Feasibility of cleaning As- and U-containing soil of a gold mine by using biologically nano-sized FeS: Implications for soil remediation technology

Gold and uranium mining has resulted in elevated concentrations of As and U contaminants in groundwater and soil, which has become a paramount concern for the environment and public health. Nanocleaning technology is one of the few permanent treatment alternatives to remove metal contaminants from soils. In recent years, nano sized FeS, a washing solution that uses nanocleaning technology, has elicited extensive interest in environmental remediation because it does not produce secondary pollution. In this study, As and U were removed from contaminated soil by employing nano-sized FeS washing solution biologically synthesized by the iron-reducing bacteria Acidiphilium cryputum JF-5 and sulphate-reducing bacteria Desulfovibrio vulgaris miyazaki SRB. After cleaning with a nano-sized FeS suspension solution, culture-medium and pure-water for three cycles, the concentration of As in the nano-sized FeS experiment was higher than that of U, suggesting that the cleaning effect for As was better than that for U. The As and U removal rates of the nano-sized FeS cleaning experiment were 12% and 1.59%, respectively, over the three cycles. By using the sequential extraction method, the nano-sized FeS cleaning experiments mainly removed the As fraction bound to Fe/Al oxides. An ATR-FTIR spectral analysis indicated that the band observed at 461 cm(-1) was attributed to the nu(4) symmetric stretching mode of AsO4 (3-.) The obvious vibrations observed at 798 cm(-1) and 778 cm(-1) , were assigned to the nu(1) vibration of AsO33- . The band at 834 cm(-1) was assigned to the weak vibration of UO2 while the band at 949 cm(-1) was attributed to the Fe-O-D bending vibration. The results of this study provide helpful information and references for designing long-term and efficient bioremediation strategies for As-and U-containing soils. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, As and U were successfully removed from contaminated soil using a nano-sized FeS washing solution biologically synthesized by iron-reducing bacteria and sulphate-reducing bacteria. The cleaning experiment showed that the cleaning effect of nano-sized FeS on As was better than on U, with removal rates of 12% and 1.59% respectively.