However, when FISH assays were conducted on digester sludge samples collected on days with high filament levels observed in the ML, it was anticipated that the digester sludge results would exhibit correspondingly high levels of Danoprevir detected by FISH. This was not demonstrated to be the case. Instead, these digester sludge samples exhibited low-to-moderate filament presence in FISH assays.
4.2.4. Digester performance – gas production and digester homogeneity
As mentioned in Section 3, Methodology, the impact of mixing frequency reduction on digester performance was evaluated by comparing the digester gas production in the control and the experimental digesters. Homogeneity of the digesters was also evaluated. It was important to determine if the contents of the digesters with reduced mixing remained homogeneous and if the digester performance was impacted by the reduction of mixing.
18.104.22.168. Gas production
In an effort to establish a baseline, the gas production observed during the three months preceding the experimental work was documented. Table 5 presents gas production data prior to and during the different experimental phases. Statistical analysis of the baseline and experimental phase gas production levels using the t-test difference of means (p < 0.05) provided significant evidence that decreased mixing did not decrease gas production from Digesters 1, 2 and 4 during any of the mixing reduction phases. It should be noted that the increase in gas production observed in Digester 1 over Phase 5 was due to GTW injection in the feed.