Nitrate and ammonium ions removal from groundwater by a hybrid system of zero-valent iron combined with adsorbents

Abstract

Nitrate (NO₃⁻) is a commonly found contaminant in groundwater and surface water. It has created a major water quality problem worldwide. The laboratory batch experiments were conducted to investigate the feasibility of HCl-treated zero-valent iron (Fe⁰) combined with different adsorbents as hybrid systems for simultaneous removal of nitrate (NO₃⁻) and ammonium (NH₄⁺) ions from aqueous solution. The maximum NO₃⁻ removal in combined Fe⁰-granular activated carbon (GAC), Fe⁰-filtralite and Fe⁰-sepiolite systems was 86, 96 and 99%, respectively, at 45 °C for 24 h reaction time. The NO₃⁻ removal rate increased with the increase in initial NO₃⁻ concentration. The NO₃⁻ removal efficiency by hybrid systems was in the order of sepiolite > filtralite > GAC. The NH₄⁺ produced during the denitrification process by Fe⁰ was successfully removed by the adsorbents, with the removal efficiency in the order of GAC > sepiolite > filtralite. Results of the present study suggest that the use of a hybrid system could be a promising technology for achieving simultaneous removal of NO₃⁻ and NH₄⁺ ions from aqueous solution.