Polishing of secondary wastewater effluents through elimination and recovery of dissolved phosphorus with reusable magnetic microsorbents

The proposed innovative technology combines nanocomposite magnetic particles with a tailored adsorbent material for the selective removal of dissolved phosphorus from pretreated wastewater and concentrating it in a purer liquid matrix as a source for further phosphorus recovery. The adsorbent deposited on the carrier magnetic particles was carefully preselected among many other options, showing high adsorption capacity, good selectivity, stability and recovery potential. The engineered composite particles can be magnetically extracted from water, regenerated in an alkaline solution, where phosphorus desorption takes place, and reused again. Their reusability is demonstrated for 55 adsorption/desorption cycles in municipal wastewater by adjusting the process parameters, without detecting any drop in performance. Important advantage of the developed technology is the dual benefit of phosphorus elimination down to concentrations < 5 mg/L PO4-P and < 50 mg/L Ptotal, which do not pose any eutrophication risk, and the option for subsequent recovery of the valuable nutrient, thus having the potential to be an attractive alternative to the conventional P-removal methods in wastewater treatment.