Reduction of Sandy Soil Erodibility Using Bacterial Enzyme–Induced Calcite Precipitation

Abstract

Bacterial enzyme–induced calcite precipitation (BEICP) has emerged as a promising technique to enhance the shear strength and reduce the erodibility of coarse-grained soils. Traditionally, research has focused on microbial-induced calcite precipitation (MICP), where calcium carbonate is generated through the bacterial activity of Sporosarcina pasteurii , utilizing urease enzymes within bacterial cells. In contrast, BEICP utilizes urease enzymes in an aqueous, cell-free suspension. This study explores the innovative application of surface-applied BEICP via a spray method to mitigate soil surface erodibility and improve the shear strength of a mixture of 20 / 30 standard Ottawa sand and Iowa loess silt. The experimental results demonstrated that increasing the total protein concentration on the soil surface enhances the shear strength by over 50% due to calcite precipitation. Furthermore, the induced calcite precipitation reduces the erodibility of the silty-sand mixtures by up to 15% under surface water erosion conditions. The novel spray application of BEICP proved to be an effective soil stabilization method against water erosion, highlighting its potential for practical implementation in erosion-prone areas.