Factors affecting biomass attachment during startup and operation of anaerobic fluidized beds

Three anaerobic fluidized bed reactors at 37 degrees C were utilized to observe the effects of startup and operational procedures on biomass attachment. Using a meat-based synthetic waste and stepped-loading regime, the influences of synthetic polymer addition and maintenance of anaerobiosis during startup were investigated. Subsequently, increasing bed expansions were applied to assess shear effects. Synthetic polymer addition enhanced biomass retention but did not improve process performance. Maintenance of a reduced environment ameliorated fluctuating process parameters during start up and aided biomass retention and substrate removal. A bed expansion of 5% was detrimental to biomass attachment and COD removal but system stability was maintained at expansions between 10% and 30%. Startup was achieved in 56 days. Anaerobiosis appeared to enhance the initial evolution of a stable, well-adapted microbial population, whereas polymer addition interfered with this. Moderate bed expansions had negligible effects on attachment and performance.