Table 4.

Box–Behnken design matrix with actual and predicted responses.

Run	Experimental conditions			Response
				Turbidity removal (%)		COD removal (%)		Zeta potential (mV)		Residual Al concentration (mg/L)
	PAC dosage (mg/L) (A)	CPAM dosage (mg/L) (B)	pH (C)	Actual	Predicted	Actual	Predicted	Actual	Predicted	Actual	Predicted
1	70 (0)	30 (0)	6.5 (0)	99.2	99.0	97.1	96.9	−6.08	−4.59	0.040	0.036
2	70 (0)	40 (+1)	5.5 (−1)	99.7	99.9	96.3	96.5	−1.66	1.83	0.050	0.049
3	90 (+1)	30 (0)	7.5 (+1)	99.8	100	97.6	97.6	−5.6	−3.67	0.070	0.068
4	70 (0)	30 (0)	6.5 (0)	98.7	99.0	96.7	96.9	−9.6	−4.59	0.040	0.036
5	90 (+1)	40 (+1)	6.5 (0)	97.1	96.9	95.6	95.5	20.51	14.85	0.080	0.081
6	50 (−1)	40 (+1)	6.5 (0)	99.6	99.5	97.7	97.6	−5.21	−10.73	0.020	0.019
7	70 (0)	30 (0)	6.5 (0)	98.9	99.0	96.8	96.9	−6.67	−4.59	0.030	0.036
8	70 (0)	30 (0)	6.5 (0)	99.3	99.0	97.3	96.9	−5.14	−4.59	0.040	0.036
9	50 (−1)	30 (0)	7.5 (+1)	97.9	98.0	95.4	95.5	−14.06	−12.27	0.020	0.020
10	70 (0)	40 (+1)	7.5 (+1)	99.8	99.8	97.4	97.4	1.73	2.28	0.040	0.041
11	70 (0)	20 (−1)	7.5 (+1)	98.7	98.5	94.7	94.5	−10.88	−18.23	0.030	0.031
12	90 (+1)	30 (0)	5.5 (−1)	99.8	99.7	96.5	96.5	11.98	10.97	0.080	0.080
13	90 (+1)	20 (−1)	6.5 (0)	99.6	99.7	96.5	96.6	−9.79	−7.55	0.060	0.061
14	50 (−1)	20 (−1)	6.5 (0)	94.5	94.7	93.4	93.4	−17.31	−14.93	0.020	0.019
15	70 (0)	20 (−1)	5.5 (−1)	99.2	99.2	96.3	96.2	0.17	−4.25	0.040	0.039
16	50 (−1)	30 (0)	5.5 (−1)	99.3	99.2	97.5	97.4	−12.24	−13.39	0.020	0.023
17	70 (0)	30 (0)	6.5 (0)	98.8	99.0	96.8	96.9	−8.22	−4.59	0.030	0.036