Removal of phosphates from wastewater using biomass ashes

The discharge of excessive concentrations of phosphorus in treated wastewaters leads to environmental problems such as eutrophication of natural water bodies. This work studied the phosphate removal potential from a synthetic wastewater of biomass ashes (bottom and fly ashes). Ca, Al and Fe were the metals with higher expression in both types of biomass ashes, making them suitable materials for phosphate sorption. Results showed good removal efficiencies of phosphates without introducing significant amounts of metals in the treated wastewater. Fly ashes were more efficient than bottom ashes, since they required a smaller mass of ash to achieve a phosphate removal higher than 99%. Ecotoxicological assays showed that the addition of biomass ashes did not contribute to any degree of toxicity to the synthetic wastewater. The results suggest that the use of biomass ashes could be a promising solution for the removal of phosphates in the wastewater treatment.