Enhanced simultaneous nitrification and denitrification via addition of biodegradable carrier Phragmites communis in biofilm pretreatment reactor treating polluted source water

A solid Phragmites communis (P. communis) decomposition results showed that the nutrient releasing rate was fast in the initial week with the main nutrients of organics and ammonia. P. communis addition of 0.4 kg m−3 and 1.2 kg m−3 in biofilm reactors with elastic filler was then established, respectively. The rapidly released dissolved nutrients in the initial week were helpful for the fast startup of biofilm reactors for simultaneous nitrification and denitrification (SND). The TN removal efficiencies reached above 60% in the reactor added 0.4 kg m−3P. communis was delayed 1 week. The gradually released carbon favored to denitrification in long-term operation. Results also showed that the biofilm attached on the elastic filler was significantly linked to nitrification and the biofilm formed on P. communis was mostly related to denitrification. Thus, coupling of P. communis and elastic filler is helpful for simultaneous removal of nitrogen and organic matters.