Heavy metals are of special ...

Heavy metals are of special concern because of their persistence. Unlike organic contaminants, heavy metals are not biodegradable and tend to accumulate in living organisms. Furthermore, many heavy metal ions are known to be toxic or carcinogenic. Thus removal of these toxic heavy metals from wastewater is of crucial importance to protect the human population and the environment. Several heavy metals are particularly important in the treatment of industrial wastewaters i.e. zinc, copper, nickel, mercury, cadmium, lead and chromium Various methods exist for the removal of harmful metal ions, particularly heavy metals, from liquids and fluids e.g. waste waters. Chemical precipitation and coagulation-flocculation are the most widely used methods for removing pollutants. Often metals are removed from solutions by increasing the pH of the effluent, converting the soluble metal into an insoluble form (i.e. its hydroxide). Flotation, electrolytic reduction, ion exchange and membrane technologies are also widely used methods. Recently adsorption has been proposed as representing an alternative treatment procedure. Naturally occurring low cost adsorbent materials have been studied: e.g. agricultural waste, industrial by-products, clays, zeolites and chemically modified cellulose materials. In recent years, many alternative solid-phase sorbents (e.g. carbon nanotubes, fullerens, ion imprinted polymers, biosorbents, nanoparticles) have been investigated.

To removing of Cu2+, Cd2+, and Pb2+ ions from solution and to investigate the adsorption isotherms, adsorption kinetics, and ion‐exchange affinities of these metals using waste activated sludge (AS) biomass. The adsorptions of the metals on biomass optimal at an acidic pH value of 6.0 based on its monolayer capacities. Maximum monolayer capacities of AS

chemicals used (magnesium nitrate, urea, and ethanol) low cost and environmentally benign.

Adsorption is known to be one of the best of the technologies for the decontamination of water because it is an effective, economical and ecofriendly treatment technique. It is a process strong enough to realize water reuse obligation and high runoff standards in the industries. Adsorption is basically a mass transfer process by which the metal ion is transferred from the solution to the surface of sorbent, and becomes bound by physical and/or chemical interactions . All adsorption bonding. Physical adsorption can only be occurred in the environment of low temperature and under appropriate pH conditions.