Patent ID: 7153393

Claim:
A process for the production of purified water from Fischer-Tropsch reaction water, wherein the purified water is an aqueous stream having a COD of between 20 and 500 mg/l, a pH of between 6.0 and 9.0, a suspended solids content of less than 250 mg/l and a total dissolved solids content of less than 600 mg/l, and wherein the process includes at least the steps of: (a) a primary treatment stage comprising an equilibrium staged separation process having at least one stage for removing at least a fraction of non-acid oxygenated hydrocarbons from the Fischer-Tropsch reaction water to produce a primary water-enriched stream; (b) a secondary treatment stage comprising evaporation of at least a portion of the primary water-enriched stream thereby reducing the total mass fraction of organic constituents in the unevaporated portion to produce a secondary water-enriched stream; (c) a tertiary treatment stage comprising biological treatment for removing at least a fraction of dissolved organic carbon from the secondary water-enriched stream to produce a tertiary water-enriched stream; and (d) a quartic treatment stage comprising solid-liquid separation for removing at least some solids from at least a portion of the tertiary water-enriched stream.