3.6. Orthogonal analysis
Although the orthogonal design has some fundamental limitations (Zeng et al., 2004), it could significantly reduce the experimental work load (Chen et al., 2009). Hsien and Lin (2005)has
applied the orthogonal design in their research to optimize the
conditions for improving the biodegradation of phenol in wastewater treatment.
According to the theory of orthogonal experiment, the optimum
of every factor and their optimal combination could be determined
by judging the averages. The larger the average is, the better the
condition is. As showed in Table 5obtained by Orthogonality
Experiment Assistant 2.3, it is easy to find that the optimal condi