Removal of ammonia from fluids

A method and equipment for removing ammonia from effluent, flue or waste fluids that include oxygen. The method includes at least the following stages: Part of the fluid (1) is conveyed to a decomposition/oxidation unit (2) and part of the fluid (1) is conveyed to a by-pass unit (3); part of the fluid (1) including ammonia is oxidized in the decomposition/oxidation unit (2) of ammonia; the fluid (1H) that was oxidized in the decomposition/oxidation unit (2) and the fluid (1) that was conveyed to the by-pass unit are mixed in a mixing unit (4) to form a fluid mixture (1S), and the fluid mixture (1S) is conveyed to a selective reduction unit (5).