Factors affecting biomineralization and various applications of nature-based solutions

Abstract

Geotechnical challenges are immense as the soil is heterogeneous and unconsolidated material, which increases the requirement of sustainable environment-friendly, and economical ground improvement techniques in lieu of carbon-intensive conventional methods. The microbially induced calcite precipitation technique uses the living phase of soil to produce the calcium carbonate precipitation between the granular media. The study was conducted to analyze the factors affecting biomineralization, that is, pH, electrical conductivity (EC), urea, and CaCl20.2H2O concentrations on biogeochemical reactions during the urea hydrolysis process and the amount of calcite formation. A nonpathogenic, gram-positive bacteria

Bacillus sphaericus was bio-augmented in sand-filled at 40% relative density in a plastic tube. The bacterially attached sand was treated with four different concentrations of urea and CaCl20.2H2O such as (1) 0.25 equimolar, (2) 0.50 equimolar, (3) 0.50M and 0.25M (2:1 sample), and (4) 0.75M and 0.25M (3:1 sample), respectively up to 14 days. Scanning electron microscopy, X-ray diffraction, and calcimeter were used to find the presence and amount of calcite precipitation. The results showed that the rate of urea hydrolysis increases with an increase in urea concentration with respect to calcium chloride. The maximum increase in pH and EC was found in the 3:1 sample, which leads to a higher amount of precipitation at the top layer only, though the uniformity in calcite precipitation was achieved in the 0.50 equimolar cementation media treated sample. © 2024 Elsevier Ltd. All rights reserved.