The Theory of Reverse Osmosis (RO)


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This presentation talks about the first commercial membranes starting in the 1960's and then moves on to discuss how membranes work and the processes required to clean them.

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The Theory of Reverse Osmosis (RO)

  1. 1. aslan Theory of Reverse OsmosisTheory of Reverse Osmosis MembranesMembranes  Dilute Solution Concentrated Solution Osmotic Pressure Dilute Solution Concentrated Solution Pressure RO Membrane RO Membrane
  2. 2. aslan Types of Reverse OsmosisTypes of Reverse Osmosis MembranesMembranes  First commercially available membrane wasFirst commercially available membrane was an asymmetric Cellulose Acetate (CA)an asymmetric Cellulose Acetate (CA) membrane (early 60’s)membrane (early 60’s) Thin film composite (TFC) polyamideThin film composite (TFC) polyamide membranes were an improvement on themembranes were an improvement on the original CA membranesoriginal CA membranes
  3. 3. aslan TFC vs. CA MembranesTFC vs. CA Membranes  Wider pH range 2 to 12 vs. 4 to 6Wider pH range 2 to 12 vs. 4 to 6 Lower operating pressure (1/2)Lower operating pressure (1/2) Higher rejections 99% vs. 96%Higher rejections 99% vs. 96% CA more resistant to chlorineCA more resistant to chlorine
  4. 4. aslan Feed Water ConsiderationsFeed Water Considerations  Scaling PotentialScaling Potential - Sparingly soluble compounds (CaCO- Sparingly soluble compounds (CaCO33,, Fe(OH)Fe(OH)33)) - Alkalinity- Alkalinity Silt Density Index (SDI)Silt Density Index (SDI) TurbidityTurbidity Biological foulingBiological fouling pHpH
  5. 5. aslan Prevention of Scale FormationPrevention of Scale Formation  Acid additionAcid addition Reduction of recoveryReduction of recovery Scale inhibitor additionScale inhibitor addition SofteningSoftening Preventative cleaningPreventative cleaning
  6. 6. aslan SDI and Turbidity ReductionSDI and Turbidity Reduction  Media filtrationMedia filtration Cartridge filtrationCartridge filtration Coagulant addition prior to coarse filtrationCoagulant addition prior to coarse filtration UltrafiltrationUltrafiltration
  7. 7. aslan Biological FoulingBiological Fouling  Chlorine additionChlorine addition OzoneOzone DechlorinationDechlorination – Activated carbonActivated carbon – Sodium MetabisulfiteSodium Metabisulfite
  8. 8. aslan System DesignSystem Design  Feed water analysisFeed water analysis Product water requirementsProduct water requirements Required flowRequired flow Materials of constructionMaterials of construction Level of instrumentationLevel of instrumentation
  9. 9. aslan Typical Flow SchematicTypical Flow Schematic  RO Membrane RO Membrane From Pressurized Treated Water Storage (if using a repressurization pump. Plug connection if using a bladder tank for storage) LPS 01 LPS - Low Pressure Switch P I - Pressure Indicator F I - Flow Indicator To Treated Water Storage Water to be Treated P I 03 SP7500 - 1 Membrane installed SP15000 - 2 Membranes installed SP22500 - 3 Membranes installed FI 01 FI 02 FI 03 P1 V3 V4 CV3 SV1 PI 02 CV2 CV1 Set @ 50 psi CV4 CV5 SP2 SP1 230 VAC, 20A, 1Ø 2 lines, Neutral & GND SP Series with NF membranes 1.5 Hp SP Series with RO membranes 2 Hp Signal From Pressure or Level Switches Control Panel V5 CV7 CV6 SV2 * * Signal from feed tank can be substitued SV3 V1 SP3 P I 04 PI 01 5044 South Service Rd., Burlington, Ontario, Canada L7L 5Y7 Tel: (905) 632-4968 Fax: (905) 632-6730 Scale: Project : Drawing # Drawn by: Rev # Dat e: THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION. DO NOT COPY WITHOUT PRIOR WRITTEN APPROVAL FROM ASLAN TECHNOLOGIES. aslanTECHNOLOGIES Designed by: Approved: File Name:Rev Description By Date None 970501 99289 MM CW 99289I02 3System P&ID SP Series Reverse Osmosis System 990904MMGeneral revisions1 001203MMAs built2 010217MMProper indication of SP3 location3
  10. 10. aslan System Operation & MaintenanceSystem Operation & Maintenance  Verification of pretreatment functionalityVerification of pretreatment functionality Setup of proper system flow dynamicsSetup of proper system flow dynamics Log operational dataLog operational data Normalize dataNormalize data Perform cleanings and maintenance asPerform cleanings and maintenance as requiredrequired