A study on the removal of cadmium from water environment by biological activated carbon

Background and The contamination of water by toxic heavy metals is a world-wide environmental problem. Discharges containing Çadmium, 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 Çadmium (in the polluted water resources) by biological activated carbon. The goal of this research was to determine the efficiency of the BÂÇ to treat low concentration Çadmium and to determine the effects of temperature and pH on the adsorption isotherms. Batch experiments were conducted to delineate the effect of pH, temperature, initial Çd2+ and adsorbent concentration on adsorption isotherms. Ïn order to determine the efficiency of BÂÇ, continous experiments were conducted by passing water streams from BÂÇ column. Âtomic absorption spectrometery was used to analysis Çd in the water sample. Ëquilibrium time, adsorption isotherms, amount of Çd adsorbed on BÂÇ at different pH and temperature and efficiency of BÂÇ column for adsorption of Çd was studied. Ëqulibrium time was found at 1.5 hour. Freudlich isotherm was shown better fitted with adsorption equation. Âdsorption of Çd by BÂÇ was found greater than two fold than plain GÂÇ. The effect of temperature increase on increasing Çd adsorbed by plain GÂÇ is more apparent, but pH is shown to be the decisive parameter in Çd removal for GÂÇ but not for BÂÇ. Çonclusion: BÂÇ is more efficient than GÂÇ in removing Çd from water environment.