بررسي ميزان حذف كادميوم از محلول هاي آبي با استفاده از كربن فعال بيولوژيكي BAC( )

Background and purpose : The contamination of water by toxic heavy metals is a world-wide environmental problem. Discharges containing Cadmium, are strictly controlled because of the highly toxic nature of this element and its tendency to accumulate in the tissues of living organisms. There is not enough study on removal of low concentration of Cadmium (in the polluted water resources) by biological activated carbon. The goal of this research was to determine the efficiency of the BAC to treat low concentration Cadmium and to determine the effects of temperature and pH on the adsorption isotherms. Materials and methods : Batch experiments were conducted to delineate the effect of pH, temperature, initial Cd^2 and adsorbent concentration on adsorption isotherms. In order to determine the efficiency of BAC, continous experiments were conducted by passing water streams from BAC column. Atomic absorption spectrometery was used to analysis Cd in the water sample. Equilibrium time, adsorption isotherms, amount of Cd adsorbed on BAC at different pH and temperature and efficiency of BAC column for adsorption of Cd was studied. Results : Equlibrium time was found at 1.5 hour. Freudlich isotherm was shown better fitted with adsorption equation. Adsorption of Cd by BAC was found greater than two fold than plain GAC. The effect of temperature increase on increasing Cd adsorbed by plain GAC is more apparent, but pH is shown to be the decisive parameter in Cd removal for GAC but not for BAC. Conclusion: BAC is more efficient than GAC in removing Cd from water environment.