Anaerobic co-digestion of lipid-spent microalgae with waste activated sludge and glycerol in batch mode

Anaerobic co-digestion of lipid-spent Botryococcus braunii (LSBB) with waste activated sludge (WAS) and glycerol was studied. Different co-digestion mixtures were assessed in biochemical methane potential tests, performed at mesophilic temperature (35°C). The experimental methane yields obtained were compared to theoretical values calculated from the methane individual yields. No significant increase in BMP was observed when mixing these substrates. A first-order exponential kinetic model was used to obtain the apparent kinetic constant of the processes assayed. The kinetic constant value of the mixture 25% WAS-75% LSBB was 116%, 16% and 43% higher than for WAS, LSBB and glycerol alone, respectively.