Cattle urine as a substitute for industrial urea for Microbially Induced Calcite Precipitation (MICP) treatment of Ganga River sand

Abstract MICP is a natural, environmentally friendly method for ground improvement and biomineralization. The versatile application of this process for bio-calcification and bio-clogging has piqued the interest of many researchers in the past few decades. Bacteria that can produce the urease enzyme are used in this treatment procedure. This enzyme is responsible for urea hydrolysis which upon the addition of a calcium source formulates the calcite crystal formation and precipitation. The use of industrial urea for the MICP treatment process has a high carbon footprint and defeats the purpose of the environment-friendly treatment method. The primary goal of this study is to investigate the utilization of cattle urine as a substitute supply of urea. Because it aids in the disposal of animal waste and the substitution of sustainable resources, using cattle urine is advantageous. Following the bioaugmentation of the urease-producing bacterium Bacillus sphaericus , MICP treatments were carried out on Ganga River sand. The results were promising as a significant amount of calcium carbonate crystals were observed after a treatment of 12 h. Microanalysis using Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) revealed the formation of calcium carbonate crystals in the soil matrix after the MICP treatment. Calcite precipitation of around 1.27 g was found in the top layer of the sand column supplemented with Bacillus sphaericus . The formation of calcium carbonate in the soil matrix led to a significant reduction of 35% in permeability for the treated sand column that was augmented with the ureolytic bacteria compared to the sand column without the required bacteria. The results revealed a promising and cost-effective alternative to urea substitution source for the MICP treatment process. Since it provides a sustainable alternative to urea sources and removes animal waste-related environmental contamination, this substitution is also beneficial for the environment.