Patent ID: 7147775

Claim:
A process for the production of purified water from Fischer-Tropsch reaction water containing oxygenated hydrocarbons, aliphatic, aromatic and cyclic hydrocarbons and inorganic compounds, wherein the purified water is an aqueous stream having a COD of between 20 and 600 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, which process includes at least the steps of: a) a primary treatment stage comprising biological treatment for removing at least a fraction of dissolved organic carbon 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 to reduce the total mass fraction of organic constituents in the unevaporated portion to produce a secondary water-enriched stream; and c) a tertiary treatment stage comprising solid-liquid separation for removing at least some solids from at least a portion of the secondary water-enriched stream.