Process for the purification of waste from acrylonitrile production

Process for the purification of waste water from a process for preparing acrylonitrile by the gas phase oxidation of propylene and ammonia with oxygen in admisture with solid catalyst wherein water is used for the separation of acrylonitrile from the reaction mixture, said waste water being substantially free of acrylonitrile, acetonitrile and hydrogen cyanide and containing volatile and toxic and high-boiling and resinous organic compounds, which comprises:

• i. treating said waste water with steam at a temperature between 100 .degree. and 125.degree. C and at a pressure of from 0 to 2 atmospheres gauge, in a detoxification column containing at least 7 distribution baffles, removing volatile toxic materials as the distillate and recovering treated waste water as the bottoms product, said steam being generated in the botom of said detoxification column by indirect heating with steam produced in the following step (iv) at the rate of 0.4 to 1.0 ton of steam per ton of waste water flowing into said detoxification column;
• ii. removing the so treated waste water from said detoxification column and passing it into an evaporator vessel;
• iii. vaporizing a major portion of the treated waste water from the detoxification column in said evaporation vessel;
• iv. recovering steam as the head product from said evaporation vessel and using said head product to generate steam in the bottom of said detoxification column by indirect heat exchange with the contents of said detoxification column, for said steam treatment;
• and
• v. removing an aqueous solution of said organic compounds as the bottoms product from said evaporation vessel.