Method for treating wastewaters

摘要

The invention relates to a method for treating wastewater containing nitroaromatics and nitrohydroxyaromatics, as for example arises in the production of nitroaromatics or in the production of nitrohydroxyaromatics, by a two-stage method consisting of pre-reduction and wet oxidation.

主权项

1. A method for treating alkaline wastewater containing nitroarornatics and/or nitrohydroxyaromatics, comprising, in a first stage combining the alkaline wastewater with an organic reducing agent which is non-salt-forming in the wastewater, said organic reducing agent being selected from the group consisting of lignite and hard coal and treating the alkaline wastewater under reducing conditions, wherein the alkaline wastewater is heated to a temperature range of from 80 to 200° C. and maintained in said temperature range for a residence time of from 5 minutes to 5 hours to produce a reduced wastewater and, in a second stage, acidifying and oxidising the reduced wastewater obtained from the first stage with an oxidising agent.