C. Zhou, B.E. Rittmann, Z. Wang, A. Ontiveros-Valencia, R. Krajmalnik-Brown
Arizona State University,
Keywords: palladium, biofilm, H2, autocatalysis, denitrification
Summary:There is an increasing demand on recycling of palladium from mining waste streams for purposes of resource retrieval and catalytic application. We introduced the novel H2-based membrane biofilm reactor (MBfR) technology to recover Pd in a more efficient, sustainable and economic way. The system successfully recovered almost 100% soluble Pd(II) through reductive immobilization under either neutral or acidic pH, reflecting its practical implication of recovering Pd from acidic mining drainage or industrial wastes. Compared to an identically established system but without inoculation, the biotic MBfR produced smaller-size nanoparticulate Pd(0), exhibited higher capacity of Pd recovery capacity, lower vulnerability of Pd(0) leaching under higher loadings, and faster denitrification due to the synergetic enzymatic and catalytic processes. Overall, our study demonstrates the a promising example of combined Pd recovery and Pd-based catalysis in a single biofilm system that could be applied for the treatment of the waste streams, and it documents the very important role of biofilms in all the processes.