Process for the purification of an aqueous stream coming from the fischer-tropsch reaction

A process for purifying an aqueous stream coming from the Fischer-Tropsch reaction, the process comprising:

• feeding said aqueous stream comprising organic by-products of the Fischer-Tropsch reaction to a distillation column, obtaining two output streams:
• an aqueous stream (i) exiting from the column head, enriched with alcohols having 1 to 20 carbon atoms, and other optional volatile compounds;
• and an aqueous stream (ii) exiting from the column bottom, enriched with organic acids having from 1 to 10 carbon atoms;
• and
• subjecting said aqueous stream (ii) to an anaerobic biological treatment to obtain a purified aqueous stream (iii),
• wherein the anaerobic biological treatment is carried out with a hydraulic retention time lower than or equal to 15 hours and with an organic substrate load higher than or equal to 17 kgCOD/m3/day to yield a purified aqueous stream, and
• wherein the purified aqueous stream (iii) has a COD lower than or equal to 50 mg/l;
• a pH of lower than or equal to 9;
• a quantity of suspended solids (SS) lower than or equal to 250 mg/l;
• and a total quantity of dissolved solid lower than or equal to 600 mg/l.