3.2 Two factor experimental design
Table 3 shows the results obtained on the effect of types of wastes and days of the experiment using two ways analysis of variance. The analysis reveals that wastes fed into the digester and days of experiment were significant at 99% confidence level. The hypothesis of equal mean treatment effect of wastes and days of experiment is therefore rejected. This study shows that the days of the experiment did not record the same mean values of biogas production. This assertion was confirmed using Duncan multiple range test as seen in Table 4. Table 4 indicates that on the fifth day the highest mean value of biogas was recorded which is significantly higher than the values recorded from the
sixth day and the seventh day (α = 0.05). The sixth day and the seventh day produced relatively the same quantity of biogas but were statistically higher compare to the yield from the fourth, third and second day respectively. The volumes of produced digestate proved to be statistically different from each digester as shown in Table 5. Table 5 shows that using Duncan multiple range Digester A produced the highest mean biogas of 4.50 mL and this value in Table 6 is shown to be significantly different than that produced by the Digester B and Digester C. The results of the estimated marginal
means test presented in Table 7 show that Digester A produced the highest mean biogas values in all the days of the experiment except the seventh day. Digester B was also seen to perform more than Digester C in terms of biogas production