This paper presents an innovative technology for the removal of nitrate from groundwater by combination of Fe0 and CO2 bubbling. The bubbling of CO2 created effectively an acidic environment favorable to Fe0 corrosion, which results in nitrate reduction. In 10 min, the solution pH dropped to 3.2 with CO2 inflow rate of 500 mL/min. In the presence of Fe0 (2 g/L), the CO2 bubbling (500 mL/min) induced conversion of nitrate-N (~7 mg/L) by 85% in 40 min. In addition, the end product in the reaction mixture was ammonium, which accounts for 90-104% of nitrate conversion with the presence of various iron dosages (0.5-2.0 g/L). Though the formation of ammonium is a drawback, the ammonium was eliminated from aqueous phase by a follow-up treatment of settling (30 min) and air-aeration (50 min). What was achieved in this study demonstrates that the Fe0/CO2 method can be applied with success for the total removal of nitrate-contaminated waters.
