Comparison of jack bean and soybean crude ureases on surface stabilization of desert sand via enzyme-induced carbonate precipitation

Enzyme-induced carbonate precipitation (EICP) is a prominent biogeotechnical technique for soil stabilization to address desert invasion and dust emission issues. This study investigates the bio-cementation efficacy of EICP mediated by jack bean crude urease (JCU) and soybean crude urease (SCU) on surface stabilization of aeolian sand from Tengger Desert. Topsoil properties of the EICP-treated sand including CaCO3, organic matter content, surface strength, and wind erosion resistance were evaluated. The urease activity of JCU was 3.4 times higher than SCU, resulting in a higher CaCO3 content and surface strength of JCU-treated topsoil. The optimum bean dosages were observed at 40 g/L jack bean and 80 g/L soybean for achieving maximum CaCO3 content and surface strength, respectively. EICP-treatments with excessive bean dosages would decrease the surface strength due to the interference of organic matter precipitation on effective bridging between the generated CaCO3 crystals and the sand particles. Wind erosion resistance was evaluated under wind-sand flow condition at a wind speed of 13.8 m/s, which was positively correlated with surface strength. JCU presented an overall greater stabilization potential of topsoil than SCU. Additionally, the urease costs of EICP-treatments with JCU and SCU were reduced by about 380-1400 times compared with commercially available ureases.