THE TREATMENT OF BAYER PROCESS EFFLUENT FOR DISCHARGE INTO A TIDAL ESTUARY

Liquid effluent from the Bayer Process operated by Alcan Chemicals Europe was, prior to 1990, discharged untreated into the Firth of Forth, with no reported environmental detriment apart from the aesthetic effect. Subsequent to the 1987 North Sea Miniisterial Conference, which set the objective of a 50% mass reduction in the disposal of the most harmful substances by 1995, the River Purification Board imposed consent limits on the Company to attain legislated Environmental Quality Standards in the river. These are being achieved using acid neutralisation and dissolved air flotation although, for reasons to be discussed, the control of vanadium has been the most problematical.