Biofiltration of Cs and Sr Ions from Aqueous Solutions by Native and Chemically Treated Azolla sp.

摘要

The accumulation of heavy and toxic metals in the environment has become a concern due to growing health risks to the public. These contaminants enter the environment through nuclear activity, industrial waste, mill tailings, smelting and landfill runoff. Azolla sp., an aquatic fern is an ideal candidate for exploitation in constructed wetlands for treating metal-contaminated wastewaters. Biosorption batch experiments were conducted to detennine the Cs and Sr binding ability of native biomass and chemically modified biosoriient derived from Azolla sp., namely hydrogen peroxide Azolla sorisent (HAS). Freundlich constants are determined from the Freundlich adsorption isotherms for all of the biosorbents. The applicability of the Freundlich isothenrt for representation of the experimental data was investigated. The best Cs and Sr removal results were obtained when Azolla was treated by 2 M MgCh and 30 ml H_2O_2 8 mM at pH 7 for 12 hr and it was then washed by NaOH solution at pH 10.5 for 6 hr. The maximum Cs and Sr sorption capacities of HAS biosorbent were obtained at pH 8 and 9 respectively. Uptal