The Application of a Surface Response Methodology in the Solar/UV-Induced Degradation of Dairy Wastewater Using Immobilized ZnO as a Semiconductor

Table 4

ANOVA of surface response methodology for the photocatalytic process of dairy wastewater.

	Coefficient	SE Coefficient	𝑡-value	𝑃 value
Constant	29.597	1.377	21.490	0.000
pH	1.798	0.746	2.409	0.025
ZnO coating thickness	1.283	0.746	1.719	0.100
pH * pH	−22.639	1.567	−14.452	0.000
pH * thickness	0.072	0.746	0.097	0.924

Where: S = 3.37352, Rsq. = 91.08%, Rsq.adj. = 89.45%, Rsq.pred. = 86.73%.