Geochemical Evaluation of Contaminated Soil for Stabilisation Using Microbiologically Induced Calcite Precipitation Method

Abandoned mines contaminated with heavy metal wastes pose health risk and environmental hazard. Common methods in managing these wastes include pond storage, dry sacking, underground and ocean disposal and phytho-stabilisation but these does not address the associated risks regarding migration of contaminated liquid or when the soil structure is compromised during natural disaster such as earthquake. Due to these limitations, microbiologically induced calcite precipitation method (MICP) is an exciting alternative as it is sustainable and environmentally friendly. This research evaluates mine waste obtained from two sites; Mamut and Lohan Dam, both located at earthquake-prone Ranau Sabah, Malaysia, in term of their physical, mineralogy and morphological characteristics for stabilisation using MICP. Physically, mining wastes from Mamut are of well graded soil with sand (53.9%) and gravel (43.5%), classified as SW (USCS) and A-1-a (AASHTO). Meanwhile, waste from Lohan Dam are of sand (49.9%) and gravel (10.1%), classified as SM (USCS) and A-4 (AASHTO). Constant head test of the soils from the sites showed results of 3.607 x 10-1 and 3.407 x 10-2 cm/s respectively indicate high permeability. Mineralogy assessment using inductively coupled plasma atomic emission spectroscopy (ICP-OES) showed high level of iron (Fe) with 528.08 and 2931.38 mg/L respectively. Other heavy metals detected include copper (Cu), 24.39 and 4.33 mg/L, lead (Pb), 2.53 and 0.53 mg/L, manganese (Mn), 5.71 and 3.64 mg/L and arsenic (As), 0.71 and 0.31 mg/L; some higher than Malaysia’s Ministry of Health and United Nations’ Food and Agricultural approved standards. Morphological observation of the size, shape and soil texture under scanning electromagnetic (SEM) further indicate the necessity and suitability of both sites for stabilisation using MICP

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

Bio-desaturation and bio-sealing techniques for mitigation of soil liquefaction: a review

Biogeotechnology is a recent area of study that deals with the improvement of engineering properties of soils in an eco-friendly and sustainable approach through the use of microorganisms. This paper first, reviewed the concept of bio-mediated soil improvement technique, components involved and the roles they played. Two processes of bio-mediation soil improvement techniques i.e. microbial-induced calcite precipitation (MICP) for producing bio-cement via ureolysis and bio-desaturation for generating specifically biogenic nitrogen gas via denitrification, their mechanisms of occurring and factors influencing them were described in details. An overview study was done on soil liquefaction. Conventional methods employed for mitigations of liquefaction hazards were reviewed and their limitations were drawn. The use of the de-saturation process for mitigation of soil liquefaction was adequately addressed. Mitigation of liquefaction using biological processes, in particular, MICP and/or bio-desaturation were introduced. The findings from the previous works have shown that both the two techniques are capable of improving liquefaction resistance of soils. Most of the results have shown that presence of biogenic nitrogen gas in soils treated with denitrifying bacteria is able to induce partial desaturation in the soil which consequently increases the cyclic shear strength, reduces pore water pressure and changes the soil behaviour from compressive to dilatant. Finally, potentials, challenges, and recommendations for future studies were identified

Montmorillonite for Adsorption and Catalytic Elimination of Pollutants from Wastewater: A State-of-the-Arts Review

Clay minerals have been recognized as one of the cheap and effective materials for wastewater remediation. Among the various clay minerals, montmorillonite (MMT) has received much attention due to its wide availability, low-cost and promising properties such as high porosity, mechanical strength, and cation exchange capacity. Additionally, MMT has high swelling properties. These features make it an ideal material for wastewater remediation applications. In addition, it possessed good cationic exchange capacity, making it easier to interact with various molecules. MMT and its composites exhibited good selectivity and catalytic activity for contaminants elimination from wastewater. Surface modification and functionalization have been identified as a way to improve the MMT’s adsorptive performance and endow it with light and light-harnessing properties. Thus, MMT composites, especially metal and metal-oxide nanoparticles, have shown good adsorption and photocatalytic activity toward the elimination/mineralization of various contaminants such as dyes, pharmaceuticals, heavy metals, and other organic and inorganic species. As such, MMT and its composites can be adopted as potential materials for wastewater remediation

