METHOD FOR THE PURIFICATION OF GASES CONTAINING VOLATILE ORGANIC COMPOUNDS

摘要

The present invention relates to a method for purifying a gas comprising: a) feeding the gas (1) to an absorber (5) and bringing into contact said gas (1) with a stream (3) (or alternatively (3′)) to obtain a liquid (4) and a purified gas stream (2); b) feeding the liquid (4) to a conditioning tank (9) and adding a mineral nutrient medium (6) and a suitable amount of base (7) to the liquid (4) to obtain a liquid effluent (8); c) feeding the liquid effluent (8) to an anaerobic bioreactor (14) to obtain a biomethane stream (11) and a liquid stream (12); d) feeding the liquid stream (12) to a degasser (20) to obtain a gas stream (18) and a stream (3′); and e) recirculating the stream (3′) by feeding it to the absorber (5).

主权项

1: A method for purifying a gas containing volatile organic compounds which comprises:
a) feeding the gas (1) to an absorber (5) and bringing into contact said gas (1) with an aqueous stream (3) the pH of which is comprised between 8.0 and 9.5 to obtain a liquid (4) comprising volatile organic compounds, and a purified gas stream (2); b) feeding the liquid (4) comprising volatile organic compounds obtained in step a) to a conditioning tank (9) and adding a mineral nutrient medium (6) and a suitable amount of base (7) to the liquid (4) to obtain a liquid effluent (8) the pH of which is comprised between 7.5 and 10 and the total alkalinity of which is comprised between 750 and 5,000 mg CaCO3/L; c) feeding the liquid effluent (8) obtained in step b) to an anaerobic bioreactor (14) to obtain a biomethane stream (11) wherein the percentage of carbon dioxide is equal to or less than 15% by volume with respect to the volume of the stream (11) expressed as a dry base, and an output liquid stream (12) exiting the bioreactor the pH of which is comprised between 7.0 and 8.5; d) feeding the output liquid stream (12) exiting the bioreactor obtained in step c) to a degasser (20) to obtain a gas stream (18) comprising methane, and an aqueous stream (3′); and e) recirculating the aqueous stream (3′) by feeding it to the absorber (5); wherein: total alkalinity of each of the streams of steps a), c), d) and e) and of each of said absorber (5), conditioning tank (9), anaerobic bioreactor (14) and degasser (20) is equal to total alkalinity of the liquid effluent (8) of step b) ±20% of the total value.