Immobilization of mercury in soils of Venezuela using phospho-gypsum and sulphate-reducing bacteria.

Abstract

The phospho-gypsum is the most important residue from phosphate fertilizer industry and it can be used as emmedant in soil recovery. In the gold mining the mercury, which used by its ability of amalgamation, reaches concentrations that are toxic for plants, animals and man. To recover these soils it is necessary to immobilize the mercury using sorbent substrates, preferably residues of contaminant industries. The main subproduct of phosphate solubilizers industry is the phospho-gypsum. According the results of this work the capability to immovilize mercury is comparable to that of the other inorganic substrates such as kaolin or hematite. Moreover, sulphate-reducing bacteria (SRB) can contribute to the detoxification of soils contaminated with mercury by forming insoluble mercury sulfide. The use of phospo-gypsum and sulfate reducing bacteria together will can allows the integral rehabilitation of the devastated areas. This study shows that the inoculation of a soil with SRB can fail due to the presence of other bacterial species that compete with those inoculated, indicating the need to know the bacterial microbiota of a soil before the inoculation with any bacteria.