Optimum fluidization velocity of granular sludge bed for anaerobic fluidized‐bed bioreactors

BACKGROUND The models presented for bed optimum fluidization velocity ( u opt ), which was worthwhile for treatment efficiency and operation stability of anaerobic fluidized-bed bioreactors (AFB), were developed for AFB, and the anaerobic granular sludge diameter ( d p ) and shape were analyzed by a dynamic image analyzer . RESULTS The results showed that the granular size from 0.05 to 0.30 cm sludge dominated the total biomass (accounted for 92.34%) in an expanded granular sludge bed reactor, the mean sphericity 0.835 and mean granular diameter 0.1606 cm were achieved. The u opt range was 0.000949–0.2851 cm s ‐1 when d p was 0.05–0.30 cm, and the fluidization number was 8.43–38.77. The maximum value of 0.2851 cm s ‐1 was the basic parameter for pump power matching. From parametric sensitivity analyses, u opt was significantly influenced by liquid holdup, granular diameter, granular density and liquid viscosity . CONCLUSION According to the models of u opt , a better operating scheme for AFB can be provided; from parametric sensitivity analysis, further optimizing designs of such bioreactors can be achieved. © 2013 Society of Chemical Industry