METHOD OF TREATING AQUEOUS SOLUTIONS CONTAINING HYDROGEN SULFIDE, HYDROGEN CYANIDE, AND AMMONIA Russian patent published in 1997 - IPC

FIELD: waste water purification. SUBSTANCE: polluted aqueous solution is acidified with sulfuric or nitric acid to pH about 3 and treated with inert gas in distilling column. Then pH of solution is raised to at least about 10 with sodium hydroxide and treated once again with inert gas in the second distilling column. In the method of invention, solution is treated with air or steam produced by solution under treatment and treatment in the both columns is carried out at 60-150 C, advantageously 80-120 C, and pressure 0.02-0.5 MPa, better 0.05-0.12 MPa. The first column contains 1-30, better 6-12 theoretical plates, the second one 5-50 and 6-20, respectively. Top product from the first and/or second column is condensed and returned into top part of corresponding column. Distilled hydrogen sulfide, hydrogen cyanide, and ammonia are catalytically burned. EFFECT: enhanced efficiency of process. 9 cl, 2 dwg