AHMAD ASHFAQ
Abstract
Increased use of metals and chemicals in process industries has resulted in generation of large quantities of effluent that contain high level of toxic heavy metals. Discharge of heavy metals is known to have adverse effects on the environment due to their non degradable and persistence nature. Environmental engineers and scientist are faced with the challenging task to develop appropriate low cost techniques for metal loaded effluents. Conventional methods for removing metals from aqueous solutions include chemical precipitation, chemical oxidation or reduction, ion exchange, electrochemical treatment, reverse osmosis, membrane technologies and evaporation. Most of these treatment processes have been successfully employed in removing heavy metals, however, a major disadvantage with conventional treatment technologies is the production of toxic chemical sludge and its disposal or treatment becomes a costly affair and is not eco-friendly. Biological materials have emerged as an economic and eco-friendly option. The purpose of this paper is to examine certain heavy metals, their biotoxic effects on humans and processes currently available for heavy metal treatment.