Effects of Ce3+ Addition on Granulation of Activated Sludge

In this study the effect of Ce3+ on activated sludge granulation were first studied. It was found that 50 mg/l Ce3+ significantly promotes the granulation of activated sludge and more compacted smaller aerobic granules are formed. Additional Ce3+ has no influences on COD removal efficiency, but improved the SOP removal efficiency significantly. Although protein contents in extracellular polymeric substances increased along with granulation in both reactors, protein content in EPS of Ce3+-fed granules was higher than that without Ce3+ addition. Polysaccharide contents in extracellular polymeric substances decreased slightly through the experiment in the two reactors. Scanning electron microscopy showed that bacilli and cocci were dominant on surface of granules in both reactors. But there were more and longer rod-shaped bacteria on surface of Ce3+-fed granules.