Wetlands for removal of sulphate and metals from mine tailings water
Natural and artificial vegetated wetlands have the unique ability to retain pollutants from water. Frequently, this ‘filtering’ property is exploited in water quality control, which is a more favourable and cost effective approach to treating wastewater. Wetlands have shown to effectively retain pollutants such as excess nutrients and metals, yet few studies report sulphate retention by wetlands. Some researchers consider this an inert compound. However, sulphate (SO4 2-) is not inert and can be reduced to sulphide (S 2-) under waterlogged conditions, rendering an insoluble sulphide complex. Plant, soil and microbial activity within wetlands can detoxify sulphate-enriched water. This research aims to develop an artificial wetland and estimate the capacity of such systems for treating sulphate-enriched water originating from mine tailings. Experimental wetlands have been constructed at Outokumpu Zinc-Tara Mines Ltd., County Meath, Ireland. It is anticipated that these systems, based on natural processes will be efficient yet require minimum maintenance and will therefore be economically attractive.