Table 4 Experimental range and levels of six operational parameters used in design of experiment.
Variables | Symbol | Level | ||
|---|---|---|---|---|
Low (− 1) | Middle (0) | High (+ 1) | ||
Initial COD concentration (mg L-1) | x1 | 63 | 104.5 | 146 |
Initial TDS concentration (mg L-1) | x2 | 320 | 960 | 1600 |
Initial TSS concentration (mg L-1) | x3 | 66 | 501.5 | 937 |
Initial total Pb concentration (mg L-1) | x4 | 2 | 3.5 | 5 |
Contact time (min) | x5 | 15 | 187.5 | 360 |
Dolomite levels (%) | x6 | 5 | 10 | 15 |
