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Evaluating a Dual Chamber Magnesium Electrolytic Process for Struvite Precipitation from Synthetic Wastewater

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2022 ASABE Annual International Meeting  2200903.(doi:10.13031/aim.202200903)
Authors:   Robinson Ndeddy Aka, Dinithi Mohotti, Alia Nasir, Linan Zhu, Yuanhang Zhan, Jun Zhu, Sarah X Wu
Keywords:   electrochemical process, magnesium anode, struvite precipitation, ammonium removal, phosphate removal

Abstract. Diminishing phosphorus resources worldwide requires developing new technologies to recover phosphorus (P) from wastewaters. A lab-scale electrolytic reactor with a magnesium anode was investigated to remove NH4+ and PO43- from synthetic wastewater by producing struvite. The effects of mixing speed, pH, and applied current on struvite yield, NH4+, and PO43- removal efficiencies were first evaluated using a factorial design. Then, the two most significant parameters were further optimized using Central Composite Design (CCD) coupled with Response Surface Methodology (RSM). A 5.7-fold increase in struvite yield was achieved by increasing the applied current from 0.1 to 0.5 A. The three regression equations generated by the CCD/RSM design with applied current and mixing speed as the two independent parameters were highly correlated with the response variables (struvite yield, NH4+ and PO43- removal efficiencies). The desirability analysis showed the best operating condition: current, 0.5 A and mixing speed, 414 rpm, for the reactor system, under which the optimal struvite yield and NH4+ and PO43- removal efficiencies were 4.75 g/L, 93.0%, and 58.4%, respectively.

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