Table 7.
Analysis of the experiments using CCD with Statistica 13—evaluation of effects.
| Parameter | Evaluation of Effects, COD, g O2/L, R2 = 0.7565, R2adj = 0.5941, 3 Parameter, 1 Block, 16 Experiments, MS = 3.4812 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Effect | Standard Error | p-Value * | −95% Confidence Interval | +95% Confidence Interval | Factor | Standard Error of Factor | Lower Confidence Interval | Upper Confidence Interval | |
| Constant value | 6.3052 | 1.3155 | 0.0010 | 3.3295 | 9.2811 | 6.3053 | 1.3155 | 3.3295 | 9.2811 |
| pH (L) | 2.0637 | 1.0098 | 0.0713 | −0.2205 | 4.3480 | 1.0319 | 0.5049 | −0.1103 | 2.1740 |
| pH (Q) | 2.4877 | 1.2260 | 0.0730 | −0.2857 | 5.2612 | 1.2439 | 0.6130 | −0.1429 | 2.6306 |
| K2FeO4 (L) | −3.3375 | 1.0098 | 0.0092 | −5.6218 | −1.0533 | −1.6688 | 0.5049 | −2.8109 | −0.5267 |
| K2FeO4 (Q) | −0.4786 | 1.2260 | 0.7054 | −3.2520 | 2.2949 | −0.2393 | 0.6130 | −1.6260 | 1.1474 |
| Time (L) | −2.2732 | 1.0098 | 0.0509 | −4.5574 | 0.0111 | −1.1366 | 0.5049 | −2.2787 | 0.0055 |
| Time (Q) | −0.8251 | 1.2260 | 0.5179 | −3.5985 | 1.9484 | −0.4125 | 0.6130 | −1.7993 | 0.9742 |
L—linear effect, Q—quadratic effect, * statistically significant if p < 0.05.