ABSTRACT
In Brazil, gold and iron mining activities contributed to spread arsenic (As) in the environment. Water samples collected at active and abandoned underground mines, wells and springs in Ouro Preto and Mariana cities have arsenic concentrations varying from 2 to 2980 μg/L values that are higher than the maximum limits for human consumption, i.e. 10 μg/L (Pimentel et al. 2003). Sulfate Reducing Bacteria (SRB) constitute a diverse group of prokaryotes that contribute to a variety of essential functions in many anaerobic environments. In addition to their obvious importance to the sulfur cycle, SRB are important regulators of a variety of processes in wetland soils, including organic matter turnover, biodegradation of chlorinated aromatic pollutants in anaerobic soils and sediments, and mercury methylation. Because of their importance to critical processes in different ecosystems and environmental remediation SRB had became an interesting research subject for many groups over the last 10 years (Fauque & Baton, 1995). The sulfidric acid produced by bacteria under anaerobic conditions may cause metal immobilization as metal sulfides. The same is expected for arsenic, due to its metabolism, SRB may be used for arsenic (bio)immobilization in active or passive treatment. The main focus of this work is to obtain arsenite immobilization by precipitation as arsenite sulfide and/or adsorption on the surface of the employed waste biomass used as solid support for bacterial growth.
