Article Index

1.1. Bioremediation of Ecosystems Contaminated With Heavy Metals

All metals, in spite of whether they are essential or non-essential, can exhibit toxic effects at elevated concentrations. Once a pollutant finds entry into a living organism, it may exhibit an injurious action. The effect of the pollutant is therefore a function of its concentration at the site of its action. Metal toxicity becomes more severe in acidic medium, nutrient-deficient ecosystem and poor physical conditions.

The remediation can be attempted through conventional remedial measures such as land filling and leaching, excavation and burial or soil washing. An extensive use of solidwaste landfills for disposal of municipal and industrial wastes as well as inappropriate use of agro-chemicals has generated a huge amount of leachate causing groundwater pollution, and the potential for groundwater contamination by leachate has necessitated for the invention of novel engineering designs for landfills. Remediation of heavy metals-polluted ecosystems could be carried out using physicochemical processes such as ion exchange, precipitation, reverse osmosis, evaporation and chemical reduction. However, due to problems such as membrane fouling, high costs, high energy requirement and low removal efficiency, these processes show little relevance in industries. In general, technical applicability, cost-effectiveness and plant simplicity are the key factors in selecting the most suitable treatment method to remove heavy metals (such as Cu, Ar, Pb and Zn) and cyanide from contaminated ecosystem. However, the latest technologies like photocatalytic reduction, surfactant-based membranes, liquid membranes and surface complexation are more efficient for heavy metals removal from contaminated ecosystems.