scholarly journals The role of bacterial urease activity on the uniformity of carbonate precipitation profiles of bio-treated coarse sand specimens

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charalampos Konstantinou ◽  
Yuze Wang ◽  
Giovanna Biscontin ◽  
Kenichi Soga
Keyword(s):  
Calcium Carbonate ◽  
Calcium Chloride ◽  
Urease Activity ◽  
Coarse Sand ◽  
Carbonate Precipitation ◽  
Population Densities ◽  
Carbonate Cements ◽  
Microbially Induced Carbonate Precipitation

AbstractProtocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise the process with regard to the amount of injected chemicals, the ratio of urea to calcium chloride, the method of injection and injection intervals, and the population of the bacteria, usually using fine- to medium-grained poorly graded sands. This study assesses the effect of varying urease activities, which have not been studied systematically, and population densities of the bacteria on the uniformity of cementation in very coarse sands (considered poor candidates for treatment). A procedure for producing bacteria with the desired urease activities was developed and qPCR tests were conducted to measure the counts of the RNA of the Ure-C genes. Sand biocementaton experiments followed, showing that slower rates of MICP reactions promote more effective and uniform cementation. Lowering urease activity, in particular, results in progressively more uniformly cemented samples and it is proven to be effective enough when its value is less than 10 mmol/L/h. The work presented highlights the importance of urease activity in controlling the quality and quantity of calcium carbonate cements.

Non-stoichiometric hydrated magnesium-doped calcium carbonate precipitation in ethanol

2019 ◽  
Vol 55 (86) ◽  
pp. 12944-12947 ◽  
Author(s):  
Giulia Magnabosco ◽  
Andrea M. M. Condorelli ◽  
Rose Rosenberg ◽  
Iryna Polishchuk ◽  
Boaz Pokroy ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Crystallization Process ◽  
Ion Solvation ◽  
Absolute Ethanol ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation

The effect of Mg2+ on the precipitation pathway of CaCO3 in absolute ethanol has been studied to investigate the role of ion solvation in the crystallization process.

Strength and Permeability of Bentonite-Assisted Biocemented Coarse Sand

2020 ◽  
Author(s):  
Guoliang Ma ◽  
Xiang He ◽  
Xiang Jiang ◽  
Hanlong Liu ◽  
Jian Chu ◽  
...  
Keyword(s):  
Unconfined Compressive Strength ◽  
Volume Fraction ◽  
Coarse Sand ◽  
Effective Concentration ◽  
Carbonate Precipitation ◽  
Natural Clay ◽  
High Concentration ◽  
Strength Enhancement ◽  
Microbially Induced Carbonate Precipitation ◽  
Clay Aggregates

To effectively stabilize coarse sand, bentonite was introduced in microbially induced carbonate precipitation (MICP) grouting. Varying concentrations (0 g/L, 20 g/L, 40 g/L and 80 g/L) of bentonite were added to bacterial suspensions (BSs), which were magnetically stirred to form bacterial-bentonite suspensions (BBSs). Then, coarse sand specimens were treated with BBSs and cementation solutions (CSs) to different cementation levels. The results showed that the addition of bentonite could increase the volume fractions of the precipitates consisting of calcium carbonate (CaCO3) and bentonite. The permeability decreased exponentially as the volume fraction of precipitates increased. As the active precipitates increased when a lower concentration (e.g., 20 g/L) of bentonite was added to the MICP grouting, the unconfined compressive strength (UCS) was substantially improved. However, detrimental effects were observed for specimens treated with a high concentration of bentonite. These results indicate that the effective concentration of natural clay aggregates used in MICP grouting was different for different engineering applications, e.g., seepage control and strength enhancement. The current work provides an encouraging method of improving the MICP technique.

