Table 1 Experimental matrix and experimental plan of Box-Behnken design
Experimental run | X1 | X2 | X3 | pH | Organic ratio G1 (%)a | Organic ratio G2 (%)b |
|---|---|---|---|---|---|---|
1 | 1 | 0 | − 1 | 3.6 | 40 | 90 |
2 | − 1 | 0 | − 1 | 2.8 | 40 | 90 |
3 | 0 | − 1 | 1 | 3.2 | 35 | 100 |
4 | 0 | 1 | − 1 | 3.2 | 45 | 90 |
5 | 0 | − 1 | − 1 | 3.2 | 35 | 90 |
6 | 0 | 0 | 0 | 3.2 | 40 | 95 |
7 | 0 | 1 | 1 | 3.2 | 45 | 100 |
8 | − 1 | 0 | 1 | 2.8 | 40 | 100 |
9 | 1 | 0 | 1 | 3.6 | 40 | 100 |
10 | 1 | 1 | 0 | 3.6 | 45 | 95 |
11 | 0 | 0 | 0 | 3.2 | 40 | 95 |
12 | − 1 | 1 | 0 | 2.8 | 45 | 95 |
13 | − 1 | − 1 | 0 | 2.8 | 35 | 95 |
14 | 1 | − 1 | 0 | 3.6 | 35 | 95 |
15 | 0 | 0 | 0 | 3.2 | 40 | 95 |