Table 1. The characteristics of inhibited sludge, active methane-producing sludge, POME, and biogas effluent.
| Parameter | Unit | POME | Biogas effluent | Active methane-producing sludge | Inhibited sludge |
|---|---|---|---|---|---|
| pH | – | 4.1 ± 0.1 | 7.8 ± 0.1 | 7.5 ± 0.1 | 3.9 ± 0.1 |
| Total solids (TS) | g/L | 55.4 ± 0.2 | 13.4 ± 0.3 | 68.4 ± 0.3 | 24.0 ± 0.2 |
| Volatile solids (VS) | g/L | 45.1 ± 0.3 | 4.8 ± 0.2 | 61.5 ± 0.2 | 17.0 ± 0.1 |
| Suspended solids (SS) | g/L | 34 ± 0.3 | 2.4 ± 0.3 | 59.8 ± 0.1 | 14.5 ± 0.2 |
| Volatile suspended solids (VSS) | g/L | 17.0 ± 1.2 | 1.3 ± 0.4 | 52.2 ± 0.3 | 11.0 ± 0.3 |
| Total nitrogen (TN) | g/L | 1.2 ± 0.2 | 0.2 ± 0.3 | 2.5 ± 0.4 | 0.7 ± 0.2 |
| Alkalinity | g/L as CaCO3 | 2.9 ± 0.2 | 3.9 ± 0.2 | 6.1 ± 0.1 | 2.4 ± 0.2 |
| Lipid | g/L | 6.5 ± 0.3 | 0.1 ± 0.02 | 0.5 ± 0.1 | 4.4 ± 0.1 |
| Total chemical oxygen demand (tCOD) | g/L | 59.0 ± 0.1 | 7.5 ± 0.1 | N.D. | 28.9 ± 0.2 |
| Soluble chemical oxygen demand (sCOD) | g/L | 38.2 ± 0.3 | 1.2 ± 0.3 | 2.5 ± 0.2 | 23.9 ± 0.3 |
| Total volatile fatty acids (TVFAs) | g/L | 1.3 ± 0.1 | 0.2 ± 0.2 | 0.9 ± 0.3 | 4.8 ± 0.1 |
| Acetic acid | g/L | 0.4 ± 0.04 | 0.02 ± 0.01 | 0.3 ± 0.01 | 1.8 ± 0.2 |
| Propionic acid | g/L | 0.06 ± 0.01 | 0.05 ± 0.02 | 0.07 ± 0.02 | 1.4 ± 0.1 |
| Isobutyric acid | g/L | 0.03 ± 0.01 | 0.03 ± 0.01 | 0.05 ± 0.01 | 0.3 ± 0.1 |
| Butyric acid | g/L | 0.6 ± 0.05 | 0.02 ± 0.01 | 0.5 ± 0.04 | 2.5 ± 0.1 |
Notes.
N.D., Not determined.