Abstract:

Operational characteristics of a continuous airlift aerobic granular sludge fluidized bed (CAFB) were discussed. The formation, mechanism and characteristics of the granule sludge in the reactor were investigated and analyzed. The reactor was operated continuously by inoculating with municipal sewage sludge and the synthetic wastewater mainly consisted of sodium acetate as carbon source. The results showed that dense and compact granules were formatted at 4-5 days, much more quickly than other reported aerobic granule sludge process. The diameter of granules is 800-1 000 μm, specific gravity is 1.006 or so, and accompanied with multi-biofacies and many extracellular polymeric substances produced. These characteristics contributed to the fast formation of the granules to some extent. As the COD loading of 8 and 13 kg COD/(m³·d) were employed, COD removal efficiency of CAFB maintained at 93%-97%. Due to the COD concentration of effluent was as low as 30-80 mg/L, eading to an overgrowth of filamentous and sludge washout eventually. These results showed that CAFB is more applicable for treatment of wastewater with higher organic loading rate.

Key words: aerobic granular sludge, continuous flow, fluidized beds, inner circulation