Abstract: In a method of removing impurities, especially iodine and/or silica ions, from a salt solution to be used for electrolysis, the salt solution and zirconium hydroxide are brought into contact with each other under acidic conditions, and the zirconium hydroxide adsorbs the impurities. Thereafter, the zirconium hydroxide containing the adsorbed impurities is brought into contact with an aqueous solution at a higher pH value to desorb the impurities from the zirconium hydroxide, thereby enabling the zirconium hydroxide to be recycled.

Abstract: In removal of sulfate groups and chlorate groups from brine used for electrolysis, concentrated brine used in an electrolysis process or dilute brine whose concentration is decreased by electrolysis is fed to an anode chamber divided by a cation exchange membrane in a brine treating electrolyzer, where the concentrated or dilute brine is electrolyzed to recover chloride ions therein. The concentrated brine is electrolyzed at a rate of decomposition of salt higher than that in the ion exchange membrane electrolysis process of brine. Thereafter, the concentrated or dilute brine is discharged out of the electrolysis process.

Abstract: The method of removing a film from a substrate (wafer) comprises a step of injecting ozone (13) into an acid aqueous solution (12) (e.g., a mixed liquid of dilute hydrogen fluoride aqueous solution and dilute hydrochloric acid); and a step of bringing bubbles (18) formed by the ozone injection step into contact with a film (17) (e.g., organic or metal contaminated film) adhering on to the substrate to remove the film (17) from the substrate (16). Therefore, the organic film or metal contaminated film adhering onto the substrate surface can be removed easily and effectively. Further, the film removing agent is bubbles formed when ozone (13) is injected into an acid aqueous solution. Each bubble is composed of an inside ozone bubble and an outside acid aqueous solution bubble. Therefore, when the bubbles are brought into contact with the film, an intermediate between ozone and the film is first formed, and then the formed intermediate can be removed from the substrate by the acid aqueous solution.

Abstract: In a brine treatment method of removing sulfate ions from sulfate-ion contained brine, sulfate-ion contained brine is brought into dispersive contact with granular ion exchange resin carrying zirconium hydrous oxide thereon in a fluid state under an acidic condition to thereby cause the sulfate ions to be adsorbed by the ion exchange resin and removed from the brine, then the granular ion exchange resin is washed with aqueous solution whose pH value is equal to or lower than a pH value in the adsorbing step, thereby removing chloride ions from the granular ion exchange resin, then in a fluid state, the granular ion exchange resin adsorbing the sulfate ions is brought into dispersive contact with aqueous solution of pH value higher than the pH value in the adsorbing step, thereby desorbing the adsorbed sulfate ions from the granular ion exchange resin, and then the granular ion exchange resin is washed with water.

Abstract: The method for removing organic film according to the present invention is very effective for removing a photo resist film in a process for manufacturing semiconductor device. A substrate (32) having a photo resist film (31) formed on it is processed in a wet processing tank (34) filled with a processing solution such as a mixed solution containing sulfuric acid and hydrogen peroxide or by a dry processing using oxygen plasma. Then, it is processed in an ozone processing tank (34) filled with a solution where ozone or ozone water has been infused, and the organic film is removed.