Tailoring of highly efficient nitrifying biofilms in fluidized bed for ammonia-rich industrial wastewater treatment

We proposed two tailoring methods for efficient nitrifying biofilms on part icles which are expected to be used in fluidized bed in nitrogen removal pr ocesses for industrial wastewaters. The first method was examined with grad ual reduction of the hydraulic retention time in continuous feeding reactor to form biofilm with high nitrification ability. As a result, nitrificatio n rate was successfully improved mainly due to acclimation of nitrifying ba cteria to higher loading. The second tailoring method for nitrifying biofil m started with the biofilm which had been previously constructed in synthet ic domestic wastewater containing high concentration of NH4+-N as well as v arious biodegradable organic compounds. Stepwise reduction of CIN ratio in inlet wastewater was performed during one month simultaneously with observa tion of microbial population dynamics in the biofilm using fluorescent in s itu hybridization (FISH) analysis. As a result, this acclimation process pr omoted occupation of the biofilm by ammonia-oxidizing bacteria and resulted in making suitable biofilm structure for nitrification of ammonia-rich ind ustrial wastewater. Moreover, it is confirmed that this new tailoring metho d greatly shortened required time to obtain nitrifying biofilms.