Immobilizing Metal-Resistant Sulfate-Reducing Bacteria for Cadmium Removal from Aqueous Solutions

Immobilized sulfate-reducing bacteria (SRB) in polyvinyl alcohol (PVA)-sodium alginate matrix were applied as biosorbents to remove cadmium (Cd) from aqueous solutions. Multiple characterization techniques including scanning electron microscope (SEM)-energy dispersive spectrometer (EDS), and Fourier transform infrared (FT-IR) spectra indicate that immobilized beads provided a suitable microenvironment for SRB. Performance tests show that Cd removal was highly affected by pH value and temperature, with optimum temperature at 35 degrees C and pH value of 8.0. A pseudo second-order model was applied to describe the adsorption kinetic. FT-IR and x-ray photoelectron spectroscopy (XPS) analyses imply that biosorption, sulfide, and hydroxide precipitation are the main mechanisms for removing Cd. The immobilized SRB beads have great potential for remediating Cd-containing wastewater.