Optimising the (Microwave) Hydrothermal Pretreatment of Brewers Spent Grains for Bioethanol Production

Table 2

Experimental design used for preliminary screening of the simultaneous impacts of reaction temperature (110°C–200°C) and reaction time (1–10 min) during microwave based autohydrolytical pretreatment of BSG according to a D-optimal design space. Autohydrolytical pretreatment utilized a Monowave 300 microwave synthesis reactor with G30 vessels (Anton Parr), 2.5% w/v solids loading.

Run	Factor 1	Factor 2
	A: temp.	B: time
	(°C)	(min)
1	110	1
2	110	7
3	155	5.5
4	110	10
5	200	5.5
6	200	5.5
7	200	1
8	200	1
9	110	1
10	155	1
11	200	10
12	155	5.5
13	133	3.25
14	155	10
15	133	7.75
16	200	1
17	200	10
18	178	7.75
19	110	4
20	178	3.25

D-optimal experimental design created using DesignExpert (Stat-Ease, USA) using a series of reaction combinations (temperatures and times) from which the D-optimal algorithm chose the treatment combinations to include in the design. This reduced the total number of experiments needed to be conducted from that of a full factorial experimental design.