The theoretical methane yield was calculated taking into account
the specific methane yields for the different macromolecules
(0.415 for carbohydrates, 0.496 for proteins and 1.014 mL CH4 g VS
in1 for lipids [32]). In order to compare the theoretical values with
the experimental results, the experimental methane yields
(expressed in mL CH4 g COD in1) were converted to mL CH4 g VS
in1 using an estimated ratio COD/VS of 1.8, corresponding to
microalgae biomass [33].When methane yield was correlated with
the macromolecular composition of the biomass subjected to AD,
the results showed theoretical methane yields ranging from 505 to
681 mL CH4 g VS in1. More precisely, the upper value (681 L CH4 g
VS in1) corresponded to the biomass collected under nonfavourable
conditions at high ammonium load. Nevertheless, this
biomass exhibited the lowest value experimentally, and thus a
mismatch of 72% between the theoretical and the experimental