Table 1 Experimental fermentation conditions of the tested variables based on Box-Behnken design and the corresponding observed and fitted Cu2+ removal % by Azotobacter nigricans NEWG-1.
Std | Run | Tested variables | Cu2+ removal (%) | Residuals | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Incubation time (X1) | pH (X2) | CuSO4 concentration (X3) | ||||||||
Coded | Actual (days) | Coded | Actual | Coded | Actual (mg/L) | Experimental | Predicted | |||
9 | 1 | 0 | 4 | −1 | 5.5 | −1 | 50 | 14.73 | 15.16 | −0.43 |
3 | 2 | −1 | 2 | 1 | 8.5 | 0 | 125 | 52.58 | 55.69 | −3.11 |
15 | 3 | 0 | 4 | 0 | 7 | 0 | 125 | 60.31 | 58.89 | 1.42 |
6 | 4 | 1 | 6 | 0 | 7 | −1 | 50 | 50.19 | 52.87 | −2.68 |
13 | 5 | 0 | 4 | 0 | 7 | 0 | 125 | 59.57 | 58.89 | 0.68 |
7 | 6 | −1 | 2 | 0 | 7 | 1 | 200 | 70.88 | 68.20 | 2.68 |
14 | 7 | 0 | 4 | 0 | 7 | 0 | 125 | 56.8 | 58.89 | −2.09 |
1 | 8 | −1 | 2 | −1 | 5.5 | 0 | 125 | 12.12 | 14.97 | −2.85 |
4 | 9 | 1 | 6 | 1 | 8.5 | 0 | 125 | 67.47 | 64.62 | 2.85 |
8 | 10 | 1 | 6 | 0 | 7 | 1 | 200 | 60.32 | 63.60 | −3.28 |
12 | 11 | 0 | 4 | 1 | 8.5 | 1 | 200 | 80.56 | 80.13 | 0.43 |
2 | 12 | 1 | 6 | −1 | 5.5 | 0 | 125 | 18.68 | 15.57 | 3.11 |
5 | 13 | −1 | 2 | 0 | 7 | −1 | 50 | 42.02 | 38.74 | 3.28 |
10 | 14 | 0 | 4 | 1 | 8.5 | −1 | 50 | 72.37 | 72.54 | −0.17 |
11 | 15 | 0 | 4 | −1 | 5.5 | 1 | 200 | 47.9 | 47.74 | 0.16 |
