Two of the trials contained within batches 4 and 5 (pH 5.5, 41◦C,150 g L−1VS) were carried out to 24 h in an effort to characterize the digestion of carbohydrates, lipids and proteins. Table 5 displays the average net digestion of macromolecules of these two trials. The combined degradation of organics was 57%, which is supported by a corresponding reduction in VS of 59%. It is also notable that these trials averaged a productivity of 1.5 ± 0.1 g lactate L−1h−1, which is lower than that observed at the higher loading rates of batch 3.This indicates that at 150 g VS L−1 loading, the rate of digestion is substrate limited. It can be concluded from Table 5 that the majority of macromolecules undergoing digestion were carbohydrates.