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 (35oC). 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%WAS75%LSBB was 116%, 16% and 43% higher than for WAS, LSBB and glycerol alone, respectively.