Jiangsu Key Laboratory of Urban Underground Engineering & Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 210096, China; Department of Civil and Environmental Engineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
Jiangsu Key Laboratory of Urban Underground Engineering & Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 210096, China.
Sci Total Environ. 2019 Jul 1;672:722-731. doi: 10.1016/j.scitotenv.2019.03.294. Epub 2019 Mar 20.
Microbial induced carbonate precipitation (MICP) is a natural bio-mediated process, which has been explored for soil stabilization and heavy metals immobilization in soil and groundwater. Previous studies have shown that MICP is capable of immobilizing various heavy metals including lead (Pb). However, most studies focus merely on the immobilization of heavy metals with relatively low concentration. This study: (1) presents results of an investigation into the toxic effects of Pb on bacterial activity and immobilization efficiency within a wide range of Pb concentrations; and (2) identifies controlling biotic and abiotic factors of Pb immobilization by MICP. In the first series of tests, bacterial strains (Sporosarcina pasteurii) are inoculated into nutrient solutions containing 0-50 mM Pb(NO) and incubated at 30 °C. Biochemical parameters are measured over time, which include pH, electrical conductivity, urease activity, and viable cell number. In the second series of tests, grown bacterial strains are mixed with urea, calcium salts and Pb(NO) in solution. Viable cell number, produced ammonium concentration, aqueous Pb concentration of the mixed solution, and total precipitation mass are measured. The results show that the presence of Pb has marginal effect on bacterial growth and associated urease activity at Pb concentration < 30 mM. The calcium source and initial bacteria concentration are found to remarkably influence Pb immobilization efficiency in terms of Pb removal percentage. Supplementary geochemical simulation results indicate that the Pb immobilization mechanisms includes abiotic precipitation, biotic precipitation and bio-sorption.
微生物诱导碳酸钙沉淀（MICP）是一种自然的生物介导过程，已被探索用于土壤稳定和土壤及地下水中重金属的固定。先前的研究表明，MICP 能够固定各种重金属，包括铅（Pb）。然而，大多数研究仅关注浓度相对较低的重金属的固定。本研究：（1）研究了在广泛的 Pb 浓度范围内 Pb 对细菌活性和固定效率的毒性影响；（2）确定了 MICP 固定 Pb 的生物和非生物控制因素。在一系列的第一组实验中，将细菌（巴氏芽孢八叠球菌）接种到含有 0-50mM Pb(NO)的营养溶液中，并在 30°C 下孵育。随着时间的推移测量生化参数，包括 pH 值、电导率、脲酶活性和活菌数。在第二组实验中，将生长的细菌菌株与尿素、钙盐和 Pb(NO)混合在溶液中。测量活菌数、产生的铵浓度、混合溶液中的水相 Pb 浓度和总沉淀质量。结果表明，在 Pb 浓度<30mM 时，Pb 的存在对细菌生长和相关脲酶活性只有微小的影响。钙源和初始细菌浓度发现对 Pb 去除百分比的 Pb 固定效率有显著影响。补充地球化学模拟结果表明，Pb 固定机制包括非生物沉淀、生物沉淀和生物吸附。
