Table 1.
Operational parameters of the AGS and CAS reactors, average ± standard deviation, from October 2020 to September 2021
| Parameter | Unit | AGS1 | AGS2 | CAS |
|---|---|---|---|---|
| Solids retention time (SRT)a | d | 28–49 | 28–66 | 26–43 |
| Influent flow | m3 d−1 | 1280 ± 570 | 1280 ± 600 | 1680 ± 660 |
| Sludge concentrationa | g MLSS L−1 | 8.8 ± 1 | 9.1 ± 1 | 3.1 ± 0.8 |
| Biomass ratioa | VSS/MLSS | 0.86 ± 0.02 | 0.86 ± 0.02 | 0.86 ± 0.04 |
| SVI10/SVI30a | ratio | 1.0 ± 0.05 | 1.0 ± 0.04 | 1.6 ± 0.35 |
| Influent pH | - | 8.2 ± 1.1 | 8.2 ± 1.1 | - |
| F/M-ratiob | kg BOD7 (kg MLSS d)−1 | 0.018 ± 0.008 | 0.018 ± 0.007 | 0.024 ± 0.007 |
| P.E. loadc | P.E | 1650 | 1650 | 1500 |
| Return sludge flow | m3 d−1 | - | - | 2174 ± 1277 |
| Exchange ratio | - | 0.46 ± 0.06 | 0.45 ± 0.06 | - |
| Feed velocity | m h−1 | 3.44 ± 0.02 | 3.44 ± 0.05 | - |
| Hydraulic retention time | h (min–max) | 14 (10–26) | 14 (10–27) | 16 (11–32); (8d (5d–16d) |
aAverage SRT based on averages ± Std. For the AGS, the different aggregate sizes have different SRTs. Sampling from June 2020 to December 2021
bBased on kg BOD7 divided by the total amount of sludge in the reactor
cBased on average BOD7 load and 70 g BOD7 per person and day
dValues do not include the secondary settler after the CAS reactor