Enhancement of Microbially Induced Carbonate Precipitation Using Organic Biopolymer

Abstract

Microbially induced carbonate precipitation (MICP) by using ureolytic bacteria is a novel and environmentally friendly way to treat the un-cemented sand. It was implemented successfully in number of geotechnical applications. Use of organic additives to improve the MICP process is a novel and interesting approach. In this research, effect of the cationic biopolymer poly-l-lysine on the MICP process was investigated by using ureolytic bacteria Pararhodobacter sp. Urea hydrolysis by the bacteria in the presence of CaCl2 was conducted with the addition of the polymer under different conditions. Morphology of the precipitate of CaCO 3 after oven dried was analyzed by using the scanning electron microscope. Bell-shaped curve was obtained for the variation between the amount of the precipitate with the increase of the amount of the poly-l-lysine. Poly-Llysine gives higher amount of precipitate than conventional MICP process and morphology of the crystals changed drastically from well-developed rhombohedral crystals to ellipsoidal shaped aggregates.

Assessing Indigenous Soil Ureolytic Bacteria as Potential Agents for Soil Stabilization

“…The success of the MICP process is promoted primarily by ureolytic bacterial species such as Bacillus sphaericus, Pararhodobacter sp., Mor-ganella morgana, Bacillus licheniformis and Bacillus cereus which are capable of utilizing urea as a source of nitrogen by passively diffusing or actively transporting the urea into the cytoplasm of the cell and the bacterial cell wall acting as nucleation sites (Dardau et al 2021). In search for alternative soil improvement technology with minimal environmental consequences, less adverse effect on the ecosystem and maintaining ecological balance (Khaliq & Ehsan 2016), over conventional methods (cement, chemical grouting & deep mixing technique) that varied in terms of environmental impact, cost, penetration depth, energy consumption and treatment uniformity which portrays their merits and demerits (Hiranya et al 2018;Duo et al 2018;Bui Truong et al 2020), and advances in material and geotechnical research, led to the development of an innovative, novel bio-mediated soil improvement technique utilizing ureaseproducing bacteria as potential agents.…”