Table 3.
Mean performance data after acclimation for AD reactors with different feeding regimes
| Reactor | RS100 | RS90 | RS70 | RS30 |
|---|---|---|---|---|
| Biogas yield (mL/g VS/day) | 222a ± 5.2b | 193 ± 5.2 | 156 ± 4.3 | 115 ± 4.7 |
| Methane content (% CH4) | 50.9 ± 1.7 | 48.2 ± 1.5 | 43.2 ± 1.8 | 40.8 ± 1.6 |
| Methane yield (mL CH4/g VS/day) | 112 ± 4.6 | 94.2 ± 4.3 | 69.9 ± 3.5 | 47.5 ± 2.7 |
| g VS/L | 13.9 ± 1.0 | 11.9 ± 0.6 | 10.6 ± 0.7 | 4.7 ± 0.2 |
| % VS reduction | 26.3 ± 2.5 | 22.8 ± 2.5 | 24.7 ± 3.2 | 37.5 ± 3.2 |
| pH | 6.1 ± 0.01 | 6.1 ± 0.01 | 6.0 ± 0.01 | 6.3 ± 0.01 |
| Total VFA (ppmc) | 506 ± 69 | 420 ± 28 | 401 ± 44 | 97 ± 31 |
| Formic acid (ppm) | 11.6 ± 9.7 | 15.3 ± 12 | 16.8 ± 15 | 18.0 ± 10 |
| Acetic acid (ppm) | 145 ± 32 | 118 ± 15 | 116 ± 21 | 106 ± 37 |
| Propionic acid (ppm) | 319 ± 50 | 259 ± 20 | 256 ± 32 | 36.9 ± 12 |
| Isobutyric acid (ppm) | 51.9 ± 21 | 57.0 ± 26 | 64.5 ± 32 | 64.2 ± 33 |
aItalic indicates the significance (p < 0.05) for that parameter on each row of data, i.e. highest gas/VSR, lowest VS/acid
bStandard error (For OLR 1.0 g VS/L/day n = 76 for biogas and methane, n = 12 for VS and total VFA, n = 30 for pH and n = 3–12 for individual VFAs
cSynonymous with mg/L and is the traditional units used in with practical AD systems