Table 2.
Sludge characteristics under different SRTs.
| Parameter | Unit | Sludge Retention Time | ||||
|---|---|---|---|---|---|---|
| SRT | d | 5 | 10 | 20 | 40 | |
| SS | mg/L | 1,103 ± 80 | 1,449 ± 67 | 3,165 ± 130 | 5,127 ± 600 | |
| VSS | mg/L | 1,041 ± 100 | 1,324 ± 104 | 2,682 ± 170 | 3,900 ± 350 | |
| SVI | mL/g | 49 ± 18 | 23 ± 5 | 69 ± 5 | 108 ± 14 | |
| EPS | Total | mg/g VSS | 157 ± 12 | 145 ± 19 | 111 ± 10 | 95 ± 10 |
| Protein | mg/g VSS | 82.3 ± 12.4 | 78.6 ± 10.8 | 73 ± 4.4 | 60.7 ± 6.3 | |
| Carbohydrate | mg/g VSS | 74.3 ± 7.5 | 66.3 ± 9.8 | 37.8 ± 6.2 | 33.9 ± 6.8 | |
| Nitrification rate | 1st step | mg/(g VSS·h) | 5.4 | 3.9 | 3 | 2.4 |
| 2nd step | mg/(g VSS·h) | 1.3 | 2.4 | 1.4 | 1.3 | |
| Denitrification rate | 1st step | mg/(g VSS·h) | 15.6 | 10.6 | 13.8 | 9.4 |
| 2nd step | mg/(g VSS·h) | 7.6 | 6.5 | 8.8 | 2.9 | |