Metal accumulation by immobilized cyanobacterial mats from a thermal spring

The metal-binding properties of lyophilized cyanobacterial mats occurring in a thermal spring were investigated. The general binding efficiency decreased in the order Cu > Ni > Pb > Cr. Most metal sorption occurred within 15 min, and it was strongly pH-dependent. The sorption of Cu was depressed in the case of competition with other metals or cations. The metal-binding properties are probably due to a high density of anionic charges, especially carboxyls, identified in the capsular polymer. The feasability to use columns packed with the biomass immobilized with silica gel for the removal of metals is demonstrated. The metals were successfully desorbed and these columns were effective during several adsorption-desorption cycles.