High-rate nitrogen removal from anaerobic digester liquor using an up-flow anammox reactor with polyethylene sponge as a biomass carrier

ABSTRACTHere, the stable performance of nitrogen removal from digester liquor after partial nitrification was experimentally demonstrated in an up-flow anammox reactor with polyethylene sponge (PE sponge) as a biomass carrier. A high nitrogen loading rate of 8.4 kg-N/m3/day with a TN removal rate of 7.6 kg-N/m3/day was obtained in this study, indicating PE sponge carrier is effective to attain high nitrogen removal performance. This high NLR should be mainly attributed to the successfully operational strategy, the biomass carrier with strong adsorption as well as the functional microbial community. The reaction ratio of NH4+:NO2−:NO3− using the anaerobic digester liquor as feeding media was 1:1.09:0.14. In addition, the channeling phenomenon was investigated in this study, and the problem could be solved through keeping the sludge bed lower than 2/3 of the effective height of the reactor. Furthermore, the settling property of the anammox granules was enhanced significantly and the bacteria community was verified by DNA analysis. The new species of anammox bacteria (kumadai-1) and KSU-1 were confirmed to be the predominant species after stable anammox performance was obtained.