Carbonate Precipitation Technique Research Articles

Sand improvement by microbial-induced carbonate precipitation with casein micelles

This study explores the incorporation of casein micelles to improve the conventional microbial-induced carbonate precipitation technique used for soil improvement. With a single application of the proposed biocementing agent containing casein micelles, a mixed slurry of natural sand solidified to self-sustaining strength within 48 h at 37°C was obtained. The stress–strain curves of the biocemented specimens obtained from a consolidated drained triaxial compression test exhibited sharp peaks at less than 1% strain. Under effective confining pressures of 30, 50 and 100 kPa, the peak deviatoric stress registered 415, 479 and 536 kPa, respectively – representing 1·8–4·1 times the maximum strength of the original sand. Vaterite calcium carbonate crystals formed by the biocementing agent ensured bridging between sand particles, resulting in the improved cohesion. The cohesion-derived residual strength tended to increase at the critical state in biocemented sand under the lowest confining stress. The localised shear band formed by the crystals may control the movement of sand particles, resulting in a change in volumetric strain behaviour. The formation of casein micelles induced the nucleation and growth of spherical crystals, acting as a casein-mediated vaterite. This formation likely contributed to the improved cohesion of sand observed in this study.

Effects of enzyme-induced carbonate precipitation technique on multiple heavy metals immobilization and unconfined compressive strength improvement of contaminated sand

Enzyme-induced carbonate precipitation (EICP) has been studied in remediation of heavy metal contaminated water or soil in recent years. This paper aims to investigate the immobilization mechanism of Zn2+, Ni2+, and Cr(VI) in contaminated sand, as well as strength enhancement of sand specimens by using EICP method with crude sword bean urease extracts. A series of liquid batch tests and artificially contaminated sand remediation experiments were conducted to explore the heavy metal immobilization efficacy and mechanisms. Results showed that the urea hydrolysis completion efficiency decreased as the Ca2+ concentration increased and the heavy metal immobilization percentage increased with the concentration of Ca2+ and treatment cycles in contaminated sand. After four treatment cycles with 0.5 mol/L Ca2+ added, the immobilization percentage of Zn2+, Ni2+, and Cr(VI) were 99.99 %, 86.38 %, and 75.18 %, respectively. The microscale analysis results presented that carbonate precipitates and metallic oxide such as CaCO3, ZnCO3, NiCO3, Zn(OH)2, and CrO(OH) were generated in liquid batch tests and sand remediation experiments. The SEM-EDS and FTIR results also showed that organic molecules and CaCO3 may adsorb or complex heavy metal ions. Thus, the immobilization mechanism of EICP method with crude sword bean urease can be considered as biomineralization, as well as adsorption and complexation by organic matter and calcium carbonate. The unconfined compressive strength of EICP-treated contaminated sand specimens demonstrated a positive correlation with the increased generation of carbonate precipitates, being up to 306 kPa after four treatment cycles with shear failure mode. Crude sword bean urease with 0.5 mol/L Ca2+ added is recommended to immobilize multiple heavy metal ions and enhance soil strength.

Co-removal and recycling of Ba2+ and Ca2+ in hypersaline wastewater based on the microbially induced carbonate precipitation technique: Overlooked Ba2+ in extracellular and intracellular vaterite

This study investigates the co-precipitation of calcium and barium ions in hypersaline wastewater under the action of Bacillus licheniformis using microbially induced carbonate precipitation (MICP) technology, as well as the bactericidal properties of the biomineralized product vaterite. The changes in carbonic anhydrase activity, pH, carbonate and bicarbonate concentrations in different biomineralization systems were negatively correlated with variations in metal ion concentrations, while the changes in polysaccharides and protein contents in bacterial extracellular polymers were positively correlated with variations in barium concentrations. In the mixed calcium and barium systems, the harvested minerals were vaterite containing barium. The increasing concentrations of calcium promoted the incorporation and adsorption of barium onto vaterite. The presence of barium significantly increased the contents of O-CO, N-CO, and Ba-O in vaterite. Calcium promoted barium precipitation, but barium inhibited calcium precipitation. After being treated by immobilized bacteria, the concentrations of calcium and barium ions decreased from 400 and 274 to 1.72 and 0 mg/L (GB/T15454–2009 and GB8978–1996). Intracellular minerals were also vaterite containing barium. Extracellular vaterite exhibited bactericidal properties. This research presents a promising technique for simultaneously removing and recycling hazardous heavy metals and calcium in hypersaline wastewater.

