Smart soil grouting using innovative urease‐producing bacteria and low cost materials

Abstract

Aims: Calcium carbonate is a biomineral whose precipitation could be mediated by ureolytic bacteria and contributes in strengthening of sandy soils. The type of bacteria and grade of reagents have significant influence on microbially induced calcite precipitation (MICP). In the present study, factorial experiments based on these two factors were designed to determine their potential on MICP process, taking into consideration the economic advantages while giving quality results as well. Methods and Results: For the first time, Alkalibacterium iburiense strain EE1 (GenBank accession no. MF355369.1) is reported for its biogrouting activity. Optimum growth conditions for MICP treatments were pH (9Á56 AE 0Á021), EC (44Á7 AE 0Á057 mS cm −1 ), OD 600 (2Á04 AE 0Á015), NH 4+ concentration (487Á06 AE 1Á021 mmol l −1 ), and urease activity (20Á0 AE 0Á75 mmol l −1 urea hydrolysed min −1 ) after 72-h incubation. Statistical analysis comparing the growth in technical-grade medium prepared in tap water and analytical-grade medium prepared in deionized water showed no significant differences (P = 1Á0) in biomass and urease activity. In contrast to previous studies, the current approach could reduce the bacterial culture and cementation solution ratio by about 50%, using a simple surface percolation method with staged injection instead of parallel injection to treat different sand columns. Using fixation solution could immobilize the bacteria over the full length of columns for better strength improvement. The unconfined compressive strength ranged between 0Á64 to 2Á11 kg cm −2 , and the corresponding CaCO 3 contents 5Á7-38Á5%. The scanning electron microscope images indicated that the precipitated CaCO 3 by bacteria was stable calcite. Conclusions: Alkalibacterium iburiense and technical-grade reagents under nonsterile conditions are satisfactory consolidating agents for sandy soils.Significance and Impact of the Study: This approach is considered ecofriendly and cost-effective for future scale-up applications in various geotechnical engineering.

Calcium carbonate bioprecipitation mediated by ureolytic bacteria grown in pelletized organic manure medium

“…Yeast extract is a protein-rich complex media that is conveniently used for bacterial cultivation. For MICPrelated studies, 20 g/L of laboratory-grade yeast extract is often used to cultivate S. pasteurii [7,8,14,21,23,[50][51][52]. However, some studies reported using 5 to 15 g/L of yeast extract [53][54][55][56].…”

“…It is Gram-positive, alkaliphilic, non-pathogenic, and has the propensity to generate endospores for survival in harsh environments [7]. The MICP has been demonstrated under various conditions (such as laboratory-scale, pilot-scale, and field-scale) as a potential sustainable technique for soil improvement and solidification [8][9][10][11], erosion control and prevention [12][13][14], and remediation of contaminants (such as copper, cadmium, and mercy) [15][16][17].…”

Assessing Indigenous Soil Ureolytic Bacteria as Potential Agents for Soil Stabilization

“…Conversely, despite the numerous advances in MICP, most urease-producing bacteria utilised for various MICP applications are commercially procured from culture collection centres, which contribute to cost (Zomorodian et al 2019). According to the present global market price, it cost approximately US$402.0 to procure the original patent of S. pasteurii ATCC 11859, which suggests the low-cost advantage of utilizing indigenous ureolytic bacteria for various MICP applications (Ezzat & Ewida 2021). Further, the procured microorganisms are often associated with drawbacks regarding reduction in the population of the introduced bacteria into the soil due to competition, mechanical stress and predation arising from the non-adaptability of the organisms to the local environment (Burbank et al 2011).…”

Grouting Mechanism of Polyurethane Composite Materials in Asphalt Pavement Subsidence

“…Those working with polyurethane grouting material can easily control the form and performance of a product by changing the type and share of its raw materials, so as to obtain the hard polyurethane foam [9,10]. Furthermore, the setting and curing time of polyurethane can be controlled comprehensively by adjusting the catalyst content and proportion of polyether polyol and isocyanate in polyurethane raw materials [11,12]. Reducing the curing time can realize rapid opening to traffic after road maintenance.…”