Table 2.
Characteristics of the four different substrates
| Parameter | Unit | Molasses | Bio-refinery waste | Liquid manure | A-sludge |
|---|---|---|---|---|---|
| pH | – | 5.68 ± 0.01 | 3.79 ± 0.01 | 7.89 ± 0.01 | 6.40 ± 0.03 |
| TS | g TS kg−1 FW | 504.6 ± 0.0 | 144.2 ± 0.4 | 20.5 ± 0.1 | 23.9 ± 0.1 |
| VS | g VS kg−1 FW | 342.1 ± 2.5 | 135.9 ± 0.3 | 11.4 ± 0.2 | 19.0 ± 0.1 |
| Total COD | g COD kg−1 FW | 445.2 ± 6.8 | 249.7 ± 9.8 | 21.6 ± 0.7 | 32.1 ± 1.2 |
| Soluble COD | g COD kg−1 FW | 405.7 ± 5.2 | 20.3 ± 0.5 | 4.7 ± 0.1 | 1.7 ± 0.0 |
| Conductivity | mS cm−1 | 25.7 ± 0.1 | 7.6 ± 0.1 | 29.4 ± 0.1 | 2.2 ± 0.0 |
| Total VFA | mg COD kg−1 FW | 5808 ± 256 | 3693 ± 72 | 119 ± 4 | 1248 ± 68 |
| Acetic acid | mg COD kg−1 FW | 5670 ± 250 | 3693 ± 72 | 119 ± 4 | 314 ± 27 |
| Propionic acid | mg COD kg−1 FW | 139 ± 6 | 0 ± 0 | 0 ± 0 | 272 ± 18 |
| TAN | mg N kg−1 FW | 1572 ± 130 | 568 ± 23 | 2640 ± 288 | 235 ± 86 |
| TKN | mg N kg−1 FW | 20 783 ± 5199 | 3781 ± 544 | 2681 ± 160 | 1458 ± 424 |
| Total P | mg P kg−1 FW | 4870 | 812 | 283 | 513 |
| COD: N ratio | – | 21.4 ± 5.4 | 66.0 ± 9.9 | 8.1 ± 0.5 | 22.0 ± 6.5 |
| COD: P ratio | – | 91.4 ± 1.4 | 307.6 ± 12.1 | 76.5 ± 2.3 | 62.6 ± 2.3 |
| TS : VS ratio | – | 1.48 ± 0.01 | 1.06 ± 0.00 | 1.79 ± 0.03 | 1.26 ± 0.01 |
| COD : VS ratio | – | 1.30 ± 0.02 | 1.84 ± 0.07 | 1.90 ± 0.07 | 1.69 ± 0.06 |
All analyses are carried out in triplicate, with the exception of the total P analysis. FW = fresh weight.