Table 2.
Process status of the reactors before initiating the process recovery strategy (day 0)
| Process stability indicator | LNR | HNR1 | HNR2 | HNR3 |
|---|---|---|---|---|
| pH | 7.11 | 8.36 | 8.32 | 8.30 |
| TAN (g_N L−1) | 0.56 | 17.92 | 18.20 | 17.64 |
| FAN (g_N L−1) | 0.01 | 4.07 | 3.84 | 3.59 |
| TS (g kg−1) | 22.5 | 27.2 | 29.90 | 30.00 |
| TVFA (g kg−1) | 0.03 | 21.99 | 21.99 | 23.63 |
| Acetate (g kg−1) | 0.02 | 17.68 | 17.49 | 18.91 |
| Propionate (g kg−1) | 0.01 | 3.34 | 3.46 | 3.73 |
|
Biogas production (LN L−1 week−1) |
6.52 | ND | ND | ND |
FAN free ammonia nitrogen, HNR1,2,3 free ammonia intoxicated reactors, LNR low nitrogen input reactor used as a reference reactor, LN normalized litre of gas, ND not detected, TAN total ammonia nitrogen, TS total solids, TVFA total volatile fatty acids.