To provide a method which can treat a waste solution containing ammonium adipate by the used of sulfuric acid and sodium hydroxide, which are easily available and economical, by a simple process and convert recovered adipic acid and ammonia into useful resources.
First, crystallized adipic acid is separated and recovered from a concentrated ammonium adipate waste solution by adding sulfuric acid and cooling. Next, after ammonia gas being recovered by adding sodium hydroxide and heating, a sodium sulfate hydrate is crystallized and separated by neutralization by the repeated addition of sulfuric acid. The solution after separation is combined with untreated ammonium adipate waste solution so that adipic acid and ammonia can be recovered continually from the waste liquid while keeping the amount of dissolved sulfuric acid and sodium hydroxide in the solution at a set value or below.
SUGIYAMA NOBORU
EGAMI YASUSHI
OZAWA HIROSHI
NIPPON CHIKUDENKI KOGYO KK
NIKKEI SANGYO KK