Santos, C. A.Pinheiro, Helena M.Reis, AlbertoMarques, Isabel P.2020-06-172020-06-172019-092183-0568http://hdl.handle.net/10400.26/32602Trabalho apresentado em WASTES: Solutions, Treatments and Opportunities, 5th International Conference, September 4th - 6th, Almada/Caparica, Portugal.The production of biodiesel from the oil fraction of the heterotrophically grown microalga Chlorella protothecoides generated two waste streams: defatted microalga residues and crude glycerol. These wastes were anaerobically digested separately and in admixture to quantify their energy potential. The defatted microalga residues (from the oil extraction process) were shown to be a suitable substrate for anaerobic digestion since they provided a methane yield of 498.4 mL CH4/g volatile solids (VS). On the other hand, because glycerol acted as an inhibitory agent for methanogenesis, anaerobic co-digestion of defatted microalga residues and crude glycerol resulted in the diversification of the produced energy carrier. By using glycerol at a ratio of 1.24 g glycerol/g volatile solids of inoculum in admixture with microalga residues, hydrogen was obtained instead of methane. The resulting yield was 39.9 mL H2/g VS of microalga residues. Based on these results, both effluents can be valorized through simple and sustainable methods in order to recover their energy potential in the form of methane or hydrogen.engHeterotrophic microalga residuesGlycerolAnaerobic digestionBiorefinery;HydrogenMethaneconference object