City of Phoenix Department of Water Services Grant for Concentrate Management Research Pilot Project

The City and Sub-Regional Operating Group (SROG) cities (Mesa, Scottsdale, Glendale, and Tempe) own and operate several wastewater treatment plants and water reclamation facilities. The reclaimed water from these facilities is used for beneficial uses such as turf or crop irrigation, cooling water for power plants, groundwater recharge, and indirect potable reuse. The total dissolved solids (TDS) in the reclaimed water (usually above 1,000 mg/L) as well as the concentrations of individual ions adversely impact the reclaimed water reuse potential. High sodium ions may jeopardize discharge permit compliance (e.g., Whole Effluent Toxicity (WET) failure). Advanced desalination technologies are available to address the TDS issues, but they generate a concentrate waste stream that is difficult and expensive to manage.

The City, SROG, and Bureau of Reclamation have been studying salinity issues in Central Arizona as part of the Central Arizona Salinity Study (CASS). CASS developed several concentrate management alternatives, including a “baseline” Zero Liquid Discharge (ZLD) train. The City, SROG, and Reclamation plan to fund a brine minimization demonstration project called the SROG Concentrate Pilot Project to advance the evaluation beyond a paper study and execute a pilot-scale test of cost-effective concentrate management technologies. The SROG Concentrate Pilot Project will use Reverse Osmosis (RO) concentrate from reclaimed water.