Evaluation of the possibility of using underground salts for the regeneration of Na-cationite filters of WTP TPP and NPP in the territory of the CFD

Abstract

When studying groundwater in the Central Federal District (CFD), it was found that the mineralization of groundwater, including brines, increases “from top to bottom” - as the depth of the aquifer complex. The possibility of using underground natural chloride sodium brines for the regeneration of Na-cationite exchange filters is determined by two boundaries - upper and lower. The upper limit of applicability of the brines is controlled by the salinity of the brines of 165 g/dm3, that is, you can use brines with a salinity of at least 165 g/dm3. The lower limit of applicability of the brines is determined by the ratio of the content of sodium ion (in mEq/dm3) to the total hardness of the brine (in mEq/dm3), which should be at least 3.5. In addition to these requirements, the ability to use underground natural chloride sodium brines as a regeneration solution for Na-cation exchange filters is influenced by the total hardness of the brine depending on the total salinity of the brine: to prevent an increase in the counterionic effect, the total hardness of the brine should not exceed 500 mEq/dm3 with a total mineralization of 100 - 150 g/dm3, and should not exceed a value of 1,500 mEq/dm3 with a total mineralization of 250 - 300 g/dm3. The regionalization of the territory of the CFD, taking into account these requirements, revealed 41 thermal power plants and one nuclear power station as potential consumers of underground sodium chloride brines. In addition, on the basis of regionalization, aquifer complexes containing underground brines of conditional quality, depths of aquifer complexes, and approximate depths of design salt-producing wells, on which the cost of well construction largely depend, were determined.