A low content of Ca and Mg in drinking water causes increased health risks. To increase the Ca and Mg contents in the drinking water supplied to the inhabitants of the village of Devičie, a prototype of a fluidized bed recarbonization reactor (RRF) was proposed and tested. A half-burnt dolomite (HBD) was used for the recarbonization. In the RRF, the HBD is kept in buoyancy with the help of water circulation. The capacity of the circulation pump is up to 5 m3 h−1 and the volume of discharged concentrate, which is added directly to the water source, is up to 0.2 m3 h−1. The volume of water circulated between the reactor and the circulating tank is many times higher than the volume of discharged water. In 24 h, the Ca and Mg contents stabilized at an equilibrium value of 80 mg L−1 for Ca and 120 mg L−1 for Mg, which corresponded to the equilibrium of formation and removal of ions from the system. The concentrate was diluted with the water in the reservoir at a ratio of 1:10, and it achieved the desired increase in Mg and Ca contents by more than 10 and 6 mg L−1, respectively.

Soil pollution by potentially toxic elements (As, Sb, Cu, Zn, Pb) near the mining areas has become a serious environmental problem. These risk elements can be released into the environment, causing a risk to human health. Stabilized pollution in various materials may constitute an additional risk in the long term. Organic acids play an important role in mobilizing contaminants. In the present work, various stabilizing agents (iron nanoparticles � nanoscale zerovalent iron (nZVI), amorphous manganese oxide (AMO), biochar (BC), natural and synthetic zeolites) were investigated in terms of their stabilizing potential under simulated rhizosphere conditions and their consequences in the mineral composition of samples. One of the aims of this work was to understand the reactivity of potential sorbents in contaminated soils of the abandoned Sb-deposit and subsequent mobility of arsenic and antimony by one-step pot experiments using citric and acetic acid. Another goal of this work was to determine the effectiveness of Aspergillus niger and Neosartorya fischeri strains producing organic acids (citric acid, oxalic acid, acetic acid) in bioleaching and bioaccumulation of Cu, Zn and Pb from mining waste from tailings pond.

In the village of Kokava nad Rimavicou, we enriched the drinking water with Ca and Mg using a recarbonatization reactor (RR). In the RR, carbonate rock is dissolved using CO2. In the RR, we produce a concentrate with a Ca and Mg content of approximately 100 mg l− 1, which is then added directly to the water reservoir at a ratio of approximately 1:10. On average, the Ca and Mg content in the drinking water increased by 10–15 mg l− 1. Subsequently, we monitored the positive effect of the increased Ca and Mg content in the drinking water by measuring the arterial stiffness of the residents, which characterizes the state of the cardiovascular system of people. We measured the arterial stiffness four times in six-month intervals. The first time was before the start of the enrichment of the drinking water with Ca and Mg, and subsequently three times after the enrichment. The increased content of Ca and Mg in the drinking water resulted in a significant improvement in the arterial stiffness. The arterial age of the people improved by approximately ten years, and the speed of the pulse wave velocity decreased by 0.9 m s− 1.