Ammonium-Free Carbonate-Producing Bacteria as an Ecofriendly Soil Biostabilizer

In the current study, a novel ecofriendly soil biostabilizer was produced based on microbial-induced calcite precipitation. An aqueous solution of carbonate ions was produced by utilizing Sporoscarcina pasteurii bacteria under laboratory conditions. Natural zeolite was then utilized to remove the ammonium ions from the aqueous solution in order to prevent any harm from the ammonium ions to the soil environment, including vegetation and groundwater resources. It was observed that injection of calcium chloride followed by ammonium-free carbonate-producing bacteria increased the unconfined compressive strength of the soil. The scanning electron microscope image and energy dispersive X-ray spectroscopy spectra clearly showed that calcite crystals are precipitated at the soil pore, thus providing high soil strength. The calcium carbonate measurement exhibited homogeneous distribution of calcite along the length of the soil specimen.