Abstract
The Aerobic Upflow Sludge Blanket (AUSB) Process is a new biological wastewater treatment process applying the concept of the self-immobilization to aerobic activated sludge. The system consists mainly of two devices : an oxygen dissolving device and a biological reactor. The sludge produced in the AUSB process formed granules (diameter : 2-8 mm), showing excellent settability.
Extracellular polymer from AUSB sludge was examined to characterize the sludges which have self-immobilizing ability. As the sludge granulation progressed in the AUSB experimental apparatus supplied with domestic sewage, the amount of extracellular polymer increased and the activity to aggregate kaoline also increased. The AUSB sludge derived from the AUSB reactor supplied with municipal sewage produced more extracellular polymer, having high activity to aggregate kaoline, than standard activated sludge derived from apparatus supplied with the same sewage. Multivalued metallic ions were necessary for aggregation. The ability was lost after protein denaturating treatment.
These results suggest that extracellular polymer plays an important role in self-immobilization of activated sludge in the AUSB process. Therefore, AUSB process could be considered as the efficient process applying the special function of the extracellular material, such as aggregating activity, to wastewater treatment.
