Removal of heavy metals from aqueous systems using a commercial biological adsorbent

A method that has been shown to be effective for removing pollutant heavy metals from water systems is the process of adsorption. Adsorption involves the addition of a particulate colloidal substrate to the aqueous system containing the metal ions, and this can reduce the pH at which the metal ions can be removed from solution compared to precipitation processes. In this study, a commercially available bacterial adsorbent, which consists of pure cultured bacteria on a cereal support, was studied for its potential as a heavy metal adsorbent. The pH-dependent adsorptive properties of Zn(II), Ni(II) and Cr(III), three metals often found in waste water streams, were measured using this adsorbent. As a comparison, the removal profiles were also determined using the cereal support component of the adsorbent alone, without the bacterial component. It was found that both substrates removed these metals from solution more efficiently than precipitation processes, however, it was found that the adsorption efficiency was principally due to the cereal component of the adsorbent rather than the presence of the bacteria. The extent of removal by adsorption onto this substrate was found to be competitive with other substrates used in conventional water treatment processes