Near-surface soil stabilization by enzyme-induced carbonate precipitation for fugitive dust suppression

To resolve the environmental and sustainability issues from fugitive dust emission and conventional mitigation methods, multiple experiments were conducted to evaluate the suppression of fugitive dust and its effect on near-surface soil stabilization by enzyme-induced carbonate precipitation (EICP). The optimal recipes for maximum CaCO3 precipitation with high- and low-purity chemicals were first identified for the EICP treatment. Soil specimens treated with both solutions were characterized by measuring shear wave velocity and cone tip resistance. A wind tunnel test was conducted to examine how the near-surface treatment suppressed particulate matter (PM 2.5 and PM 10) against wind and dynamic impacts. The results showed that both the shear wave velocity and the peak cone tip resistance increased almost linearly with increasing solution volume up to 7 L/m2. Dust emission was effectively mitigated by increasing solution volume up to 3 L/m2. Both high- and low-purity chemicals showed a similar ability to suppress fugitive dust. Upon vibration, the treatment effect vanished, but treatment with 7 L/m2 solution made the soil remain intact. Scanning electron microscopic imaging confirmed the precipitation of vaterite when low-purity chemicals were used.