Combined sodium hydroxide and ammonium hydroxide pretreatment of post-biogas digestion dairy manure fiber for cost effective cellulosic bioethanol production

Sustainable Chemical Processes

Table 4 Statistical analysis of the effect of pretreatment parameters on manure fiber pretreatment recovery and following enzymatic saccharification

	Total sugar recovery		Delignification		Enzymatic saccharification
^aR²	0.96		0.97		0.95
Prob. > F	< 0.0001*		< 0.0001*		< 0.0001*
Terms	Estimate	^bProb. > \| t \|	Estimate	^bProb. > \| t \|	Estimate	^bProb. > \| t \|
Temp (°C)	−2.43	0.0011*	1.66	0.061	5.88	0.0035*
Time (min)	−3.26	0.0001*	5.17	< 0.0001*	11.0	< 0.0001*
Chemical loading (% on dry solids)	−5.42	< 0.0001*	10.4	< 0.0001*	12.6	< 0.0001*
Temp x Temp	−1.50	0.1613	1.43	0.360	7.13	0.0345*
Time x Time	2.41	0.0372*	−2.61	0.113	−4.65	0.139
Chemical loading x Chemical loading	−0.079	0.938	−0.76	0.620	−4.64	0.140
Temp x Time	−1.73	0.015*	3.26	0.0046*	3.47	0.0681
Temp x Chemical loading	−0.44	0.463	0.91	0.322	0.33	0.848
Time x Chemical loading	−1.37	0.0414*	2.14	0.0363*	3.36	0.0755

^a Correlation coefficient; ^b p-value of the two-tailed test; * Numbers with asterisk indicate that the term has a significant effect at 95% confidence level.