Managing Salt in Southern Arizona Water Department of Chemical and Environmental Engineering University of Arizona 04/18/2009 By Justin Nixon, Dr. Robert Arnold and Dr. Wendell Ela

Year Supply (1000s of AF) Incidental Reuse CAP Delivery Renewable Groundwater Water Reuse Total Demand Water Supply/Demand Projections Tucson Active Management Area

Tucson Primary Water Sources Conversion to CAP

Salinity Impact in TAMA Projected TDS levels in TAMA ground waters 5-8 mg/L annual increase Arizona (all sources): 1.0M-1.3M tons/yr TAMA (all sources): 140, ,000 tons/yr TAMA (CAP only): 85, ,000 tons/yr Research Objective: Find cost effective ways to manage salt in inland water supplies.

Reverse Osmosis For Salt Separation Single RO Element RO Treatment Schematic  

Sources of Membrane Scaling *Courtesy of Kevin Alexander, SPI Amount of Water Loss:  163 Billion Gallons per year Value of Water Loss:  $160M/year

Cross-flow Filtration High velocity fluid flow Plate & frame; tubular; spiral- wound cartridge assembly Unknown Causes of membrane scaling during RO treatment of CAP water *(images from eco-tec.com and vsep.com) Unknown Sustainability of brine minimization at % water recovery *(images from vsep.com) V-SEP System Intense shear waves on the face of a membrane Solids and foulants to be lifted off the membrane surface Principles of RO vs VSEP

Q conc Q feed Q perm Semi-permeable membrane During open valve period closed/ open How VSEP Works Series LP (in P Mode): Membrane Area: ft 2 (1.58 m 2 ) Hold-Up Volume: 0.8 gal (3 L) Q feed Q perm Q conc = 0 Semi-permeable membrane During closed valve period

VSEP Results Relationship of closed valve time with water recovery and permeate flux. Permeate flow rate decreases as closed valve time increases Water recovery increases as closed valve time increases

VSEP Results Permeate Flow vs. Water Recovery Tradeoff Between Recovery and Membrane Flux Increased recovery reduces amount of permeate flow rate Must purchase additional V-SEP Machines

Optimization: MF/Ion Exchange / RO / V-SEP in series Permeate0.9 MGD 110 mg/l MGD TS ~ 10% Concentrate Permeate0.098 MGD TDS = TBD 0.1 MGD 6000 mg/l 90% Recovery Brine 98% Recovery RO Unit V-SEP Unit Influent 1 MGD 700 mg/l IX Unit Removal of Barium & Calcium Future Experimental Work

Desalination Research Facility Participating Water Utilities  Slow Sand Filtration  Reverse Osmosis  Concentrate Management

Questions? Acknowledgements  Chris Hill (MDWID)  Mike Dew, Jeff Biggs (City of Tucson)  Martin Yoklic (ERL, U of A)  Dr. Chuck Moody, Eric Holler (BOR)  Dongxu Yan, Bob Seaman, Andrea Corral, James Lykins, Dane Whitmer, Brian McNerney (UA)  Special Thanks to Dr. Wendell Ela, Dr. Robert Arnold, and Dr. Umur Yenal (U of A)

Acknowledgement  Bureau of Reclamation  Tucson Water  Metropolitan Domestic Water Improvement District  Oro Valley Water Utility  Marana Municipal Water Department  Flowing Wells Water District  TRIF/WSP