Enzyme-Induced Carbonate Precipitation for the Stabilization of Heavy Metal-Contaminated Landfill Soils: A Sustainable Approach to Resource Recovery and Environmental Remediation

Wangqing Xu (), Junjie Zheng, Mingjuan Cui and Hanjiang Lai ()
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Wangqing Xu: School of Civil Engineering and Architecture, Hubei University of Arts and Science, Xiangyang 441053, China
Junjie Zheng: School of Civil Engineering, Wuhan University, Wuhan 430072, China
Mingjuan Cui: College of Civil Engineering, Fuzhou University, Fuzhou 350108, China
Hanjiang Lai: Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350108, China

Sustainability, 2025, vol. 17, issue 10, 1-21

Abstract: Heavy metal pollution in landfill soil poses a dual challenge of environmental toxicity and resource depletion. Enzyme-induced carbonate precipitation (EICP) was systematically evaluated as a sustainable stabilization method for cadmium (Cd), lead (Pb), and chromium (Cr) under both solution- and soil-phase conditions. Laboratory-scale experiments demonstrated that EICP achieved over 80% removal efficiency for Cd, Pb, and copper (Cu) in solution-phase systems, while soil-phase trials focused on Cd, Pb, and Cr to simulate realistic field conditions. Optimal performance was achieved using a 1:1 molar ratio of soybean-derived urease (1.0 U/mL) to CaCl 2 (0.5 M), with Cd stabilization reaching 91.5%. Vacuum-assisted filtration improved treatment uniformity by 29.2% in clay soils. X-ray diffraction identified crystalline otavite in Cd systems, while Pb and Cu were stabilized via surface adsorption. Sequential extraction confirmed that over 70% of Cd was transformed into carbonate-bound phases. Treated soils met TCLP leaching standards and reuse criteria, maintaining neutral pH (7.2–8.1) and low salinity. Compared to cement-based methods, EICP avoids CO 2 release from calcination and fossil fuel use. Carbon in urea is retained as solid CaCO 3 , reducing emissions by 0.3–0.5 t CO 2 -eq per ton of soil. These findings support EICP as a scalable, low-carbon alternative for landfill soil remediation.

Keywords: biomineralization; urease; carbonate precipitation; soil remediation; metal immobilization (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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