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MEMBRANE TECHNOLOGIES By Peter S. Cartwright, PE CWQA PROFESIONAL DEVELOPMENT SEMINAR May 4, 2007

Cartwright Consulting Co. United States Office European office 8324 16 th Avenue South President Kennedylaan 94 Minneapolis, MN 55425-1742 2343 GT Oegstgeest Phone: (952) 854-4911 The Netherlands Fax: (952) 854-6964 Phone: 31-71-5154417

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MEMBRANE TECHNOLOGIES By Peter S. Cartwright, PE CWQA PROFESIONAL DEVELOPMENT SEMINAR May 4, 2007

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  1. Cartwright Consulting Co. United States Office European office 8324 16th Avenue South President Kennedylaan 94 Minneapolis, MN 55425-1742 2343 GT Oegstgeest Phone: (952) 854-4911 The Netherlands Fax: (952) 854-6964 Phone: 31-71-5154417 pscartwright@msn.com Fax: 31-71-5156636 www.cartwright-consulting.com MEMBRANE TECHNOLOGIES By Peter S. Cartwright, PE CWQA PROFESIONAL DEVELOPMENT SEMINAR May 4, 2007

  2. Water Contaminants

  3. Filtration Range

  4. Particle Size Yeast Cell = 3.00 microns Bacteria = 0.45 microns Ferric Iron Molecule = 0.001 microns Human Hair ~ 75 microns

  5. Relative Sizes of Particles xxx

  6. Feed Barrier media Permeate or Filtrate Conventional “dead-end” Filtration

  7. Feed Concentrate Membrane Permeate Crossflow Filtration

  8. “Sweeping” by Tangential Flow Concentrate Feed Membrane Permeate

  9. Membrane Separation Technologies Features • Continuous process resulting in automatic and uninterrupted operation • Low energy utilization involving neither phase nor temperature changes • Modular design – no significant size limitations • Minimal moving parts with low maintenance requirements • No effect on form or chemistry of the contaminant • Discrete membrane barrier to ensure physical separation • No chemical addition requirements

  10. Microfiltration

  11. Microfiltration xxx

  12. Ultrafiltration

  13. Ultrafiltration

  14. Nanofiltration

  15. Higher concentration Lower concentration Semi-permeable Membrane Osmosis

  16. Level rises Difference in level is Osmotic Pressure Water Flow Osmosis

  17. Pressure Can force (reverse) osmotic flow to lower-concentration side Semi-permeable Membrane Reverse Osmosis

  18. Pressure Feed Water Concentrate Flow Fresh water Semi-permeable Membrane Reverse Osmosis Applied

  19. Reverse Osmosis xxx

  20. Reverse Osmosis

  21. Reverse Osmosis

  22. Pure Water Layer Theory High Pressure Bulk Solution Pure Water Layer o 7A Membrane Atmospheric Pressure

  23. RO Fundamentals • Semi-permeable membrane uses two mechanisms for removal of impurities: Rejection (repels mineral salts involving dielectric and molecular forces) Sieving (does not allow particulate matter to pass on a small scale ~0.0005 microns. Tiny organics and gas molecules can pass.)

  24. Osmotic Pressure Equation p = 1.19(T + 273) SMi p = Osmotic Pressure (psi) T = Water Temperature (oC) Mi = Molar Concentration of individual ions (gmol/L)

  25. Sodium chloride Lithium chloride Magnesium sulfate Ethylene glycol Ethyl alcohol Zinc sulfate Seawater Fructose Sucrose 500 400 300 Osmotic Pressure (psi) 200 100 0 5 10 15 20 25 30 35 Concentration in Water (w/w %) Solute Concentration as a Function of Osmotic Pressure

  26. RO Performance Equations • Osmotic Pressure: The pressure, due to the effect of TDS in the feed water, that must be overcome in order to generate product water flow. • For monovalent salts, assume 1 psi of osmotic pressure per 100 mg/L of TDS. • For multivalent salts, assume ½ psi of osmotic pressure per 100 mg/L of TDS.

  27. R.O. Contaminant Rejection CTA-Cellulosic Membrane TFC-Thin Film Composite All rejections nominal for 60 psi net pressure and at 77oF

  28. Membrane Comparisons

  29. Membrane Technology Comparison Chart

  30. Membrane Devices

  31. Plate & Frame

  32. Capillary (Hollow) Fiber

  33. Hollow Fiber UF

  34. Tubular

  35. Tubular Membrane Elements

  36. Spiral Wound

  37. Membrane Element Configuration Comparison * Membrane area per unit volume of element ** Tolerance to suspended solids

  38. Feed Permeate Pump Concentrate Membrane Schematic

  39. Concentration Effects x

  40. Concentration Factor vs. Percent Recovery

  41. POU RO Performance Equations • Production Rate: The rate at which product water is made directly from the RO membrane. It is customarily expressed at Standard Operating Conditions (50-60 psi for POU at 77oF) by applying the appropriate conversion factors. • Conversion Factor: ml/min x 0.38 = gal/day

  42. Reverse Osmosis Recovery • Recovery: the percentage of feed water that passes through the membrane as product water. (i.e. how efficiently water is being used to make product water)

  43. Reverse Osmosis Recovery • Example: A membrane is making 10 gallons per day as product, while 40 gallons go to drain. What is the recovery? • Feed Water = product + reject = 10 + 40 = 50 • Recovery = product/feed = 10/50 = 20% • Note: at 50% recovery, reject water TDS is double that of the feed water

  44. Generic POU RO System Flow Diagram

  45. Generic Undersink RO Installation

  46. RO System Controls • Product Water Check Valve: Protects membrane from back pressure. • Automatic Shut-off Valve: Maintains storage tank pressure between ½ to 2/3 feed line pressure. • Brine Flow Restrictor: Maintain reject rinse flow at 3x to 5x product flow; Membrane life and water quality; Prevent water wasting.

  47. Typical Pure Water System

  48. Aerobic MBR Applications

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