Oxidation of ammonium ions and organic carbon in wastewaters

Oxidation of ammonium ions and organic carbon in ammonium-ion-containing and organic carbon-containing waste waters (effluents) by nitric acid at 100 to 350@C, in that the molar ratio of organic carbon to ammonium nitrogen is established at a range of 0.3:1 to 4:1 by addition of organic carbon or ammonium nitrogen. In a preferred embodiment which is reproduced by way of example in the figure, the waste water, which can be enriched, depending on the TOC content, with organic carbon, is transported via the feedline (1), possibly from an intermediate tank (2), by a pump (3) through a heat exchanger (4) in which it is preheated to, for example, 270@C. The preheated waste water is then heated by direct feed of 100 bar high-pressure steam via feedline (5) or by indirect heating to 290@C. After establishing the nitric acid concentration necessary for the ammonium degradation, e.g. via a feedline (6) in the waste water at 290@C, this is conveyed through a reactor (7) without back-mixing (e.g. a tubular reactor having internals and which is clad with titanium). After a residence time of, for example, 5 to 10 min, the reaction solution is cooled in counter-current with the feed and is depressurised in a separator (8). The waste water is removed via a line (9), via an intermediate tank (10) and a heat exchanger (11).