Abstract: A process for the destruction of organics in a Bayer process stream, the process comprising the steps of: a) Passing a volume of a Bayer process stream to a reactor vessel in which is provided a population of a mixed bacterial culture; and b) Retaining that volume of the Bayer process stream in the reactor vessel for a period of time during which at least 10% by mass as carbon of the organic compounds destroyed originate from non-oxalate organic compounds, wherein the mixed bacterial culture comprises a mix of bacterial species capable of destroying organics and which has previously been adapted to the Bayer process stream, or a stream of substantially similar composition, prior to introduction to the reactor vessel.