Low Temperature Ammonia Nitrogen Removal from an Iron, Manganese, and Ammonia Groundwater Purification Process with Different Concentrations of Iron and Manganese

Abstract

In a groundwater plant, removal of iron, manganese, and ammonia nitrogen was performed via a purification process using a filter column at a low temperature (5-6℃). Iron, manganese and ammonia [Fe(Ⅱ) 0-19.26 mg·L-1, Mn(Ⅱ) 0.52-2.05 mg·L-1, and NH4+-N 0.37-2.59 mg·L-1] were analyzed to explore the ammonia nitrogen removal efficiency under different iron and manganese concentrations. The results showed that when the concentration of manganese in the inlet water was maintained at approximately 0.6 mg·L-1 and the concentration of ferrous iron in the inlet water was increased, with the increase of iron oxides in the filter layer, the ratio of ammonia nitrogen removed by adsorption of iron oxides increased, while the ratio of ammonia nitrogen removed by nitrification will decreased and adsorption preceded nitrification. When the concentration of ferrous iron in the water was maintained at approximately 8 mg·L-1and 11 mg·L-1, and the concentration of manganese in the water was increased, the proportion of ammonia nitrogen removed by adsorption did not increase with the increase of manganese oxide, and the removal route of ammonia nitrogen hardly changed. This is because less manganese oxides were formed 20 cm before the filter layer, which had little effect on the ammonia nitrogen adsorbed in this range. The production area of manganese oxides was concentrated below 20 cm of the filter layer, and most ammonia nitrogen was removed by adsorption and nitrification before this area, and the manganese oxides in this area did not adsorb ammonia nitrogen.