Technosols designed for rehabilitation of mining activities using mine spoils and biosolids. Ion mobility and correlations using percolation columns

The restoration technologies in areas degraded by extractive activities are more efficient under the use of their own spoils. Reducing deficiencies in physical properties, organic matter, and nutrients with a contribution of treated sewage sludge is proposed. This experiment was based on a controlled study using columns. The work was done with two limestone quarry spoils, both very rich in calcite. Two biosolid doses were undertaken (30,000 and 90,000 kg/ha of sewage sludge) in addition to different quarry spoils used as substrates. The water contribution was provided by a device simulating short duration rain. The leached water was collected 24 h after the last application. Nitrate, ammonium, phosphate, sulfate, and chloride ions were determined, as well as Ca, Mg, Na and K, the pH and electrical conductivity. The electrical conductivity limit value is < 1000 μS/cm. These values will be met from the fourth irrigation application onward, while the values up to that point were far superior. Significant nitrate concentrations appeared that may pose an environmental contamination risk. A comparison between the concentrations of the chemical elements obtained in the leachates from our experiment and the established limit values for water of the third quality group has been performed. The electrical conductivity correlated well with the cations, with the exception of potassium. For sulfates, significant correlations were obtained with the Mg2 +, Ca2 +, and K+ cations. The chlorides showed excellent correlation with the sodium. The good correlations obtained for some physical–chemical parameters can help to establish indicators of environmental quality of leachates over time.