[Start-up and biofilm formation in an aerobic conical fluidized-bed biofilm reactor]

Both aerobic tapered (A-TFBBR) and cylindrical fluidized-bed biofilm reactors (A-CFBBR) were set up. The start-up characteristics, performance, characteristics and microstructure of the biofilm were also investigated in both reactors with similar condition of start-up. Compared with the traditional method that using activated sludge as bacteria source (mostly 100-300 d for start-up), cultivating bacteria naturally could save the acclimation time. It took much shorter time (11 d for the cylindrical bed, while 16d for the tapered bed) to start up the reactors. Further more, the biofilm thickness in A-TFBBR and A-CFBBR was only (32 +/- 1) microm and (24 +/- 2) microm, respectively. The biofilm was thinner than most of reported bifilm obtained by other researchers. Both A-TFBBR and A-CFBBR showed high COD removal capacity, and COD removal rate of A-TFBBR was more than 95%, 15% higher than that of A-CFBBR.