Assessing the potential of low-cost minerals for the removal of hexavalent chromium from groundwater: A case study from Ukraine

Yuliia Trach^1,2*

• ¹National university water managment, Rivne, Ukraine
• ²Warsaw University of Life Sciences, Warsaw, Masovian, Poland

This study investigated the feasibility of passively treating acidic Cr 6+ wastewater and reducing the migration of toxic Cr 3+ using locally sourced, low-cost minerals from the mining industry, which are either waste products or secondary raw materials. Iron-rich aluminosilicates, quartzglauconite sand (18% glauconite), volcanic tuff (30% chlorite and 10% pyroxene), and glauconite concentrate (70%) were evaluated in combination with limestone. Cr 6+ reduction experiments were conducted at varying dosages (10-50 g/L) of the test materials in batch experiments, with changes in pH (initial 3.2), Eh, and total dissolved solids (TDS) measured.Natural limestone (0-20 mm), sourced from an active limestone quarry in the Ternopil region, Ukraine, was used to assess its feasibility in reducing the migration of Cr 3+ formed during Cr 6+ reduction. The results demonstrated that the greatest Cr 6+ reduction was achieved using a combination of volcanic tuff and quartz-glauconite sand. Both batch and column studies indicated that limestone effectively reduced Cr 3+ concentrations by raising the water's pH to the range of 7.8-8.2, aiding in its immobilization. Overall, the study confirmed the feasibility of utilizing local mining waste as valuable and cost-effective reagents or adsorbents for the highly toxic Cr6+. These findings enabled the development of practical recommendations for employing iron-rich aluminosilicates in combination with limestone.