Potential of biosorption and bioaccumulation processes for heavy metals removal in bioreactors

Environmental contamination with heavy metals, especially of soils and water, became a significant problem because most of them are toxic to the living organisms, non-degradable and persistent in the contaminated media. Physico-chemical methods, such as chemical precipitation, electrochemical treatment, filtration, ion exchange, evaporation, reverse osmosis and membrane technologies are currently the most used methods to remove heavy metal ions from wastewaters. Bioremediation technologies, which are known to be environmentally sound natural processes, have become attractive alternatives to the conventional methods. Among these, biosorption and bioaccumulation address various interactions and concentration of toxic metals in either living (bioaccumulation) or non-living (biosorption) biomass. The aim of this paper is to emphasize the proficiency of biosorption and bioaccumulation processes applied in different types of bioreactors (stirred tank, fixed bed, fluidized-bed and air-lift) using various microorganisms for the removal of heavy metals from contaminated effluents.