Red Mud as Adsorbent to Recover Phosphorous from Wastewater Streams

Background: Phosphorous (P) is an essential nutrient with finite and non-renewable resources; however, it can cause eutrophication in freshwater. The use or storage of red mud (RM), a by-product of alumina production with high iron and aluminium content, poses another environmental issue. Objective: This paper examines the possibility of P recovery from various wastewaters and landfill leachate with RM. Methods: Pulverized, on-site pre-treated red mud was used. Synthetic P solution, poultry wastewater effluent, the spiked effluent of a municipal wastewater treatment plant and landfill leachate were examined. Results and conclusions: Removal efficiencies of 0.41–1.24 mg P/mg RM for the wastewater effluents and 0.10–0.13 mg P/g RM for the leachate resulted in a decreased phosphorous concentration (0.02–0.57 mg P/L) for each liquid. Despite the doses being substantially higher than the stoichiometric value (103 mg P/g RM), the dosage increase did not result in a considerable cost increase. Further investigation is in progress to insert this solution into existing wastewater treatment technologies to facilitate excellent effluent quality and utilize the nutrient content of red mud.