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

Bian, Yi1; Chen, Yanbo1,2; Zhan, Liangtong1; Guo, Haowen3; Ke, Han1; Wang, Yuze4; Wang, Qingyang1; Gao, Yufeng5; Gao, Yunqi6

2024-10-15

10.1016/j.scitotenv.2024.174409

SCIENCE OF THE TOTAL ENVIRONMENT   影响因子和分区

0048-9697

1879-1026

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 Zn 2 + , Ni 2 + , 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 Ca 2 + concentration increased and the heavy metal immobilization percentage increased with the concentration of Ca 2 + and treatment cycles in contaminated sand. After four treatment cycles with 0.5 mol/L Ca 2 + added, the immobilization percentage of Zn 2 + , Ni 2 + , 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 CaCO 3 , ZnCO 3 , NiCO 3 , 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 CaCO 3 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 Ca 2 + added is recommended to immobilize multiple heavy metal ions and enhance soil strength.

Enzyme induced carbonate precipitation Calcium carbonate Urease activity Heavy metal contamination

SCI ; EI

英语

其他

Key Research and Development Program of Zhe- jiang[2022C03095] ; National Natural Science Foundation of China["51988101","52208373"] ; Fundamental Research Funds for the Central Universities[226202400057] ; Hebei Natural Science Foundation[E2023201036]

Environmental Sciences & Ecology

Environmental Sciences

WOS:001267783400001

ELSEVIER

ENVIRONMENT/ECOLOGY

Web of Science

1.Zhejiang Univ, MOE Key Lab Soft Soils & Geoenvironm Engn, Hangzhou, Peoples R China
2.Zhejiang Univ, Ctr Hypergrav Expt & Interdisciplinary Res, Hangzhou, Peoples R China
3.Chinese Acad Sci, Guangzhou Inst Energy Convers, Guangzhou 510640, Peoples R China
4.Southern Univ Sci & Technol, Dept Ocean Sci & Engn, Shenzhen 518055, Peoples R China
5.Hohai Univ, Key Lab Minist Educ Geomech & Embankment Engn, Nanjing, Peoples R China
6.Hebei Univ, 180 Wusi Dong Rd, Baoding, Hebei, Peoples R China

Bian, Yi,Chen, Yanbo,Zhan, Liangtong,et al. Effects of enzyme-induced carbonate precipitation technique on multiple heavy metals immobilization and unconfined compressive strength improvement of contaminated sand[J]. SCIENCE OF THE TOTAL ENVIRONMENT,2024,947.

Bian, Yi.,Chen, Yanbo.,Zhan, Liangtong.,Guo, Haowen.,Ke, Han.,...&Gao, Yunqi.(2024).Effects of enzyme-induced carbonate precipitation technique on multiple heavy metals immobilization and unconfined compressive strength improvement of contaminated sand.SCIENCE OF THE TOTAL ENVIRONMENT,947.

Bian, Yi,et al."Effects of enzyme-induced carbonate precipitation technique on multiple heavy metals immobilization and unconfined compressive strength improvement of contaminated sand".SCIENCE OF THE TOTAL ENVIRONMENT 947(2024).