1. MEMBRANE TECHNOLOGY FOR WATER TREATMENT D. JAGAN MOHAN New Technology Research Centre University of West Bohemia Plzen, Czech Republic

2. Fresh Water Need..

3. 0.00010.0010.010.1110 100  m hair Crypto- sporidium smallest micro- organism polio virus Suspended solids Parasites Bacteria Org. macro. molecules Viruses ColloidsColloids Dissolved salts Sand filtration Microfiltration Ultrafiltration Nanofiltration Reverse Osmosis Membranes for Water Treatment

4. Asymmetric. In a cross section, one can see two different structures, a thin dense layer and below a porous support layer. Symmetric. A cross section shows a uniform porous structure. Integral: the layers are continuous. Composites: the active layer (thickness 0.1-1 μm) is supported over a highly porous layer (50-150 μm), sometimes both layers are of different materials. Membrane Separations

5. The cross section shows a uniform and regular structure SurfaceCross section Symmetric ceramic membrane (Al 2 O 3 ) Symmetric Membranes

6. Polysulfone support PA membrane surface Polyester Fabric Thin Film Polyamide Membrane

7. top layer thickness (0.1-1  m) sub layer thickness (50-150  m) The flux is inversely proportional to the thickness. commercial interest Pore Geometry

8. PS Support PA Layer PS Support PA Layer

9. Cross-Flow Feed Water Semipermeable Membrane (~0.2 micrometers) Asymmetric CA Membrane Porous Interior (~0.5 mm thick) Flux Permeate

10. Aqueous Phase Organic Phase (Heptane, etc.) N NH 2 COCl C H O + HCl Reaction + Acid Chloride COCl Random Structure Cross-Link or Extension Diffusion NH 2 Di-Functional Amine +

11. Polyamide (~100 nm) NHCO NH 2 CONHNHCO CONHCOOH Pressurized feed Amine group Carboxylic group Amide link Functional groups in the active layer

12. Reverse osmosis (RO) Support Layer (Polysulfone) Selective barrier (polyamide) ~150 nm

13. Catalytic Membrane Materials... PA Layer Polyester Support Porous PS Pure water N-N CH 3 = O Catalyst(s) (Pd, PEIs, etc.)

14. Charged membranes Positively charged membrane +++++ + +++++ Na + Ca ++ SO 4 -- Cl - ------ ------ Na + Ca ++ SO 4 -- Negatively charged membrane Quaternary ammonium groups like -N + (CH 3 ) 4 Cl - contribute to the fixed positive charge of the membrane Negatively charged groups like SO 3 H +, COOH groups contribute to the negative charge of the membranes

15. Feed Retinate (Concentrate) Permeate (Filtrate) Membrane Membrane Separations Simple scheme of a membrane module CpCp CfCf Rejection :

16. Crossflow Mode Feed Recirculation Filtrate Membrane Concentrate Pump

17. Feed Pump Membrane Filtrate Dead End Mode

18. Materials Used Synthetic polymeric membranes Hydrophobic Hydrophilic PTFE, teflon PVDF PP PE Cellulose esters PSF/PES PI/PEI PA PEEK Ceramic membranes Alumina, Al 2 O 3 Zirconia, ZrO 2 Titania, TiO 2 Silicium Carbide, SiC

19. 1. Bio-organic Fouling The Issues... Molecular Adsorption 2. Physico-Chemical Integrity De-lamination PA PS  Flux loss  Solute passage

20.  Membrane fouling is referred to as the deposition or adsorption of the particles contained in the feed stream on the membrane surface or in the membrane pores  This gel layer forms a secondary barrier to flow through the membrane  Membrane fouling has a negative impact on filtration performance as it decreases the permeate flux ↓ flux ↓ membrane life ↑ energy use Membrane Fouling Schematics of membrane fouling mechanisms: (A) pore blockage, (B) pore constriction, (C) intermediate blockage and (D) cake filtration.

21. Physical/chemical/biological plugging of membranes by inorganic salts, dissolved organic matters, colloids, bacteria, etc. Affects permeate water quality Increases operational burden and cost Reduces permeate water flux Reduces feed water recovery Damages membranes Membrane Fouling

22. Membrane Cleaning chemicals (if needed) Filtrate Tank Cleaning in Backwash mode

23. Cleaning in Forward Flush mode Pump Feed Membrane Concentrate

24. Structure-related parameters (pore size, pore size distribution, top layer thickness, surface porosity) Permeation-related parameters (actual separation parameters using solutes that are more or less retained by the membranes - ‘cut-off’ measurements * ) Instruments : SEM, TEM, GPC, DMA, bubble point method, porosimetry, AFM, IR (structural determination) etc. * ‘cut-off’ is defined as the molecular weight which is 90% rejected by the membrane Characterization of membrane

25. Membrane Configurations

27. 1. Waste-water treatment 2. Clarification of fruit juice, wine and beer 3. Ultrapure water in the semiconductor industry 4. Metal recovery as colloidal oxides or hydroxides 5. Cold sterilization of beverages and pharmaceuticals 6. Medical applications: transfusion filter set, purification of surgical water 7. Continuous fermentation 8. Purification of condensed water at nuclear plants 9. Separation of oil-water emulsions Some Industrial Applications