Comparison of Proven Technologies for Reverse Osmosis at 95% Recovery for a Full-scale Potable Reuse Facility

Padre Dam Municipal Water District is considering two technologies to achieve a high recovery with reverse osmosis for its upcoming advanced water purification facility. Pilot testing from 2016-2017 at Padre Dam?s demonstration facility has shown that 95% recovery is possible with either a closed circuit desalination process and a conventional 2-stage RO system when treating concentration from a primary 2-stage RO system. This paper will detail the economic considerations (including energy usage and operability) in the selection of which technology to apply to the full-scale 3.5 mgd facility, with provisions for expansion to 10.4 mgd in the near future.