Brine Mineral Recovery as a Zero-Waste Solution for the Proposed South Padre Island Desalination Plant

The proposed $1 billion RGV-Desal seawater reverse osmosis desalination plant on South Padre Island, Texas, represents the most significant water infrastructure investment in South Texas history. At a projected production capacity of 50–100 million gallons of fresh water per day, the facility will simultaneously generate an estimated 75–150 million gallons of concentrated brine daily — waste the current design routes directly into the Laguna Madre. The Laguna Madre is one of only seven hypersaline lagoons in the world, covering 280,910 acres with an average depth of less than one meter and a near-zero water exchange rate of 25 cubic meters per second, making it structurally incapable of dispersing concentrated brine discharge. This paper proposes a Brine Mineral Recovery Module — a sequential six-stage processing system that extracts commercially valuable minerals including sodium chloride, magnesium, bromine, potassium, and lithium from the brine stream before any environmental discharge occurs. Based on published cost-benefit analyses and current global market prices, the mineral recovery operation generates an estimated $320 million or more in combined annual revenue from salt and magnesium production alone, sufficient to offset processing costs and reduce long-term water production costs for Valley residents. The magnesium recovery component carries additional national security significance, as the United States currently imports approximately 70 percent of its magnesium, with China controlling the dominant global supply. This proposal presents the technical framework, economic analysis, environmental justification, existing industrial precedents, and specific recommendations for incorporating brine mineral recovery into the South Padre Island plant design.