Non-invasive Removal of Phosphorus from Lakes Using Processed Calcite-Based Materials

In this study, milled ground calcium carbonate (GCC) consisting of calcite is developed as an orthophosphate (OP) binding agent to be used in a strategy for non-invasive orthophosphate (OP) removal from eutrophic lakes. Planetary ball mill and 74 different grinding methods were applied differing in grinding time (0.5–24 h), grinding force (150–400 rpm) and mass of grinding balls (150–500 g). The obtained materials had specific diameter d90 of 7.3–86.6 µm and specific surface area (SSA) of 4.9–24.0 m2/g. Grinding resulted in 98% OP removal, being five times higher compared to the initial GCC material (21%). Grinding substantially improved OP removal’s ability as compared to the source GCC, without using chemicals, and at low cost. Such GCC materials were used to develop a strategy for non-invasive OP removal from the aquatic environment which assumes application of a GCC containing carrier into the water body and its subsequent removal. Three different solutions were analysed, differing in type and the adjustment of the carrier’s adhering to GCC. GCC efficiency on/in a carrier was reduced due to embedded GCC grains in glue (on laminates) or limited water exchange caused by the carrier (in bags). Technical conditions for two of the tested solutions allowed the effective use of GCC.