Heavy metal removal and recovery as nanoparticles from multicomponent system at low pH condition by biogenic sulfide precipitation using anaerobic sulfate reducing biomass

Acid mine drainage (AMD) represents an environmental and human health hazard in many countries with historic or ongoing mining industries. Biological sulfide precipitation is an emerging technique for recovery of heavy metals from such wastewater. This study reports heavy metal removal and recovery from multicomponent system containing Cd2+, Cu2+, Pb2+, Zn2+, Ni2+, and Fe2+ at low pH condition by anaerobic sulfate-reducing biomass. Plackett-Burman design of experiments was employed to carry out this mixture study and evaluate the combined effect of these metals on their recovery as nanoparticles. The maximum removal was observed in case of Cd2+ (100%) and Cu2+ (100%), followed by that for Pb2+ (99%), Zn2+ (98%), Ni2+ (88.2%), and Fe2+ (64%). The metals were recovered in the form of metal sulfide nanoparticles, and the metal recovery was in the order: Cu > Pb > Cd > Zn > Fe > Ni. Analysis of nano-sized metal bioprecipitate by field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the role of biogenic sulfide in the process. The size and shape of the metal nanoparticles were confirmed using field emission transmission electron microscopy, which revealed their excellent potential for industrial application. This study demonstrates successful recovery of metal sulfides in the form of nanoparticles using SRB from a multicomponent system at low pH condition.