Bio-desaturation and bio-sealing techniques for mitigation of soil liquefaction: a review

Biogeotechnology is a recent area of study that deals with the improvement of engineering properties of soils in an eco-friendly and sustainable approach through the use of microorganisms. This paper first, reviewed the concept of bio-mediated soil improvement technique, components involved and the roles they played. Two processes of bio-mediation soil improvement techniques i.e. microbial-induced calcite precipitation (MICP) for producing bio-cement via ureolysis and bio-desaturation for generating specifically biogenic nitrogen gas via denitrification, their mechanisms of occurring and factors influencing them were described in details. An overview study was done on soil liquefaction. Conventional methods employed for mitigations of liquefaction hazards were reviewed and their limitations were drawn. The use of the de-saturation process for mitigation of soil liquefaction was adequately addressed. Mitigation of liquefaction using biological processes, in particular, MICP and/or bio-desaturation were introduced. The findings from the previous works have shown that both the two techniques are capable of improving liquefaction resistance of soils. Most of the results have shown that presence of biogenic nitrogen gas in soils treated with denitrifying bacteria is able to induce partial desaturation in the soil which consequently increases the cyclic shear strength, reduces pore water pressure and changes the soil behaviour from compressive to dilatant. Finally, potentials, challenges, and recommendations for future studies were identified

Review on biological process of soil improvement in the mitigation of liquefaction in sandy soil

Recently, the concept of using biological process in soil improvement otherwise called bio-mediated soil improvement technique has shown greater prospects in the mitigation of liquefiable soils. It is an environmental friendly technique that has generated great interest to geotechnical engineers. This paper presents a review on the microorganism responsible for the biological processes in soil improvement system, factors that affect biological process, identifying the mechanism of liquefaction and commonly adopted method to mitigate liquefaction. Next, the effect of microbial induced calcite precipitation (MICP) on the strength and cyclic response were also analyzed, where it was identified that higher cementation level leads to formation of larger sized calcite crystals which in turn leads to the improved shear strength, stiffness and cyclic resistance ratio of the soil. However, the effects of various bacteria, cementation reagent concentrations amongst other factors were not fully explored in most of the studies. Finally, some of the challenges that lay ahead for the emerging technology are optimizing treatment factors (bacteria and cementation reagent concentration), upscaling process, training of researchers/technologist and long – time durability of the improved soils

Improvement of strength behaviour of residual soil via enzymatically induced calcite precipitation

Enzymatic induced calcium carbonate precipitation (EICP) is a biomediated soil improvement technique that utilizes free enzyme to produce a biocement material. This research investigated by performing test tube test the effect of varying urea-CaCl2 concentrations from 0.25 to 1.25 M on the mass and efficiency of calcium carbonate precipitation formed via EICP technique. The study also evaluated, by conducting UCS test, the strengths of EICP-treated residual soil prepared at various concentrations of cementation solution and different moulding water contents (– 2% to + 4% OMC). The test tube test results showed that the mass of calcium carbonate precipitation increased with an increment in the urea-CaCl2 concentrations from 0.25 to 1.00 M. Maximum mass of calcium carbonate precipitation of 1.577 g, 1.603 g and 1.603 g were obtained due to 1.00 M urea-CaCl2 at 3, 7 and 14 days, respectively. The effect of curing period beyond 3 days were found to be insignificant on the amount of CaCO3 precipitations. The strength of the EICP-treated soil increased with increasing concentrations of urea-CaCl2 and decreased with an increment in moulding water content. The maximum strengths values at all moulding water contents were obtained at 1.00 M urea-CaCl2. The highest shear strength of 728.5 kPa was determined at -2% OMC when 1.00 M was used as urea-CaCl2 and 4.33% calcium carbonate content was yielded. It was determined that there is a strong linear relationship (R2 = 0.8696) between UCS and calcium carbonate content in the treated soil. The amount of calcium carbonate content formed was found to decrease with an increase in mixing water content from 2% dry to 4% wet of optimum moisture content. Finally, the results from the field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) analyses confirmed the formation of calcite crystals in the EICP treated soil

Immobilization of heavy metal contaminants in mining waste through enzyme-induced calcite precipitation biocementation

