A new oxygen supply method to biofilm is proposed for simultaneous organic carbon removal and nitrification. The main feature of the method is use of hydrophobic porous membrane or oxygen enrichment membrane as substratum of biofilm. In the biofilm formed on oxygen permeable membrane, oxygen is supplied from the bottom to the surface of the biofilm through the membrane while organic pollutants are supplied from the surface to the bottom of the biofilm. The oxygen supply method allows nitrifiers near the bottom region to grow with less competition from BOD oxidizers. The microbial population was investigated in the biofilm formed on hydrophobic microfilter. Nitrifiers grew mainly in the bottom region while denitrifiers grew in the middle region of the biofilm formed on the membrane. Simultaneous organic carbon removal and nitrification were carried out successfully by the biofilm. Furthermore, the potential of the new oxygen supply method was demonstrated with the biofilm formed on an oxygen enrichment-type biomass carrier in a single-stage treatment of domestic wastewater. The nitrification rate was about 1.9 g/m2d and was comparable to that in the conventional biofilm process designed especially for nitrification.
Organic carbon removal from wastewater by a PHA storing biofilm using direct atmospheric air contact as oxygen supply