Suppression of coal dust by microbially induced carbonate precipitation usingStaphylococcus succinus

Coal dust from open-cast mines is a significant air pollutant; thus, dust particles and toxins contained in the dust are a severe threat to human health and ecosystems. Microbially induced carbonate precipitation (MICP) is a low-cost and environmentally friendly way to suppress coal dust. With high urease activity and tolerance to coal dust, a bacterial strain, Staphylococcus succinus J3, was isolated from soil in a mine area. Thus, in dust suppression experiments, we used coal dust dominated by fine granule particles (100-250 μm) from an open-cast mine. Consequently, four factors were identified: initial bacterial biomass, calcium concentration, urea concentration, and spraying frequency; we investigated their effects on MICP as a dust suppression technique using one-factor-at-a-time experiments. Maximum threshold broken wind speed (45.5 m s^-1) and pressure (912 kPa) were obtained under the following condition: OD₆₀₀ = 0.7, 40 mmol calcium, 6% (w/w) urea in the bonding solution which was sprayed five times in 35 days. Pearson correlation analysis described that urea concentration and spraying frequency both significantly positive correlations with the threshold broken wind speed and pressure via Pearson analysis. When the coal dust suppression process was complete, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy showed that a solidified layer of calcareous precipitate had formed on the surface of the dust. These results indicate that Staphylococcus succinus J3 has considerable potential for use in MICP as a coal dust suppression technique.