Polyurethane foam as biomass support for removal of thiosalts from flotation process water

Abstract

Water recycling is a common practice in sulphide ore processing plants by flotation. Inherent thiosalts accumulation in process water often causes efficiency drop and environmental issues for wastewater discharging. Passive and active depuration methods have been applied for thiosalts removal and bio-oxidation in packed bed bioreactors can be considered the most promising option. In this work, polyurethane foam is for first time used as biomass support material in continuous bio-oxidation of thiosalts. Two columns, 15 and 197 cm in height and 8.4 cm in diameter, packed with 1 cm in edge length cubic particles were trialled. A new and fast start-up procedure was performed allowing to effectively operate them in less than seven days. Complete removal of thiosalts in real liquors were achieved with bio-oxidation rates close to 0.45 kg/hm3 and residence time lower than 7 h. Stability, robustness and versatility showed by the bioreactors allows to affirm that polyurethane foam is a suitable material as biomass support in continuous packed bed bioreactors for thiosalts bio-oxidation.