Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

‣ Thermal Multiple Effect Distillation (MED) Multistage Flash (MSF) Vapor compression (thermal and mechanical) Solar ‣ Electrodialysis/ Electrodialysis reversal ‣ Reverse Osmosis RO membrane and process basics Scaling and biofouling Energy recovery - Pelton wheels, turbines, work exchangers New RO process configurations Post-treatment - remineralization Boron removal 3

4 High value Industrial, medical Human consumption Livestock, agriculture Saline (brackish, seawater, brine) Use, reuse Energy $$ Recycle, desalinate Cost of recycling < economic value of the water?

5 Salinity Levels: Seawater: ~35 g/L (0.6 M) Brackish: ~1-5 g/L (0.08 M) Potable: <0.5 g/L (0.008 M) ‣ chemicals that dissolve in water to form ions: NaCl -> Na + + Cl - CaSO 4 -> Ca +2 + SO 4 -2 ‣ measures: concentration = mol/liter (M)1 mol = 1 molecular weight in grams e.g. NaCl = = 58 g weight % or ppm = weight solute/weight of water e.g. 1 M NaCl = 58 g NaCl / 1000 g H 2 O = 5.8% = ppm What else is in water? dissolved non-ionic species (SiO 2 ) dissolved organic compounds (polymers, drugs, biological materials, bacteria, viruses, etc.) suspended solids (particles, colloids)

6 Na Cl HCO 3 Ca SO 4 Mg Seawater 35,000 mg/L TDS Brackish Water 2,500 mg/L TDS Seawater and Brackish Water are very Different

7 Taweelah, UAE mgd steam in fresh water saline feed condensate concentrate disposal vapor Energy required to boil (or freeze) water: C p = 4 kJ kg -1 deg -1  H vap = 2500 kJ kg -1  H fus = 323 kJ kg -1 large amount of energy necessary for phase change heat recovery essential typical energy use ~250 kJ kg -1 (conc. independent) distillation only makes sense if energy is cheap (Middle East) and salt conc. is high (seawater) freezing processes have slight advantage Flash evaporation Note: theoretical minimum energy required to extract fresh water = 3 kJ/kg! Thermal Processes: Phase Change

8 Source : IDA Freshwater outside tube bundle Multistage Flash Distillation : MSF

9 Source: IDA Freshwater inside tube bundle

10 Freshwater inside tube bundle

11

12 MSF RO MSF World GCC (46% of total) Source-1998 IDA Inventory Tampa Bay, Florida Jubail, Saudi Arabia

13 major application is in chlor-alkali process energy use = I 2 R; ~5-10 kJ kg -1 (conc. dependent) chemical stability, electrical resistance of membrane is crucial selective membranes for specific ions possible Ion exchange membranes: polyelectrolytes CH 2 CH CH 2 CH R-A+R-A+ R-A+R-A+ CH 2 CH CH 2 CH R+A-R+A- R+A-R+A- R = -SO 3 - -COO - R = -NR 3 + cation exchange anion exchange

14 The Membrane Separation Spectrum Essentially non porous Source: Perry’s Chemical Engineers Handbook

15 Tampa Bay Water - 25 mgd saline feed pre- treatment high pressure pump post- treatment fresh water concentrate disposal membrane energy use (pump) ~ 10 – 50 kJ kg -1 concentration dependent energy recovery essential for seawater RO membranes susceptible to fouling; pre-treatment required polyamide membranes degraded by Cl 2 dense polyamide membrane porous polymer mechanical support Thin film composite membrane polyamide

16 wowo P ww pure saline membrane seawater brackish water Applied external pressure: pure saline P <  P >  P = 

17 RO-MembraneGFD Salt Conc mg/L pressure psig recovery % Cl reject % Filmtec SW30HR Koch TFC-SSHR SWRO Hydranautics SWC Toray SWRO TM820H GFD = gallons / ft 2 -day Source: manufacturers information Modern RO Membranes Reject Over 99% of Salt

18 Typical RO Installation: Multiple Spiral Wound Modules in Series

19 Fouled RO membrane ‣ Large problem in the RO industry ‣ Fouling causes increased energy consumption, lower product output, shorter membrane life → higher cost Courtesy: Tom Mayer Sandia National laboratories

20 The waste stream is at high pressure and therefore has useful energy

21 TurboCharger Pelton Wheel

22 DWEERERI

23 DWEERERI

24 ‣ NF/NF - The Long Beach Method ‣ RO/RO - SWCC ‣ NF/RO - SWCC ‣ RO/RO – Brine Conversion ‣ RO/RO – Three Stage Cascade

25 NF Recovery Recovery (%) Pressure (psi) TDS feed (mg/L) TDS perm (mg/L) NF Permeate Brine

26 RO-RO Treatment at SWCC RO Recovery Recovery (%) Pressure (psi) TDS feed (mg/L) TDS perm (mg/L) Desalination 184 (2005) Permeate Brine RO

27 NFRORecovery Recovery (%) Pressure (psi) TDS feed (mg/L) TDS perm (mg/L) Desalination 184 (2005) Permeate Brine NF RO

28 RO Recovery Recovery (%) Pressure (psi) TDS feed (mg/L) TDS perm (mg/L) Journal of Membrane Science 183 (2001) 249–257 Permeate Brine RO

29 NF RO Recovery Pressure TDS feed TDS perm % 60% 26% 37% Brine Conversion

30 Desalination 165 (2004) ‣ Desalinated water is corrosive – has little buffering Langelier index (LI) Ryznar index (RI) Saturation index (SI) ‣ It is tasteless – need calcium and bicarbonates ‣ It may be unusable for irrigation : Sodium absorption ration (SAR) SAR = [Na + ] / {{[Ca +2 ][Mg +2 ]}/2} 0.5

31 ‣ Filtration Pass RO permeate across CaCO 3, CaCO 3 /MgCO 3 and CO 2 injection Next inject Na 2 CO 3 to increase saturation index (LSI) to 1.2 (slightly scaling) ‣ Injection Na 2 CO 3, NaHCO 3, CaCl 2, Ca(OH) 2 Next inject CO 2 CO 2 stripping is not usually practiced

32 Increasing temperature decreases boron rejection as well. Especially important for seawater permeate Desalination 223 (2008) 10–16) Dissociation at high pH leads to Boron rejection. Boron affects citrus Source: Univ of Florida

33  Introduction to Membrane Design Software  ROSA – available at