Previously uninvestigated strains of cyanobacteria can adsorb metals

Recycling Rare Earths with biomass

Brück and his colleagues determined the potential of twelve strains of cyanobacteria for what is called "biosorption" of the Rare Earth metals lanthanum, cerium, neodymium and terbium. The majority of these strains had never been investigated in terms of their biotechnological potential. They are found in habitats with harsh environmental conditions, for example in the Namibian deserts, soda lakes in Chad, rock crevices in South Africa and polluted streams in Switzerland.

As the scientists demonstrated in laboratory testing, the cyanobacteria investigated are capable of adsorbing amounts of the Rare Earth metals equivalent to as much as ten percent of their dry mass. Lead author Michael Paper says: "The cyanobacteria biomass has a high proportion of sugar compounds with negative charges. These attract positively charged metal ions which are then bound to the biomass."

The researchers also observed that the biosorption of Rare Earth metals by cyanobacteria is even possible with low concentrations of the metals. The process is also fast: Thus for example most of the cerium contained in a solution was bound within five minutes after the reaction started.

Now, in a subsequent project the scientists plan to conduct more experiments on a larger scale in order to further improve the industrial application of the results.