Magnetic particles as new adsorbents for the reduction of phosphate inputs from a wastewater treatment plant to a Mediterranean Ramsar wetland (Southern Spain)

This study assessed the convenience of using magnetic particles (MPs) to reduce phosphorus (P) concentration in treated wastewater. The working hypothesis is that MP addition increases P removal in artificial wastewater treatment ponds. Water samples were collected at the inlet and outlet of a semi-natural pond receiving secondary municipal effluent that is discharged in a Ramsar site (Fuente de Piedra, Malaga, Spain). Then, laboratory batch experiments were run to (i) assess the effect of adding MPs on the chemical composition of treated wastewater, (ii) identify the number of adsorption cycles (by reusing MPs) which are able to trap a high percentage of P (>50%) and (iii) select the optimum ratio between MP mass and initial dissolved inorganic P (DIP) concentration. The results show the suitability of using MPs to remove P in treated wastewater due to both their high equilibrium adsorption capacity (q) and P removal efficiency. Lastly, considering its practical and economical relevance, based on the advantages (P removal efficiency) and disadvantages (economic price), the optimum dose of MPs (0.16 g MP mg(-1) P) to achieve a high P removal efficiency (>50%) was identified. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study assessed the feasibility of using magnetic particles to reduce phosphorus concentration in treated wastewater, and identified the optimal dose of MPs and number of adsorption cycles for efficient phosphorus removal.