ABSTRACT
This chapter explores the mechanism behind the accumulation, chemical form, and spatial distribution of calcium ion in acetate-fed aerobic granules. Compared to acetate-fed aerobic granules, aerobic granules grown on ethanol showed very low calcium and ash contents. To investigate the chemical form of calcium ion accumulated in acetate-fed aerobic granules, Z. W. Wang, Y. Li, and Y. Liu quantified the elemental composition of acetate-fed aerobic granules. The calcium distribution in acetate-fed aerobic granules was investigated using a scanning electron microscope; meanwhile, energy dispersive x-ray spectroscopy was also employed for mapping of calcium distribution. It should be pointed out that the accumulation of calcium in the form of CaCO3 in acetate-fed aerobic granules was found to be granule size-dependent. The excessive calcium accumulation phenomenon appears to be substrate dependent, and it only happens to the acetate-fed aerobic granules.
