Coefficient Standard Error T- value P- value
PFS Constant -384.334 88.1186 -4.362 0.003
Dosage 0.938 0.2044 4.589 0.003
pH 70.868 15.2103 4.659 0.002
Dosage x Dosage -0.0006 0.0001 -5.182 0.001
pH x pH -3.320 0.7999 -4.151 0.004
Dosage x pH -0.055 0.0239 -2.296 0.055
PFPD1 Constant -332.359 74.8698 -4.439 0.003
Dosage 0.240 0.1736 1.381 0.210
pH 93.517 12.9234 7.236 0.000
Dosage x Dosage -0.00035 0.0001 -3.361 0.012
pH x pH -6.408 0.6796 -9.429 0.000
Dosage x pH 0.006 0.0203 0.317 0.761
PFPD2 Constant -631.322 96.1025 -8.217 0.000
Dosage 0.373 0.396 0.943 0.377
pH 165.118 29.448 5.607 0.001
Dosage x Dosage -0.001 0.000 -0.306 0.768
pH x pH -9.469 1.549 -6.115 0.000
Dosage x pH -0.046 0.046 -0.999 0.351
PFPD3 Constant -789.707 96.1025 -8.217 0.000
Dosage 1.064 0.2229 4.776 0.002
pH 170.463 16.5884 10.276 0.000
Dosage x Dosage -0.001 0.0001 -9.233 0.000
pH x pH -11.093 0.8723 -12.716 0.000
Dosage x pH -0.007 0.0261 -0.265 0.799
Table 7: Estimated regression coefficients and corresponding T- and P-values for COD removal.