Table 1 Characteristics of the studied biogas plants performing wet or dry fermentation technology
| Â | Biogas plant operating dry fermentation (Sampling date: 14 August 2007) | Biogas plant operating wet fermentation (Sampling date: 1 March 2011) |
|---|---|---|
pH | 7.7 ± 0.01 | 7.8 ± 0.01 |
Conductivity (mS/cm) | 17.1 ± 1 | 21.6 ± 1 |
VOA (mg/l) | 7,739 ± 60 | 3,987 ± 31 |
TIC | 15,159 ± 120 | 14,517 ± 115 |
VOA/TIC | 0.51 | 0.27 |
NH 4 -N (g NH 4 -N/l) | 2.25 ± 0.02 | 2.85 ± 0.02 |
Acetic acid (mg/l) | 2,628 ± 50 | 344 ± 7 |
Propionic acid (mg/l) | 179 ± 3.6 | 14 ± 0.3 |
Fed substrates | Maize silage (63%), green rye (35%), chicken manure (2%) | Maize silage (approximately 72%), pig manure (approximately 28%) |
Biogas yield (l/kg oDM) | 698.2 | 810.5 |
Methane yield (l/kg oDM) | 350.5 | 417.8 |