a b s t r a c t
Previous studies have shown that ammonium and manganese could be removed from water by biofilm in
a trickling filter. However, it always takes several months to start up a biofilm filter. In this study, by oxidizing
manganese and ferrous ion from raw water using potassium permanganate continuously, an ironmanganese
co-oxide filter film (MeOx) was formed quickly on the surface of virgin quartz sand in a pilotscale
filter, and the start-up period was less than 30 days. Interestingly, 90% ammonium and manganese
could be removed by the filter film even after the bacteria were inactivated completely in both the filter
film and raw water (by aerating ozone and injecting hydrogen peroxide), suggesting that microorganisms
may play a negligible role in our system. Additionally, the filter film exhibited high oxidation activity
when the temperature was down to 6.6 C. The filter film was characterized by scanning electron microscopy,
X-ray fluorescence spectroscopy and X-ray photo electron spectroscopy methods. Finally, a chemical
catalytic oxidation mechanism for ammonium removal was proposed by the analysis of the oxidation
process. Ammonium was oxidized to nitrate through the process of catalytic oxidation, generating hydrogen
ions. MeOx plays as a catalyst, and the intermediates O can potentially serve as both oxidant and
reductant in one-electron-transfer reactions with NH4 + and O2.