Affiliation:
1. School of Civil Engineering, Luoyang Institute of Science and Technology, Luoyang 471023, China
2. School of Civil Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China
Abstract
Lead (Pb) contamination in loess poses a significant environmental challenge that impedes sustainable development. Microbially induced carbonate precipitation (MICP) is an innovative biomimetic mineralization technology that shows considerable promise in remediating soil contaminated with heavy metals. However, the toxicity of lead ions to Bacillus pasteurii reduces the efficiency of mineralization, subsequently diminishing the effectiveness of remediation. Although biochar can immobilize heavy metal ions, its adsorption instability presents a potential risk. In this study, we first compared the pH, electrical conductivity (EC), unconfined compressive strength (UCS), permeability coefficient, and toxicity leaching performance of lead-contaminated loess specimens remediated using biochar (BC), red mud (RM), red-mud-modified biochar (MBC), and MICP technology. Additionally, we evaluated the mechanism of MICP combined with varying amounts of MBC in remediating lead-contaminated loess combing Zeta potential, X-ray diffraction (XRD) analyses, and scanning electron microscopy (SEM) tests. The results showed that MICP technology outperforms traditional methods such as RM, BC, and MBC in the remediation of lead-contaminated loess. When MICP is combined with MBC, an increase in MBC content results in a higher pH (8.71) and a lower EC (232 us/cm). Toxic leaching tests reveal that increasing MBC content reduces the lead leaching concentration in loess, with optimal remediation being achieved at 5% MBC. Microscopic analysis indicates that the remediation mechanisms of MICP combined with MBC involve complexation, electrostatic adsorption, ion exchange, and precipitation reactions. The synergistic application of MICP and MBC effectively adsorbs and immobilizes lead ions in loess, enhancing its properties and demonstrating potential for pollution remediation and engineering applications.
Reference60 articles.
1. Heavy metals pollution assessment and its associated human health risk evaluation of urban soils from Indian cities: A review;Adimalla;Environ. Geochem. Health,2020
2. Research progress of methods for determining sampling numbers of soil heavy metals survey;Huang;Trans. Chin. Soc. Agric. Eng.,2019
3. Assessment of Environmental Geochemistry of Lead-Zinc Mining at Ishiagu Area, Lower Benue Trough, Southeastern Nigeria;Odika;Earth Sci. Res.,2020
4. Synergistically effect of heavy metal resistant bacteria and plants on remediation of soil heavy metal pollution;Chen;Water Air Soil Pollut.,2024
5. Li, J., Zheng, Q.W., Liu, J.Y., Pei, S.W., Yang, Z., Chen, R.T., Ma, L., Niu, J.P., and Tian, T. (2024). Bacterial-fungal interactions and response to heavy metal contamination of soil in agricultural areas. Front. Microbiol., 15.