Biosorption of Cd, Cr, Mn, and Pb from aqueous solutions by Bacillus sp strains isolated from industrial waste activate sludge

Resumen

The microorganisms are capable of accumulating heavy metal ions from water as biosorbent agents, offering a potential alternative for the detoxification and recovery of toxic/precious metals in industrial wastewater. In the present work, metal-resistant bacterial strains were isolated and  identified from activated sludge of a waste treatment plant in the Municipality of Santa Rosa Jauregui, Querétaro. To obtain bacteria tolerant to metals, 37 bacterial strains and two isolates were selected based on their ability to show high tolerance (strains C-13 and C-16), maximum adsorption capacity for the studied metals. In this article, the term biosorption is used to encompass uptake by whole (dead) biomass via physicochemical mechanisms such as adsorption or ion exchange. The adsorption capacity was measured with alkaline and acid treatments to determine the conditions for maximum adsorption. The adsorption capacity with acid treatment was lower than biosorbent with alkaline treatment. A second part of the study was the biosorption of heavy metals (Cd, Cr, Mn, and Pb) from aqueous dead biomass of Bacillus sp (strain C13 and C16) isolated from the activated sludge in the first stage.