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Improving hydrogen and volatile fatty acids production through pretreatment of spent coffee grounds. | LitMetric

Improving hydrogen and volatile fatty acids production through pretreatment of spent coffee grounds.

Waste Manag

University of Galway, University Road, H91 TK33, Galway, Ireland; Science Foundation Ireland MaREI Centre for Energy, Climate and Marine, Environmental Research Institute, University College Cork, Cork, Ireland.

Published: January 2025

AI Article Synopsis

  • - The study explores how different pretreatments (alkaline, ultrasound, static magnetic field) affect the bioconversion of spent coffee grounds (SCG), a waste product rich in valuable nutrients.
  • - The research found that alkaline pretreatment led to the highest hydrogen production (25-30 mL H/g VS) at low concentrations, but excessive NaOH use inhibited production at higher concentrations.
  • - Ultrasound pretreatment resulted in significant accumulation of volatile fatty acids, with acetic acid being the most abundant at higher volatile solid concentrations.

Article Abstract

Consumption of coffee produces large amounts of waste in the form of spent coffee grounds (SCG), a lignocellulosic material rich in carbohydrates, proteins, and polyphenols. This abundant feedstock is promising in terms of biofuels and value-added product generation. This study investigated the impact of pretreatments, such as alkaline (NaOH), ultrasound, and static magnetic field, on SCG bioconversion in terms of biomolecule release, H potential and volatile fatty acids production. Following treatment, the slurry (solid and liquid fraction mixture) was utilised in anaerobic fermentation tests at varying volatile solid (VS) concentrations (23.3 and 46.7 g VS/L). The highest H production range, 25 - 30 mL H/g VS, was obtained using the alkaline-pretreated SCG slurry at 23.3 g VS/L. Nevertheless, inhibition of H production was observed when utilising the alkaline-pretreated slurry at 46.7 g VS/L owing to the excessive use of NaOH for pretreatment and chemicals to adjust the initial pH. In contrast, increasing the VS concentration had a positive impact on volatile fatty acids accumulation, with acetic (HAc) and caproic acid being dominant. Ultrasound-pretreated SCG achieved 3260.0 mg HAc/L at a concentration of 46.7 g VS/L.

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Source
http://dx.doi.org/10.1016/j.wasman.2024.10.033DOI Listing

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