1. Concentrate and permeate treatment processes for improving the sustainability of inland brackish water desalination W. Shane Walker, Ph.D. Anthony Tarquin, Ph.D. Center for Inland Desalination Systems The University of Texas at El Paso Multi-State Salinity Coalition Summit Las Vegas, Nevada January 26, 2012

2. Objectives Review indicators of sustainability Highlight several CIDS investigations demonstrating improved sustainability

3. Sustainability Environmental Economic Socio- Political

4. Environmental Economic Socio- Political Select Sustainability Indicators Higher water recovery (product/feed) Lower specific energy consumption (kWh/kgal) Less chemical consumption, waste production Lower economic cost ($/kgal; $/MGD) Technical/operational complexity

5. Inland Membrane Desalination Brackish Water Source pretreatment membrane process concentrate treatment permeate treatment Distribution Reuse/Disposal

6. Permeate Treatment Brackish Water Source pretreatment membrane process concentrate treatment permeate treatment Distribution Disposal

7. Permeate Stabilization by Calcite Three-step process 1.Lower pH with CO 2 – Relatively abundant and inexpensive gas 2.CO 2 reacts with calcite – CO 2 + CaCO 3 → Ca 2+ + 2 HCO 3- 3.Add small dose of base for LSI > 0 Carollo Engineers, Inc. and Shane Walker, UTEP Texas Water Development Board (1004831105)

8. Permeate Stabilization by Calcite Feed: KBH permeate TOMCO 2 : pH 5.6-5.7 Upflow calcite contactor – Media: 0.5-2 mm particles – EBCT: 1-10 min – Overflow: 2-17 gal/ft 2 /min Product Quality: – pH: 7.5-8.5 – Ca 2+ : 20-30 mg/L – ALK: 50-75 mg/L (as CaCO 3 ) – LSI: -0.5-0.0 Energy: < 0.1 kWh/kgal Carollo Engineers, Inc. and Shane Walker, UTEP CIDS Texas Water Development Board (1004831105)

9. Concentrate Treatment Brackish Water Source pretreatment membrane process concentrate treatment permeate treatment Distribution Disposal

10. CERRO Anthony Tarquin, UTEP US Bureau of Reclamation, DWPR R10AP81217 concentrate Seawater RO Distribution Concentrate Enhanced Recovery RO (CERRO) Batch-continuous seawater RO process exploiting induction time of precipitation

11. CERRO Demonstrated at KBH (El Paso) and BGNDRF (Alamogordo) Feed: KBH- >10,000 mg/L BGNDRF- 6000 mg/L Product Flow: 1 gpm Recovery: KBH- 97% BGNDRF (ongoing) Energy: 6-7 kWh/kgal (w/ energy recovery) Anthony Tarquin, UTEP US Bureau of Reclamation, DWPR R10AP81217

12. Zero Discharge Desalination (ZDD) Demonstrated at KBH (El Paso) and BGNDRF (Alamogordo) BGNDRF Feed: 2500 mg/L NF/RO and Electrodialysis Metathesis (EDM) Product Flow: 20 gpm Recovery: 97-98% Energy: 6.6 kWh/kgal Tom Davis & Malynda Cappelle, UTEP US Bureau of Reclamation, DWPR R10AP81212

13. Conclusions Sustainability of inland brackish water desalination can be improved by: – increasing system recovery – reducing specific energy consumption – reducing chemical consumption and production – reducing economic cost – designing appropriate technical complexity

14. Acknowledgements Permeate Stabilization by Calcite – Texas Water Development Board – El Paso Water Utilities, KBH Desalination Plant – Carollo Engineers: Winnie Shih, Bradley Sessions, Justin Sutherland – UTEP CIDS: Luis Maldonado, Cora Martinez, Sami Al-Haddad CERRO (High Recovery) – US Bureau of Reclamation, BGNDRF (Alamogordo, NM) – UTEP CIDS: Anthony Tarquin, Guillermo Delgado ZDD (High Recovery) – US Bureau of Reclamation, BGNDRF (Alamogordo, NM) – UTEP CIDS: Tom Davis, Malynda Cappelle, Lucy Camacho, Noe Ortega, Jesse Valles

15. Questions or Comments W. Shane Walker, Ph.D. Assistant Professor The University of Texas at El Paso 500 W. University Ave., Civil Engineering El Paso, TX 79968 (915) 747-8729 wswalker2@utep.edu