Enhanced MTBE removal in fixed-bed bioreactor with iron-modified carriers: Biofilm structure and microbial community

The residue of methyl tert-butyl butyl ether (MTBE) in groundwater poses a great threat to human health and needs to be addressed urgently. An efficient fixed-bed biofilm reactor was constructed by immobilizing MTBE-degrading bacteria Stenotrophomonas, Pseudoxanthomonas and Sphingobacterium on iron-modified activated carbon. The introduction of iron improved the specific surface area, zeta potential and hydrophilicity of the carrier, thus enhancing microbial adhesion. During reactor start-up, iron modification promoted the production of protein-dominated extracellular polymers, increased the biomass loaded on the carrier, and accelerated the formation of thicker (75.4 μm) and denser three-dimensional mesh biofilms. During operation, the iron-loaded reactor retained a thicker biofilm (157.9 μm) with greater stability and biological activity, which facilitated the removal of MTBE. Moreover, the iron-loaded biofilm system promoted the enriched growth of Stenotrophomonas with a higher percentage of MTBE-degrading bacteria (80 %), increased species richness and diversity under adverse conditions, thereby enhancing metabolic capacity and environmental tolerance.