Biomass concentration in fluidized bed biological reactors

Synthetic wastewater treatment was carried out in a fluidized bed biological reactor with sand as support media. Biomass concentration in the bed was measured as total attached solid and recorded together with the bed expansion characteristics throughout the period of operations. A new method to estimate the reactor biomass concentration was developed and tested on the collected data. The method combines the Richardson and Zaki (1954) law for fluidized bed expansion, the definition of overall bed voidage and available literature data on biofilm dry density and gives an estimate of the biomass concentration by means of a non-linear minimization routine using experimental data of bed height versus fluid superficial velocity. The comparison between the values derived from the experimental measures and those calculated by means of the method has proved reasonably successful.