High-level of bio-cementation by microbially induced carbonate precipitation technique with nano calcite seeds

The bio-cementation process through bacterial mineralization has emerged as an eco-friendly solution for soft or loose sandy soils, particularly in areas with ground slopes and high rainfall. This approach is aligned with sustainable development goals, promoting environmentally responsible and long-lasting solutions. In this context, ureolytic bacteria capable of decomposing urea for calcium carbonate precipitation are the primary agents for bio-cementation. This study explores the effects of nano calcite as nucleation sites on the MICP capacity to enhance the bio-cementation process. The microstructure of the precipitation was analyzed alongside its capacity for MICP. In addition, a simulated rainfall model was set up to evaluate the erosion resistance of sand samples. The findings of this study can guide the development of eco-friendly solutions for soil stabilization in environmentally vulnerable areas.

Factors affecting soil treatment with the microbially induced carbonate precipitation technique and its optimization

The microbially induced carbonate precipitation (MICP) technique has been used to increase mechanical strength, reduce permeability, and fix radionuclides of soils, etc. To achieve effective soil cementation by MICP, 3 aspects should be considered: MICP efficiency, bacterium retention (in soils after injections), and precipitation uniformity. Here, experiments and statistical analyses were conducted to understand the parameters affecting the 3 aspects. Moreover, the parameters leading to better performance in these aspects were designed and used to conduct MICP soil cementation with varying the number of injections. The results present that temperature and OD600nm of bacterial suspension are the most important parameters affecting MICP efficiency, followed by reaction time, pH, and concentration of cementation solution, and they are all statistically significant. As these parameters increased, MICP efficiency (ratio of CaCO3 formed to Ca2+ added) first increased quickly and then slowly or decreased. The soil particle size distribution and injection rate affected bacterium retention greatly. Smaller particle sizes, wider particle-size-distribution spans, and slower injection rates are beneficial to bacterium retention. However, higher injection rates favour precipitation uniformity. Finally, the unconfined compressive strength (UCS) of the bio-treated soil can be increased further by increasing the number of injections.

Mitigating alkali-silica reaction in cement mortars through microbial carbonate precipitation technique

Alkali-Silica Reaction (ASR) is a major cause of durability reduction in cement mixtures. This reaction takes place between the reactive silica contained in aggregates and the alkaline elements contained in cement (sodium and potassium), producing a hydrophilic gel known as glass water. This gel swells upon absorbing water, causing a damaging internal pressure in the mortar. This study aimed to investigate the impact of Microbial-Induced Calcite Precipitation (MICP) with Sporosarcina pasteurii on the progress of ASR in cement mortars. The mortars were made using the accelerated mortar bar method (ASTM C1260) by substituting 0, 25, 50, 75, and 100 % of aggregates with waste glass, as the extreme material causing ASR. The glass was treated by two methods named Wet Calcite Precipitation (WCP) and Fixed Calcite Precipitation (FCP), which both involved spraying 0.5 ml/cm2 of bacterial suspension on the glass. After 28 days of exposure to alkaline conditions, the mortars were examined by Scanning Electron Microscopy, X-ray Diffraction spectroscopy, and Energy-dispersive X-ray spectroscopy to verify the occurrence of ASR. The mortars were subjected to the expansion test, the ultrasonic pulse velocity (UPV) test, and the compressive strength test to measure their physical and mechanical properties. Both MCP treatments managed to significantly reduce the adverse effects of ASR (compared to the control) at the 95 % confidence level. Between WCP and FCP, WCP was more effective in improving the results of UPV and expansion tests, and FCP was more effective in improving compressive strength. The findings showed that MICP can effectively inhibit the adverse effects of ASR in cement mortars.

