved salt ands and smaller molecules pass through the membrane. </li></ul><ul><li>Items rejected by the membrane include collide proteins, microbiological contamination and large organic molecules. </li></ul><ul><li>Transmembrane pressure are typically 1 to 7 bar (15 to 100 PSI). </li></ul>
  10. 10. Nano Filtration (NF) <ul><li>Nanofiltration refers to a specialty membrane process which rejects particles in the approximate size range of 1 nanometer (10 Angstrom). </li></ul><ul><li>Organic molecules with molecular weight greater than 200-400 are rejected, Also dissolved salt are rejected in the range of 20 to 98%, Salts which have movement anions (eg. Sodium Chlorine, Calcium Chlorine), salts with divalent anions (Magnesium Sulfate) have higher rejections of 90 to 98%. </li></ul><ul><li>Typical applications include removal of color and total organic carbon (TOC) from surface water, removal Hardness or radium from well water, Overall reduction of total dissolved solids (TDS) and Separation of organic from inorganic matter specially food and wastewater applications. </li></ul><ul><li>Items rejected by the membrane include collide proteins, microbiological contamination and large organic molecules. </li></ul><ul><li>Transmembrane pressure are typically 3.5 to 16 bar (50 to 225 PSI). </li></ul>
  11. 11. Reverse Osmosis (RO) <ul><li>Reverse Osmosis is the finest level of filtration available. </li></ul><ul><li>The RO membrane acts as a barrier to all dissolved salts and inorganic molecules, as well as organic molecules with a molecular weight greater than approximately 100 water molecular, rejection of dissolved salts in typically 95 – 99 %. </li></ul><ul><li>The application for RO are desalination of sea water recovery, food, beverage processing, biomedical separations, purification of home drinking water and industrial process water </li></ul><ul><li>Reverse osmosis is often used in the production of ultra pure water for use in the semiconductor industry, Power industry (Boiler Feed Water) and medical / laboratory applications. </li></ul><ul><li>Utilizing Reverse osmosis prior to ion exchange (IX) dramatically reduces operating costs and regeneration frequency of the IX system. </li></ul><ul><li>Transmembrane pressure are typically 14 bar (200 PSI) for brackish water, to 69 bar (1000 PSI) for sea water. </li></ul>
  12. 12. Range of filtration Processes Electron Microscopy Optical Microscopy Visible to Naked Eye Human Hair Sand Blood Cells Colloid Proteins / Enzymes Metal ion Bacteria Virus Yeast Cells Oil Emulsions Reverse Osmosis Nano-filtration Ultra-filtration Micro-filtration Particle Filtration Note: 1 Angstrom = 10 -10 Meters = 10 -4 Micron Ionic Range Molecular Range Micro Molecular Micro Particle Range Macro Particle Range 10 -3 10 -2 10 -1 1 10 100 Micrometer 10 10 2 10 3 10 4 10 5 10 6 Angstrom
  13. 13. Factors Influencing With increasing effective pressure The permeate flux will increase Permeate Flux Salt Rejection Pressure The permeate TDS will decrease
  14. 14. Factors Influencing With increasing Temperature The permeate flux will increase Permeate Flux Salt Rejection Temperature The salt passage will increase
  15. 15. Factors Influencing With increasing Recovery ratio The permeate flux will decreasing Permeate Flux Salt Rejection Recovery The salt rejection will decreasing
  16. 16. Factors Influencing With increasing Feed Water Salt Concentration The permeate flux will decreasing Permeate Flux Salt Rejection Feed Concentration The salt rejection will decreasing