Increasing of drinking water quality by adding carbonate rocks to low mineralized groundwater: Case study from the Krupina district, Slovakia.

The research has revealed that the increased mortality on cardiovascular and oncological diseases in the Krupina district, belonging among the most serious in Slovakia, is caused mainly by the low calcium and magnesium contents in the groundwater, being used for drinking by inhabitants of the Krupina district. The paper provides the research results of artificial mineralization tests for one model (distilled) water and two waters from the representative home wells from the Krupina district at standard parcial air pressure (CO2 ~ 0.03 vol.%.), as well as at increased CO2 concentration in the water in laboratory static and dynamic conditions, applying carbonatic rocks (dolomite, magnesite, limestone), as well as the half-calcined dolomite (HCD) in amounts of 10, 20 and 100 kg/m3 of the water and duration of mineralization process 1, 2, resp. 4 hours. The laboratory tests of the mineralization of the water have manifested that there is possible significantly increase the content of Ca and Mg in the water to values reaching, or even overreaching, the requested values for drinking water. The highest enrichment was obtained using HCD and it related to magnesium increase. However, the HCD application caused the decrease of the Ca content. Therefore, the limestone or dolomite must be also used in the mixture, so for water mineralization in the home wells we recommend using a mixture of limestone and HCD, where the HCD content in the mixture should be about 30%. No significant differences were found from the point of view of the grain-size of the carbonate rock used. The Ca and Mg contents increase with longer duration of mineralization process. The recommended amount of added rock is from 20 to 100 kg.m-3 of the water. The controlled addition of carbon dioxide to waters with deeply deficient calcium and magnesium contents when using dolomite (or half-calcined dolomite) at the amount of 20 kg/m3 causes a significant increase in the hardness and Ca and Mg concentrations in a relatively short time (up to 5 minutes) in mineralized water up to / above the recommended values according to the valid legislation. [ABSTRACT FROM AUTHOR]