Wastewater Treatment Using a Photoelectrochemical Oxidation Process for the Coffee Processing Industry Optimization of Chemical Oxygen Demand (COD) Removal Using Response Surface Methodology

Table 1

CCD results for COD removal by ECO/NaCl and CaCl₂.

Factors					Responses
Run	pH	Time (min)	Current (amp)	Electrolyte (g/L)	COD removal efficiency (%) NaCl (g) used	% COD removal by CaCl2 (g) used
1	7	60	0.5	1.5	94.991	96.387
2	9	30	0.3	1	91.708	93.204
3	7	40	0.4	2.5	94.951	95.945
4	5	30	0.5	1	89.937	90.333
5	7	40	0.4	1.5	94.241	95.537
6	7	40	0.2	1.5	94.166	95.662
7	5	30	0.3	2	89.566	88.962
8	9	30	0.5	2	92.833	93.329
9	9	50	0.5	2	93.750	94.245
10	7	40	0.4	1.5	94.525	95.175
11	9	40	0.4	1.5	94.083	93.579
12	7	20	0.4	1.5	94.625	95.620
13	5	50	0.3	2	89.916	90.912
14	9	30	0.3	2	92.500	93.095
15	5	50	0.3	1	89.006	89.062
16	7	40	0.4	0.5	92.083	94.579
17	7	60	0.4	1.5	94.925	96.220
18	5	50	0.5	2	90.511	90.995
19	9	50	0.3	2	93.375	94.370
20	5	50	0.5	1	89.291	89.125
21	5	30	0.3	1	88.545	88.041
22	7	40	0.4	1.5	94.629	95.125
23	5	30	0.5	2	89.770	90.966
24	9	50	0.3	1	92.091	93.287
25	7	40	0.6	1.5	94.995	95.791
26	7	40	0.4	1.5	93.051	95.445
27	9	40	0.4	1.5	93.752	93.245
28	7	20	0.4	1.5	93.125	95.620
29	9	30	0.5	1	92.875	94.370
30	9	50	0.5	1	93.841	93.53