Superfund Research Program
Using Microbial Induced Calcite Precipitation by Indigenous Soil Bacteria to Reduce Mobility of Lead in Soil
Project Leader: Malcolm Burbank
Grant Number: R43ES025132
Funding Period: Phase I: September 2014 – February 2015
This project is demonstrating the feasibility of using microbial induced calcite precipitation by indigenous soil bacteria to reduce the mobility of lead in contaminated soils and collect metal adapted ureolytic strains from the soil that can potentially be used as exogenous organisms for bioremediation.
Lead contamination of soil poses a risk to the health of humans, animals and environment. Humans can uptake lead by inhalation or ingestion. In situ remediation of heavy metal contaminated soil has lower energy and labor costs. The disturbance to the environment and workers exposure to toxic metals is much lower than during the excavation, removal, and storage of contaminated soil. The EPA identified three effective in situ methods to remediate lead and other heavy metals. Those methods include the installation of physical barriers, mechanically adding solidifying or stabilizing agents to reduce the mobility of metals, and the removal of metals through electrokinetic separation. Though effective, each of these methods has limitations. This study focuses on lead as a common soil contaminant known to co-precipitate with calcite and which poses a significant risk to human health.
To test the effectiveness of this approach, the researchers are collecting lead contaminated soil from previously characterized sites. They are treating the soil to enrich for indigenous ureolytic microbes and following with treatments to promote carbonate accumulation, precipitation of calcite, and co-precipitation of lead. Indigenous ureolytic bacteria native to the contaminated soils is isolated and characterized with respect to their identity, growth conditions, and specific urease activity. After treatment the research team flushes the soils with artificial ground water and collects the effluent. The lead that remains leachable after treatment and the remaining metals sequestered in the soil is quantified by ICP-MS.
This project has a significant potential to add a simple new environmentally friendly method to reduce the mobility of lead and other heavy metals in soil. This project investigates the use of microbial induced calcite precipitation by indigenous soil bacteria to reduce the mobility of lead in soils and to isolate metal-adapted ureolytic bacteria for bioremediation. This high risk, high reward approach is fundamentally different from current in situ approaches to sequester heavy metals, and is expected to add a novel, green technology for the remediation soils contaminated with lead and other toxic metals.