Table 3.
Effect inoculum-to-substrate ratio (ISR) on total biogas production (TBP), specific biogas yields (SBY) and methane concentration
| Sample | ISR | TBP (ml/g COD total)a | SBY (ml/g COD fed)b | Methane Concentration (%) |
|---|---|---|---|---|
| BMP1 Inoculum only | 0.4 | 153 (±6) | N/A | 76 |
| BMP2 Inoculum only | 0.8 | 103 (±3) | N/A | 69 |
| BMP3 Inoculum only | 0.8 | 168 (±19) | N/A | 80 |
| BMP1 Biosludge + Inoculum | 0.4 | 150 (±3) | 148 (±3) | 74 |
| BMP2 Biosludge + Inoculum | 0.8 | 171 (±4) | 225 (±9) | 75 |
| BMP3 Biosludge (gamma irradiated) + Inoculum | 0.8 | 164 (±16) | 150 (±9) | 75 |
| BMP1Synthetic feed + Inoculum (Positive Control)c | 0.4 | 344 (±8) | 425 (±11) | 74 |
| BMP2 Synthetic feed + Inoculum (Positive Control)c | 0.8 | 316 (±8) | 489 (±15) | 75 |
| BMP3 Synthetic feed + Inoculum (Positive Control)c | 0.8 | 340 (±12) | 462 (±16) | 87 |
All values were calculated base on the last biogas sample of each BMP assay i.e. 62 days of anaerobic digestion for BMP 1 and 2 and 50 days for BMP 3.
a
Biogas produced per total chemical oxygen demand (COD) in the bottle.
b
Biogas produced per chemical oxygen demand (COD) fed. Biogas produced from the inoculum was subtracted from all samples with inoculum.
c
For reference, the theoretical maximum biogas production for the synthetic feed is 532 (±35) ml/g COD fed and methane content in the biogas should be between 70 and 80%).