Accelerated startup of full-scale drinking water biofilters using mature media: Insights into microbial communities and manganese oxide coating

This study addressed the critical challenge of expediting biofilter commencement in groundwater treatment. By incorporating 8 cm-thick mature media, the start-up period was reduced to approximately 7 days. Significantly, NH₄ ⁺-N and Mn²⁺ removal efficiencies reached 96.5% and 95.7%, with effluent concentrations at 0.07 mg/L and 0.04 mg/L, respectively. The loose and porous manganese oxide coating (MnOx) emerged as a pivotal factor in facilitating rapid biofilter maturation, providing attachment points for microorganisms. Analysis revealed variations in microbial communities associated with Fe²⁺ and Mn²⁺ removal between primary and secondary filters. The convergence of microbial communities in the mature and original medium of the secondary filter highlights the critical role of MnO_x. Bacteria's essential contribution during the startup phase, driving MnO_x formation, proves crucial for contaminant removal in the stable phase. This research provides concise insights into improving groundwater treatment system efficiency.