Hydroxyapatite Precipitation and Accumulation in Granules and Its Effects on Activity and Stability of Partial Nitrifying Granules at Moderate and High Temperatures

Precipitation and accumulation of calcium phosphate in granular sludge has attracted research attention recently for removal recovery from wastewater. This study investigated granulation stage to steady state by forming heterotrophic granules at different COD/N ratios 21 32 °C, respectively, followed the transformation partial nitrifying granules. It was found that mature accumulated around 60–80% minerals granules, much higher than young with only 30% ash contents. In addition, high temperature promoted co-precipitation hydroxyapatite calcite more 4.1% P content, while mainly moderate 7.7% content. The 75–80% content also led disintegration instability Specific ammonium oxidation rates were reduced, as well, day 58 121 both temperatures due increased mineral These results are meaningful control or manipulate phosphorus accumulating well maintenance microbial activities