Anaerobic Oxidation of Ferrous Iron by Microbial Mixture and its potential to remove Mercury and Nitrate from the Groundwater

Groundwater contaminated by nitrate and heavy metals was an important and cosmopolitan environment problem especially in the rural area. However, there are no efficient techniques to remove nitrate and heavy metals simultaneously at present. In this study a mixture of microorganisms was enriched from the sediments of anaerobic aquifer Experiments demonstrated that the mixture has the ability to reduce nitrate to nitrite and gaseous end product N-2 using Fe (II) as the electron donor in anaerobic condition. At the same time, the Fe (II) was oxidized to Fe(III) minerals. The microbial mixture and biogenic Fe (III) minerals have the ability to adsorb mercury ions. In this study, soluble mercury was reduced from 20 mu g L-1 to 2.11 mu g L-1 in 7 days of incubation in the presence of the microbial mixture and biogenic Fe (III) minerals. This suggests that nitrate and soluble mercury were directly or indirectly removed through the anaerobic oxidation of Fe(II) by AFODN.