Evaluation of Reverse Osmosis Scaling Prevention Devices at High Recovery
USBR; Denver, CO and Yuma, AZ, Burns and Roe Services Corporation; Yuma AZ.
Report #91 - Abstract -
This study evaluated the effectiveness of a magnetic device (MD) and a high voltage capacitance device (HVC) as possible alternatives to the dosing of chemical antiscalants for preventing scaling during RO operation at high product recovery.
The tests were conducted on feedwater to the Bureau of Reclamation's 72-MGD Yuma Desalting Plant located in Yuma, AZ.
High overall recoveries of greater than 90% were achieved by operating a 2-stage 4 GPM RO pilot unit (membrane unit 1 [MU1]) on the concentrate from a 200 GPM RO unit operating at a water recovery of 70%.
In these tests, neither the MD nor the HVC were effective in preventing calcium sulfate scaling at 91% water recovery.
In contract, the addition of 2 mg/L of sodium hexametaphosphate (SHMP) to MU1 feedwater was successful in avoiding scale at recoveries of 93%.
Dosing of SHMP (or other chemical antiscalant) remains the recommended method of achieving high recovery operation without scaling at the Yuma Desalting Plant.
For more information about the DWPR program, contact Kevin Price at: Bureau of Reclamation, 86-69000, PO Box 25007, Denver CO 80225; phone (303) 445-2260; or e-mail a message to MPrice@usbr.gov.