Calcium migration inside anaerobic granular sludge: Evidence from calcium carbonate precipitation pattern

Calcification of anaerobic granule sludge caused the decrease of reactor deactivation has been focused in paper industry for decades, the mechanism of calcium immigration is still in curiosity. In this study, evidences relevant to the calcium immigration involving surface adherence, crystallite size and precipitation pattern were analyzed in a calcified granule. Crystal larger than 2 mu m would be sterically stuck in the channel and calcium transfer occurred through serial deposition and resolution. Ca2+ diffusion in the confined channel through Ostwald ripening was in consisted with the Liesegang rings pattern. Thus, a hypothetical mechanism of calcium migration was proposed used to understand the calcium-precipitation control strategy in granule-based anaerobic reactor. The findings of this study are referable for the regulation of mineral precipitation during granule-based wastewater treatment system.