A process is provided for the recovery of useful products, including fertilizers and nutritional supplements, from the organic matter and minerals contained in seawater and other brines. The dissolved organic carbon-based chemicals and suspended particulate carbon-based organic matter are co-precipitated together with the contained magnesium and/or calcium, along with incidental trace minerals, entrained water and water of hydration. Caustic soda (NaOH) and other alkali base or alkaline earth bases and/or carbon dioxide (CO2) are added to the brine until a pH of 10.75 to 11.0 is achieved. The settled or non-dry filtered or centrifuged precipitate is utilized as a slurry and the supernatant brine is discarded.