Design and startup of an anaerobic fluidized bed reactor

A 101 anaerobic fluidized bed reactor (AFBR) was designed and constructed, using beach sand as the solid support for the biomass. Considering the complexity of this type of system, previously to the startup, several experiences were performed in a series of minireactors, Such as: determination of the bed expansion and the feed distribution. The startup was made increasing gradually the organic load rare (OLR), using the alkalinity ratio (alpha) and the removal of the organic load, as mg/l of GOD, as leading parameters. The system attained a COD removal of over 85%, for an OLR of 3.4 [kg COD/m(3).d]. The best removal of 92% was obtained at an OLR of 1.04 [kg COD/m(3).d], with a hydraulic retention time (HRT) of 12 hours. The best gas production of 1.8 [m(3) of biogas/m(3).d], equivalent to a production of 0.16 [m(3)/kg CODremoved], was obtained at an (HRT) of 4.8 hours. The best startup results were obtained using Ethanol as the Carbon source. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.