Photo-Fenton and Fenton Oxidation of Recalcitrant Industrial Wastewater Using Nanoscale Zero-Valent Iron

Table 2

Variable levels applied in the 2-level factorial design.

Variables	Symbol	−1	0	+1
H2O2 : COD	χ 1	2 : 1	3.5 : 1	5 : 1
H2O2 : nZVI	χ 2	2 : 1	8.5 : 1	15 : 1
Dosing mode	χ 3	1	2	3

Notations: +1(high level); 0 (centre point); −1 (lower level).