Integrating nano-scale zero valent iron (nZVI) in phosphorus removal from aqueous solution through porous media: packed-column experiment

This study investigates phosphorus removal from water through nZVI/river-sand packed columns. In order to evaluate their maximum phosphorus adsorption capacity, batch tests were first conducted for a synthesized nZVI (5:3.5 g / 퐹푒퐶푙_3 : 푁푎퐵퐻_4 and river-sand. Aqueous solution of 25 mg/l phosphorus concentration was introduced to three-Plexiglas packed-columns (65 cm length, 10 cm inner diameter and PV=1.53 L with different layers configuration. Solid precipitates of nZVI were characterized using TEM, XRD, BET and LD analyzers. Break-through curves showed that maximum phosphorus removal efficiency was recorded as 98.8% in Column 2 with two layers of nZVI/river-sand after only 17 hours, whereas Column 3 as a control column showed a rapid saturation (fully saturated by day 9 . Dissolved oxygen values were clearly decreased in the first and second columns due to oxygen consumption by nZVI oxidation, unlike Column 3 in which the values were almost close to the influent value. River-sand showed relatively high adsorption capacity of phosphorus as a porous medium.