Table 1 Level of different process variables in coded and uncoded form for the removal of E. coli from wastewater using Cyperus papyrus
Variable | Factor | Range and level | ||
|---|---|---|---|---|
Level (− 1) | Level (0) | Level (+ 1) | ||
Area of wetland(m2) | X1 | 1 | 2 | 3 |
Initial E. coli concentration(cfu/100 ml) | X2 | 3 | 6 | 9 |
Flow rate (L) | X3 | 20 | 40 | 60 |
Contact time (day) | X4 | 1 | 2 | 4 |