A balance analysis of phosphorus elimination by artificial calcite precipitation in a stratified hardwater lake

Elimination of phosphorus was achieved by artificial calcite precipitation in the Dagowsee, a stratified eutrophic hardwater lake. The artificial calcite precipitation was induced by hypolimnetic injection of CaO in enclosures during the summer stagnation. The hypolimnetic injection of CaO was combined with aeration for 1 day. The coprecipitation of phosphorus with calcite was shown by energy dispersive X-ray analysis. The content of phosphorus in the calcite was about 0.1 wt%. Phosphorus was homogeneously distributed throughout the precipitated calcite and throughout the calcinated particles of water and sediment. The phosphorus coprecipitation efficiency was calculated from the ratio of the decrease of phosphorus to decrease of calcium in the water according to the Houseʹs coprecipitation model.