Calcium alternative on microbial dust suppressant and the mechanism of action

Calcium alternative is an important factor affecting microbial-induced carbonate precipitation (MICP) process of microbial dust suppressants, however, previous research only focused on a single strain. To analyze the impact of calcium alternative on microbial community, calcium alternative was introduced in the MICP process of treating coal dust with microbial dust suppressants. Results showed that calcium alternative affected the MICP process of the enriched microorganisms. During the growth period of 48 h, calcium alternative improved the species richness of the genera. Urease activity of the microbial community after calcium nitrate treatment could reach 7.48 mM min(-1), and the bioavailability during mineralization cycle was 94.57%. The biochemical processes of MICP were more diversified, such as urea hydrolysis, organic oxidation and nitrate dissimilation reduction. In addition, the mechanisms of calcium tolerance were also diverse, such as osmotic adjustment, metabolism, signal transduction, and interspecific cooperation. Quorum sensing strategy was the dominant of defense mechanism. Next, dust suppression experiments showed that calcium nitrate microbial dust suppressant had strong dust suppression ability, with a rain erosion mass loss of 29.25%, and a wind erosion rate 0.92 g m(-2)center dot min(-1) under the wind speed of 10 m/s. Although further study was still needed, the findings provided a theoretical basis for calcium alternative and exploited great potentials of microorganisms in coal dust suppression.