Nano manganese dioxide coupling carbon source preloading granular activated carbon biofilter enhancing biofilm...

The formation of stable and mature biofilms affects the efficient and stable removal of ammonium by biological activated carbon (BAC). In this study, the new granular activated carbon (GAC) was preloaded with the carbon source (glucose and sucrose) and nano manganese dioxide (nMnO₂) before using. Then tests were performed to determine whether substrate preloading promoted ammonium removal. The ammonium removal treated by nMnO₂ coupled with sucrose-loaded BAC reached 49.1 ± 2.5%, which was 1.7 times higher than that by the nonloaded BAC 28.2 ± 1.9%). The biomass on the substrate-loaded BAC reached 5.83 × 10⁶-1.22 × 10⁷ cells/g DW GAC on Day 7, which was 4.6-9.5 times higher than the value of the nonloaded BAC (1.28 × 10⁶ cells/g DW GAC). The amount of extracellular polymer (i.e., protein) on nMnO₂ coupled to sucrose-loaded BAC was promoted significantly. Flavobacterium (0.7%-11%), Burkholderiaceae (13%-20%) and Aquabacterium (30%-67%) were the dominant functional bacteria on the substrate-loaded BAC, which were conducive to the nitrification or denitrification process. The results indicated that loading nMnO₂ and/or a carbon source accelerated the formation of biofilms on BAC and ammonium removal. Additionally, the ammonium removal treated by nMnO₂ coupled with sucrose-loaded BAC was contributed by microbial degradation (56.0 ± 2.5%), biofilm adsorption (38.7 ± 2.1%) and GAC adsorption (5.3 ± 0.3%), suggesting a major role of microbial degradation.