The effect of iron oxidation in the groundwater of the alluvial aquifer of the Velika Morava River, Serbia, on the clogging of water supply wells

Abstract

The oxidation of iron(II) dissolved in groundwater and subsequent precipitation of the oxidation products on the screens and discharge pipes of water wells that tap shallow alluvial aquifers leads to the formation of well encrustations. The main goal of the presented research was to determine the reasons for the rapid clogging of water supply wells. In the particular case of the alluvial aquifer of the Velika Morava River, Serbia, the encrustations include mostly iron-(hydr)oxides (62.6 to 76.2 wt. %). Groundwater over-exploitation leads to the mixing of different geochemical zones and the formation of a redox front. During the two-year survey, the concentrations of the dissolved oxygen in the groundwater varied over a wide range from 0.1 to 7.1 mg L-1 as the result of unsuitable exploitation regime. The on site measured groundwater temperature, concentrations of dissolved oxygen and pH values, and the laboratory analysis of dissolved iron concentrations showed that iron precipitation was favorable under groundwater over-exploitation conditions.