The promoting effect on the formation of granular sludge by inoculating activated sludge in the enhanced process of biological phosphorus removal was studied in a laboratory-scale sequencing batch reactor (SBR).The results showed that the activated sludge kept in stabilized flocculent state at biological denitrification stage

and the average SVI was 138.9 ml·g-1

while at biological de-phosphorus one the activated sludge flocs became granular sludge gradually as the performance of P removal became better.The average SVI decreased to 74.1 ml·g-1 and the average diameter of the granules was 0.8 mm.Therefore

the biological phosphorus removal process performed in SBR favored for the formation of granular sludge.Moreover

it was found that a lot of positive charged particles were formed with the release of phosphorus at the anaerobic stage in the biological de-phosphorus process.These particles could serve as the cores of granules to attract the negative charged cells and stimulate the granulation.The granular sludge system of enhancing biological de-phosphorus have an excellent ability for the removal of phosphorus. The average removal rate of P was nearly 100%.