Heavy metal water pollution: an overview about remediation, removal and recovery of metals from contaminated water

Heavy metals are known to be metallic elements that have a comparatively high density to water. They are considered as noteworthy pollutants of the environment due to high toxicity and high density even at minute concentrations. According to the United States Environmental Protection Agency (US-EPA) collection, eight heavy metals, particularly, lead (Pb), chromium (Cr), arsenic (As), zinc (Zn), cadmium (Cd), copper (Cu), mercury (Hg), and nickel (Ni) are named to be the most extensively found heavy metals in the environment. Human activity is solely responsible for the pollution of heavy metals in our atmosphere, soils and water. They are vital in our daily diet but in very small amounts. It can be life-threatening and lead to number of diseases such as cancer, Alzheimer’s and Parkinson’s disease if consumed in larger doses. Heavy metals are perilous because they tend to bioaccumulate. Bioaccumulation refers to the increase of chemical’s concentration in a biological organism over a period of time as compared to the concentration of chemical in the environment. Industrial effluents and consumers waste are the biggest contributor in releasing of heavy metals into the water bodies. A broad line-up of toxic heavy metals like Cr, Cd, Hg, Pb, etc., dumped by the industries remains as nondegradable and contaminate the soil and water to larger extent. Heavy metal toxicity in water has proven to be a major threat and there are number of health hazards related to it. They are adversely affecting the marine ecosystem as well. This has encouraged a number of researchers to advance many technological processes of remediation to bring down the contamination level within the regulatory limit in the environment. Therefore, in this chapter the discussion is focused on the remediation, removal, and recovery of heavy metals from the contaminated water.