Long-term performance and biofilms of the novel nano manganese dioxide coupling carbon source pre-loaded biological activated carbon filters for drinking water

In order to accelerate the start-up of biological activated carbon (BAC) filters and enhance ammonium (NH₄⁺-N) removal performance, three substrates (sucrose and/or nano manganese dioxide (nMnO₂)) pre-loaded BAC filters were set up to investigate the pollutants removals and microbiological characteristics for a long-term operation of 197 days. The average NH₄⁺-N removal performance treated by the sucrose coupled with nMnO₂ loaded BAC filter was the highest (71.18 %), which was 3.83 times of that by the control filter (18.58 %). 29 % of NH₄⁺-N treated by the sucrose coupled with nMnO₂ loaded BAC removed through the traditional nitrification and denitrification, or simultaneous nitrification and denitrification (SND) pathways according to the calculation of the alkalinity consumption (6.12 mmol/L). There was no leakage of carbon source and Mn, and no accumulation of nitrite from the substrates loaded BAC. The dominant bacteria in the sucrose coupled with nMnO₂ loaded BAC were Dechloromona (accounting for 8.02% of the total bacterial) and Acidaminobacter (accounting for 15.16% of total bacterial) on the Day 180, which had the capacity of nitrification or denitrification. NH₄⁺-N and micropollutants removals treated by the combined process of peracetic acid (PAA) pre-oxidation and substrates loaded BAC were significant due to the generation of assimilable organic carbon (AOC) (5.98 ± 1.93 μg-C/mL) by PAA (100 μM)/Fe²⁺ pre-oxidation and the higher biomass ((4.57 ± 3.07) × 10⁷ cells/g DW BAC) in the sucrose coupled with nMnO₂ loaded BAC filter. Therefore, nMnO₂ coupling carbon source pre-loading strategy could not only enhance initial colonization, but also promote pollutants removals for long-term operation.