Bioreduction of Antimonate by Anaerobic Methane Oxidation in a Membrane Biofilm Batch Reactor

Employing a special anaerobic membrane biofilm batch reactor (MBBR), we demonstrated antimonate (Sb(V)) reduction using methane (CH₄) as the sole electron donor. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman and photoluminescence (PL) spectra identified that Sb₂O₃ microcrystals were the main reduced products. The Sb(V) reduction rate increased continually over the 111-day experiment, which supports the enrichment of the microorganisms responsible for Sb(V) reduction to Sb(III). Copy numbers of the mcrA gene and archaeal and bacterial 16 S rRNA genes increased in parallel. Clone library and Illumina sequencing of 16S rRNA gene demonstrated that Methanosarcina became the dominant archaea in the biofilm, suggesting that Methanosarcina might play an important role in Sb(V) reduction in the CH₄-based MBBR.