[Effect of mixed carbon sources in the granulation process of EBPR system].

Activated sludge highly enriched of phosphorus accumulating organisms (PAOs) were seeded, and cultivated with mixed carbon sources of different propionate to acetate ratios, to obtain granule-based enhanced biological phosphorus removal (EBPR) system. The results showed that the granule growth rate was obviously increased as the proportion of propionate in the mixed carbon sources increased. After operating for 90 d, the volume average particle diameters of the mature granules were 550.64 microm, 599.41 microm, 642.38 microm, 680.99 microm and 745.08 microm, and the sludge volume indexes (SVI) of the mature granules were 30 mL x g(-1), 40 mL x g(-1), 50 mL x g(-1), 60 mL x g(-1) and 75 mL x g(-1), in the treatment of 0%, 25%, 50%, 75% and 100% propionate in mixed carbon sources, respectively. The phosphorus (P) removal performances of granule-based EBPR system cultivated with different carbon sources showed significant differences under the same P-loading. It was about 0.78 mg x g(-1), 2.29 mg x g(-1), 2.96 mg x g(-1), 3.23 mg x g(-1) and 3.77 mg x g(-1) of net P removed in the treatment of 0%, 25%, 50%, 75% and 100% propionate in mixed carbon sources, respectively, which resulted in the phosphorus removal efficiencies were 31.5%, 56.5%, 77.4%, 85.9% and 97.0%, respectively.