The present treatment for spent brine of high hardness utilizes a closed cycle wherein the calcium and magnesium values are removed by treatment with soda ash to precipitate calcium carbonate and sequentially also sodium hydroxide to precipitate magnesium hydroxide. Subsequently, the water layer or solution is removed, acidified with HCl to a pH of below 8.0, and later returned during the regeneration process as input soft brine to the zeolite column.