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Symbols and levels of independent experimental variables investigated for % removal of Pb+2 by strain AUMW.
| Variables | Units | Symbols | Coded levels (Range) |
||
|---|---|---|---|---|---|
| Low (−1) | Mean (0) | High (+1) | |||
| Time | h | A | 1 | 36 | 72 |
| Temperature | °C | B | 20 | 35 | 50 |
| pH | -log[H+] | C | 3 | 6.5 | 10 |
| Initial concentration of Pb+2 | ppm | D | 50 | 100 | 150 |