The presence of heavy metals affects the properties of soil due to a decrease in the dielectric constant, which increases the risk of contamination. Current conventional treatments are costly, slower, and environmentally unsustainable. Therefore, soil biocementation improvement using enzymatically induced calcium carbonate precipitation has gained attention due to its cost-effectiveness, sustainability, and environmental friendliness. This study investigates the effect of this technique on the retention and immobilization of heavy metal-contaminated mine waste sourced from Lohan Dam, Sabah, Malaysia, under different curing periods (1 and 3 days), degrees of compactions (70 and 80% of the maximum dry density), and curing temperatures (5 °C, 15 °C, and 25 °C) but at constant 1.0M cementation solution using inductively coupled plasma-optical emission spectrometry, acid washing test, and scanning electron microscopy. Results indicate that the treatment effect is immediate and able to increase the retention of heavy metals in the order of Ni> Cu > Pb, with the highest retention observed at 25 °C and higher retention at lower degrees of compaction. SEM images confirm the formation of calcite in soil particles. In conclusion, the optimum treatment conditions for a 1.0 M EICP cementation solution are 25 °C, 70% MDD, and 1-day curing

Immobilization of heavy metal contaminants in mining waste through enzyme induced calcite precipitation biocementation

The presence of heavy metals affects the properties of soil due to a decrease in the dielectric constant, which increases the risk of contamination. Current conventional treatments are costly, slower, and environmentally unsustainable. Therefore, soil biocementation improvement using enzymatically induced calcium carbonate precipitation has gained attention due to its cost-effectiveness, sustainability, and environmental friendliness. This study investigates the effect of this technique on the retention and immobilization of heavy metal-contaminated mine waste sourced from Lohan Dam, Sabah, Malaysia, under different curing periods (1 and 3 days), degrees of compactions (70 and 80% of the maximum dry density), and curing temperatures (5 °C, 15 °C, and 25 °C) but at constant 1.0M cementation solution using inductively coupled plasma-optical emission spectrometry, acid washing test, and scanning electron microscopy. Results indicate that the treatment effect is immediate and able to increase the retention of heavy metals in the order of Ni> Cu > Pb, with the highest retention observed at 25 °C and higher retention at lower degrees of compaction. SEM images confirm the formation of calcite in soil particles. In conclusion, the optimum treatment conditions for a 1.0 M EICP cementation solution are 25 °C, 70% MDD, and 1-day curin

Geochemical evaluation of contaminated soil for stabilisation using microbiologically induced calcite precip

Abandoned mines contaminated with heavy metal wastes pose health risk and environmental hazard. Common methods in managing these wastes include pond storage, dry sacking, underground and ocean disposal and phytho-stabilisation but these does not address the associated risks regarding migration of contaminated liquid or when the soil structure is compromised during natural disaster such as earthquake. Due to these limitations, microbiologically induced calcite precipitation method (MICP) is an exciting alternative as it is sustainable and environmentally friendly. This research evaluates mine waste obtained from two sites; Mamut and Lohan Dam, both located at earthquake-prone Ranau Sabah, Malaysia, in term of their physical, mineralogy and morphological characteristics for stabilisation using MICP. Physically, mining wastes from Mamut are of well graded soil with sand (53.9%) and gravel (43.5%), classified as SW (USCS) and A-1-a (AASHTO). Meanwhile, waste from Lohan Dam are of sand (49.9%) and gravel (10.1%), classified as SM (USCS) and A-4 (AASHTO). Constant head test of the soils from the sites showed results of 3.607 x 10-1 and 3.407 x 10-2 cm/s respectively indicate high permeability. Mineralogy assessment using inductively coupled plasma atomic emission spectroscopy (ICP-OES) showed high level of iron (Fe) with 528.08 and 2931.38 mg/L respectively. Other heavy metals detected include copper (Cu), 24.39 and 4.33 mg/L, lead (Pb), 2.53 and 0.53 mg/L, manganese (Mn), 5.71 and 3.64 mg/L and arsenic (As), 0.71 and 0.31 mg/L; some higher than Malaysia’s Ministry of Health and United Nations’ Food and Agricultural approved standards. Morphological observation of the size, shape and soil texture under scanning electromagnetic (SEM) further indicate the necessity and suitability of both sites for stabilisation using MICP