Bio-cementation by using microbially induced carbonate precipitation technique by using sporosarcina pasteurii with oxidizing agent supplements

In recent years, the natural biomineralization of bacterial metabolism to form calcium carbonate has drawn researchers and engineers' attention to exploring various applications for industrial purposes. Generally, microbially induced carbonate precipitation (MICP) is a biogeochemical process that can be applied to strengthen materials, including soil and sand structure, to overcome the chemical soil stabilization technique's limitations. In this study, Sporosarcina pasteurii was used to form CaCO3 by ureolytic MICP for soil-sand reinforcement in LAB-scale. As preliminary results, the increasing of CaCO3 crystals over curing time was an essential parameter for creating strong bonding between the soil-sand particles. Besides, the positive results in the water permeability test with the materials analysis as SEM, XRD demonstrated bacterial bio-cementation of sand specimens. Also, experimental results about oxidizing agent supplements show a positive effect on improving MICP capacity. Despite many challenges, bio-mineralization or bio-cementation is a promising technique for soil-sand stabilization in geotechnical engineering and building material applications, leading to sustainable development

Desiccation Induced Shrinkage of Compacted Lateritic Soil Treated via Enzymatic Induced Calcium Carbonate Precipitation Technique

Exploring the biological process to enhance the engineering properties of soil have received enormous recognition in recent years. Enzymatic induced calcium carbonate precipitation (EICP) is one of the bio-inspired methods of utilizing free urease to precipitates calcite from urea and calcium ions for bettering the geotechnical properties of poor soils. In this research, the EICP technique was used to improve the volumetric shrinkage strain of compacted soil liner. In this work, the residual soil was treated with various concentrations of cementations ranging from 0.25 to 1.0 M, and the soil was subjected to Atterberg limit tests, compaction test using British standard light (BSL) and reduced British standard light (RBSL) and desiccation drying volumetric shrinkage strain test. The study's findings revealed a remarkable improvement in the liquid limit and plasticity index of the treated residual soils compared to natural soil. It was also found that the volumetric shrinkage strain of the treated soil reduces progressively from 5.24% of natural to 1.49% at 1.0 M cementation solution when the soils were prepared at 0% OMC and BSL compaction effort. Based on the consideration of permissible VSS of less than 4%, the best treatment was obtained at 1.0 M for both BSL and RBSL prepared samples. Similarly, the best compaction plane is found in the treated with 1.0 M cementation solution.

Bioremediation of lead-contaminated mine waste by Pararhodobacter sp. based on the microbially induced calcium carbonate precipitation technique and its effects on strength of coarse and fine grained sand

Lead (Pb2+) is a toxic heavy metal that has a severe negative effect on human health and the environment. Physical, chemical and biological remediation techniques have long been used to remediate lead contamination. However, because of the great danger posed by lead contamination, there is increasing interest to apply eco-friendly and sustainable methods to remediate lead. Therefore, this study was conducted to use the microbially induced calcium carbonate precipitation (MICP) technique in conjunction with the bacterium Pararhodobacter sp. to bioremediate lead. Laboratory scale experiments were conducted and complete removal of 1036mg/L of Pb2+ was achieved. These results were further confirmed by scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis, which indicated coprecipitation of calcium carbonate (CaCO3) and lead. The unconfined compressive strength increased with an increase in injection interval with maximum unconfined compressive strength of 1.33MPa for fine sand, 2.87MPa for coarse sand and 2.80MPa for mixed sand. For Pararhodobacter sp. to efficiently induce lead immobilisation the bacterial interval required is four times with a calcium and urea concentration of 0.5M and bacterial concentration of 109cfu/mL. Very few low-cost in situ heavy metal treatment processes for lead bioremediation are available; therefore, bioimmobilization of lead by MICP has the potential for application as a low-cost and eco-friendly method for heavy metal remediation.

