Inhibition Effect of Heterotrophic Microorganisms on Cu and Zn Cations Mobilization from Contaminated Soil and Sediment

Chelating agents, surfactants and many chemicals have been widely used for the extracting heavy metals from contaminated soil and sediment. The EDDS (S,S-ethylene-diamine-disuccinic acid), SDS (sodium dodecylsulfate) or Na4P2O7 (tetrasodium pyrophosphate) were studied as chemicals enhancing the metal extraction. However, by using of EDDS, metal exchange of extracted metal EDDS and chemicals complexes with microorganisms and mineral cations may result in metal re-adsorption on the bacterial cells or soil and sediment particles. Therefore, this study deals with the investigation of presence of resistant bacteria in the soil and sediment with different Cu and Zn cations concentration, characterization of soil and sediment contamination, and with the biochemical releasing of Cu and Zn cations in the static flask experiments. Because of bacterial resistance, the bacterial growth on agar plate and medium with addition of 3mM and 8mM was retarded and the bacterial extraction of Cu and Zn cations from soil and sediment was lower than for the abiotic control especially with chemicals. Moreover, EDDS increased the Zn cations extraction from the soil and sediment and SDS increased the Cu cations extraction from the soil. The significance of Cu and Zn cations releasing was the decrease in the presence of heterotrophic resistant bacteria and not only in the presence of dissolved organic source. The higher adsorption of Cu cations than Zn onto cell surfaces during the biochemical leaching of soil and sediment samples is considerable. (C) 2015 Published by Elsevier B.V.