[Effects of composite substrates on the phosphorus removal in granule-based EBPR system and its optimization experiment].

Based on the mature granular sludge, effects of composite substrates [m(C)/m(N)/m (P)] on the process of phosphorus removal in granule-based EBPR system was conducted by the optimal mixed-carbon sources ratio. Results showed that it was observed with the expanded filamentous bulking to granular sludge in the system of R2 [m(C)/m(N)/m (P) = 400:10:5], R3 [m(C)/m(N)/m (P) = 600: 10:10] and R5 [m(C)/m(N)/m (P) = 400:20:15]. The presence of large amount of granular fragments led to the poor performance of R6 [m(C)/m(N)/m (P) =600:20:5], and it returned back after the particulate debris was removed off the system.

[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.

Impact of Cr(VI) on P removal performance in enhanced biological phosphorus removal (EBPR) system based on the anaerobic and aerobic metabolism.

Influence of Cr(VI) on P removal in enhanced biological phosphorus removal (EBPR) system was investigated with respect to the composition of poly-phosphate-accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs), the transformation of poly-β-hydroxyalkanoates (PHA) and glycogen, enzymes' activities, and the intracellular Cr. Whether EBPR system could revive after Cr(VI) shock was also explored. Results showed P removal performance was completely inhibited by Cr(VI) with the concentration more than 5 mg L(-1).

[Effects of C/P on the competition between PAOs and GAOs and PHAs metabolism in EBPR system].

Based on accumulating enrich phosphorus accumulating organisms (PAOs) in activated sludge and by fluorescence in situ hybridization (FISH) technique, the effects of C/P (25: 1, 20: 1, 15: 1 and 10: 1) on flora changes and polyhydroxyalkanoates (PHAs) metabolism in enhanced biological phosphorus removal (EBPR) system were systematically studied. The results show that after 10 days treatment (acetate as carbon source), the systems with C/P of 25: 1, 20: 1 and 15: 1 have good phosphate removal rate (> 88%); while for C/P of 10: 1 system, the phosphate removal rate was 0%. FISH results showed that the content of PAOs decreased from( 76.