Pretreatment of Color Filter Wastewater towards Biodegradable by Fresnel-Lens-Assisted Solar TiO₂ Photocatalysis

Table 2

Experimental range and levels of the process parameters in this study.

	Factor	Range and level
Independent variable		−1	0	+1
Initial pH	𝑋1	5	7.5	10
TiO2 dose, g/L	𝑋2	0.5	1.0	1.5
Reaction time, hr	𝑋3	1	2	3
Y (response) – BOD5/COD