SELECTIVE SALT RECOVERY FROM REVERSE OSMOSIS BRINE USING INTER-STAGE ION EXCHANGE

Transcription

1 SELECTIVE SALT RECOVERY FROM REVERSE OSMOSIS BRINE USING INTER-STAGE ION EXCHANGE Joshua E. Goldman PhD Candidate University of New Mexico Kerr y J. Howe Associate Professor University of New Mexico Bruce M. Thomson Regents Professor University of New Mexico

2 ACKNOWLEDGMENTS WateReuse CDM Purolite Kerry Howe Bruce Thomson Mehdi Ali Steve Cabannis Angela Montoya Lana Mitchell ResinTech 2 of 38

3 PRESENTATION OUTLINE Background Project Overview Bench Test Conclusions Pilot Testing Objectives Pilot Testing Results Conclusions 3 of 38

4 CONCENTRATE PRODUCTION RO Fresh Water (Typically 70%-90%) Brackish Well Concentrate (Typically 10%-30%) Concentrate disposal is a big problem in inland areas Expensive Complicated state and EPA regulations depending on constituents in water 4 of 38

5 CONCENTRATE REDUCTION Inter-stage sequential ion exchange Remove ions that form sparingly soluble salts from concentrate Calcium, magnesium, sulfate Replace them with sodium and chloride 2 nd RO stage to treat sodium chloride solution without worrying about scaling 2 nd stage RO concentrate used a regeneration solution for cation and anion exchange columns 5 of 38

6 SALT RECOVERY Calcium carbonate Pulp and paper Building construction (marble floors, roof materials, and roads) Glass (improves chemical durability) Rubber and plastic Paint (extend resin and polymers and control texture) Dietary supplement (antacids) Water treatment (ph control, softening) Calcium sulfate Drywall 6 of 38

7 PROPOSED PROCESS TRAIN Concentrate Reverse Osmosis Stage 1 Stage 1 Permeate 7 of 38

8 PROPOSED PROCESS TRAIN Ca Mg CO 3 SO 4 Concentrate Anion Exchange Reverse Osmosis Stage 1 Cation Exchange Na CO 3 SO 4 Stage 1 Permeate Na Cl 8 of 38

9 PROPOSED PROCESS TRAIN Concentrate Anion Exchange Reverse Osmosis Stage 1 Cation Exchange Stage 1 Permeate Stage 2 Permeate Reverse Osmosis Stage 2 9 of 38

10 PROPOSED PROCESS TRAIN Concentrate Regeneration Anion Exchange Reverse Osmosis Stage 1 Cation Exchange Brine Reservoir Stage 1 Permeate Stage 2 Permeate Reverse Osmosis Stage 2 Waste 10 of 38

11 PROPOSED PROCESS TRAIN Concentrate Regeneration Anion Exchange Reverse Osmosis Stage 1 Cation Exchange Brine Reservoir Stage 1 Permeate Stage 2 Permeate Reverse Osmosis Stage 2 Waste Precipitation Basin 11 of 38

12 PILOT TESTING OBJECTIVES Determine the consistency of the mass and purity of the recovered salt products. Determine the best fraction of the regenerant solution to use for salt recovery. Optimize the operation cycle length to maximize ion concentrations in regeneration solutions and minimize unused cation exchange capacity. Determine if pilot effluent recycle affects the performance of the 2nd stage RO system. Determine the effect of anti-scalant addition on the resin capacity. 12 of 38

13 PILOT SCALE TESTING Outside of Brighton, CO In conjunction with CDM June 6 th July 14 th Continuous operation Average Pilot Feed RO Concentrate mg/l Ca 456 Mg 191 K 17 Na 570 Cl 613 SO TDS 4450 M CO of 38

14 PILOT SCALE TESTING Service Cycle 1-4 Service Cycle 5-6 Service Flow Rate 20 BV 28 BV 10 BV/hr Regeneration Cycle 0.75 BV Rinse Cycle Rinse and Regeneration Flow Rate 1 BV 2 BV/hr 14 of 38

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17 MASS ANALYSIS AND QUANTIFICATION METHODS Tare Erlenmeyer flask Mixed 100 ml of each regeneration solution in flask For low ph prepetition, adjust ph of anion regeneration solution to 4 Allow precipitates to form and settle for 36 hours. Separate liquid and solid by centrifuge Dry in the lab oven at 104 C for 24 hours Mass of flask - tared mass = precipitate mass Analyze precipitated solid by SEM, EDS, XRD 17 of 38

18 ph VISUAL MINTEQ MODELING M Ca 1 M SO 4 1 M CO 3 Calcite Gypsum Saturation Index 18 of 38

