Modeling and Multiresponse Optimization for Anaerobic Codigestion of Oil Refinery Wastewater and Chicken Manure by Using Artificial Neural Network and the Taguchi Method

Table 2

Experimental parameters with levels.

Parameters	Levels
	Level 1	Level 2	Level 3
A: portion in digester (%)	33	44	55
B: temperature (°C)	36	46	56
C: sonication time (min)	15	30	0
D: total solids level in digester (%)	6	11	18

Oil refinery wastewater.