Heavy Metals Immobilization in Contaminated Smelter Soils Using Microbial Sulphate Reduction

Abstract

The main environmental problems associated with the mining activities are related to the production of large amounts of wastes; Different pathways are responsible for heavy metals dispersion, by air due to wind action, by water mediated by acid mine drainage and erosion, and the metals could be mobilized in the soil by different transport mechanisms. Different remediation alternatives have been studied and reported in literature. In situ stabilization is a cheaper method. The heavy metals stabilization enables the decrease of metal mobility, reactivity and toxicity in the soil, decreasing heavy metals availability and phytoavailability. Sulphate reducing bacteria (SRB) have been successfully utilized in groundwater bioprecipitation of heavy metals. In this study, this biological agent has been used in the immobilization of heavy metal in the subsurface of the soil due to its dissimilative metabolism. SRB produces hydrogen sulfide that reacts with soluble metals present in the media, generating as final product low soluble metal compounds (metal sulfides). The bio-stabilization was studied at pilot scale to determine the stabilization efficiency using biological agent, SRB. The metals studied were Fe, Cu, Pb and Zn in the contaminated smelter soil. Bioaugmentation and biomagnification were applied. After 4 months, the metal stabilization efficiency was determined by leaching with acid solution at different pH to stimulate the metal mobility. The remediation pilot scale system showed that copper, lead and iron were much more stable at pH 3.0, with only 3.7% and 1% of total metal eluted, and compared with the system without biological agent. In the case of zinc, the elution was similar with or without remediation. The metal stabilization using biological agent was successful in the contaminated smelter soil and these results are promising antecedents for full scale in situ remediation strategy.

Microbial Population Dynamics and the Role of Sulfate Reducing Bacteria Genes in Stabilizing Pb, Zn, and Cd in the Terrestrial Subsurface

“…A handful of studies have examined non-redox-sensitive element removal via constructed wetland treatment systems [3,40]. Earlier studies by Almendras et al [6] tested Pb, Cu, and Zn stability via sulfide formations and showed that biostimulation plays a vital role in stabilizing Pb, Zn and Cd in the subsurface environment.…”

“…Generation of large amounts of mine waste containing several toxic metals is the main environmental concern associated with milling and mining activities [1,2] via different pathways such as wind erosion and surface water runoff to neighboring water bodies [3,4]. The Tri-State mining district in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma was one of the largest Pb and Zn ore-mining districts in the world for 120 years (until 1970).…”

Microbial Population Dynamics and the Role of Sulfur Reducing Bacteria Genes in Stabilizing Pb, Zn and Cd in the Terrestrial Subsurface

“…A handful of studies have examined non-redox-sensitive element removal via constructed wetland treatment systems (Almendras et al, 2009 andWhite et al, 2000). Earlier studies by Almendras et al (6) tested Pb, Cu, and Zn stability via sulfide formations and showed that biostimulation plays a vital role in stabilizing Pb, Zn and Cd in the subsurface environment.…”

“…Generation of large amounts of mine waste containing several heavy metals is the main environmental concern associated with milling and mining activities (Baker et al, 2003, Bhattacharya et al, 2008. Heavy metals are dispersed via different pathways such as wind, surface water runoff, and metal-laden sediments are transported to neighboring water bodies (Almendras et al, 2009 andJohnson et al, 2005). The Tri-State mining district in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma was one of the largest Pb and Zn ore-mining districts in the world for 120 years (until 1970).…”