| abstract |
(57) [Problem] To provide a method of treating tetraalkylammonium hydroxide (TMAH) -containing wastewater containing a photoresist, which can efficiently treat the wastewater and regenerate and recover the TMAH. SOLUTION: In a method for removing a tetraalkylammonium cation by adsorption using a cation exchange resin from a wastewater containing a photoresist and a tetraalkylammonium hydroxide and recovering the cation as a salt, the wastewater is removed from near neutrality. After keeping the photoresist weakly acidic, removing the photoresist in advance, passing the waste liquid through a cation exchange resin to adsorb the tetraalkylammonium cation, regenerating the cation exchange resin with an acid, and removing the tetraalkylammonium salt. The solution is recovered in a regenerating solution, and an aqueous solution of perchloric acid is added thereto, and the perchlorate of tetraalkylammonium is crystallized and recovered. |