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Rajasekar A, Zhao C, Wu S, Murava RT, Wilkinson S. Synergistic biocementation: harnessing Comamonas and Bacillus ureolytic bacteria for enhanced sand stabilization. World J Microbiol Biotechnol 2024; 40:229. [PMID: 38825655 PMCID: PMC11144680 DOI: 10.1007/s11274-024-04038-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 05/28/2024] [Indexed: 06/04/2024]
Abstract
Biocementation, driven by ureolytic bacteria and their biochemical activities, has evolved as a powerful technology for soil stabilization, crack repair, and bioremediation. Ureolytic bacteria play a crucial role in calcium carbonate precipitation through their enzymatic activity, hydrolyzing urea to produce carbonate ions and elevate pH, thus creating favorable conditions for the precipitation of calcium carbonate. While extensive research has explored the ability of ureolytic bacteria isolated from natural environments or culture conditions, bacterial synergy is often unexplored or under-reported. In this study, we isolated bacterial strains from the local eutrophic river canal and evaluated their suitability for precipitating calcium carbonate polymorphs. We identified two distinct bacterial isolates with superior urea degradation ability (conductivity method) using partial 16 S rRNA gene sequencing. Molecular identification revealed that they belong to the Comamonas and Bacillus genera. Urea degradation analysis was performed under diverse pH (6,7 and 8) and temperature (15 °C,20 °C,25 °C and 30 °C) ranges, indicating that their ideal pH is 7 and temperature is 30 °C since 95% of the urea was degraded within 96 h. In addition, we investigated these strains individually and in combination, assessing their microbially induced carbonate precipitation (MICP) in silicate fine sand under low (14 ± 0.6 °C) and ideal temperature 30 °C conditions, aiming to optimize bio-mediated soil enhancement. Results indicated that 30 °C was the ideal temperature, and combining bacteria resulted in significant (p ≤ 0.001) superior carbonate precipitation (14-16%) and permeability (> 10- 6 m/s) in comparison to the average range of individual strains. These findings provide valuable insights into the potential of combining ureolytic bacteria for future MICP research on field applications including soil erosion mitigation, soil stabilization, ground improvement, and heavy metal remediation.
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Affiliation(s)
- Adharsh Rajasekar
- Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CIC-AEET), Nanjing University of Information Science &Technology, Nanjing, 210044, China.
- School of Geography and Environmental Sciences, University of Reading, Reading, RG6 6AH, UK.
| | - Cailin Zhao
- School of Geography and Environmental Sciences, University of Reading, Reading, RG6 6AH, UK
| | - Suowei Wu
- School of Geography and Environmental Sciences, University of Reading, Reading, RG6 6AH, UK
| | - Raphinos Tackmore Murava
- Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CIC-AEET), Nanjing University of Information Science &Technology, Nanjing, 210044, China
| | - Stephen Wilkinson
- Faculty of Engineering and Information Sciences, University of Wollongong in Dubai, Dubai, UAE
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Hu J, Fan F, Huang L, Yu J. Experimental Study on Enhancing the Mechanical Properties of Sandy Soil by Combining Microbial Mineralization Technology with Silty Soil. MATERIALS (BASEL, SWITZERLAND) 2024; 17:2362. [PMID: 38793429 PMCID: PMC11122880 DOI: 10.3390/ma17102362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2024] [Revised: 05/09/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024]
Abstract
Currently, coastal sandy soils face issues such as insufficient foundation strength, which has become one of the crucial factors constraining urban development. Geotechnical engineering, as a traditional discipline, breaks down disciplinary barriers, promotes interdisciplinary integration, and realizes the green ecological and low-carbon development of geotechnical engineering, which is highly important. Based on the "dual carbon" concept advocating a green and environmentally friendly lifestyle, Bacillus spores were utilized to induce calcium carbonate precipitation technology (MICP) to solidify coastal sandy soils, leveraging the rough-surface and low-permeability characteristics of silty soil. The mechanical-strength variations in the samples were explored through experiments, such as calcium carbonate generation rate tests, non-consolidated undrained triaxial shear tests, and scanning electron microscopy (SEM) experiments, to investigate the MICP solidification mechanism. The results indicate that by incorporating silty soil into sandy soil for MICP solidification, the calcium carbonate generation rates of the samples were significantly increased. With the increase in the silty-soil content, the enhancement range was 0.58-3.62%, with the maximum calcium carbonate generation rate occurring at a 5% content level. As the silty-soil content gradually increased from 1% to 5%, the peak deviator stress increased by 4.2-43.2%, enhancing the sample shear strength. Furthermore, the relationship between the internal-friction angle, cohesion, and shear strength further validates the enhancement of the shear strength. Silty soil plays roles in adsorption and physical filling during the MICP solidification process, reducing the inter-particle pores in sandy soil, increasing the compactness, providing adsorption sites, and enhancing the calcium carbonate generation rate, thereby improving the shear strength. The research findings can provide guidance for reinforcing poor coastal sandy-soil foundations in various regions.
