Browsing by Author "Santos, C. A."
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- Energetic valorization of a heterotrophic microalga residue from biodiesel production through anaerobic digestionPublication . Santos, C. A.; Pinheiro, Helena M.; Reis, Alberto; Marques, Isabel P.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.
- Evaluation of group work in the Chemistry and Biotechnology laboratory: Case studyPublication . Santos, C. A.; Gomes, Ana G.
- Pretreatments applied to microalgae residues to enhance anaerobic digestionPublication . Rodrigues, M.P.; Eusébio, A.; Santos, C. A.; Marques, I. P.Biomass of microalga Chlorella protothecoides, grown under autotrophic and heterotrophic conditions and subjected to pretreatments, were energetically valorized through anaerobic digestion process according to the substrates: autotrophic algae (A), heterotrophic algae (H), heterotrophic algae extracted (HE), autoclave pretreated heterotrophic algae (HPA), enzyme pretreated heterotrophic algae (HPE), ultrasound pretreated heterotrophic algae (HPU), and inoculum (I). Despite the application of pretreatments, the highest methane production was obtained in the algae extracted digestion with 172 mL CH4, against 153, 126 and 142 mL obtained in HPA, HPE and HPU, respectively. The COD removal capacity was higher in the HPA sample while the TS and VS removal reached higher values in the autotrophic alga.