Treatment method of composition containing fluorine-containing organic acid having carbon number of 2 to 7 and impurities

A treatment method of at least partially removing impurities from a composition containing a fluorine-containing organic acid having the carbon number of 2 to 7 and impurities, the method comprising:

• a composition preparing step of preparing a composition in which a content of the fluorine-containing organic acid is 0.1 to 60 parts by weight based on 100 parts by weight of the composition, by concentrating the fluorine-containing organic acid with a means selected from the group consisting of ultrafiltration, reverse osmosis membrane concentration, anion-exchange resin treatment, activation-treated activated carbon treatment, and evaporative concentration for a waste liquid or an intermediate product generated or discharged at a step of producing, or a step of using, the fluorine-containing organic acid;
• a flocculant mixing step of mixing the composition and a flocculant;
• a separating step of separating a mixed phase obtained at the mixing step into a solid phase and a liquid phase;
• a contacting step of contacting the liquid phase obtained at the separating step with activated carbon;
• a second separating step of separating a contacting mixed phase obtained at the preceding step into a solid phase and a liquid phase;
• and
• an acid washing step of mixing the liquid phase obtained at the second separating step with an inorganic acid to perform washing, wherein
• the flocculant is a metal salt containing a divalent or higher metal element, and wherein
• the impurities contain one or more selected from a carboxylic acid having the carbon number of 8 to 50 and derivatives thereof, hydrocarbon having the carbon number of 8 to 50, phenol having the carbon number of 6 to 50, alcohol having the carbon number of 3 to 30, and polyether having the carbon number of 8 to 50.