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Affiliation(s)
- Jun Hu
- School of Civil Engineering and Architecture, Hainan University, Haikou 570228, China; (J.H.); (F.F.); (L.H.)
- Collaborative Innovation Center of Marine Science and Technology, Hainan University, Haikou 570228, China
| | - Fei Fan
- School of Civil Engineering and Architecture, Hainan University, Haikou 570228, China; (J.H.); (F.F.); (L.H.)
- Collaborative Innovation Center of Marine Science and Technology, Hainan University, Haikou 570228, China
| | - Luyan Huang
- School of Civil Engineering and Architecture, Hainan University, Haikou 570228, China; (J.H.); (F.F.); (L.H.)
- Collaborative Innovation Center of Marine Science and Technology, Hainan University, Haikou 570228, China
| | - Junchao Yu
- School of Architecture and Art Design, Nanjing Polytechnic Institute, Nanjing 210048, China
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Wang Q, Hu X, Zhao Y, Jiang N, Yu X, Feng Y, Zhang J. Microscopic deposition-property relationships in microbial-induced consolidation of coal dusts. ENVIRONMENTAL RESEARCH 2024; 244:117956. [PMID: 38128598 DOI: 10.1016/j.envres.2023.117956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/07/2023] [Accepted: 12/14/2023] [Indexed: 12/23/2023]
Abstract
In recent years, the preparation of new microbial dust suppressants based on microbial induced carbonate precipitation (MICP) technology through enriched urease-producing microbial communities has become a new topic in the field of coal dust control. The deposition of CaCO3 was the key to suppress coal dust. However, deposition characteristics in the field is not sufficient and the relationship between deposition characteristics and erosion resistance is not clear, which hinders the development of engineering application of new microbial dust suppressant. Therefore, based on X-CT technology, this paper observed and quantified micro-deposition of bio-consolidated coal dust with different calcium sources. Furthermore, a conceptual framework for deposition was proposed and its correlation with erosion resistance was revealed. The results showed that CaCO3 induced by calcium chloride and calcium lactate was aggregate deposited. Aggregate deposited CaCO3 was small in volume, showed the distribution of aggregation in the central area and loose outside, and mosaiced pores. CaCO3 induced by calcium nitrate was surface deposition due to attached biomass. Surface deposition was mostly large volume CaCO3 expanding from the inside out, which could cover coal dust to a high degree and completely cemented pores. In addition, the threshold detachment velocity of coal dust cemented by surface deposition was increased by 17.6-19.1% compared to aggregate deposition. This depended on the abundance and strength of CaCO3 bonding between coal dust particles under different deposition. The two-factor model based on porosity and CaCO3 coverage can well express relationship between erosion resistance and depositional characteristics. Those results will help the engineering application of MICP technology in coal dust suppression.
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Affiliation(s)
- Qingshan Wang
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China; Key Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China
| | - Xiangming Hu
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China; Key Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China
| | - Yanyun Zhao
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China; Key Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China; Institute of Yellow River Delta Earth Surface Processes and Ecological Integrity, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China.
| | - Ningjun Jiang
- Institute of Geotechnical Engineering, Southeast University, Nanjing, China; Department of Civil and Environmental Engineering, University of Hawaii at Manoa, Honolulu, USA
| | - Xiaoniu Yu
- Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing, 211189, China; School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Yue Feng
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China; Key Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China
| | - Juan Zhang
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China; Key Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, Shandong, 266590, China
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