Biostabilization of mine tailings for improving wind erosion resistance

Abstract

One of the leading anthropogenic origins of wind erosion is mine tailings; therefore, finding a sustainable practice for mitigating dust emissions from mine tailings is of critical importance. Cyanobacteria have shown promising results in the surface stabilization of erosion-susceptible soils in desert regions and moving dunes. However, little information is available on their application in mine tailings. Experimental studies were conducted to identify potential cyanobacteria that can survive in gold mine tailings. The experiments were carried out in Pb-containing BG110 media to stimulate nutrient-poor and metal-enriched conditions in gold mine tailings while isolating the impact of other variables. Two nitrogen‐fixing cyanobacteria, Anabaena sp. and Nostoc muscorum, were tested. Both cyanobacteria could sustain growth. However, Anabaena sp. showed better performance in resisting Pb(II) inhibitory effects. Hence, Anabaena sp. was selected for the tailings experiments due to its high resistance to metal toxicity, and N. muscorum was selected due to its reported ability to create biocrusts. The performance of Anabaena sp. and N. muscorum, individually and as a consortium, in creating biocrusts on gold mine tailings was investigated (inoculation-based method). The cyanobacteria showed complementary traits in improving the biophysicochemical properties of the mine tailings and inoculation using the consortium led to the formation of a stronger structure. The cyanobacterial consortium inoculation successfully created stable biocrusts, which significantly reduced wind erosion (0.85% vs. 81.99% mass loss), increased compressive strength (1.90 vs. 0.1 kg cm-2), and improved organic carbon (17.23 vs. 3.26 mg g-1 tailings) and nitrogen (3.89 vs. 0.036 mg g-1 tailings). A photosynthetically induced carbonate precipitation approach was assessed by inoculating N. muscorum with an essential substrate. The biocemented crusts showed superior performance in reducing wind erodibility compared to the inoculation-based crusts. The proposed strategy could not only overcome the environmental drawbacks of the ureolysis-driven carbonate precipitation but also take advantage of the beneficial effects of cyanobacteria in surface stabilization, biological CO2 sequestration, and N2 fixation. The work outlined in this thesis has contributed to mitigating dust emissions from gold mine tailings in an environmentally friendly and energy-efficient manner while laying the groundwork for the subsequent establishment of vegetation covers.