Table 4 Response of TPH on factorial design of experiment used for variable screening
From: Factorial design study of total petroleum contaminated soil treatment using land farming technique
| Std | Run | Type | Factor 1:pH | Factor 2: Moisture content (%) | Factor 3: Mass of substrate (g) | Factor 4: Turning rate (Nil) | TPH response (mg kg−1) |
|---|---|---|---|---|---|---|---|
| 17 | 1 | Center | 8.0 | 30 | 0.8 | 3 | 847 |
| 18 | 2 | Center | 8.0 | 30 | 0.8 | 3 | 723 |
| 19 | 3 | Center | 8.0 | 30 | 0.8 | 3 | 782 |
| 20 | 4 | Center | 8.0 | 30 | 0.8 | 3 | 862 |
| 1 | 5 | Fact | 6.0 | 10 | 0.6 | 1 | 1346 |
| 2 | 6 | Fact | 10.0 | 10 | 0.6 | 1 | 1204 |
| 3 | 7 | Fact | 6.0 | 50 | 0.6 | 1 | 1183 |
| 4 | 8 | Fact | 10.0 | 50 | 0.6 | 1 | 1048 |
| 5 | 9 | Fact | 6.0 | 10 | 1 | 1 | 1248 |
| 6 | 10 | Fact | 10.0 | 10 | 1 | 1 | 1344 |
| 7 | 11 | Fact | 6.0 | 50 | 1 | 1 | 1394 |
| 8 | 12 | Fact | 10.0 | 50 | 1 | 1 | 1304 |
| 9 | 13 | Fact | 6.0 | 10 | 0.6 | 5 | 900 |
| 10 | 14 | Fact | 10.0 | 10 | 0.6 | 5 | 630 |
| 11 | 15 | Fact | 6.0 | 50 | 0.6 | 5 | 749 |
| 12 | 16 | Fact | 10.0 | 50 | 0.6 | 5 | 490 |
| 13 | 17 | Fact | 6.0 | 10 | 1 | 5 | 675 |
| 14 | 18 | Fact | 10.0 | 10 | 1 | 5 | 450 |
| 15 | 19 | Fact | 6.0 | 50 | 1 | 5 | 679 |
| 16 | 20 | Fact | 10.0 | 50 | 1 | 5 | 573 |