Table 3 Ranges and levels of selected input variables
From: Factorial design study of total petroleum contaminated soil treatment using land farming technique
| S/No | Input variables | Unit | Lower level | Upper level |
|---|---|---|---|---|
| 1 | pH | Nil | 6 | 10 |
| 2 | Moisture content | % | 10 | 50 |
| 3 | Mass of substrate | kg | 0.6 | 1.0 |
| 4 | Turning rate | Times per week | 1 | 5 |