The tremendous increase in the use of heavy metals over the past few decades has inevitably resulted in an increased flux of metallic substances in the environment. Industrial processes like petroleum refining, metal refining, coal combustion, tanning, metal extraction, electroplating, paints and pigments, the manufacture of batteries etc. discharge effluents in solid, liquid, and gaseous forms. They contain heavy metals such as lead, chromium, cadmium, nickel, arsenic, etc. But the major sources of heavy metals in the environment are traditional chemical processes for extraction of heavy metals. There are various disadvantages of these metal extraction processes like requirement of sufficient concentrations of elements in ores, environmental unfriendliness as huge amount of waste is generated, eco­nomically noncompetitive, nonrecovery of metals from low grade deposits i. e. minerals and inefficient use of energy.

Also, lot of metal containing effluent is produced during these processes, which is discharged as such without any treatment. This causes heavily loaded metal contaminated sites due to metal toxicity and non-biodegradability. The heavy metals are easily percolated through the soil and further trapped and biomagnified along the food chain via consumption of affected plants and animals. The increased concern about the environment and stringent national and international regulations on water pollution and the discharge of heavy metals makes it essential to develop efficient and cost effective technologies for their removal. Hence, it is the utmost need to extract metal ions (not only from the low grade ores but also from the contaminated sites) by the methods which are eco-friendly and greener in nature. The answer is provided by the nature itself: bioextraction.