Hydrothermal post-treatment of digestate to maximize the methane yield from the anaerobic digestion of microalgae

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1016/j.wasman.2017.06.021
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Name affiliation
  1. National Research Council of Canada. Energy, Mining and Environment
FormatText, Article
Journal titleWaste Management
ISSN0956-053X
1879-2456
Subjectanaerobic digestion; biomethane; hydrothermal carbonization; microalgae; scenedesmus; solubilization; wet oxidation
Abstract
As an alternative to applying the hydrothermal treatment to the raw algal feedstock before the anaerobic digestion (i.e. pre-treatment), one considered a post-treatment scenario where anaerobic digestion is directly used as the primary treatment while the hydrothermal treatment is thereafter applied to the digestate. Hydrothermal treatments such as wet oxidation (WetOx) and hydrothermal carbonization (HTC) were compared at a temperature of 200°C, for initial pressure of 0.1 and 0.82MPa, and no holding time after the process had reached the temperature setpoint. Both WetOx and HTC resulted in a substantial solids conversion (47-62% with HTC, 64-83% with WetOx, both at 0.82MPa) into soluble products, while some total chemical oxygen demand-based carbon loss from the solid-liquid phases was observed (20-39%). This generated high soluble products concentrations (from 6.2 to 10.9g soluble chemical oxygen demand/L). Biomethane potential tests showed that these hydrothermal treatments allowed for a 4-fold improvement of the digestate anaerobic biodegradability. The hydrothermal treatments increased the methane yield to about 200 LSTP CH4/kg volatile solids, when related to the untreated digestate, compared to 66 LSTP CH4/kg volatile solids, without treatment.
Publication date
PublisherElsevier
LanguageEnglish
Peer reviewedYes
NPARC number23002191
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Record identifierae32461e-3735-432a-a02f-978352c1be0a
Record created2017-08-31
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