19 % Composition (Atomic) % Composition (Atomic) PURE CALCIUM CARBONATE C O Na Mg P S Cl Ca Sr C O Ca 19 of 38

20 % Composition (Atomic) PURE CALCIUM SULFATE O Na Mg Si S Cl Ca 2 O Na Mg P S Cl Ca Sr O S Ca 20 of 38

21 MASS ANALYSIS RESULTS Ambient ph Representative Sample Low ph 21 of 38

22 MASS ANALYSIS RESULTS - XRD Spectra Identified as CaCO 3 Ambient ph precipitate from Weeks 2-4 Spectra Identified as CaSO 4 Low ph precipitate from Weeks 3,4,6 Ambient ph precipitate from Week 6 Other Spectra Identified Halite (NaCl) Week 2 Ambient ph Week 4 Low ph 22 of 38

23 CONCLUSIONS FROM MASS ANALYSIS Calcium sulfate and calcium carbonate can be precipitated separately Low ph mixing conditions - calcium sulfate Ambient ph mixing conditions calcium carbonate Except for Week 6 23 of 38

24 kg Precipitate per m3 RO Concentrate MASS QUANTIFICATION RESULTS Ambient ph Low ph Week 1 Week 2 Week 3 Week 4 Week 5 Week of 38

25 MASS QUANTIFICATION CONCLUSIONS Salts precipitate spontaneously when the regeneration solutions are mixed Possible to precipitate approximately 12 kg of gypsum per cubic meter of regeneration solution Approximately 45% of the calcium is recovered Approximately 28% of the sulfate is recovered 25 of 38

26 Concentration (C/Cmax) METHOD TO DETERMINE BEST PORTION OF REGENERATION SOLUTION Regeneration and rinse cycles total 1.75 BV Results from column tests showed sharp regeneration curves Effluent samples taken every 5 minutes (0.17 BV) Anion column - conductivity and total carbonate Cation column - conductivity and calcium BV 26 of 38

27 C/Cmax C/Cmax PILOT ELUTION CURVES SBA SAC Conductivity TotCO3 Conductivity Ca Bed Volumes Bed Volumes 27 of 38

28 kg Precipitate per m3 RO Concentrate RESULTS ION CONCENTRATION AND SALT YIELD 0.35 Significant increase in ion concentrations 5.8x increase in salt yield per unit treated RO concentrate Increased total recovery of total Ca and SO 4 in system from 5% to 20% Ambient Low Week 5 Week 6 Ca Mg SO4 NO3 CO3 Week mg/l mg/l mg/l mg/l M CF of 38

29 OPTIMIZATION OF OPERATION CYCLE Constructed breakthrough curve Started at end of standard operation cycle (20 BV) Grabbed samples of SBA and SAC effluent Sample taken every 2 BV (12 minutes) 29 of 38

30 C/Cin BREAKTHROUGH CURVE CO3 Ca Mg SO Bed Volumes Started taking samples at end of standard regeneration and rinse cycle Extended cycle to point just before magnesium breakthrough (28 BV) 30 of 38

31 Resin Phase Ionic Ratio OPTIMIZED OPERATION CYCLE Week 2 Week 5 Increase in Ratio Ca:Mg 1.3x 15 SO4:CO3 2.7x 10 5 SO4:NO3 2.4x 0 Ca:Mg SO4:CO3 SO4:NO3 Ca Mg NO3 SO4 CO3 mg/l mg/l mg/l mg/l M Week Week of 38

32 Predicted α Ca/Na OVERALL CONCLUSIONS Separation factors can be predicted based on solution characteristics Measured α Ca/Na 32 of 38

33 Calculated Number of BV to Breakthrough OVERALL CONCLUSIONS Column performance well predicted by separation factor regressions and modeling Measured Number of BV to Breakthrough 33 of 38

34 OVERALL CONCLUSIONS Gypsum can be spontaneously precipitated from mixed cation and anion regeneration solutions Lab and pilot tests Requires ph adjustment when system not optimized for sulfate recovery Can recover 45% of calcium and 28% of sulfate from the mixed solution 15% of total possible gypsum recovered from RO concentrate stream For a 5 MGD plant 6 tons/day of gypsum could be recovered 34 of 38

