This Small Business Innovation Research Phase I project will demonstrate 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 bioremediations. 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 will focus on lead as a common soil contaminate known to coprecipitate with calcite and which poses a significant risk to human health. To test the effectiveness of this approach, we will collect lead contaminated soil from previously characterized sites. We will treat the soil to enrich for indigenous ureolytic microbes and follow with treatments to promote carbonate accumulation, precipitation of calcite and co-precipitation of lead. Indigenous ureolytic bacteria native to the contaminated soils will be isolated and characterized with respect to their identity, growth conditions and specific urease activity. After treatment we will flush the soils with artificial ground water and collect the effluent. The Pb tha remains leachable after treatment and the remaining metals sequestered in the soil will be 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.
Lead can replace calcium in bones and can cause major health problems to humans, especially to children under the age of six where even low levels can cause mental retardation, anemia and can slow growth. This application seeks to investigate 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.