A process for treating sulphide-containing water includes maintaining a steep redox potential gradient in an interface zone of the sulphide-containing water. The water is exposed to an oxygen-containing environment, and the interface zone is located immediately below the surface of the water. Sulphide in the water is biologically oxidized, in the interface zone, to sulphur. The sulphur may be removed by settling, thereby achieving a final removal of sulphur compounds.