Removal of Heavy metal from aqueous environments using Bioremediation technology – review

Background and Aims: In the last two centuries, world metal pollution level has increased extremely. Presence of some heavy metals in aquatic ecosystems is a constant threat to the health of human societies. Bioremediation- using biological agents to detoxify and degradation of environmental pollutants- provides a suitable alternative method for substitution of current heavy metals removal strategies. Materials and Methods: In the present review study, about 30 papers, among approximately 300 papers, were selected from databases such as SID, sciencedirect, pubmed and scopus. The papers were analyzed to obtain the latest findings in the bioremediation of heavy metals from aquatic environments. Key words such as heavy metals, bioremediation, galvanic industry wastewater, bioleaching, biotransformation, and bioaccumulation were used to databases search. Results: In order to get decontamination efficiently, it should be determined the performance of process according to the different range of metal ions concentrations. Moreover, microorganisms should be selected as they have shown the best performance in metals and their compounds bioremediation studies. For full-scale applications, bioabsorption compared with other various microbial methods such as bioaccumulation is more practical. This may be explained by the fact that the addition of nutrients is essential in bio-accumulative adsorption of metals. Conclusion: This combination of findings provides some support for the conceptual premise that use of bioremediation in order to decontamination of wastewaters containing heavy metals is advantaged by resolving the limitations of physiochemical methods and also in terms of economical issues. However, further studies are needed to overcome the current limitations of this technology, especially to use in practical scales. Keywords: Heavy metals, Microorganisms, aquatic environments, Bioremediation, Sulfur metabolism