摘要 |
Waste digester liquor, containing dissolved triazines, ammonium salts and iron, is treated with a mineral base until the pH is about 2.5 to 4 whereby triazines are precipitated while most of the iron remains dissolved. The triazines are separated and recycled back to the digester. The pH of the filtrate is increased to about 11 and the ammonia stripped off and recovered leaving an essentially nitrogen free aqueous solution. This can be sewered directly or concentrated to recover the salts. |