Ahmad Azari

Heavy metals like arsenic (As), copper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), zinc (Zn), lead (Pb) and mercury (Hg) are major pollutants of fresh water reservoirs because of their toxic, non-biodegradable and persistent nature. The industrial growth is the major source of heavy metals that introduce such pollutants into different segments of the environment including air, water, soil and biosphere. Heavy metals are easily absorbed by fishes and vegetables due to their high solubility in the aquatic environments. Hence, they may accumulate in the human body by means of the food chain. Various methods have been developed and used for water and wastewater treatment to decrease heavy metals concentration existing in them. These technologies include membrane filtration, ion-exchange, adsorption, chemical precipitation, nanotechnology treatments, electrochemical and advanced oxidation processes. In this review, the most useful methods are discussed and their mechanisms and efficiency are mentioned.