Table 2.
Average effluent CODTot, CODSus, CODCol and CODSol values during the five phases of reactor operation for R1 and R2. a; concentration in mg l−1, b; removal efficiency percentage, c; standard deviation, d; VFA:COD ratio based on average VFA concentrations and CODSol for each phase.
| Sample | Total COD | Suspended COD | Colloidal COD | Soluble COD | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (Conc)a | (RE)b | (SD)c | (Conc) | (RE) | (SD) | (Conc) | (RE) | (SD) | (Conc) | (RE) | (SD) | |
| R1 Phase 1 | 73 | 86 | ±11 | 22 | 71 | ±8 | 11 | 60 | ±0.1 | 41 | 84 | ±2 |
| R2 Phase 1 | 140 | 73 | ±4 | 62 | 17 | ±0.2 | 23 | 17 | ±5 | 56 | 78 | ±2 |
| R1 Phase 2 | 61 | 88 | ±4 | 18 | 75 | ±6 | 4 | 84 | ±2 | 40 | 83 | ±1 |
| R2 Phase 2 | 76 | 85 | ±6 | 31 | 58 | ±0.7 | 13 | 27 | ±0.7 | 32 | 86 | ±4 |
| R1 Phase 3 | 110 | 79 | ±3 | 41 | 46 | ±6 | 25 | 9 | ±2 | 45 | 82 | ±1 |
| R2 Phase 3 | 103 | 80 | ±19 | 39 | 47 | ±15 | 24 | 14 | ±4 | 40 | 84 | ±2 |
| R1 Phase 4 | 124 | 75 | ±25 | 46 | 36 | ±13 | 39 | 0 | ±6 | 44 | 84 | ±3 |
| R2 Phase 4 | 105 | 79 | ±8 | 27 | 63 | ±14 | 33 | 0 | ±5 | 46 | 83 | ±0.2 |
| R1 Phase 5 | 215 | 59 | ±12 | 125 | 0 | ±0.5 | 25 | 9 | ±1 | 67 | 73 | ±2 |
| R2 Phase 5 | 114 | 78 | ±5 | 61 | 19 | ±0.9 | 15 | 45 | ±1 | 37 | 85 | ±3 |
| VFA:COD (Ratio)d | Phase 1 | Phase 2 | Phase 3 | Phase 4 | Phase 5 | |||||||
| R1 | 0.07 | 0.1 | 0.14 | – | 1.47 | |||||||
| R2 | 0.04 | 0.14 | 0.48 | – | 0.56 | |||||||