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AssigneeENI S.p.A.
InventorsGiuliana Franzosi, Pietro Cesti, Roberto Paglino, Lino Carnelli, Roberta Miglio
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Process for the purification of an aqueous stream coming from the Fischer-Tropsch reaction which comprises: —feeding said aqueous stream containing the organic by-products of the reaction to a distillation column, obtaining two output streams: —an aqueous stream (i) exiting from the column head, enriched with alcohols having from 1 to 20 carbon atoms, preferably from 1 to 9 carbon atoms, and other optional volatile compounds; an aqueous stream (ii) exiting from the column bottom, enriched with organic acids having from 1 to 10 carbon atoms, preferably from 2 to 6 carbon atoms; —subjecting said aqueous stream (ii) to an anaerobic biological treatment obtaining a purified aqueous stream (iii); wherein said anaerobic biological treatment is carried out with a hydraulic retention time lower than 15 hours, preferably ranging from 4 hours to 10 hours, more preferably ranging from 5 hours to 8 hours.
Process for the purification of an aqueous stream coming from the Fischer-Tropsch reaction comprising:
Process according to any one of the preceding claims, wherein said aqueous stream (i) has a concentration of alcohols higher than or equal to 20% by weight with respect to the total weight of said aqueous stream (i).
Process according to any one of the preceding claims, wherein said aqueous stream (ii) has a concentration of organic acids higher than or equal to 0.05% by weight with respect to the total weight of said aqueous stream (ii).
Process according to any one of the preceding claims, wherein said purified aqueous stream (iii) has the following characteristics:
Process according to any one of the preceding claims, wherein said anaerobic biological treatment is carried out using an organic substrate load higher than or equal to 17 kgCOD/m3/day.
Process according to any one of the preceding claims, wherein said anaerobic biological treatment is carried out at a temperature ranging from 20° C. to 45° C.
Process according to any one of the preceding claims, wherein said anaerobic biological treatment is carried out at a pH ranging from 5.5 to 8.5.
Process according to any one of the preceding claims, wherein to said aqueous stream (ii) an inorganic base is added which can be selected from hydroxides, oxides, carbonates, bicarbonates of alkaline or alkaline-earth metals, or mixtures thereof such as, sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium carbonate, magnesium oxide, magnesium carbonate, sodium bicarbonate, or mixtures thereof.
Process according to any one of the preceding claims, wherein to said aqueous stream (ii) nutrients are added which are selected from nitrogen-containing compounds such as urea, ammonia, ammonium salts, or mixtures thereof;
Process according to any one of the preceding claims, wherein said anaerobic biological treatment is carried out in a reactor selected from:
Process according to any one of the preceding claims, wherein said process comprises subjecting the aqueous stream (iii) to an ultrafiltration or microfiltration treatment and to a subsequent reverse osmosis treatment obtaining two output streams:
Dependencies are inferred from the claim text.