Degradation of nitrates with the participation of Fe(II) and Fe(0) in groundwater: A review
2015
Vodyanitskii, Yu. N. | Mineev, V. G.
Nitrates from soil and nitrogen fertilizers unused by plants become hazardous pollutants and contaminate surface and ground waters. In the water-saturated layers, into which nitrates are leached, the content of organic matter (i.e., electron donors necessary for nitrification) can be insufficient. The deficiency of electrons in the groundwater can be eliminated by Fe(II) minerals that remained in the heavy rocks and are available to microorganisms due to dispersion. However, when the groundwater table is shallow (less than at 10 m), the natural denitrification develops poorly; therefore, remediation is needed to enrich the contaminated water with electron donors. Zerovalent iron is most frequently used for this purpose. The efficiency of the Fe⁰barriers for the purification of groundwater from nitrates increases due to the activation of anaerobic denitrifying bacteria. In addition, the geochemical conditions and the composition of the bacterial community change in the Fe⁰barrier zone, which favors the development of a wide range of anaerobic hydrogenotrophic bacteria (primarily Fe(III) reductants).
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