Performance of nitrogen removal and biofilm structure of porous gas permeable membrane reactor

A porous gas permeable membrane can supply oxygen effectively, utilizing th e high ability of oxygen uptake of nitrifying biofilm. If the membrane with the biofilm is applied to wastewater treatment, simultaneous denitrificati on occurs, but control of the biofilm thickness is necessary to maintain th e high efficiency of the treatment. In this research, small fluidized cylinders were tested as the media for sl ough off of excess biofilm, and the performance of nitrogen removal was inv estigated supplied with municipal wastewater. The results showed that the n itrogen removal efficiency was well kept for a long period with the method tested, especially the nitrification rate in the range of 1.1 to 3.1 gN/(m( 2) d), and that the biofilm formed a stable structure of double layers. tha t is, an inner firm nitrifying biofilm and an outer loose denitrifying biof ilm.