Effect of different microorganisms on rare earth phosphors

The usage of compact fluorescent lamps (CFLs) increased in the last years. The gas discharge lamps occupy 22% of the German lighting market in 2006 and 41% in 2010. According to the directive 2002/96/EG end-of-life lighting products shall be recycled.
CLFs consist of glass tube, electronic components, rare earth phosphor, and low quantities of mercury. Used discharge lamps should be collected and recycled via specific companies for waste management. Currently, separation of phosphor components is carried out using flotation or acidic leaching. In the present study, alternative leaching of rare earth phosphor using microorganisms was tested. Interaction of algae, pseudomonads, and bacilli with phosphor has been investigated. Results of full factorial plan show, that certain metals are released at specific conditions. Variables of full factorial plan were pH, amount of phosphor and biomass, and time. Chlorella vulgaris, Pseudomonas fluorescens, and Lysinibacillus sphaericus were incubated with the phosphors in shake flasks. The content of released rare earths was analysed in liquid and biomass via ICP-MS. It was observed that main interactions occur with Y and Eu, the rare earth components of red band phosphor.