Reverse osmosis for desalination of water from the Guarani AquiferSystem to produce drinking water in southern Brazil

Like other regions around the world, southern Brazil has experienced periods of drought, having to find alternative water resources for producing drinking water during these times. The deep wells drilled in the Guarani Aquifer could help with this water imbalance, but the water, in some places, is brackish. This work is an exploratory study of the use of the brackish water from the Guarani Aquifer as an alternative supply for drinking water, using reverse osmosis to reduce the content of F−, SO2− and TDS (Total Dissolved Solids). The desalinated water 4 obtained from reverse osmosis at a pressure of 2 MPa and a cross-flow velocity of 1.61 m.s−1 showed rejections of approximately 94% for SO2−, 97% for TDS and 100% for F−. Blended water, produced by mixing groundwater 4 and permeate, was proposed to optimize the produced drinking water with a recovery rate of 93%. Reverse osmosis is an excellent alternative for the supply of water in southern Brazil. © 2014 Elsevier B.V. All rights reserved.

This study gave a brief description of the water supply in southern Brazil, showing that the country should implement desalination to meet drinking water demand in drought-prone areas. The Guarani Aquifer is a potential source for water harvesting, but the total dissolved solids, sulfate and fluoride concentrations exceed the limits for drinking water without additional treatment. Reverse osmosis has been shown to be an efficient method for improving the quality of brackish water from the Guarani Aquifer to the quality required for drinking water. A blend of fresh water and the permeate produced drinking water at a water recovery rate of approximately 93% (drinking water produced/fresh water). Increased pressure applied to the RO membrane feed enhanced the permeated flux while the cross-flow velocity increased the rate of sulfate rejection. The operating condition of 2 MPa and 1.61 m·s−1 was the best strategy for the desalination of water from the Guarani Aquifer by reverse osmosis. Table 6 Mass balance in the system for two strategies adopted to desalinate the water from the Guarani Aquifer. Flow rate (m3/h) (a) (b) W A R P F D B R′ Recovery (%) – – 3.76 0.76 0.24 94.00 1.24 0.31 0.93 2.79 3.72 – – 93.00 Acknowledgments The corresponding author (VBB) would like to thank FAPERGS for the financial support (process number 12/3129-6). We would also like to thank Professor Claud van Goellner for helping.