Table 5.
ANOVA for the quadratic model of PCP in PNG removal.
| Source | Sum of squares | df | Mean square | F-value | p-value | |
|---|---|---|---|---|---|---|
| Model | 823.78 | 14 | 58.84 | 162.95 | <0.0001 | significant |
| A-pH | 160.17 | 1 | 160.17 | 443.54 | <0.0001 | |
| B-Dose | 240.67 | 1 | 240.67 | 666.46 | <0.0001 | |
| C-PNG Con | 73.50 | 1 | 73.50 | 203.54 | <0.0001 | |
| D-Time | 121.50 | 1 | 121.50 | 336.46 | <0.0001 | |
| AB | 36.00 | 1 | 36.00 | 99.69 | <0.0001 | |
| AC | 20.25 | 1 | 20.25 | 56.08 | <0.0001 | |
| BC | 30.25 | 1 | 30.25 | 83.77 | <0.0001 | |
| CD | 90.25 | 1 | 90.25 | 249.92 | <0.0001 | |
| A2 | 15.43 | 1 | 15.43 | 42.73 | <0.0001 | |
| B2 | 3.86 | 1 | 3.86 | 10.68 | 0.0052 | |
| C2 | 3.86 | 1 | 3.86 | 10.68 | 0.0052 | |
| D2 | 27.43 | 1 | 27.43 | 75.96 | <0.0001 | |
| Residual | 5.42 | 15 | 0.3611 | |||
| Lack of Fit | 5.42 | 10 | 0.5417 | 3.2 | 0.981 | Not significant |
| Pure Error | 0.0000 | 5 | 0.0000 | |||
| Cor Total | 829.20 | 29 |
Accordingly, the F-value is 162.95 and the P-value is 0.0001, which indicates the model is well suited to explain the amplification of the relationship between response values. In addition, the model discernment is satisfactory if the precision ratio is greater than 4.0 [47].