Partial nitrification of non-ammonium-rich wastewater within biofilm filters under ambient temperature

This study evaluated the partial nitrification performances of two biofilm filters over a synthetic non-ammonium-rich wastewater at a 20 degrees C room temperature under both limited DO (similar to 2 0 mg/L) and unlimited DO (similar to 4 0 mg/L) conditions The two filters were each of 80cm long and used different biofilm carriers activated carbon and ceramic granule Results showed that partial nitrification was accomplished for both filters under the limited DO condition However, the effluent NO(2)-N was higher in the ceramic granule filter than in the activated carbon filter, and was less susceptible to the influent COD/N changes Further investigation into the water phase COD and NH(4)-N depth profiles and bacteria population within the two filters showed that by putting upper filter layer (upstream) to confront relatively higher influent COD/N ratios, the filtration process naturally put lower filter layers (downstream) relatively more favorable for nitrifying bacteria (ammonia oxidizing bacteria in this study) to prosper, making the filter depth left for nitrification a crucial factor for the effectiveness of nitrification with a filter The potentially different porous flow velocities of the two filters might be the reason to cause their different partial nitrification performances, with a lower porous flow velocity (the ceramic granule filter) favoring partial nitrification more In summation, DO, filter depth, and filtration speed should be played together to successfully operate a biofilm filter for partial nitrification