35 OVERALL CONCLUSIONS Process has potential to improve RO recovery and to generate to gypsum 35 of 38

36 REFERENCES Committee on Advancing Desalination Technology, N.R.C., Desalination: A National Perspective. 2008: National Academies Press. Jordahl, J., Beneficial and Non Traditional Uses of Concentrate. 2006, WateReuse Foundation. Zagorodni, A.A., Ion exchange materials : properties and applications. 2007, Amsterdam; London: Elsevier. Harland, C.E., Ion exchange: theory and practice. 2 ed. Monographs for teachers. Vol : Royal Society of Chemistry paperbacks Crittenden, J. and Montgomery Watson Harza (Firm), Water treatment principles and design. 2nd ed. 2005, Hoboken, N.J.: J. Wiley. xx, 1948 p. Helfferich, F.G., Ion exchange. 1962, New York: McGraw-Hill.Howe, K., Class Notes. 2009, University of New Mexico. Marton, A. and J. Inczédy, Application of the concentrated electrolyte solution model in the evaluation of ion exchange equilibria. Reactive Polymers, Ion Exchangers, Sorbents, (2-3): p Muraviev, D., J. Noguerol, and M. Valiente, Separation and concentration of calcium and magnesium from sea water by carboxylic resins with temperature-induced selectivity. Reactive and Functional Polymers, (2): p MATSUSAKI, K., Selectivity of Anion Exchange Resin Modified with Anionic Polyelectrolyte. Analytical Sciences, (3). Amara, M. and H. Kerdjoudj, Modification of the cation exchange resin properties by impregnation in polyethyleneimine solutions: Application to the separation of metallic ions. Talanta, (5): p Marina, M.L., et al., Ion exchange in concentrated media. Correlations for variation of selectivity coefficients with medium. Reactive Polymers, (3): p Christensen, S.G. and K. Thomsen, Experimental measurement and modeling of the distribution of solvent and ions between an aqueous phase and an ion exchange resin. Fluid Phase Equilibria, : p Ostroski, I.C., et al., Mass transfer mechanism of ion exchange in fixed bed columns. Journal of Chemical and Engineering Data, (3): p Mehablia, M.A., D.C. Shallcross, and G.W. Stevens, Prediction of multicomponent ion exchange equilibria. Chemical Engineering Science, (14): p Vo, B.S. and D.C. Shallcross, Multi-Component Ion Exchange Equilibria Prediction. Chemical Engineering Research and Design, (10): p Melis, S., et al., Multicomponent equilibria on ion-exchange resins. Fluid Phase Equilibria, (1-2): p Letterman, R.D. and American Water Works Association., Water quality and treatment : a handbook of community water supplies. 5th ed. 1999, New York: McGraw-Hill. 1 v. (various pagings) (9): p of 38

37 REFERENCES Wilson, D.J., Modeling of Ion-Exchange Column Operation. I. Equilibrium Model for Univalent-Divalent Exchange, in Separation Science and Technology. 1986, Taylor & Francis. p Bromley, L.A., Thermodynamic properties of strong electrolytes in aqueous solutions. AIChE Journal, (2): p Wilson, G.M., Vapor-Liquid Equilibrium. XI. A New Expression for the Excess Free Energy of Mixing. Journal of the American Chemical Society, (2): p Nakamura, K., et al., A Prediction Method for the Breakthrough Curve in the Column Packed with H, Na, NH4 form Ion Exchange Resins. JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, (6): p Borba, C.E., et al., Application of the mass action law to describe ion exchange equilibrium in a fixed-bed column. Chemical Engineering Journal, (1): p Hendricks, D.W., Water treatment unit processes: physical and chemical. Civil and Environmental Engineering. 2006: CRC Press Rahardianto, A., et al., High recovery membrane desalting of low-salinity brackish water: Integration of accelerated precipitation softening with membrane RO. Journal of Membrane Science, (1-2): p Benjamin, M.M., Water chemistry. McGraw-Hill series in water resources and environmental engineering. 2002, Boston: McGraw-Hill. Wang, L.K., Membrane and desalination technologies. 2011, New York, NY: Humana Press. Gabelich, C.J., et al., High-recovery reverse osmosis desalination using intermediate chemical demineralization. Journal of Membrane Science, (1-2): p Ahmed, M., et al., Feasibility of salt production from inland RO desalination plant reject brine: A case study. Desalination, (1-3): p Heijman, S.G.J., et al., Zero liquid discharge: Heading for 99% recovery in nanofiltration and reverse osmosis. Desalination, (1-3): p Fogler, H.S., Elements of chemical reaction engineering. 1999: Prentice Hall PTR. Levenspiel, O., Chemical reaction engineering; an introduction to the design of chemical reactors. 1962, New York: Wiley. Antony, A., et al., Scale formation and control in high pressure membrane water treatment systems: A review. Journal of Membrane Science, (1-2): p Jasbir S, G., A novel inhibitor for scale control in water desalination. Desalination, (1-3): p Greenlee, L.F., et al., The effect of antiscalant addition on calcium carbonate precipitation for a simplified synthetic brackish water reverse osmosis concentrate. Water Research, 37 of 38

38 QUESTIONS??? 38 of 38