Effect of Temperature on Calcium Carbonate Precipitation in Biomimetic Calcium Chloride Solution

2021 ◽  
Vol 107 ◽  
pp. 76-81
Author(s):  
Intan Nurfarzana Mohd Razib Fatheen ◽  
Che Husain Syuhani ◽  
Hamzah Fazlena ◽  
Najwa Mohd Rodhi Miradatul ◽  
Veny Harumi
Keyword(s):  
Calcium Carbonate ◽  
Calcium Chloride ◽  
Chloride Solution ◽  
Calcium Chloride Solution ◽  
Effect Of Temperature ◽  
Precipitation Process ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
Calcium Carbonate Precipitate ◽  
Temperature Range

In the present work, the effect of temperature on calcium carbonate precipitation in the biomimetic calcium chloride solution was investigated. A spontaneous calcium carbonate precipitate was formed in the biomimetic calcium chloride solution as a result of the carbon dioxide hydration process. The reaction was conducted at different temperature range vary from 30°C to 100°C. The mass of the calcium carbonate precipitate and the pH solution was measured in the study. The finding indicated that an increment of the temperature has led to the fast pH reduction of the solutions to 7.0. However, the process has retarded the calcium carbonate precipitation process. The optimum temperature for higher calcium carbonate precipitation has occurred at the temperature range of 47.5°C – 65°C which gave the highest calcium carbonate precipitate at 0.121g. The addition of Tris buffer into the calcium chloride solution in this study did not gave an inhibition effect on the calcium carbonate precipitate. Based on the results, an operating condition at 47.5°C – 65°C was recommended to be used in mineral carbonization of CO2 using the biomimetic calcium chloride solution.

scholarly journals Role of Na-Montmorillonite on Microbially Induced Calcium Carbonate Precipitation

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6211
Author(s):  
Guowang Tang ◽  
Cangqin Jia ◽  
Guihe Wang ◽  
Peizhi Yu ◽  
Haonan Zhang
Keyword(s):  
Calcium Carbonate ◽  
Sandy Soil ◽  
Carbonate Precipitation ◽  
Soil Consolidation ◽  
X Ray Diffraction ◽  
Calcium Carbonate Precipitation ◽  
X Ray ◽  
Significant Attention ◽  
Previous Reaction

The use of additives has generated significant attention due to their extensive application in the microbially induced calcium carbonate precipitation (MICP) process. This study aims to discuss the effects of Na-montmorillonite (Na-MMT) on CaCO3 crystallization and sandy soil consolidation through the MICP process. Compared with the traditional MICP method, a larger amount of CaCO3 precipitate was obtained. Moreover, the reaction of Ca2+ ions was accelerated, and bacteria were absorbed by a small amount of Na-MMT. Meanwhile, an increase in the total cementing solution (TCS) was not conducive to the previous reaction. This problem was solved by conducting the reaction with Na-MMT. The polymorphs and morphologies of the CaCO3 precipitates were tested by using X-ray diffraction and scanning electron microscopy. Further, when Na-MMT was used, the morphology of CaCO3 changed from an individual precipitate to agglomerations of the precipitate. Compared to the experiments without Na-MMT in the MICP process, the addition of Na-MMT significantly reduced the hydraulic conductivity (HC) of sandy soil consolidated.

scholarly journals Experimental Investigation on Effects of Bacterial Concentration, Crack Inclination Angle, Crack Roughness, and Crack Opening on the Fracture Permeability Using Microbially Induced Carbonate Precipitation

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yulin Zou ◽  
Hao Bai ◽  
Fan Shen ◽  
Hong Xu ◽  
Yundong Shou
Keyword(s):  
Calcium Carbonate ◽  
Inclination Angle ◽  
Crack Opening ◽  
Experimental Results ◽  
Carbonate Precipitation ◽  
Fracture Permeability ◽  
Bacterial Concentration ◽  
Angle Crack ◽  
Microbially Induced Carbonate Precipitation ◽  
Crack Roughness

Uncontrollable leakage has significant effects on the safety of fractured rock mass, and microbially induced carbonate precipitation (MICP) is an effective way to control the seepage. In this study, four sets of seepage experiments are conducted on transparent rock-like specimens containing MICP filled single cracks to investigate the effects of bacterial concentration, crack inclination angle, crack roughness, and crack opening on fracture permeability. The experimental results show that calcium carbonate precipitation is produced when Sporosarcina pasteurii and cementing fluid are injected into the cracks, which can seal the cracks and reduce the permeability of the cracks. Moreover, the calcium carbonate produced by Sporosarcina pasteurii increases with increasing bacterial concentration. Furthermore, the fracture permeability of the MICP filled crack increases first and then decreases with increasing inclination, roughness, and opening of cracks. The experimental results provide a better understanding of the influence of different construction conditions on fracture permeability when the MICP technology is applied in rock engineering.

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