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

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.