Effects of Pretreatment on RO Membranes During a Brackish Groundwater Desalination Pilot Study

The San Antonio Water System (SAWS) launched a feasibility assessment as part of its Brackish Groundwater Desalination (BGD) Project. The purpose of the assessment was to evaluate the potential of developing brackish groundwater (1,000 – 3,000 mg/l total dissolved solids) from the Lower Wilcox Aquifer as an additional water supply source to the existing portfolio of water resources. A pilot study was developed to evaluate the performance of RO treatment and pre-treatment options to meet the Texas Commission on Environmental Quality’s (TCEQ) treated water quality requirements. The study included four phases to evaluate three brackish water RO membranes (Toray (TM-710), Hydranautics (ESPA2), and Dow FilmTec (BW4030)), two recoveries (85 and 90%), and multiple pre-treatment options (acid/antiscalant, raw water (RW) tank, and granular media filters (GMF)).