Reducing the hydraulic erosion of sand using microbial-induced carbonate precipitation

Hydraulic erosion is one of the main causes of failure within earth dams and embankments. Various methods are used to mitigate against such erosion, a common approach being grouting with cement, clay or chemical materials. Biogrouting using the microbial-induced carbonate precipitation technique is a relatively new, cost-effective, technically appropriate and environmentally friendly soil improvement method. Bacteria injected into the soil produce urease enzyme, which converts urea to ammonium and carbonate, causing calcite precipitation that binds soil grains together. In this study, the erodibility parameters of dense silica sand specimens treated with different injection strategies were investigated at bench scale. More effective treatment – in terms of greater and more uniform calcite precipitation over the test-specimen length, and hence greater erosion resistance – was achieved by aeration during solution injections and by incorporating a drained stage between injection cycles. With the latter, calcite precipitated as larger crystals, accumulating extensively over grain surfaces and also formed integrated in the pore voids. The best-performing treatment strategy produced a 95% reduction in erodibility and a five-fold increase in critical shear stress relative to untreated sand. These findings were confirmed by scanning electronic microscopy and calcium carbonate titration tests.

Review of ground improvement using microbial induced carbonate precipitation (MICP)

ABSTRACTMechanical compaction and chemical grouting are the two most widely used methods in geotechnical engineering for ground improvement. However, the disadvantages of the methods including high cost, high energy consumption, and potential environmental pollution are obvious. A new ground treatment technique, i.e., microbial induced carbonate precipitation, was developed recently. Review of ground improvement using microbial induced carbonate precipitation technique was performed in this study. The mechanism of microbial induced carbonate precipitation-treated soils was first introduced followed by the review of many aspects of the microbial induced carbonate precipitation technique. Thereafter, the related engineering applications were presented and summarized. Moreover, some problems existing in current theoretical and experimental studies as well as the possible solutions for future development were also discussed. Some recommendations were proposed for a wider application of this technique.

Characterization of the Microbial Induced Carbonate Precipitation Technique as a Biological Cementing Agent for Sand Deposits

Characterization of the Microbial Induced Carbonate Precipitation Technique as a Biological Cementing Agent for Sand Deposits

Synthesis of BiFeO 3 by carbonate precipitation

Magnetoelectric multiferroic BiFeO3 (BFO) was synthesized by a simple carbonate precipitation technique of metal nitrate solutions. X-ray powder diffraction and thermo-gravimetric analysis (TGA) revealed that the precipitate consists of an intimate mixture of crystalline bismuth carbonate and an amorphous hydroxide of iron. The precipitate yielded BiFeO3 at an optimal calcination temperature of ~560°C. Energy dispersive X-ray (EDX) analysis showed 1:1 ratio between Bi and Fe in the oxide. X-ray photoelectron spectroscopy (XPS) studies confirmed that Fe to be in +3 oxidation states both in the precipitated powder and BiFeO3. The synthesized BFO exhibits a very weak ferromagnetic correlation at room temperature and the degree of which increases slightly on cooling down to 10 K suggesting alteration in the long range spatial modulation of the spins arrangement as compared to the bulk BiFeO3.

Catalytic combustion of methane: surface characterization of manganese-substituted barium hexa-aluminate catalysts

In order to achieve a good activity with respect to methane combustion, a good route would be via catalysts incorporating transition metals. For devices operating at high temperatures, such as gas turbines, substituted hexa-aluminates present the advantage of good thermal stability when compared to impregnated Al2O3. For the purpose of this study, manganese-substituted hexa-aluminates were prepared either by the sol–gel method or by carbonate precipitation. Surfaces were analysed by soft x-ray emission, namely low-energy electron-induced x-ray spectroscopy (LEEIXS), and by photoelectron spectroscopy, namely x-ray photoelectron spectroscopy. The results on samples incorporating increasing amounts of manganese show the existence of an upper limit to the number of atoms substituted at the catalyst surface. This limit is about 2.7 manganese ions per unit cell, for samples prepared either by the sol–gel or by the carbonate precipitation technique and then calcinated at 1200°C. The interpretation of the Auger parameter variations shows that the relative amount of Mn in oxidation state III increases when the surface amount of Mn increases, as well as with the Mn substitution level. This fact can be related to an increased activity for methane conversion. © 1998 John Wiley & Sons, Ltd.